Projects Available

This page gives details of all projects currently on offer for research towards a DPhil in Materials Science at the Department of Materials, University of Oxford.

The website lists available projects in two categories, 'Funded Projects' and 'Other Projects'. Some projects listed in the 'Other Projects' section may be suitable also for an MSc(Research) in Materials, and those offered by staff who are members of one or more of Oxford's EPSRC CDT's may be suitable for a CDT programme DPhil project. In all these cases please contact the supervisor(s) for clarification.

Admissions for entry in the academic year 2018/19: Admissions Field 2 - Deadline 19 January 2018

 


Important information for applicants

Important information for applicants

 

SELECTION OF PROJECTS

When completing the Oxford application form, under the 'Supporting Materials' section entitled 'statement of purpose/personal statement', you must list in order of preference up to five preferred research topics/supervisors selected from those advertised on this website. In addition you must include a short statement (up to 400 words) to outline your research interests and indicate the rationale behind your choice of projects. We do not require a research proposal.

For further information see the "How to Apply" section of the prospectus entry for the relevant Materials programme (www.ox.ac.uk/admissions/graduate/courses/mpls/materials).

If you wish to learn more about a specific project you may e-mail the relevant supervisor.

In the present Materials 'Projects Available' webpages we describe available projects in two categories, 'funded projects' and 'other projects'. Generally the projects do not have specific deadlines, as we intend to consider applicants within the University of Oxford's Graduate Admissions standard application fields. Some of the descriptions on this website are of projects that carry earmarked funding and in these cases the eligibility of home, EU and overseas applicants is indicated. These classifications as ‘Home’, ‘EU’ or ‘Overseas’ are set by the University.

Normally overseas students will require a visa and, for Materials Science, an ATAS certificate (http://www.ox.ac.uk/students/visa). More information is given below in our guide for overseas applicants.

CLOSING DATES

Until the middle of March applications will be considered in three fields, as advertised in the Oxford University Graduate Studies Prospectus. Deadlines for the receipt of fully completed applications and references are 12.00 noon (UK time) on: 17 November 2017, 19 January 2018 and 9 March 2018. Applications received after 9 March will be considered on an individual basis soon after receipt. Overseas or scholarship applicants are strongly advised to apply in the November field and home/EU applicants in the January field. In addition, project studentships with specific closing dates may be advertised on our website.

Details of how to apply are found at http://www.ox.ac.uk/admissions/graduate/applying-to-oxford/application-guide.

Before submitting an application you are strongly encouraged to contact the Department of Materials' Graduate Studies Secretary (graduate.studies@materials.ox.ac.uk) for advice and assistance.

FUNDING and PLACES

Please note that funding and places may be exhausted after the first two application fields: applications received after 19 January 2018 will be considered only if places and/or funded projects remain unfilled. We expect to make a small number of offers, to outstanding candidates, following evaluation of the November applications. The remaining good candidates from November will be considered automatically in January, along with the new applicants for that deadline, and we normally expect to offer the majority of available places following evaluation of the January applications.

The Department of Materials strongly advises applicants for scholarships to apply in the first application field (application deadline 12 noon UK time on 17 November 2017), although those who apply in the second field (application deadline 12 noon UK time on 19 January 2018), will also be considered.

One or two EPSRC DTP studentships may be offered to world-class applicants (those of similar quality to successful Clarendon Scholarship applicants) following evaluation of the November applications, but normally we expect to award the majority following evaluation of the January applications. Prior to final ranking, interviews will be held for all short-listed applicants from the November and January gathered fields who are eligible for EPSRC DTP awards. We do not assign Departmental EPSRC DTP studentships to specific projects unless this is advertised in advance on our website. Overall there are many more projects advertised in the 'other project' category than the number of DTP studentships we have available. Hence, in a given year, some of the 'other projects' may be designated as ineligible for DTP funding. These projects are marked with the symbol §. Normally the most able and suitable applicants, as judged against our Graduate Admissions Criteria, are offered the awards; normally subject to a limitation of no more than one DTP studentship per supervisor per year.

UK applications
EU applications
Overseas applications

Further details may be obtained from the secretary to the Director of Graduate Studies:
Mrs Marion Beckett: tel: 01865 (2)83226; fax: 01865 273789; email:graduate.studies@materials.ox.ac.uk


Funded projects - important information

FUNDED PROJECTS - Important information

Projects in this section carry their own funding (and may require the successful applicant to sign a contract with the sponsor), so finance in the form of a stipend and payment of fees is available to the successful candidate. However, eligibility for funding is in some cases restricted by the applicant's country of legal residence: below and in the detailed description of funded projects we use the term 'citizen' in respect of this country. Please see www.ox.ac.uk/admissions/graduate/fees-and-funding/fees-and-other-charges/fee-status/ for information on classifications of Home, EU or overseas.

For projects marked *: full funding is available only to UK citizens, although EU citizens are eligible to have their fees paid if they can provide their living costs from another source.

For projects marked **: applicants should in general be citizens of either a member state of the European Union or an Associated State (except the United Kingdom) or have resided in the European Union for several years. UK citizens are eligible only if they have been resident outside the EU Member or Associated States for several years. Precise details of eligibility vary from project to project; more information is included as part of the detailed project description.

For projects marked ***: the funding is available to all applicants, but students classified as overseas fee status would have to provide the difference between home/EU and overseas student fees from some other source such as a scholarship or personal funds. Please see http://www.ox.ac.uk/admissions/graduate/fees-and-funding for a statement of the actual fees.

For projects marked ****: there are no eligibility restrictions.

8 funded projects available at present.

*/**Dynamic TEM development for improved understanding of reactions and processes on the ns timescale
( A.I. Kirkland)

*/**Enabling 3D Atomic-Scale Imaging of Hydrogen in to Investigate Hydrogen Embrittlement of Zirconium Alloy Fuel Cladding in Fission Reactors
( D. Haley, P. Bagot, M. Moody)

*/**Exploring low energy excitations with electron microscopy
( Dr R J Nicholls, Prof J R Yates, Prof P D Nellist)

*/**From light to heavy: making predictions of solid-state NMR parameters truly multi-nuclear
( Prof J R Yates)

*/**Thermo-mechanical property measurement of nuclear graphites at elevated temperatures
( T J Marrow)

*/**Unconventional Computing using a Materials Science Approach
( H. Bhaskaran)

*/**Understanding battery chemistry with in-situ electron microscopy
( Dr Alex W Robertson and Prof Peter G Bruce)

*/**X-ray video imaging and machine learning to understand alloy solidification
( Prof Patrick Grant / Dr Enzo Liotti)

New projects are added from time-to-time, so please review the list regularly.


Supervisors who are members of an EPSRC CDT

SUPERVISORS WHO ARE MEMBERS OF AN EPSRC CDT

Projects offered by staff who are members of one or more of Oxford's EPSRC CDT's may be suitable for a CDT programme DPhil project. In all these cases please contact the supervisor(s) for clarification.

Science & Technology of Fusion EPSRC CDT

Prof D.E.J. Armstrong, Prof P.S. Grant, Prof S.L. Lozano-Perez, Prof T.J. Marrow, Prof M.P. Moody, Prof A.J. Wilkinson

Diamond Science & Technology EPSRC CDT

Prof J.M. Smith, Prof R.I. Todd,

New & Sustainable Photovoltaics EPSRC CDT

Prof H.E. Assender, Prof F. Giustino, Prof A.A.R. Watt

Science & Applications of Plastic Electronics EPSRC CDT

Prof H.E. Assender, Prof A.A.R. Watt

Theory & Modelling in Chemical Sciences EPSRC CDT

Prof F. Giustino, Dr J.R. Yates

Biomedical Imaging MRC & EPSRC CDT

Prof C.R.M. Grovenor

Projects - listed by supervisor in alphabetical order

PROJECTS - listed by supervisor, in alphabetical order

  •  

Dr Natalia Ares (natalia.ares@materials.ox.ac.uk)

Dr David Armstrong (david.armstrong@materials.ox.ac.uk)

Professor Hazel Assender (hazel.assender@materials.ox.ac.uk)

Professor Simon Benjamin (simon.benjamin@materials.ox.ac.uk)

Professor Harish Bhaskaran (harish.bhaskaran@materials.ox.ac.uk)

Professor Lapo Bogani (lapo.bogani@materials.ox.ac.uk)

Professor Andrew Briggs (andrew.briggs@materials.ox.ac.uk)

Professor Peter G Bruce FRS (peter.bruce@materials.ox.ac.uk)

Professor Martin Castell (martin.castell@materials.ox.ac.uk)

Professor Jan Czernuszka (jan.czernuszka@materials.ox.ac.uk)

Professor Marina Galano (marina.galano@materials.ox.ac.uk)

Professor Feliciano Giustino (feliciano.giustino@wolfson.ox.ac.uk)

Professor Patrick Grant FIMMM FREng (patrick.grant@materials.ox.ac.uk)

Professor Nicole Grobert FRSC FYAE (nicole.grobert@materials.ox.ac.uk)

Professor Chris Grovenor, FIMMM, FIP (chris.grovenor@materials.ox.ac.uk)

Professor Angus Kirkland (angus.kirkland@materials.ox.ac.uk)

Professor James Marrow (james.marrow@materials.ox.ac.uk)

Dr Jan Mol (jan.mol@materials.ox.ac.uk)

Professor Michael Moody (michael.moody@materials.ox.ac.uk)

Professor Peter Nellist (peter.nellist@materials.ox.ac.uk)

Dr Rebecca Nicholls (rebecca.nicholls@materials.ox.ac.uk)

Professor Keyna O'Reilly (keyna.oreilly@materials.ox.ac.uk)

Professor Mauro Pasta (mauro.pasta@materials.ox.ac.uk)

Professor Kyriakos Porfyrakis FRSC (kyriakos.porfyrakis@materials.ox.ac.uk)

Professor Jason Smith (jason.smith@materials.ox.ac.uk)

Professor Susie Speller (susannah.speller@materials.ox.ac.uk)

Dr Edmund Tarleton CEng, MIMMM (edmund.tarleton@materials.ox.ac.uk)

Professor Richard Todd (richard.todd@materials.ox.ac.uk)

Professor Jamie Warner (jamie.warner@materials.ox.ac.uk)

Professor Andrew Watt (andrew.watt@materials.ox.ac.uk)

Professor Angus Wilkinson (angus.wilkinson@materials.ox.ac.uk)

Professor Peter R Wilshaw (peter.wilshaw@materials.ox.ac.uk)

Professor Jonathan Yates (jonathan.yates@materials.ox.ac.uk)

(return to top of list of other project titles listed by supervisor)

Projects - listed by primary research area

PROJECTS - listed by primary research area

 

Centre for Applied Superconductivity

The Materials Department will open a new £6M Centre for Applied Superconductivity in 2015; a collaboration with the Clarendon Laboratory and a team of industrial partners. This centre will specialise initially in the measurement of superconducting properties and in materials discovery across the whole range of practical applications for superconducting materials. We have openings for graduate students to join this new centre, all of whom will have the opportunity to work on industry-related projects at the interface between materials, physics and engineering.

Characterisation of Materials

Computational Materials Modelling

Device Materials (including semiconductors)

Energy Materials (including batteries)

Nanomaterials

Polymers and Biomaterials

Processing and Manufacturing

Quantum Information Processing

Structural and Nuclear Materials

(return to list of other project titles listed by research area)


 

FUNDED PROJECTS - full details, listed by title

Eligibility for some projects is restricted and these are marked with asterisks. For further details of these restrictions, please see the introductory section on funded projects earlier in these web pages on 'New DPhil Projects Available'.

*/**Dynamic TEM development for improved understanding of reactions and processes on the ns timescale
A.I. Kirkland

This EPSRC Industrial CASE (iCASE) project in conjunction with Johnson Matthey will support the development of DTEM (dynamic TEM) for improved understanding a range of technologically important materials such as batteries, zeolites, sensors and pharmaceutical materials. DTEM is a cutting edge technique using laser pulses to form short time duration electron bunches which can yield spatial and temporal information on the nm and ns scales. The project will be based at the University of Oxford and ultimately at the Rosalind Franklin Institute at Harwell where a novel pulsed source instrument is being constructed. The study of dynamic non equilibrium processes will form a central part of the project and a number of commercial areas will be studied as exemplar projects.

The project may also involve the development of compressive sensing as an alternative route to increased time resolution.

This project would suit a student with a background in physics, materials science or chemistry with a strong interest in developing new methods (and possibly instrumentation) for materials characterisation.

Candidates are considered in the January 2018 admissions cycle which has an application deadline of 19 January 2018.

This is a 4-year EPSRC Industrial CASE studentship in conjunction with Johnson Matthey and will provide full fees and maintenance for a student who has home fee status (this includes an EU student who has spent the previous three years (or more) in the UK undertaking undergraduate study). The stipend will be at least £16,553 per year. Other EU students should read the guidance at http://www.materials.ox.ac.uk/admissions/postgraduate/eu.html for further information about eligibility.

Any questions concerning the project can be addressed to Professor Angus Kirkland (angus.kirkland@materials.ox.ac.uk). General enquiries on how to apply can be made by e mail to graduate.studies@materials.ox.ac.uk. You must complete the standard Oxford University Application for Graduate Studies. Further information and an electronic copy of the application form can be found at http://www.ox.ac.uk/admissions/postgraduate_courses/apply/index.html.

Also see homepages: Angus Kirkland

*/**Enabling 3D Atomic-Scale Imaging of Hydrogen in to Investigate Hydrogen Embrittlement of Zirconium Alloy Fuel Cladding in Fission Reactors
D. Haley, P. Bagot, M. Moody

The Atom Probe Research Group is undertaking leading research into the atomistic origins of Hydrogen Embrittlement (HE). HE is a critical issue and is highly prevalent across a diverse range of engineering applications, including the design of fission reactors. In particular, hydrogen is absorbed during the oxidation of Zircaloys, during service as fuel cladding in nuclear reactors, and can lead to embrittlement through delayed hydride cracking. The development of microscopy techniques which are able to characterise the behaviour of hydrogen at the atomic scale are key to developing an improved understanding of the mechanisms driving the degradation of zirconium alloy components. This is a key challenge facing the nuclear industry, particularly with new limits on the amount of hydrogen uptake into the material coming into force.

Atom probe tomography (APT) is unique in its ability to spatially locate in 3D individual hydrogen atoms within a complex alloy microstructure. Hence, this project underpinned by the development of new isotopic doping techniques combined with APT.  It will utilise novel instrumentation and methodologies for studying the interaction between gases and atomically clean surfaces, as well as the examination of samples electrolytically charged in heavy water. In particular, the project will focus on the interaction between hydrogen and irradiation induced damage to the Zircaloy microstructure, correlating this to hydride formation and ultimately the failure of the material due to HE. This project will be undertaken in close collaboration with researchers at the National Nuclear Laboratory (NNL).

Candidates are considered in the January 2018 admissions cycle which has an application deadline of 19 January 2018.  

This 4-year industrial studentship is funded by NNL will provide full fees and maintenance for a student who has home fee status (this includes an EU student who has spent the previous three years (or more) in the UK undertaking undergraduate study).  The stipend will be at least £16,553 per year.  Other EU students should read the guidance at http://www.materials.ox.ac.uk/admissions/postgraduate/eu.html for further information about eligibility.

Any questions concerning the project can be addressed to Professor Michael Moody (michael.moody@materials.ox.ac.uk).  General enquiries on how to apply can be made by e mail to graduate.studies@materials.ox.ac.uk.  You must complete the standard Oxford University Application for Graduate Studies.  Further information and an electronic copy of the application form can be found at http://www.ox.ac.uk/admissions/postgraduate_courses/apply/index.html.

Also see homepages: Michael Moody

*/**Exploring low energy excitations with electron microscopy
Dr R J Nicholls, Prof J R Yates, Prof P D Nellist

Recent advances in electron microscopy mean that a new generation of microscopes have the ability to combine atomic resolution imaging with high resolution spectra showing bond vibrations. The first of these new microscopes in Europe was unveiled at the UK SuperSTEM facility. The high resolution spectra produced by these microscopes are indicative of the bonding within a material and the combination of imaging and spectroscopy is a powerful tool for understanding the chemical, electronic and catalytic properties of a materials. Interpretation of experimental data is not always straightforward and can be aided by computer simulation. In the case of this new spectroscopic data, however, there are still fundamental questions about the interaction between the electron beam and the sample to answer in order to allow us to model experimental data. This project will use data obtained at the new SuperSTEM facility and focus on the formulation of quantum mechanical simulations to aid the interpretation of experimental data.

Candidates are considered in the January 2018 admissions cycle which has an application deadline of 19 January 2018.

This 3.5-year EPSRC DTP studentship will provide full fees and maintenance for a student who has home fee status (this includes an EU student who has spent the previous three years (or more) in the UK undertaking undergraduate study). The stipend will be at least £15,553 per year. Other EU students should read the guidance at http://www.materials.ox.ac.uk/admissions/postgraduate/eu.html for further information about eligibility.

Any questions concerning the project can be addressed to Dr Rebecca Nicholls (rebecca.nicholls@materials.ox.ac.uk) or Professor Pete Nellist (peter.nellist@materials.ox.ac.uk). General enquiries on how to apply can be made by e mail to graduate.studies@materials.ox.ac.uk. You must complete the standard Oxford University Application for Graduate Studies. Further information and an electronic copy of the application form can be found at http://www.ox.ac.uk/admissions/postgraduate_courses/apply/index.html.

Also see homepages: Rebecca Nicholls Jonathan Yates

*/**From light to heavy: making predictions of solid-state NMR parameters truly multi-nuclear
Prof J R Yates

TMCS is an EPSRC Centre for Doctoral Training operated by the Universities of Oxford, Bristol and Southampton.

In year one you will be based in Oxford with a cohort of around 12–15 other TMCS students, and will receive in-depth training in fundamental theory, software development, and chemical applications, delivered by academics from all three Universities. Successful completion of the year-one program leads to the award of an Oxford MSc, and progression to the 3-year DPhil project detailed below.

The ability to predict from first-principles NMR parameters for solid-state systems has had a significant impact on the solid-state NMR community (see Chemical Reviews 112 (11), 5733-5779 (2012). Such calculation are often an integral part of any experimental solid-state NMR study. However, a major limitation is the poor description of compounds containing heavier elements (say > Te). This applies not just to the heavy atom itself, but to any light atoms (H, C) directly bonded to the heavier atom (the so called ‘heavy atom - light atom effect)

The reason for this is a neglect of relativistic effects which become important for increasing Z. While scalar relativistic effects are sufficient in some situations, e.g. Journal of chemical physics 140 (23), 234106 (2014), a full treatment including spin-orbit coupling is essential to predict phenomena such as the heavy atom - light atom effect. We have recently extended the CASTEP code to include spin-orbit coupling in the calculation of ground state properties. The aim of this project will be to apply this functionality to the calculation of NMR properties in solids - enabling the accurate prediction of NMR parameters across the periodic table. This will involve the development of new theoretical equations and their implementation into a parallel electronic structure code (CASTEP). Applications of the new methodology will be extensive - and include areas such as catalysis, geominerals and pharmaceuticals, with collaborations in both academia and industry.

Funding will be subject to normal EPSRC rules. UK and EU students will be eligible for full-fee studentships.  In addition, UK students will be eligible for an annual stipend at or above £14,296 each year. 

Applicants would typically be expected to have a first class degree (or overseas equivalent) in chemistry or a closely related discipline. TMCS is committed to promoting equal opportunities in science, and we particularly welcome applications from women. Applications should be made as soon as possible, but will be considered throughout the year until the programme is full. Deadlines for upcoming recruitment rounds and further information on the application process can be found at our website: www.tmcs.ac.uk

Please ensure that you specify clearly that you are making a project-specific application and give the name of the project in your application.  Funding for this project is available through the Theory and Modelling in the Chemical Sciences Doctoral Training Centre (http;//www.tmcs.ac.uk).  Further details can be found at https://www.findaphd.com/search/PhdDetails.aspx?CAID=2278.

Any questions concerning the project can be addressed to Professor Jonathan Yates (jonathan.yates@materials.ox.ac.uk).  General enquiries on how to apply can be made by e mail to graduate.studies@materials.ox.ac.uk.  You must complete the standard Oxford University Application for Graduate Studies.  Further information and an electronic copy of the application form can be found at http://www.ox.ac.uk/admissions/postgraduate_courses/apply/index.html

Also see homepages: Jonathan Yates

*/**Thermo-mechanical property measurement of nuclear graphites at elevated temperatures
T J Marrow

This EPSRC iCASE project with the Uk National Nuclear Laboratory (NNL) aims to understand the thermo-mechanical properties of nuclear graphites at elevated temperatures (up to 850°C) that are relevant to current and future nuclear systems.

The experimental studies will investigate the relationships between applied total strains (tensile and compressive, measured by image correlation in 2-D and 3-D) and the elastic strains in the graphite crystals (measured, for instance, by synchrotron X-ray and neutron diffraction).

The local effects on microstructure and its properties will be examined by correlative Focussed-Ion Beam (FIB) tomography, electron microscopy, Raman spectroscopy and micromechanical testing at ambient and elevated temperatures. These studies aim to understand how tensile and compressive deformations are accommodated by competing mechanisms such as micro cracking, basal slip and twinning, and what effects this may have on the coefficient of thermal expansion.

These data will provide inputs for non-linear finite element modelling of the behaviour of graphites at elevated temperatures. The objective is to validate micro-mechanistic models for graphite deformation, and to provide the foundations for future work on irradiated graphites. During the secondment with the sponsor, the student will engage with NNL's work on modelling and property measurement of irradiated graphites.

Candidates are considered in the January 2018 admissions cycle which has an application deadline of 19 January 2018.

This is a 4-year EPSRC Industrial CASE studentship in conjunction with NNL and will provide full fees and maintenance for a student who has home fee status (this includes an EU student who has spent the previous three years (or more) in the UK undertaking undergraduate study). The stipend will be at least £16,553 per year. Other EU students should read the guidance at http://www.materials.ox.ac.uk/admissions/postgraduate/eu.html for further information about eligibility.

Any questions concerning the project can be addressed to Professor James Marrow (james.marrow@materials.ox.ac.uk). General enquiries on how to apply can be made by e mail to graduate.studies@materials.ox.ac.uk. You must complete the standard Oxford University Application for Graduate Studies. Further information and an electronic copy of the application form can be found at http://www.ox.ac.uk/admissions/postgraduate_courses/apply/index.html

Also see homepages: James Marrow

*/**Unconventional Computing using a Materials Science Approach
H. Bhaskaran

We want to achieve something unusual - creating a computing system where data storage and processing are closely linked using a materials science approach. In this exciting and pioneering project we aim to create nanoscale devices using phase change materials, and investigate arithmetic computations on these devices - this is our attempt to mimic biological computing processes (albeit at a very early stage). See recent publications on our Advanced nanoscale Engineering Group website: http://nanoeng.materials.ox.ac.uk

This is difficult to achieve, and so we need very, very bright and motivated colleagues. This project provides significant scope for a doctoral student potentially to effect a large-scale impact in the future of computing. We also have several international academic collaborations for this project, and hence there may be a possibility of opportunities for the student to travel to partner institutions in Germany and the USA

This project has the potential to enable the DPhil student to become an expert in phase change materials and memories as well as advanced measurement techniques. All our projects allow for significant creative contributions and the right DPhil candidate will have the freedom to shape research directions.

Your profile will be one of a highly motivated and very able student; the former evidenced perhaps by previous stints in research laboratories. The successful candidate (i) is most likely to have achieved or be predicted to achieve at least a first class honours degree, or equivalent, at undergraduate level in Physics, Materials, Engineering or a closely related field, (ii) may have a Masters level qualification in one of these subject areas too (a UK Integrated UG Masters qualification meets this level of qualification) and (iii) will possess a deep desire to carry out independent experimental research. You must like working on hands-on laboratory experiments and have the desire to try out and refine many novel ideas. Evidence of your initiative and ability to work collaboratively is desirable, including in the context of an experimental project.

Candidates are considered in the January 2018 admissions cycle which has an application deadline of 19 January 2018.

This 3.5-year EPSRC DTP studentship will provide full fees and maintenance for a student who has home fee status (this includes an EU student who has spent the previous three years (or more) in the UK undertaking undergraduate study). The stipend will be at least £15,553 per year. Other EU students should read the guidance at http://www.materials.ox.ac.uk/admissions/postgraduate/eu.html for further information about eligibility.

Any questions concerning the project can be addressed to Professor Harish Bhaskaran (harish.bhaskaran@materials.ox.ac.uk). General enquiries on how to apply can be made by e mail to graduate.studies@materials.ox.ac.uk. You must complete the standard Oxford University Application for Graduate Studies. Further information and an electronic copy of the application form can be found at http://www.ox.ac.uk/admissions/postgraduate_courses/apply/index.html.

Also see homepages: Harish Bhaskaran

*/**Understanding battery chemistry with in-situ electron microscopy
Dr Alex W Robertson and Prof Peter G Bruce

Lithium-ion batteries have revolutionised the way we think of energy storage, allowing for powerful devices that fit the palm of our hands, and massive battery arrays to supplement intermittent renewables. However there are fundamental limitations; the recent high profile fires that occurred in the Samsung Galaxy Note phones, and the 2013 grounding of the Boeing Dreamliner fleet, both illustrate this. The materials failures that occurred in these batteries risk becoming increasingly prevalent as we push Li-ion batteries to their maximum potential. New battery systems will be needed, such as Na-ion or Li-air, and a more fundamental understanding of the materials degradation mechanisms will be required to prevent failure.

This PhD project is based on using state-of-the-art transmission electron microscopy to characterise and understand these fundamental failure mechanisms at the atomic level, ultimately leading to the development of resilient battery designs.

Transmission electron microscopy (TEM) permits the characterisation of a material’s structure down to the atomic level, along with its chemical constitution by spectroscopy. TEM has been around for many years, but recent advances have seen the profile of this venerable technique rise dramatically, with a 2017 Nobel Prize awarded for its application to biological systems. Using this technique to aid the understanding battery chemistry has been historically difficult, as most battery chemistry occurs in solution. However, recent developments now allow for liquid phases to be studied within the TEM, permitting an unprecedented insight into the processes that occur in a battery during operation. The student, working with the world-leading battery and electron microscopy communities within the Materials Department, will harness TEM to understand the fundamental chemical and materials processes that occur in batteries.

Candidates are considered in the January 2018 admissions cycle which has an application deadline of 19 January 2018. 

This 3.5-year EPSRC DTP studentship will provide full fees and maintenance for a student who has home fee status (this includes an EU student who has spent the previous three years (or more) in the UK undertaking undergraduate study).  The stipend will be at least £15,553 per year.  Other EU students should read the guidance at http://www.materials.ox.ac.uk/admissions/postgraduate/eu.html for further information about eligibility.

Any questions concerning the project can be addressed to Dr Alex Robertson (alex.w.robertson@gmail.com).  General enquiries on how to apply can be made by e‑mail to graduate.studies@materials.ox.ac.uk.  You must complete the standard Oxford University Application for Graduate Studies.  Further information and an electronic copy of the application form can be found at http://www.ox.ac.uk/admissions/postgraduate_courses/apply/index.html.

Also see homepages: Peter Bruce

*/**X-ray video imaging and machine learning to understand alloy solidification
Prof Patrick Grant / Dr Enzo Liotti

We have developed X-ray imaging equipment and experimental approaches to record real-time videos of the solidification of alloys with high temporal and spatial resolution. This technique is providing new information to help understand and resolve long-standing and important issues in solidification science, including the role of grain refiners, impurities, external fields and many other important practical parameters. The particular novelties developed in the group include: (i) the ability to apply a highly controlled and reproducible pulsed electromagnetic field during solidification to break-up dendrites and to mimic industrial processes; (ii) the use of new multi-element detector (with STFC) that allows the investigation of more complex composition, realistic alloys; and (iii) a range of image analysis techniques including state-of-the-art pattern recognition machine learning algorithms (with Engineering Science) that allow quantified data to be extracted from videos automatically. This project will exploit and further develop these capabilities to study and quantify the nucleation and growth behaviour of equiaxed grains during commercial casting practices. The work will involve X-ray imaging solidification experiments, microstructural analysis and computer programming for automated analysis of images and videos. The project will also require travel and stays of typically 5 days to X-ray synchrotron sources around the world, particularly the Diamond Light Source (UK), ESRF and Soleil (Grenoble and Paris, France) and the Swiss Light Source (Geneva, Switzerland). This project is in collaboration with the EPSRC Future Manufacturing Hub - Liquid Metal Engineering

Candidates are considered in the January 2018 admissions cycle which has an application deadline of 19 January 2018.  

This 3.5-year EPSRC DTP studentship will provide full fees and maintenance for a student who has home fee status (this includes an EU student who has spent the previous three years (or more) in the UK undertaking undergraduate study).  The stipend will be at least £15,553 per year.  Other EU students should read the guidance at http://www.materials.ox.ac.uk/admissions/postgraduate/eu.html for further information about eligibility.

Any questions concerning the project can be addressed to Professor Patrick Grant (patrick.grant@materials.ox.ac.uk).  General enquiries on how to apply can be made by e mail to graduate.studies@materials.ox.ac.uk.  You must complete the standard Oxford University Application for Graduate Studies.  Further information and an electronic copy of the application form can be found at http://www.ox.ac.uk/admissions/postgraduate_courses/apply/index.html.

Also see homepages: Patrick Grant

(return to list of funded project titles)


OTHER PROJECTS - full details, listed by title

128 projects

Nanomechanical Systems (NEMS) based on 2D materials
H. Bhaskaran

Nanoelectromechanical systems (NEMS) are systems where a tiny mechanical element is fabricated to add certain functionality to a device or a system. These systems are functional not only because they occupy less space, but more so because they can perform functions that larger devices cannot or carry out certain tasks with greater precision and efficiency. Our group is seeking DPhil students to carry on this work starting from October 2014. The focus will be on using non-traditional materials, especially 2D materials, in NEMS devices. We will also seek to study fundamental aspects of materials science, which will help us create even better devices in future.

An incoming DPhil student will have significant advantages: our experimental capability in this area is now set-up, and we have some of the most advanced instrumentation in the field. Our group has several individuals who can informally work with the student, so the student will not feel lost in their first few months.

Your Profile:
Your profile will be one of a highly motivated undergraduate (evidenced by previous stints in Research laboratories), first class honors degree (or equivalent) earning undergraduate in Physics, Materials, Engineering or a closely related field with a deep desire to carry out independent experimental research. You must like working on hands-on laboratory experiments and have the desire to try out many novel ideas. Evidence (via references) of initiative and ability to work collaboratively would be a plus, as this is an experimental project.

Also see homepages: Harish Bhaskaran

2-Qubit systems based on endohedral fullerene dimer molecules
Professor K. Porfyrakis

Quantum information has the potential to change a whole range of currently used computational technologies. Carbon nanomaterials offer the potential for bottom-up control of the quantum information processing building blocks. Endohedral nitrogen fullerenes exhibit some of the longest lifetimes for electron spins due to the excellent protection offered to the incarcerated spins by the carbon cage. The project involves the synthesis of two-qubit systems via covalently linking two endohedral nitrogen fullerene molecules. The spin coupling between adjacent electron spins shall be controlled by varying the length of the bridge molecule and by careful alignment of the dimer molecules within a liquid crystal matrix. The research is interdisciplinary. It will involve the development of chemical functionalization methodologies and electron spin resonance manipulation for quantum physics experiments.

Also see homepages: Kyriakos Porfyrakis

3D printing and additive manufacturing approaches for microwave metamaterials
Prof Patrick Grant

Meta-materials are artificial materials that have properties unavailable from single material classes or composites and have been demonstrated in the lab to enable physical phenomena as cloaking, invisibility, advanced communications, energy transfer, sensors and security. Many of the novel properties of meta-materials involve their unusual interactions with electromagnetic radiation such as light and microwaves. However, theorectical designs with meta-materials are outstripping practical demonstration and testing, and there is an urgent need and exciting opportunity to develop new processing approaches to fabricate new, practical meta-materials for engineering applications.

This project focuses on new processing approaches to build active meta-materials with graded dielectric and magnetic properties using 3D printing. An active meta-material is one that can be switched or controlled using an external stimulus such as electricity, magnetism, light, etc, and are at the early stages of development. The project will develop a number of active meta-material ideas suitable for our in-house 3D printing facility, and then design novel arrangements of these materials to make functioning demonstrators at the 5 - 15 cm scale for measurement. The work will involve interaction with designers using simulations and specialists in measurements in the mega-gigahertz range. At all stages, a key aspect will be to characterise the microstructure and performance of the feedstock materials you have developed. The project will also involve developing novel implementations of the additive manufacture process itself in order to allow 3D active devices to be fabricated.

Also see homepages: Patrick Grant

A new concept for an ultra-sensitive gas sensor
Prof Martin Castell

The aim of the work in this project is to develop sensing technology that can be readily miniaturised and provide lightweight mobile or networked molecular detection of chemicals in the vapour phase. A further requirement is that the sensor is cheap and does not require protracted training for the user. In Oxford we have been working on developing such sensors through research into the use of conducting polymer networks operating near the electrical percolation threshold, which we refer to as percolation sensors. A studentship is available to develop percolation sensors for the detection of a variety of analytes, especially volatile organic compounds. The student will be involved in a broad range of interdisciplinary activities including design, building, and testing of the sensor. This project will be integrated into the larger WAFT collaboration, involving a number of UK Universities (www.waftcollaboration.org).

Also see homepages: Martin Castell

A new way to manufacture high performance NbTi superconducting wires
C R M Grovenor / S C Speller

The workhorse material for high field superconducting magnets has for many years been a 2 phase NiTi alloy processed by a long and complex thermomechanical process to give a microstructure optimised to give strong flux pinning. The use of artificial pinning centres to achieve even better superconducting performance has been explored in industry, but rejected because it is too expensive. Working in the new Centre for Applied Superconductivity (www.cfas.ox.ac.uk), this project will explore an alternative route to give a microstructure that gives strong flux pinning in a simple two-stage process. The student will be involved in the metallurgical processing, microstructural assessment and superconducting property measurements on the new alloys, with advice and close interaction from our industrial partners.

Also see homepages: Chris Grovenor Susannah Speller

Advanced Diffraction Analysis in the SEM (EBSD and ECCI)
Prof Angus J Wilkinson

Electron back scatter diffraction (EBSD) is now a ubiquitous tool for the characterisation of crystalline materials (grain orientations, phase identification, strain mapping).  Electron channelling contrast imaging (ECCI) on the other hand is a method for imaging and characterising lattice defects (dislocations, stacking faults) that has slowly reached a level where it is now robust and reliable in producing impressive defect images.  
This project will continue our development of these methods and exploitation of the synergies between them by combining ECCI images of indivual defects with quantification of the resulting stress fields by HR-EBSD.  The availability of good pattern and image simulations based on dynamical diffraction theory, and the possibility of advanced direct electron detection systems opens up new possibilities opportunities.  

Also see homepages: Angus Wilkinson

Advanced Gettering of Multicrystalline Silicon for Commercial Solar Cells
Prof PR Wilshaw and Dr S Bonilla

In order to move to a low-carbon future, and avoid the worst effects of anthropogenic climate change, continuing reductions in the cost of renewable energy are required. The semiconductor group at Oxford Materials, in collaboration with international research partners at Fraunhofer ISE in Germany and the University of New South Wales in Australia as well as industry partners, is working to reduce the cost of photovoltaic cells. Graduate students would work as part of a dedicated group of researchers on state-of-the-art techniques for improving the performance of crystalline silicon solar cells, which account for over 90% of all currently manufactured solar cells. Multicrystalline silicon is the most common wafer material for current solar cell production. As multicrystalline solar cell efficiencies increase, recombination due to impurities in the material becomes more and more important. These impurities may be present in the silicon feedstock, or introduced during casting of the multicrystalline ingot. The graduate student will work on developing advanced gettering techniques to remove these impurities from multicrystalline wafers, and on characterizing the improvement in device parameters that may be achieved. This will be done in collaboration with the atom probe tomography unit at Oxford Materials. These technologies may improve the performance of commercial multicrystalline silicon or enable the use of materials currently considered too contaminated for solar cell production. The student would work closely with a range of wafer suppliers, as well as international research partners to ensure the commercial relevance of the work.

Also see homepages: Peter Wilshaw

Advanced Manufacture and Characterisation of Thick Tungsten Coatings for Nuclear Fusion
Professor David Armstrong / Professor Patrick Grant

Tungsten coatings greater than 4mm thickness will are a key plasma facing technology to enable the development of a nuclear fusion device. These coatings will be subjected to severe conditions including steady state temperatures in excess of 1300K, high levels of radiation damage and sputtering erosion.

 

Recent work performed in collaboration between Oxford and CCFE has developed novel “sculpted” substrates which allow coatings of up to 4mm thickness to be manufactured repeatedly using vacuum plasma spraying on a stainless steel substrate. However there is a lack of understanding on how the microstructure controls the key mechanical and thermos-physical properties of the coatings. In particular fracture toughness, local modulus, sputtering erosion and thermal conductivity. This project will use a range of advanced characterisation and mechanical testing methods to study these properties and relate them to processing conditions. The findings from these will then be used to further optimise the deposition parameters. In addition tungsten coatings will be deposited directly on to tungsten as a proof of concept study to demonstrate the feasibility of using VPS coatings to perform in-situ repairs to plasma facing surfaces. This project will be in conjunction with UKAEA-CCFE and maybe funded through the Fusion CDT.

Also see homepages: David Armstrong

Advanced nano materials characterization via atomic force microscopy
H. Bhaskaran

Nanoparticle toxicity is of high interest because of emerging concerns regarding their environmental impact. However, recent methods to manufacture nanoparticles using bio-inspired processing have been reasonably successful. The big question is: what is the difference between such bio-inspired processing routes and conventional routes. The DPhil student who will work on this project will pursue very advanced atomic force microscopy techniques in our laboratory to understand how surface texture at the nanoscale, as well charge contribute to theor toxicity. 

Our group is very well set-up to perform these measurements. We are now in possession of one of the most advanced atomic force microscopes with excellent collaborations with Asylum Research in Santa Barbara. Thus a DPhil student will be able to start on this project with plenty of informal as well as formal mentoring and support.

Your Profile:
Your profile will be one of a highly motivated undergraduate (evidenced by previous stints in Research laboratories), first class honors degree (or equivalent) earning undergraduate in Physics, Materials, Engineering or a closely related field with a deep desire to carry out independent experimental research. You must like working on hands-on laboratory experiments and have the desire to try out many novel ideas. Evidence (via references) of initiative and ability to work collaboratively would be a plus, as this is an experimental project.

Also see homepages: Harish Bhaskaran

Applications of aberration-corrected high resolution electron microscopy
A Kirkland

The department has installed one of the world’s few electron microscopes with aberration correctors in both the condenser (probe-forming) and objective (image forming) lenses and with a unique monochromated electron source. This instrument is capable of recording images with 70pm resolution. Several projects are available that will develop experimental, theoretical and computational techniques for exploiting aberration corrected imaging. Possible materials candidates for experimental and theoretical studies include complex oxide ceramics, surfaces, nanocatalysts and carbon nanotubes.

Also see homepages: Angus Kirkland

Atom Probe Tomography of CERN and ITER superconducting wires
C Grovenor / M Moody

Some of the highest performing superconducting materials are now being developed for very high current applications in the magnets and power cables for large international machines for physics research (CERN) and for fusion demonstrators (ITER). These materials have extremely complex microstructures that are optimised for carrying very high currents in large magnetic fields, and controlling the elemental distributions at the nanaoscale is a vital part of the manufacturing process.  Atom Probe Tomography is the ideal technique to study these materials, but has not yet been much used in the optimisation in this field.  This project will allow the student to work closely with our collaborators in CERN and the USA to apply this technique to developing a better understanding of how the details of the manufacturing process influence the nanoscale chemistry and hence the superconducting properties of these materials.

Also see homepages: Chris Grovenor Michael Moody

Atomic resolution imaging of ultra-thin oxide films
Professor Martin Castell

We are working on a new class of hybrid material that is so thin it is both a surface and an interface. These are oxide films that are one atomic layer thick and can be imaged in the scanning tunnelling microscope (STM) with atomic resolution. The structure of the films is unique to the thin film system, is not a bulk termination, and is determined through the interaction with the gold substrate. To date we have explored TiOx, NbOx, and FeOx films. The new project in this area will concentrate on ternary oxide films such as FeCrOx. These systems are of fundamental importance to understanding the effects of high temperature encapsulation of noble metal catalysts. Particular emphasis will be placed on learning about the point and extended defects that occur in the films.

Also see homepages: Martin Castell

Atomic structure and secondary electron emission
Professor Martin Castell

The most popular method for image creation in the scanning electron microscope (SEM) is to use the secondary electron signal. Until recently it was assumed that secondary electrons are emitted isotropically i.e. with no particular preferred direction, but we now know that the atomic structure of the surface does in fact play a role. This DPhil project is concerned with correlating secondary electron emission using an ultra high vacuum SEM with atomic structure imaged in a scanning tunnelling microscope (STM). Both these techniques are located on the same world-leading instrument in Oxford. The powerful combination of signals will provide a hitherto unexplored path into some very fundamental aspects of nanoscale surface structure. There is also the likelyhood that the experiments will be further expanded through the use of the PEEM instument at the Diamond synchrotron.

Also see homepages: Martin Castell

Atomic-scale characterisation of Li battery materials
Prof P D Nellist, Prof P G Bruce

Transmission electron microscopy (TEM) is now capable of imaging individual atoms in materials, and electron spectroscopy data can provide atomic-scale information about the elements present and the nature of the bonding. Oxford Materials is one of the leading departments in high-precision quantitative measurements of materials using these methods. These methods have great potential for measuring structure and local chemistry to explain the performance of Li battery materials and to guide their development. The big challenge, however, is that the materials used are very sensitive to damage due to the illuminating electron beam. The aim of this project is to make use of methods recently developed in Oxford to maximise the amount of information gained from the microscope for the minimum electron irradiation. In particular, the recently developed method of electron ptychography (somewhat related to holography) can provide very sensitive measurements of Li and O atoms with three-dimensional information available. This will allow, for example, the positions of Li and O atoms in an electrode to be determined at various stages of the charge and discharge cycle of a battery. The project is suitable for someone interested in applying state-of-the-art atomic resolution electron microscopy to an important and rapidly developing class of materials.

Also see homepages: Peter Nellist

Atomic-Scale Characterisation of Reactor Pressure Steels
M P Moody / P A J Bagot

The reactor pressure vessel (RPV) is a critical component of a nuclear fission reactor. Hence, the long-term stability, strength and toughness of RPV steels are of vital importance for the power-generating industry. The main experimental technique to be used will be atom probe tomography. This cutting edge microscopy technique enables a three-dimensional, atom-by-atom characterisation of the microstructure of the steel, providing unique insight into the fundamental mechanisms of solute clustering and the resulting embrittlement. Additional experimental work will involve complementary techniques such as focused ion beam, electron microscopy and mechanical property measurements. This is an ongoing collaboration between Oxford and Rolls Royce. The current ageing experiments will be continued with removal from furnaces and testing/examination of aged samples at suitable intervals. Current mechanistic understanding is that any nano-scale precipitation will be more likely found either on dislocations or grain boundaries. Because of this more emphasis will be placed on grain boundary behaviour and in particular the segregation of elements such as phosphorus, as well as Ni/Mn/Cu. 

Also see homepages: Michael Moody

Atomic-scale design of perovskites for high-performance photovoltaics
Prof F Giustino

In the past five years perovskite solar cells have emerged as a disruptive solar technology. Last year the solar-to-electricity power conversion efficiency of perovskite solar cells reached the record value of 22%, marking the fastest efficiency rise of all time across existing photovoltaic technologies. Key remaining challenges in this research area are to increase the stability of the active materials, and to develop ever more efficient light absorbers and electron/hole transporters.

In our group we have been working on the atomic-scale computational design of new photovoltaics perovskites, using advanced electronic structure techniques based on density-functional theory and many-body perturbation theory. Recent successes include the prediction and subsequent experimental synthesis of the double perovskites Cs2BiAgBr6, Cs2BiAgCl6, and Cs2InAgCl6 [1,2,3]. Our computational discoveries led to the filing of two patent applications. Please see group webpage for further information, recent publications, and research highlights: http://giustino.materials.ox.ac.uk.

In this DPhil project we want to broaden the scope of our investigation towards new materials families, including chalcogenide perovskites, antiperovskites, and layered perovskites. We will combine medium- to high-throughput combinatorial design techniques with advanced electronic structure methods to predict compound stability, electronic, optical, and transport properties. For the most promising materials candidates our collaborators in the Department of Physics (Prof. Snaith's group) will attempt the experimental synthesis and materials characterisation.

The prospective student is expected to have a strong background in Solid State Physics and Quantum Mechanics, aptitude for mathematical models, and knowledge of at least one major programming or scripting language. Previous experience with density-functional theory calculations and familiarity with supercomputing clusters is desirable but not essential, as appropriate training will be provided as needed.

[1] G. Volonakis, A. A. Haghighirad, R. L. Milot, W. H. Sio, M. R. Filip, B. Wenger, M. B. Johnston, L. M. Herz, H. J. Snaith, and F. Giustino, Cs2InAgCl6: A New Lead-Free Halide Double Perovskite with Direct Band Gap, J. Phys. Chem. Lett., 8, 772 (2017).

[2] M. R. Filip, S. Hillman, A. A. Haghighirad, H. J. Snaith, and F. Giustino, Band gaps of the lead-free halide double perovskites Cs2BiAgCl6 and Cs2BiAgBr6 from theory and experiment, J. Phys. Chem. Lett. 7, 2579 (2016).

[3] G. Volonakis, M. R.Filip, A. A. Haghighirad, N. Sakai, B. Wenger, H. J. Snaith, and F. Giustino, Lead-Free Halide Double Perovskites via Heterovalent Substitution of Noble Metals, J. Phys. Chem. Lett. 7, 1254 (2016).

Also see homepages: Feliciano Giustino

Batteries for grid-scale energy storage
Prof M. Pasta

New types of energy storage are needed in conjunction with the deployment of solar, wind, and other volatile renewable energy sources and their integration with the electrical grid. No existing energy storage technology can provide the power, cycle life, and energy efficiency needed to respond to the costly short-term transients that arise from renewables and other aspects of grid operation. We are currently working on a new family of insertion electrodes based on the Prussian Blue open-framework crystal structure. This structure is fundamentally different from other insertion electrode materials because of its large channels and interstices. It is composed of a face-centered cubic framework of transition metal cations where each cation is octahedrally coordinated to hexacyanometallate groups and has wide channels between the A sites, allowing rapid insertion and removal of sodium, potassium and other ions. In addition, there is little lattice strain during cycling because the A sites are larger than the ions that are inserted and removed from them. The result is an extremely stable electrode: over 40,000 deep discharge cycles were demonstrated in the case of the copper hexacyanoferrate cathode. 

The student will work on synthesizing new open-framework materials, perform an in-depth structural characterization at the Diamond Light Source and evaluate their electrochemical properties. Collaborations (both internal, external and with Silicon Valley based start-up) are expected.

Also see homepages: Mauro Pasta

Bench-top experimental tests of gravitation in quantum systems
Dr N. Ares / Dr E. A. Laird / Professor G. A. D. Briggs

The territory where quantum mechanics has to be reconciled with gravitation is still experimentally unexplored. Gravitational effects in quantum systems are typically small, making laboratory-scale experiments extremely challenging. Advances in mechanical resonators at the micro-scale and cryogenic temperatures are beginning to bring such experiments within reach. We plan to evaluate the feasibility of bench-top experiments based on two micromechanical oscillators to explore the effect of gravity in quantum systems. 

Heating of mechanical resonators is expected from gravitational decoherence. To determine whether this heating effect can be measured, we will build the world’s most sensitive calorimeter based on an optomechanical system at cryogenic temperatures. The optomechanical system will consist of two mechanical oscillators inside a 3D microwave cavity, whose interaction will allow for measurement of the mechanical oscillators’ temperature. The microwave cavity will be fabricated in an aluminium block and the mechanical resonators will be commercially available silicon nitride membranes with excellent mechanical properties. 

This is an ambitious project with the goal of elucidating whether quantum gravitational effects can arise in table-top experiments, opening up the possibility for a whole new direction for the quest of quantum gravitational effects. 

Also see homepages: Natalia Ares Andrew Briggs

Bulk superconducting MgB2 magnets for biomedical applications
S C Speller / C R M Grovenor / P S Grant

Magnetic Resonance Imaging (MRI) is a very widely used technique for medical diagnosis, but the current instruments based on superconducting solenoids are large and expensive. There are emerging designs for much smaller and cheaper instruments for knees, elbows, wrists etc based on bulk superconductors acting as permanent magnets. Permanent magnets also have potential applications in novel drug delivery systems. Magnesium diboride (MgB2) is a possible new material to use in this application. This project will focus on firstly the fabrication of bulk MgB2 materials using the Field Assisted Sintering Technique (FAST), which may offer significant benefits over conventional hot pressing. Working jointly in the Oxford Centre for Applied Superconductivity (www.cfas.ox.ac.uk) and the Processing of Advanced Materials group (users.ox.ac.uk/~pgrant), the student will be involved in powder processing of the precursor material, the design of processing conditions, and understanding the critical links between final microstructure and superconducting properties, with the aim of optimising the magnetic field that can be trapped in the smallest possible volume. This student will be involved with a new EPSRC-funded project in collaboration with Cambridge University, RAL and industrial partners at Element Six, providing opportunities to access industrial processing facilities and to integrate their material with test devices in the Institute for Biomedical Engineering.

Also see homepages: Patrick Grant Chris Grovenor Susannah Speller

Carbon-based quantum devices characterised electrically and by imaging
Dr E. A. Laird, Dr J. H. Warner and Professor G. A. D. Briggs

Carbon nanomaterials are attractive materials for electronic devices, especially for quantum computers using the spin of single electrons. One challenge in realising these applications is that the detailed device structure cannot be fully controlled during fabrication. The aim of this project is to characterize the same devices both through electrical measurements and by high-resolution electron microscopy, with the aim of understanding the electronic properties in terms of the atomic structure.

The goal of project will be to determine how the bandstructure and spin-orbit coupling of carbon nanotubes depend on the atomic structure – in particular on the chirality, which describes how the carbon atoms are aligned. Through aberration-corrected high-resolution transmission electron microscopy (AC-HRTEM), it is possible to measure the chiral indices of individual nanotubes, but so far this has not been performed on nanotubes integrated into electronic devices. You will combine these two kinds of measurement by incorporating a TEM window into existing fabrication technology for ultra-low-disorder nanotubes. You will then make electrical measurements of selected devices in a dilution refrigerator, with the aim of correlating the measured spin-orbit coupling to the previously determined chirality and comparing with existing theoretical predictions.

Also see homepages: Andrew Briggs Jamie Warner

Charge sensitive imaging
A Kirkland

“If one knew the positions of all the electrons in a material, there would be no need to find where the nuclei are”. Traditional electron microscopy determines the nuclei positions and we are now aiming to develop methods for locating the electrons. This will revolutionise the study of almost all materials and will provide a new level of structural information for comparison with theoretical models. This project will aim to establish new methods using oxides and low dimensional materials including Graphene as test materials using aberration TEM with advanced image simulation incorporating Density Functional Theory.

Also see homepages: Angus Kirkland

Chip-based atomic clocks
Dr E. A. Laird / Professor G. A. D. Briggs

Atomic clocks are among the most precise scientific instruments ever made, and are key to advanced navigation, secure communication, and radar technology. We are pursuing a new approach to create a clock that will fit on a chip. Instead of atomic vapours, we will use electron and nuclear spins in endohedral fullerene molecules, whose energy levels offer an exquisitely stable frequency reference. To make this novel approach work, we must overcome a range of physics and engineering challenges, including detecting spin resonance from a small number of spins, identifying the energy levels involved, and miniaturizing the control electronics and magnet. The reward will be a completely new technology with a wide range of civilian and military uses. We are looking for a candidate who has a strong interest in applying quantum physics in new technology, and is motivated to develop the new and demanding electronic measurement techniques that will be necessary.

Also see homepages: Andrew Briggs

Chiral networks and the origin of life
Professor Martin Castell

In this project 2D molecular networks are synthesized through self-assembly on metal and mineral surfaces. Scanning tunnelling microscopy is used to investigate their ordering. In particular, methods will be studied that influence the chirality (handedness) of the molecular arrangements. Examples of this are networks that consist of DNA and RNA nucleobases such as adenine and uracil. These experiments are motivated by the question of what gives rise to a particular chirality in biomolecules such as DNA and amino acids, and as such are relevant to the origin of life.

Also see homepages: Martin Castell

Colloidal Quantum Dot Displays and Lighting
Andrew Watt

Optoelectronic devices made from Colloidal Quantum Dots (CQD) have started to transition from the lab to consumer products, the Sony Triluminous display being a prime example. CQD have great promise in a number of applications, but there are still challenges to be met, primarily methods for continuous production in bulk and lowering the toxicity of the constituent material, and for the integration process of devices and systems.

This project focuses on manufacturing process of CQD materials and next-generation smart display/lighting devices based on LEDs. The latest CQD display technology uses back lit LCD units and Cd based CQD as the phosphor. A second generation of LED driven by electroluminescent (EL) CQD devices (CQD LED) is envisaged to replace current organic LED (OLED) for use in both displays and smart lighting. The main advantage of the CQD LED over OLED are improved reliability/stability, lower production costs, lower power consumption and improved colour purity/gamut. This project is focused on the manufacturing technologies we believe are needed to augment current, and develop additional markets for CQD based companies and also create new businesses.

Also see homepages: Andrew Watt

Colloidal Quantum Dot Photovoltaics
Andrew Watt

The ability to tune the band gap across the solar spectrum through quantum confinement allows the possibility to create broadband multi-junction and multi-band gap solar cells. If this can be harnessed alongside multiple exciton generationand emerging energy transfer mechanisms there is a very real opportunity to break the Shockley Queisser limit. This project will address the challenge of improving device efficiency by using a number of strategies including improving energy level matching and limiting recombination losses by passivation.

Also see homepages: Andrew Watt

Coupling molecular spins to valley-spin qubits in carbon nanotubes
Professor G. A. D. Briggs, Professor J. H. Warner, Professor K. Porfyrakis and Dr E. A. Laird

Carbon-based quantum technologies require the ability to transfer quantum information from one form to another. Valley-spin qubits (so called because of the hybridisation between electron spin states and the valleys in the band structure of the nanotube) enable single states to be manipulated and measured in electron dipole spin resonance, but the coherence times are not long enough for scaleable quantum computing. Molecular qubits are known from ensemble experiments to have useful quantum coherence times, but to exploit these in useful devices we must have ways to measure them individually. By attaching molecules to the nanotube, and transferring quantum states between the nanotube and the molecule, it should be possible to exploit the best of each. The storage time can be increased a further thousandfold by using molecular nuclear spins as a further resource.

Successful development of this scheme will require nanofabrication of the devices, attachment of the spin-bearing molecules, microscopy of the resulting structures, and magnetic resonance at cryogenic temperatures. This project will involve training in nanofabrication, together with electron microscopy and low-temperature electronic measurements. Aspects of the project will be undertaken in collaboration with other members of the laboratory. The goal will be to show that quantum information can be effectively transferred between the nanotube device and the spin states of the attached molecules. This will be achieved by entangling quantum mechanically the molecular spin with an electron spin on the nanotube, and measuring the molecular spin state through its effect on the electron.

Also see homepages: Kyriakos Porfyrakis Jamie Warner

Defects in diamond as spin qubits in quantum networks
Prof Jason Smith

Diamond has unsurpassed properties for quantum technologies such as quantum sensing and quantum computing, and point defects in the material can act as trapped atoms with properties ideal for the storage and manipulation of quantum states. A major challenge is the efficient coupling of these atom-like systems with optical systems, so that quantum states can be transferred between electrons (or nuclei) and photons to enable the construction of scalable networks. This doctoral project will involve the coupling of single nitrogen-vacancy defects in diamond to optical microcavities in order to maximise the efficiency of quantum state transfer and facilitate scalable networking. You will be part of a small team working towards this goal, which will involve a range of techniques including optical characterisation and spectroscopy, fabrication and handling of diamond microstructures and optical devices, and lasers and cryogenic instrumentation. As such the project is well suited to an energetic and hands-on student who enjoys building apparatus and has a good working knowledge of optics. The project is part of a substantial nationwide program to build scalable quantum networks involving matter systems and photons.

Also see homepages: Jason Smith

Deposition of organic and inorganic layers on polymer substrates by roll-to-roll coating in vacuum
Prof H E Assender

The project will make use of our state-of-the art roll-to-roll polymer web coater to deposit under vacuum acrylate or other organic layers on polymer substrates, followed by evaporation or magnetron sputtering deposition of thin film inorganic layers such as metals or oxides. The resulting materials will then be characterized using a suite of methods. Possible applications include optical coatings, gas barrier films (often for electronics applications), or flexible electronics.

Also see homepages: Hazel Assender

Developing Atom Probe for 3D Atomic-Scale Imaging of Biomaterials
M. P. Moody / P. A. J. Bagot

Atom Probe Tomography (APT) underpins the research and development into a wide range of materials and devices. This 3D atom-by-atom imaging offers the exciting potential to provide truly unique insights to biomaterials research into materials such as teeth, bone, synthetic implant. However, the application to APT to the analysis of biomaterials can be extremely complicated. There are significant challenges to not only to undertake successful experiments, but also to maximise the quantity and accuracy of information that can be extracted from the data. In this project we will develop APT specimen preparation, experiment, 3D atom-by-atom image reconstruction and data analysis for reliable and routine characterisation of biomaterials in collaboration with our research partners at Imperial College and UCL.

Also see homepages: Michael Moody

Development of aluminium matrix nanocomposites for high temperature applications
M Galano / F. Audebert

This project  is based on the development of Aluminium Matrix Complex Nanocomposties (AlMCNCs) with combinations of reinforcement strategies at the nanoscale that offer unique properties to target specific applications with an enhancement of combined properties i.e. increase thermal stability, ductility at forging temperature, and higher strength and Young’s modulus in higher performance applications. New materials will be used as nanoreinforcements for improving Young’s modulus and strength of nanoquasicrystalline alloys (NQX). Small Al-particles will be used as a plasticizer for improving the ductility of NQX alloys at forging temperature. These combinations of reinforcement strategies at the nanoscale will create unique complex nanocomposites with a unique combination of properties. Thus, a detailed study on the processing and the mechanisms responsible for microstructural stability and mechanical properties is required to develop these new Al matrix complex nanocomposites and to provide a platform for a disruptive knowledge for designing the right material for each application. Several aspects will be developed within the project: (i)Investigation the different processing routes that lead to obtaining AlMCNCs in bulk shape for industrial applications. (ii)Development of bulk AlMCNCs with different combinations of exciting mechanical properties for producing high industrial impact. (iii)Testing of the new AlMCNCs in real applicationsThe project makes use of processing, microstructural characterisation facilities and expertise and draws on the latest alloy developments within the research group that offer genuine prospects for industrially useful nanomaterials. This project will be within an already running EPSRC/RAEng project that is working on the development of bulk nanostructured alloy alloys and will run with the collaboration of several industrial partners representing a range of interests to pull through developed know-how.

Also see homepages: Marina Galano

Development of metal-metal matrix nanocomposites for hight strength applications
M Galano / F. Audebert

This project is based on the development of Metal Matrix Complex Nanofibril composites using new materials as reinforcements for improving Young’s modulus and strength of nanofibril alloys.  A combination of experimental and simulation studies will be carried out to help understanding of the optimum metal-metal combination, phase fractions, and processing conditions for obtaining the finest nanoparticles and nanofibers size
Several aspects will be developed within the project some of them with help of industrial and academic collaborators:
(i)    Investigation of the different processing routes
(ii)    Development of bulk Metal-Metal Matrix Complex composites with different combinations of exciting mechanical properties for producing high industrial impact.
(iii)    Modelling of the strengthening and deformation mechanisms at the nanoscale in order to predict the mechanical properties of the different composites types.
The project makes use of processing, microstructural characterisation facilities and expertise and draws on the latest alloy developments within the research group that offer genuine prospects for industrially useful nanomaterials. Strong industrial support is already in place for different aspects of the project in particular a company specializing in processing simulations will be carrying out the modelling for the different nanocomposites developed.

Also see homepages: Marina Galano

Development of novel wet chemical techniques towards dedicated nanoparticles manufacturing
Dr. F. Dillon, Professor N. Grobert

Nanomaterials' properties are highly depended on their atomic structure and composition. This project will focus on the synthesis of dedicated nanoparticles defined properties. The student will investigate the influence of various parameters on particle size, shape, concentration and composition. Experiments will involve wet-chemical techniques in conjunction with state-of-the-art electron microscopy techniques. This project is essential to the group and will be an integral part of the ongoing research activities. It will be carried out in close collaboration with Dr K Moh, Prof E Arzt (Leibniz Institute for New Materials Saarbruecken, Germany), and industrial partners.

Also see homepages: Nicole Grobert

Direct electron beam lithography of graphene
J H Warner

Graphene holds a lot of promise for electronic applications. In order to be an effective semiconductor in transistors it is desirable for the width of graphene channels to be sub-10nm. This project will focus on fabricating sub-10nm features in graphene using the novel concept of direct electron beam lithography. Electron beam irradiation will be used to directly sputter carbon atoms from graphene with the aim of fabricating structures for nanoelectronic devices. Graphene structures such as nanoribbons will be produced and implemented in field effect transistors. This will involve fabricating graphene nanoelectronic devices that are compatible with high resolution transmission electron microscopy. Parameters that enable control over the graphene sputtering process will be elucidated. Atomic structure will be gained by aberration-corrected HRTEM and correlated with the electronic device properties.

Also see homepages: Jamie Warner

Dislocation based modelling of engineering alloys
E Tarleton and Prof A J Wilkinson

You will be part of a small dynamic team developing state of the art computational models which are used to simulate a range of micro mechanical tests and microscopy data. This project focuses on simulating delayed hydride cracking in Zr alloys as used in compact nuclear reactors for submarine propulsion. You will simulate the coupled mechanical/hydrogen diffusion process within a discrete dislocation plasticity framework. This will involve developing a FEM code to solve the H diffusion equation, and coupling this with a discrete dislocation plasticity code to simulate dislocation-hydrogen interactions. The majority of the coding will be in Matlab, with the opportunity to learn and use C and CUDA to accelerate the code.

The project will link to experimental work within the wider Materials for Fusion and Fission Power group and may involve interaction with Rolls Royce (Marine).

 

Also see homepages: Edmund Tarleton Angus Wilkinson

Electron ptychographic imaging of polymer and macromolecular ordering
Prof P D Nellist, Prof H E Assender

Electron ptychography is a newly available mode of imaging in the transmission electron microscope that is somewhat related to holography. Recent work in Oxford has shown that it can provide sensitive imaging of low atomic number elements while minimising the number of illumination electrons required. A major challenge associated with electron microscopy of polymers is the damage caused to the sample by the electron beam. The development of electron ptychography creates an opportunity to overcome this challenge and to create a new method for high-resolution imaging of polymers. The project will focus on applying electron ptychography to study local molecular ordering processes in polymer thin films that cannot be studied using conventional X-ray and neutron diffraction methods. The polymer interaction with the substrate will form an important part of the study. The project would suit someone interested in applying state-of-the-art electron microscopy methods to materials that have not traditionally been widely studied using electron microscopy.

Also see homepages: Peter Nellist

Energy extraction from water salinity differences
Prof M. Pasta

The large-scale chemical energy stored as the salinity difference between seawater and fresh water is a renewable source that can be harvested. The entropic energy created by the difference in water salinities (also called “blue energy”) is normally dissipated when river water flows into the sea. This reduction in free energy due to mixing is estimated at 2.2 kJ per liter of fresh water.  We have previously developed a device called a “mixing entropy battery” that efficiently extracts this wasted energy. The device employed sodium manganese oxide and silver as sodium and chloride capturing electrodes respectively. While this device worked well, there are some limitations. Sodium manga has a limited specific capacity (i.e. number of sodium ions storable per gram of active material), while the silver-silver chloride electrode is much too expensive for this application. Moreover, both manganese and silver are heavy metals and their release in seawater is severely regulated. In addition, by operating the mixing entropy battery in reverse we demonstrated the possibility of efficiently desalinating seawater through a device I called a “desalination battery”. The development of the two devices will progress in parallel.

The student will work on new electrode materials as well as improving the design of the device and will be part of an international network working on developing this technology. 

Also see homepages: Mauro Pasta

Enhancing the photoluminescence of Er-containing endohedral fullerenes via linking them to gold nanoparticles
Professor K. Porfyrakis, Dr P Dallas

Erbium ions or erbium containing organometallic complexes have been used as amplifiers in optical fibers, either silica or poly methyl methacrylate (pmma). Erbium doped fiber amplifiers can amplify light in the 1520 nm, a fingerprint emission from the erbium ion, a wavelength where telecommunication fibers are demonstrating their loss minimum. The project involves the synthesis of dyad molecules made from Er-endohedral fullerenes and gold nanoparticles with the aim to enhance the photoluminescence from the fullerene moiety. The distance between the fullerenes and the plasmonics nanoparticles influences the degree of enhancement of the quantum yield and the photoluminescence intensity. The research is interdisciplinary. It will involve the development of chemical functionalization methodologies and photoluminescence experiments in collaboration with Prof. R. A. Taylor’s group in the department of Physics.

Also see homepages: Kyriakos Porfyrakis

Epitaxial oxide nanocrystals
Professor Martin Castell

Very small crystals, nanocrystals, of one type of oxide can be grown onto another oxide substrate. The shape, structure, and electrical / optical properties of these nanocrystals is influenced by the strain that builds up between the substrate and the nanocrystal. The idea is to grow an oxide of one type onto a different oxide substrate that has a slight lattice mismatch. The strain that builds up in the oxide nanocrystals will then affect the electronic properties such as the bandgap. This is called strain engineering, and has been carried out for many years in the semiconductor industry with e.g. germanium on silicon systems. In this project the scope of strain engineering will be expanded into the realm of oxide materials. We have some exciting preliminary data of Mn3O4 and TiO2 nanocrystals on SrTiO3 substrates that show the feasability of the proposed work.

Also see homepages: Martin Castell

Experimental Validation of Crack Propagation Criteria under Mixed Mode Loading
James Marrow

To accurately predict crack paths in brittle materials, it is important to properly address the effect of mixed mode loading in multi-axial stress states.  Predictive models exist, and their experimental validation needs support from direct measurement the crack tip strain fields for comparison with the predicted strain fields; the latter are currently used to predict the crack path.  Discrepancies are expected due to material microstructure effects such as aggregate interlocking (from shear loading), for instance.  We have developed tools so that direct measurement of crack tip displacement fields can be used to calculate the stress intensity factor, via the J-integral.  This is done by injecting the measured displacements as boundary conditions into a Finite Element mesh; the displacement field is obtained by digital image correlation.

This project will apply these methods to examine the crack propagation criteria in brittle materials, such as the polygranular graphite used in current and next generation nuclear reactors.  The project will also investigate the relationships between the applied stress state, the local strain fields and the crack propagation path.  This experimentally-based study will support ongoing modelling and experimental studies.

The project is suitable for students with an engineering, physics or materials background and will involve techniques such as digital image correlation, finite element modelling and computed X-ray tomography.

Also see homepages: James Marrow

Experimentally-informed 3D modelling of damage development in interfacially-toughened composite laminates
James Marrow

Aviation and wind power rely on long fibre-reinforced polymer composites for key structural components (fuselage, wings and blades). However, these can fail by delamination (cracking between layers bonded during manufacture), and the necessary conservative design approaches add weight and cost and reduce efficiency. The project's partners at Sheffield have improved delamination resistance without a weight penalty via a novel ink-jet printing manufacturing method, but its actual mechanism is unproven.

The aim of this project is to develop and apply experimentally informed multi-scale modelling to optimise the design and manufacture of ink-jet print toughened and self-healing lightweight composites.

Oxford developed a method for damage simulation in heterogeneous materials. This multi-scale approach introduces fine scale microstructural description into larger scale structural integrity models. In situ measurements of damage development, obtained by digital volume correlation of high resolution X-ray tomographs of mechanically tested samples, can be used to tune the FEMME model [Saucedo-Mora, L., and Marrow, T.J. (2016) http://dx.doi.org/10.1098/rsta.2015.0276]. This permits damage simulation in different loading states and with alternative microstructure architectures. Modelling-led structural design and microstructure optimisation is then feasible, due to the computational efficiency of the FEMME method being 2-3 orders of magnitude greater than conventional image-based finite element simulations.

You will design and perform critical X-ray tomography experiments to observe, in situ and in 3D, the mechanism by which the inkjet printed interfaces fail and potentially self-repair. The aim is then to demonstrate FEMME model simulation of the experimentally observed fracture behaviour, and show its potential to predict the structural integrity of engineering components under different states of load.

The project is suitable for students with an engineering, physics or materials background and will involve techniques such as digital image correlation, finite element modelling and computed X-ray tomography.

Also see homepages: James Marrow

Exploiting extrinsic passivation on antireflection coatings for high efficiency silicon solar cells
Supervisors Prof PR Wilshaw and Dr S Bonilla

In order to move to a low-carbon future, and avoid the worst effects of anthropogenic climate change, continuing reductions in the cost of renewable energy are required. The semiconductor group at Oxford Materials, in collaboration with international research partners at Fraunhofer ISE in Germany and the University of New South Wales in Australia as well as industry partners, is working to reduce the cost of photovoltaic cells. Graduate students would work as part of a dedicated group of researchers on state-of-the-art techniques for improving the performance of crystalline silicon solar cells, which account for over 90% of all currently manufactured solar cells.

Silicon solar cells capture solar energy when light is absorbed near the cell’s surface. The surface of the cell represents a major material defect where loss of charge carriers may occur. The reduction of charge loss at the surface, termed passivation, is hence a critical feature requiring improvement. For solar energy to be cost competitive with other technologies, manufacturing costs of solar cells must be brought down while maintaining device performance. This project aims to explore a new generation of cost effective dielectric coatings that provide optimal passivation using the technologies proposed and patented by the group, as well as improving the optical qualities over current industrial films. The student performing the work will be involved in deposition of dielectrics using semiconductor facilities and characterisation of their properties using electronic techniques. These films will then be extrinsically treated to exploit their passivation characteristics.

Also see homepages: Peter Wilshaw

Exploring metal plasticity through atomic imaging of core structure
Prof P D Nellist, Prof D E J Armstrong

Almost all materials we use in our civilisation are crystals, and the things that make crystals interesting are their defects. One of the most important crystals defects are dislocations, and they are key to understanding how materials deform plastically. In some materials, for examples the tungsten used in fusion reactors, certain types of dislocations can behave in unusual ways, by having low mobility making the materials much more brittle. The explanation of this unusual behaviour probably lies in the detailed atomic arrangement at the core of the dislocation, but a full 3D characterisation of such defects has not before been possible. Here we make use of a novel “optical sectioning” procedure we have developed in our laboratory to determine the structure of dislocations at atomic resolution in 3D using electron microscopy. Using this approach to relate atomic structure to materials properties allows the rational design of alloys to improve the ductility of important structural materials.

This project would suit someone who enjoys challenging experiments but also wants to experience the excitement of seeing atoms in materials. In addition to hands on experiments, the project will involve data processing using scripting in software packages such as Matlab.

Also see homepages: David Armstrong Peter Nellist

Exploring the frontiers of electron ptychography
Prof P D Nellist, Prof A I Kirkland

Electron ptychography is emerging as an important new imaging tool allowing greater image contrast of light elements, lower doses for radiation sensitive materials, the ability to correct for imperfections in the optics and the retrieval of 3D information. The technique is already being used for a range of materials applications (see other projects) and is likely to be revolution in the way we perform atomic resolution characterisation of materials. The aims of this project are to explore how far the technique can be pushed and how new measurements of materials can be made. Broadly, ptychography can be performed in two different configurations. The sample can be illuminated by a converged beam which is then scanned over the sample. Fast cameras are used to record diffraction patterns for each illuminating position, to form a 4D data set. Alternatively, a parallel illuminating beam can be tilted and a series of images recorded in a conventional TEM. Both modes will be developed as part of exploring the optimal conditions. Leading electron microscopes in the Department of Materials and at the Diamond Light Source at Harwell will be used.

Also see homepages: Angus Kirkland Peter Nellist

Flash sintering of ceramics
R I Todd

Normally, it takes several hours at a temperature well in excess of 1000 C to sinter a ceramic. However, it has recently been discovered that this can be achieved in a few seconds with much lower furnace temperatures by applying an electric current to the specimen whilst it is heated. We have shown that the "flash event" originates in a thermal runaway effect and have recently suggested that the rapid sintering observed during this flash event is primarily a consequence of the extremely rapid heating produced. The project aims to investigate the reasons for this and to establish models which will enable the commercial exploitation of the phenomenon.

Also see homepages: Richard Todd

Fundamentals of High Cycle Fatigue Crack Initiation
Prof Angus J Wilkinson and Dr Jicheng Gong

In the (very) high cycle fatigue regime crack initiation and short fatigue crack growth dominate fatigue lives.  We have developed novel methods for very rapid (~106 cycles in 1 min) fatigue testing of very small (~0.5 to 200 µm across) material volumes. Focussing the testing down to a small region allows the progression of deformation to be followed in detail for which a range of characterisation methods will be used.  Secondary electron imaging in SEM will allow a rapid assessment of slip feature development and crack formation, while electron channelling contrast imaging will allow assessment of local dislocation structures.  AFM will be used to quantify slip step heights and surface roughening which will be related to the underlying crystallography revealled by EBSD which also map intra-granular distributions of local stress and dislocation density.  These experimental observations will be combined with crystal plasticity level finite element modelling. The aim is to gain insight into formation of 'hot spots' leading to crack initiation and the microstructural features that tend to encourage this local deformation. 

Also see homepages: Angus Wilkinson

Grain Boundary Sliding and Superplasticity
Prof Angus J Wilkinson and Prof Richard I Todd

Grain boundary sliding is an important deformation mechanism in the creep and superplastic regimes.  It is clear that sliding happens more readily on some boundaries than others but the links between grain boundary character and resistance to sliding have not been established.  In polycrystals grain boundary sliding is generally thought to be accompanied by other accommodation processes such as diffusion, or dislocation mediated plasticity. 
This project will use state of the art micro-mechanical testing methods to probe properties of individual grain boundaries isolated in FIB-machined micron scale test pieces.  This uncouples grain boundary sliding from other accommodation processes and through testing many boundaries will link behaviour to structural characteristics of the boundaries.  Similarly, diffusional creep processes may be studied on isolated boundaries under well-controlled stress gradients.  The work on individual grain boundaries will be augmented by experiments on bulk polycrystalline samples.  In particular, we would build on initial success in using diffraction contrast tomography to follow in 3-D and in the interior of polycrystals during superplastic flow the relative motion and neighbour grain switching events that must occur.

Also see homepages: Richard Todd Angus Wilkinson

Graphene based 2D nanoelectronics
Jamie Warner

Graphene has exceptional electronic properties, combined with a 2D structure that makes it attractive for a wide range of electronic applications. Other 2D crystals such as MoS2 and BN have similar 2D structure, but are semiconducting and insulating. This project will focus on the fabrication and characterization of nanoelectronic devices such as field effect transistors and ultrathin optoelectronic devices using 2D crystals. It will involve working in a clean-room environment using electron beam lithography to fabricate nanostructured electrodes and the patterning of graphene from the top down. The graphene and other 2D materials will be available within the group and are grown by chemical vapour deposition. The aim of this project is to solve processing and materials issues that currently limit the potential of 2D materials in electronics.

Also see homepages: Jamie Warner

Graphene electrodes for nanocrystal solar cells
Jamie Warner and Andrew Watt

Graphene is an ideal 2D material for utilization as a transparent conducting electrode in photovoltaics (solar cells). High efficiency photovoltaic devices will require the effective integration of other nanomaterials with graphene to produce hybrid nanosystems. Inorganic nanocrystals such as PbS, ZnSe, TiO2 and Si, have unique semiconducting properties with band gaps that span from the near-IR to UV. This project will focus on synthesizing inorganic nanocrystals using solution-phase chemistry. Control over the shape to tailor spherical, rod and branched structures will be investigated. Variation of surface state morphology will be conducted through various chemical approachs to control the inter-nanocrystal interactions. Synthetic graphene will be produced using chemical vapour deposition. Composite hybrid devices will be fabricated that use synthetic graphene as a working transparent conducting electrode and the inorganic nanocrystal as the active functional nanomaterial.

Also see homepages: Jamie Warner Andrew Watt

Graphene ribbons for nanoelectronics
Dr. A.A. Koos, Professor N. Grobert

Controlling the structure and hence properties of nanomaterials is essential for their successful implementation in devices. This project will focus on the generation of graphene ribbons and their detailed characterisation using state-of-the-art in-situ characterisation techniques.

Also see homepages: Nicole Grobert

Growth and spectroscopy of metallic nanocrystals and clusters
Professor Martin Castell

Nanometre sized metal islands on oxide supports are used in diverse applications from catalytic materials to gas sensors. Interaction between the oxide support and the islands, the island shape, the temperature dependence of island ripening, and molecular interactions with the islands are all active areas of study. In this DPhil project a variety of transition metal clusters on single crystal oxide supports will be investigated. The atomic structure of the nanocrystals will be imaged with scanning tunnelling microscopy, and their electronic structure will be probed using optical spectroscopies.

Also see homepages: Martin Castell

Hierarchical nanostructures for energy applications
Dr. F. Dillon, Dr. A.A. Koos, Professor N. Grobert

This project will aim to develop fast, facile, and inexpensive routes to manufacturing hierarchical inorganic nanostructures for energy applications. Various production techniques and combinations of these will be explored including hydrothermal methods, chemical vapour deposition techniques, and wet chemistry.

Also see homepages: Nicole Grobert

High Entropy Alloys for Nuclear Applications
David EJ Armstrong and Angus J Wilkinson

High entropy alloys are a relatively new and unexplored class of metallic alloys in which three to five elements are mixed in near equal proportions in a single phase solid solution. The high entropy of mixing suppresses phase separation and should lead to high strength retained to high temperatures. We have demonstrated that some of these alloys can have excellent resistance to radiation damage and as such they are garnering interest as potential future fuel cladding material for fission reactors or as a structural material for fusion reactors.
This project will aim to produce a low activation alloy suitable for nuclear fusion or fission application.  Elemental powder will be combined using arc melting to produce small quantities of test alloys. Microstructures stability will be studied using thermal treatments, X-ray diffraction and SEM-EDX and EBSD. Mechanical testing will be carried out across length scales and at reactor relevant temperatures, using both nanoindentation and macro-scale mechanical testing. This will for a fundamental study of deformation processes in this relatively new class of alloys. The most promising alloys will be ion irradiated to simulate neutron damage, with TEM and micromechanical testing used to study the effect of the irradiation on mechanical behaviour. This will then lead to an understanding of the irradiation resistance of these alloys. The project may be linked to the Fusion CDT and will also link with collaborators both in the UK and USA.

Also see homepages: Angus Wilkinson

High gas barrier layers for encapsulation of flexible electronics
Prof Hazel Assender

High performance transparent gas barrier layers are required for the encapsulation of air-sensitive elements of many flexible device technologies.  Recent experiments in our group have demonstrated the important role of nano-scale defects in the barrier layers that contribute to the overall transport of water vapour through the encapsulation.  This project will utilize our recent developments in Ca test characterization to better understand the transport of water vapour through layered structures under a range of temperature and humidity environments, exploring both the fundementals of what controls of water vapour transport in polymer and composite layered materials, and the key transport processes, linked with the materials microstructure, in novel composite films generated both within this project and from elsewhere.

Also see homepages: Hazel Assender

Hydrogen Passivation of Defect Engineered Silicon Solar Cells
Prof PR Wilshaw and Dr S Bonilla

In order to move to a low-carbon future, and avoid the worst effects of anthropogenic climate change, continuing reductions in the cost of renewable energy are required. The semiconductor group at Oxford Materials, in collaboration with international research partners at Fraunhofer ISE in Germany and the University of New South Wales in Australia as well as industry partners, is working to reduce the cost of photovoltaic cells. Graduate students would work as part of a dedicated group of researchers on state-of-the-art techniques for improving the performance of crystalline silicon solar cells, which account for over 90% of all currently manufactured solar cells. While multicrystalline silicon is currently the most cost effective material for the fabrication of solar cells, the high levels of defects and impurities present in this material limits the cell efficiencies that can be obtained. This is mostly through recombination of excited charge carriers at defect sites in the silicon bulk. The two most common approaches for reducing bulk recombination in crystalline silicon solar cells are defect engineering via gettering and hydrogen passivation. While both approaches are capable of reducing the recombination rate by more than an order of magnitude they are typically optimized separately. The graduate student would work in close collaboration with the world-leading hydrogen passivation group at the University of New South Wales to develop and apply hydrogen passivation techniques to defect engineered silicon. This would allow observation of how gettering techniques affect the ability of hydrogen to passivate the impurities remaining in the silicon and subsequently address optimization of both processing techniques.

Also see homepages: Peter Wilshaw

Image reconstruction techniques for super-reconstruction electron microscopy
A Kirkland

We are developing techniques for reconstructing the exit wavefunction of various specimens from images recorded with different focus values or with different illumination tilts. In this way it is possible to obtain fully quantitative structural data at higher resolution than the instrinsic limit set by the optics of the electron microscope. This project will apply this approach to a variety of nanomaterials with the aim of understanding their structure property relationships at higher spatial resolution than is otherwise possible.

Also see homepages: Angus Kirkland

Imperfect quantum technology: Finding applications for first generation quantum computers.
Prof S C Benjamin

Simon Benjamin has an ongoing theory project which uses conventional supercomputers to predict the behaviour of 1st generation quantum computers including their limitations and flaws. The aim is to find applications for these powerful but imperfect systems. While there is no specific earmarked studentship for this topic, Simon welcomes applications and he will explore funding options with successful applicant(s).
Regarding funding, note that applicants will be considered automatically for certain Oxford scholarships for which they are eligible. There is also the option to use our online 'funding search tool’ to identify any Oxford scholarships for which they are eligible and which require a separate application.

Background: Many research groups around the world are getting close to realizing the first generation of a profoundly powerful new class of technology: quantum computers. Building such a machine means learning to control qubits (quantum bits). Different approaches are being tried: qubits may be individual atoms, or nanostructures in diamond, or superconducting loops. But all have one thing in common: the control we can achieve is far lower than the control we have over bits in conventional computers. The first generation of quantum computers will therefore be imperfect, by comparison to our reliable conventional technologies, but they will still have the potential to be vastly more powerful. 

The project: Since 1st generation quantum computers will have imperfect qubits, therefore one must look for tasks that can be successfully performed even in the presence of small errors. A priority would be to study certain physical systems that Oxford experimentalists are working on, especially a hybrid matter-light networks, but the approach would also apply to pure optical processors, monolithic matter systems, and some alternative approaches such as the D-Wave systems. 

There is some interesting work from Oxford (e.g. Scientific Reports volume 6, article 32940 and arXiv:1611.09301) and various other groups worldwide (for one example, arXiv:1602.01857) which suggest that that indeed small errors are not a “show stopper” and thus we should be able to put first generation quantum computers to work on useful tasks. But much more work needs to be done here. 

We use conventional supercomputers, including the Oxford-based dedicated NQIT cluster operated by ARC which has a value of ~£600,000 to discover which of the many tasks that are suggested for quantum computers can in fact operate successfully in the presence of errors. The work will be tied closely to experimental teams in the UK and internationally so that there are opportunities to influence the design of emerging machines — if, for example, we discover that a particular task can work well providing that measurement errors are below a certain threshold, then this can inform the priorities for the experimental teams. 

This project would suit a student with a strong physics background who wants to work on a theory topic – someone who is interested in analytic “pen and paper” theoretical analysis as well as programming for numerical simulations on high powered computers. 

Also see homepages: Simon Benjamin

Improving melt cleanliness
K A Q O'Reilly

Most metals have, at some stage in their processing, been in the liquid state. Such metallic melts can be chemically dirty (containing impurities and dissolved gases) and physically dirty (containing unwanted hard particles, oxide films etc). It is now becoming accepted that the cleanliness of a melt can significantly influence the ease with which a melt can be handled and cast, and the properties of the final components into which it is made. This project will investigate the effect of melt cleanliness in Al alloys. Novel intrinsic and extrinsic methods will be developed, including chemical doping and thermal excursions of the melt, in order to improve melt cleanliness. Melt cleanliness will be measured in-house both directly in the melt and by investigating the effect on primary grain size and properties. The effectiveness of these novel methods will be compared to current industrial methods such as rotary flux degassing and filtration. The overall aim is to develop new methods for improving melt cleanliness which are both quicker and cheaper than existing technology, while being suitable for use on an industrial scale.

Grain refiner additions, impurity levels and melt cleanliness have all recently been shown to individually affect secondary intermetallic phase selection in Al alloys. In turn, the type, size and morphology of such intermetallics can significantly affect the ability to carry out downstream processing and the mechanical properties of final components. This project will investigate the effects of combining these and other factors (such as solidification conditions) in order to determine the dominant factors affecting intermetallic selection under more realistic, commercially relevant conditions.

Also see homepages: Keyna O'Reilly

Improving the resolving power of the scanning tunnelling microscope (STM)
Prof Martin Castell

A common method to increase the signal to noise ratio of a data set is to take repeated measurements and average them. This is routinely performed for 2D spectra, where their alignment is straightforward. However, for images the nature and variety of the distortions can severely complicate accurate registration. The usual way to treat images from a scanning tunneling microscope (STM) is to take multiple images of the same area and select the one that appears to be of the highest quality whilst discarding the information contained in the other almost identical images. In this project a step change in the resolving power of the STM will be achieved through automated multi-frame averaging (MFA). Our work so far has shown that images with sub 10 pm height resolution can be routinely obtained.

Also see homepages: Martin Castell

In Situ Full-Field Characterisation of Strain Concentrations (Slip Bands and Twins)
James Marrow

The intense localised deformation of twins and slip bands can be sufficient to initiate fracture, particularly in anisotropic metals such as zirconium, uranium and magnesium.  Microstructure-informed design of alloys with improved mechanical performance, using crystal plasticity modelling for instance, requires data on the intensity of these interactions.  It is now possible to quantify strain concentrations via finite-element based methods, applied to full-field analysis of elastic strain data (e.g. http://dx.doi.org/10.1016/j.prostr.2016.06.315 and http://dx.doi.org/10.1016/j.scriptamat.2017.06.053)

This project aims to develop and validate a high-resolution development of this analysis method, employing HR-EBSD data (High-resolution Electron BackScatter Diffraction) to measure the elastic strain field.  The initial studies will be conducted on the strain fields at blocked slip bands, twins and initiated cleavage cracks in a model material (age-hardened duplex stainless steel).  This material has been chosen due to its suitability for EBSD (ease of sample preparation) and well characterised slip/twinning behaviour that is caused by 475°C embrittlement.  The study will continue into further materials, particularly those relevent to nuclear energy in which irradiation damage can affect the deformation behaviour. 

This project is suitable for students with a materials, engineering or physics background.

Also see homepages: James Marrow

In situ studies of strain accommodation in MAX phase materials for advanced nuclear energy
James Marrow

MAX phases are 2D-layered hexagonal carbides or nitrides that can exhibit very high mechanical damage tolerance at high temperatures.  In common with ceramics, they are significantly less activated than metals by fast neutron irradiation.  Hence they have potential applications in structural applications for advanced nuclear fission.  However, the structure/property relationships and mechanisms of damage accumulation in MAX phases need to be better understood for microstructure-based modelling to support the design and development of materials and engineering components.

Strain mapping by both image analysis and diffraction has revolutionized studies of deformation in structural materials.  Together, they can provide excellent knowledge of both the elastic and plastic strain states within complex structures, which are internally “strain gauged” in three-dimensions with high spatial resolution.  Image correlation tools applied to tomographs can measure three-dimensional deformation and total strain states with high precision.  Diffraction analysis to measure elastic strains within bulk materials is also routine with neutrons and also on high energy synchrotron X-ray beam-lines.  

The project aims to use X-ray and neutron diffraction and imaging to map, in situ and in 3D, both the total and elastic strains under load and at elevated temperature, and thereby study the mechanisms of strain accommodation in bulk MAX phase materials for nuclear energy, with emphasis on the effects of strain history, microstructure texture and material heterogeneity, in order to improve material reliability and performance.

This project collaborates with SCK-CEN (Belgium) who are developing NbZr carbide and nitride MAX phases for nuclear applications in conjunction with the European Energy Research Alliance Joint Programme in Nuclear Materials that aims to develop materials for next generation sustainable nuclear energy.  Standard mechanical testing (including studies of irradiated materials) are being conducted by SCK-CEN, together with electron-microscopy microstructure characterisation by EBSD and TEM.

The project is suitable for students with a background in materials science, engineering or physics

Also see homepages: James Marrow

In situ, 3D characterisation of mechanical damage and functional behaviour in novel materials for satellite applications
Supervisors James Marrow

The challenges of designing innovative engineering components for space satellite applications requires the use of quite novel materials and processing. High reliability is essential, and these bespoke components with complex, heterogeneous structures must be developed and fabricated at an effective cost. This requires sound understanding of the mechanics of damage development, modelling tools that effectively simulate the microstructure with high fidelity, and experimental test methods that can inform and tune these models. This project will focus on three-dimensional imaging by X-ray computed tomography and quantitative measurement of deformation by digital volume correlation during in situ mechanical tests.

The aim is to improve data analysis methods to detect and characterise the onset of mechanical damage, and to develop multi-scale models of its effect on the mechanical and functional performance of the materials.  Emphasis will be placed on development of small scale test methods to calibrate these models, to allow their application under a wide range of thermo-mechanical loading conditions and histories. The project is in collaboration with Oxford Space Systems (https://oxford.space), and will consider a range of layered and composite materials for various applications.

The project is suitable for students with a background in engineering, materials science or physics.

Also see homepages: James Marrow

In-line patterning in vacuum roll-to-roll processing
Prof Hazel Assender

Vacuum deposition by roll-to-roll processing is attractive for some or all components of flexible functional materials and devices, but methods for in-vacuum deposition of patterned layers (i.e. coating only selected areas), using processes desirable for continuous high through-put processing, are less well developed than those based on ambient processing using solution deposition.  This project will explore one or more of various options for in-line patterning based on vacuum deposition, developing the process technique on our semi-industrial scale roll-to-roll procesing equipment and characterising the properties of the layers produced.

Also see homepages: Hazel Assender

Insulating and Semiconducting 2D crystals for electronic applications
Jamie Warner

Graphene is a semi-metal 2D crystal, Boron Nitride (BN) an insulating 2D crystal, and MoS2/WS2 are semiconducting 2D crystals. Realizing the potential of 2D crystals in electronic applications requires all 3 of these variants. We have undertaken years of research in growing graphene crystals by chemical vapour deposition and can now produce high quality materials. However, further improvement is needed to advance the synthesis of BN and MoS2/WS2 2D crystals to obtain similar quality films. In this project 2D crystals will be synthesized by chemical vapour deposition to produce materials with varying band structure. New synthetic strategies will be developed in order to produce large single crystal structures on a variety of substrates compatible with device processing. The atomic structure of the new 2D crystals will be characterized using advanced electron microscopy (scanning electron microscopy and transmission electron microscopy). The electronic properties of the new materials will be analysed by fabricating nanoelectronic devices such as transistors. This is a unique opportunity to undertake a project involving new materials synthesis, characterization of the atomic structure, and implementation in nanoelectronic transistor arrays. The project is well integrated into the group's goals by developing new 2D crystals that will have large up-take amongst other researchers for applications ranging from flexible electronics, pressure sensors, optical detectors, LEDs and solar cells.

Also see homepages: Jamie Warner

Integrating Inorganic Nanocrystals into Graphene Devices
Jamie Warner

Utilizing graphene in opto-electronic devices will require the effective integration of other nanomaterials to produce hybrid nanosystems. Inorganic nanocrystals such as PbS, ZnSe, TiO2 and Si, have unique semiconducting properties with band gaps that span from the near-IR to UV. This project will focus on synthesizing novel inorganic nanocrystals using solution-phase chemistry. Control over the shape to tailor spherical, rod and branched structures will be investigated. Variation of surface state morphology will be conducted through various chemical approachs to control the inter-nanocrystal interactions. Synthetic graphene will be produced using chemical vapour deposition. Composite hybrid devices will be fabricated that use synthetic graphene as a working transparent conducting electrode and the inorganic nanocrystal as the active functional nanomaterial. Viability in photodetectors and photo-catalysis will be explored.

Also see homepages: Jamie Warner

Investigation of atomic structures of bioactive glasses for biomedical applications
A I Kirkland / K Borisenko

Bioactive glasses play a key role in bone tissue engineering due to their ability to form strong bond with the living tissues . This is often related to the ability of such glasses to precipitate bone-compatible hydroxyapatite phasesat rhe surface. It is also  observed that their bioactivity can be modified by various additives or dopants. However, the mechanisms of the hydroxyapatite formation and the influence of dopants/additives and composition of the glass on  hydroxyapatite precipitation are poorly understood. This is in part related to the fact that there is no reliable experimental information on structures of such glasses. In the project we will study the atomic structures of various bioactive glasses prepared by different methods and containing different additives using advanced electron selected area and nanodiffraction, reduced density function (RDF) analysis, imaging and modelling methods.

Also see homepages: Angus Kirkland

Making and manipulating metal nanowires inside carbon nanotubes
Professor N. Grobert

Ferromagnetic nanowires have attracted much interest and are widely used across different disciplines, including biology and medicine. In preliminary experiments, ferromagnetic nanoparticles and -wires have proven to be highly efficient for manipulating nano- and micro-scale objects. Recently it has been shown that carbon nanotubes (CNTs) can be filled during growth with pure metals and alloys simply by varying catalyst concentration. The carbon coating prevents nanowire oxidation making them easy to handle.

This project is aimed at the production of metal-filled carbon nanotubes, their structural characterisation using state-of the art analytical electron microscopy. The project will be carried out in close collaboration with Professor Toru Maekawa (Bio-Nano Electronics Research Centre, Toyo University, Japan). The candidate will have the opportunity to interact with researchers based at the Bio-Nano Electronic Research Centre and will be participating at the 21st Century's Centre of Excellence Programme on Bioscience and Nanotechnology.

Also see homepages: Nicole Grobert

Manufacture, characterisation and properties of coatings for nuclear power applications
Prof Patrick Grant

Next generation fusion and fission reactors require a combination of neutron irradiation, temperature and corrosion resistance unavailable from current commercial alloys. Two coating approaches have emerged for materials use in these environments that will be explored in this project. First, to stabilise the microstructural features of alloys for use in fusion or fission applications (e.g. Cu, Fe and W based), such as grain size, a low fraction but very high number density of stable ceramic nano-particles are introduced, to form oxide dispersion strengthened (ODS) alloys. These particles are also effective in acting as sinks for vacancies and He formed by neutron damage, helping to prolong useful lifetime and properties. However, ODS alloys are expensive to manufacture into engineering structures and therefore we will explore the feasibility of applying ultra-thick (1 mm) ODS alloy coatings, using vacuum plasma spraying (VPS), as an alternative to bulk alloy manufacture. The second approach (which can be combined with the first) is to "armour" structural components, usually made from Cu or Fe based alloys just behind the first wall of fusion devices, with a low load carrying, sacrificial refractory metal (e.g. W) ultra-thick coating. Here the challenge is to manage the differential thermal expansion between coating and substrate during thermal cycling of the device, which will be addressed using micro-patterned or sculptured substrates. Large scale manufactriuring research will be combined with modelling of thermal stresses, microstructural characterisation and performance assessment.

Also see homepages: Patrick Grant

Manufacturing and characterization of new light weight alloys
M. Galano/ F. Audebert

The design of new light weight materials (Al and Mg based) is of extreme importance to industry due to the constant need to develop materials that combine high strength and light weight. This project is based on the development of new alloys systems by means of diverse rapid solidification techniques achieving cooling rates of 10 6 K/s. These rapid solidification techniques allow obtaining microstructures that combine several stable and metastable phases such as amorphous, quasicrystalline and crystalline phases opening wide range of alternative phases to be able to produce innovative light weight alloys for demanding applications. Materials are going to be characterised by X- Ray analysis, calorimetry and electron microscopy techniques. The evolution of the microstructure is going to be studied by means of heat treatments, structural characterisation and mechanical testing in order to understand the phase transformations and the potential properties for structural applications.

Also see homepages: Marina Galano

Mechanisms for the control of fatigue resistance of advanced lightweight nano-composites
James Marrow, Marina Galano, Fernando Audebert

This project is concerned with the role of microstructure in the fatigue resistance of novel high strength Light weight nanostructured alloys. A new family of rapid solidified alloys show good mechanical properties with combined high strength and low density, these alloys have the potential to be used in pistons in car engines and replace Ti-alloys in gas turbines; the consequent reduction in weight and inertial forces will reduce fuel consumption and increase power output.

Tests performed to data show these alloys have very good fatigue resistance, but there have been no fundamental studies to investigate the mechanisms for this; the hypothesis is that initiated fatigue cracks are arrested at interfaces between the matrix and reinforced zones.  If so, then the strain paths arising from process variations during forging may have a significant effect on microstructure and the local fatigue properties.  To study this, a range of microstructures of a nanostructured Al alloy obtained by different heat treatments and processing conditions  will be produced and tested to correlate fatigue crack initiation and growth with the microstructure; importantly the interactions between arrested fatigue cracks and local microstructure will be studied using advanced electron microscopy, including high resolution EBSD and TEM of FIB-milled selected regions, to develop mechanistic models for fatigue resistance.  The interactions between microstructure and crack propagation may also be studied by in situ high-resolution computed tomography (Marrow, T.J. et al (2014) http://dx.doi.org/10.1016/j.ijfatigue.2014.04.003).

The project is suitable for students with an engineering, physics or materials background and will involve techniques such as electron microscopy, materials processing digital image correlation, finite element modelling and computed X-ray tomography.

 

Also see homepages: Marina Galano James Marrow

Mesoscale investigations of Deformation Rate Effects in Metallic Crystals
David Armstrong and James Marrow

The objective of this project is to evaluate the response at the meso-scale (10-4m) of metallic crystals that are deformed at different strain rates that range from quasi-static to high rates (103 s-1). The evolution of the dislocation density and deformation mechanisms such as twinning will be characterised by high resolution Electron Back Scatter Diffraction (EBSD) and Transmission Electron Microscopy (TEM). Three-dimensional studies will be conducted, with emphasis on the interactions of dislocations with strengthening features such as precipitates, grain boundaries and defects in the crystal structure.

The deformations will be introduced primarily by nanoindentation, and will be carried out on metals with typical face centred cubic (FCC), body centred cubic (BCC) and hexagonal close packed (HCP) crystal structures, which are representative of engineering alloys. The data obtained will be used to validate and improve models for single crystal deformation, which are required for crystal plasticity simulation of polycrystalline materials.

The project is in collaboration with a nationally important industrial partner, and is most suited to graduates with a background in materials science, physics or engineering.

Also see homepages: David Armstrong James Marrow

Metal Nanowires for Optoelectronics
Andrew Watt

Transparent conductors are part of life from iPod touch screens to solar cells. Current technologies utilise doped metal oxides, however the constituent materials and processing method are expensive and not applicable to a wide range of substrates (eg plastics). This project will involve the synthesis of metal nanowire alloys, thin film processing on a variety of substrates, conductivity and mobility measurements along with physicochemical characterization eg XRD, SEM, XPS, TEM. The last stage of the project will be to apply the new materials in photovoltaic and LED devices.

Also see homepages: Andrew Watt

Micromechanical Testing of Irradiated Nuclear Fusion Materials
Dr David Armstrong, Dr Angus Wilkinson, Dr Edmund Tarleton, Oxford, Chris Hardie CCFE

Understanding how irradiation damage from neutrons affects the mechanical properties of structural materials is a key step towards realising nuclear fusion as a sustainable power source.  However working on irradiated materials is costly, and generating mechanical data from them is difficult. Neutron damage can be simulated with ion irradiations but the damage layers are thin -  200nm to 100µm. As such traditional mechanical testing methods cannot be used and novel micro-mechanical tests must be conducted. This leads to difficulties in interpreting the results due to size effects inherent in testing small material volumes.

This project will utilise the newly opened Materials Research Facility at the Culham Centre for Fusion Energy to study the effects of ion irradiation on fusion materials and correlate this with the defect populations produced. This will then be used to develop methods to use small scale mechanical tests to aid engineering design of future fusion systems. Materials of interest include chromium, vanadium and tungsten based alloys.

 

Ion irradiations will be carried out using protons and heavy ions at a range of international irradiation facilities, at fusion reactor relevant doses and temperatures. Advanced electron microscopy at the Department of Materials, University of Oxford will be used to characterise the damage and defect types produced. Micromechanical tests will be performed at the MRF to understand how these defects affect mechanical behaviour, such as fracture toughness, work hardening, and flow localisation. Tests conducted will include nano-indentation, micro-cantilever and compression tests and micro-scale tensile tests. Finite element modelling will be used to interpret the results. This work will be in close collaboration with a defect based modelling phd based at Oxford Materials, to fully understand the mechanisms which control deformation of irradiated materials. The student will be enrolled on the Fusion CDT and the project will involve significant periods of experimental work at the MRF at CCFE as well as work in the Oxford Materials Department.

Also see homepages: Edmund Tarleton

Microstructural control of Al alloys using intrinsic oxides
K O'Reilly

The world produces 37 million tons of Al every year. All of this metal will have grain refiner additions made to it to promote the nucleation of a fine primary Al grain size.
Oxide particles exist in nearly all liquid metals and alloys exposed to air or even under protective atmospheres. Oxide particles are often considered harmful inclusions since they reduce castability of alloy melts, deteriorate ductility and fatigue strength of castings and cause severe difficulties in down stream processing of continuous cast feedstock. As a result, considerable effort is expended to prevent oxide formation and to clean the melt by expensive melt filtering. However, recent research work at Brunel has demonstrated that by liquid metal engineering they can not only eliminate the harmful effects of the oxides but also make positive use of them for effective enhancement of nucleation for structural refinement of the Al grains, so reducing the need for grain refiner additions.
Work in Oxford has demonstrated that grain refiner additions not only nucleate the Al grains, but also control intermetallic selection in Al alloys, hence modifying mechanical properties. This project will investigate the potency of oxide particles for heterogeneous nucleation of intermetallics. The nucleation sequence of various intermetallic phases due to unavoidable oxides and their control will be studied during solidification of Al-alloys. A phase extraction technique will be used to facilitate the detailed characterisation of intermetallic phases and their interaction with extrinsic and intrinsic alloy additions. Special reference will be made to inclusions and impurity elements in recycled materials.

Also see homepages: Keyna O'Reilly

Microwave to optical conversion using molecular magnetic emitters
Dr L. Bogani /Dr E. A. Laird / Professor J. M. Smith / Professor G. A. D. Briggs

Future quantum systems will likely use several elements conceived with different strategies. These elements, such as photonic networks or superconducting circuits, typically operate at extremely different frequencies, and making them communicate is fundamental for integrated quantum devices. Even techniques to coherently connect remotely-located superconducting nodes would necessitate optical signals and is yet to be developed. This project will develop a coherent microwave-to-optical interface within hybrid quantum architectures for large scale distributed quantum computing. The platform will allow interfacing devices consisting of superconducting microwave resonators by coupling them to emitting spin centres. The resulting scheme will thus allow converting quantum information between two completely different regimes, GHz and optical, that are of crucial relevance for networking. The work will comprise the fabrication of nanodevices with superconducting and magnetic properties and their characterization at low temperatures. The thesis is strongly multidisciplinary and candidates from materials, chemistry and physics will be welcome. The work is developed in the context of an international collaboration, so different aspects can be privileged depending on the interests and attitude of the candidate. You will join an active and lively laboratory with an international atmosphere, and will be assisted in developing a personal vision and an autonomous scientific profile, as well as possible industrial links and scientific collaborations. Please refer directly to Dr. Lapo Bogani, Dr. Edward Laird, Prof. Jason Smith or Prof. Andrew Briggs for details.

Also see homepages: Lapo Bogani Andrew Briggs

Mimicking electronics with magnetic systems
L Bogani

In this DPhil project you will explore the possibilities opened by almost-perfectly one-dimensional systems, composed by metal chains ordered in a crystal. You will build on our previous expertise to create novel systems, where the usual properties of an electronic circuit (energy bands, capacitor etc…) are mimicked into a molecular spin system. This will produce the first spin analogues of nanoscale electronic devices, and will help establish the first tenets of a new area of research. The characterization will be developed using magnetometry and electron paramagnetic resonance spectroscopy at low temperatures and in magnetic field. The thesis is strongly multidisciplinary and candidates from materials, chemistry and physics will be welcome. The work is developed in the context of national and European collaborations, so different aspects can be privileged depending on the interests and attitude of the candidate. Visits and learning periods to international laboratories can also be arranged. You will join an active and lively laboratory with an international atmosphere, and will be assisted in developing a personal vision and an autonomous scientific profile, as well as possible industrial links and scientific collaborations. Please refer directly to Dr. Lapo Bogani for details.

Also see homepages: Lapo Bogani

Modeling of Micromechanical Testing of Irradiated Nuclear Fusion Materials
Edmund Tarleton, Angus Wilkinson, David Armstrong Oxford, Chris Hardie CCFE

Understanding how irradiation damage from neutrons affects the mechanical properties of structural materials is a key step towards realising nuclear fusion as a sustainable power source.  However working on irradiated materials is costly, and generating mechanical data from them is difficult. Neutron damage can be simulated with ion irradiations but the damage layers are thin -  200nm to 100µm. As such traditional mechanical testing methods cannot be used and novel micro-mechanical tests must be conducted. This leads to difficulties in interpreting the results due to size effects inherent in testing small material volumes.

This project will involve coding, debugging and performing simulations with state of the art computer models being developed in Oxford namely a coupled 3D (DDP) discrete dislocation plasticity / finite element code and a crystal plasticity finite element code (Abaqus UMAT) to simulate nano-indentation experiments. The experiments you will simulate are being performed at the Materials Research Facility at the Culham Centre for Fusion Energy to study the effects of ion irradiation on fusion materials and correlate this with the defect populations produced. The insight gained will then be used to develop methods to use small scale mechanical tests to aid engineering design of future fusion systems. Materials of interest include chromium, vanadium and tungsten based alloys.

 

Key challenges will be how to accelerate the code using a GPU, how to implement the correct traction/displacement boundary conditions, and how to incorporate complex geometry such as multiple precipitates. You will be part of a small team developing the codes and performing simulations and will also interact closely with experimental researchers at MRF at CCFE as well as work in the Oxford Materials Department and therefore will have access to rich data sets to validate and improve the model. The ultimate goal of the project is to be able to perform virtual experiments that reproduce real experiments and in doing so fully understand the mechanisms which control deformation of irradiated materials.

Also see homepages: David Armstrong Edmund Tarleton

Multi-component molecular crystals
Professor Martin Castell

The surfaces of a variety of nanostructured oxides can be used to order molecules, such as fullerenes (e.g. C60, C70), into specific two dimensional patterns. This is called templated molecular ordering. In this DPhil project fullerenes of different sizes will be mixed together to give rise to molecular alloys. Specific concentrations and relative sizes of fullerenes are thought to form ordered systems. The structure of these molecular alloy crystals will be studied at atomic resolution with scanning tunnelling microscopy. Ultimately the idea is to create molecular architectures that can be used in advanced electronic devices.

Also see homepages: Martin Castell

Nanocrystalline metal and metal oxide catalysts
A Kirkland

Nanocrystalline metal and metal oxide particles play a key role in catalysis. This project aims to characterize these materials, and in particular their surfaces and shapes using combinations of high resolution imaging and three dimensional tomographic reconstruction. The project will also involve interactions with theoretical modelling groups and for suitable systems prototype catalytic studies. 

Also see homepages: Angus Kirkland

Nanomaterials for quantum technologies
Professor G. A. D. Briggs, Professor K. Porfyrakis, Professor J. H. Warner and Dr E. A. Laird

Quantum information processing offers one of the most exciting challenges in the study and development of nanomaterials. It is at the cutting edge of quantum nanoelectronics, and Oxford is part of the world-wide endeavour to develop scalable quantum computers. Instead of classical bits of information, these will work with qubits (quantum bits). We need materials with quantum states that can be individually controlled and measured, and yet which are sufficiently robust against decoherence that they can sustain a sequence of quantum manipulations and interactions. We lead the world in using the new family of fullerene materials (popularly known as Bucky balls), which can be used to contain atomic species inside a cage that separates them from the environment. We can store the quantum information in an electron or nuclear spin, and exchange it between the two. We can manipulate and characterize the spin states by electron paramagnetic resonance and also optically. By creating entanglement between several spins, it is possible to develop sensors that exceed the standard quantum limit. A core thrust of our research is to incorporate molecular materials in working devices for practical quantum technologies. There will be several projects with these nanomaterials, ranging from synthesis and microscopy to experimental implementation of candidate schemes for quantum computing. The research is highly interdisciplinary, and there is scope for a range of skills and interests from materials science and chemistry to experimental quantum physics. There may be possibilities for industrial support and for international travel and collaboration.

Also see homepages: Andrew Briggs Kyriakos Porfyrakis Jamie Warner

Nanorobots for pick and place assembly of nano particles
H. Bhaskaran

We have an ambitious plan to deliver pick-and-place manufacturing at the nanoscale. To realize our ambitions, we are looking for a team member to pursue the doctorate on fundamental aspects of nanoscience, including the study of surface forces at the nanoscale and the ability to attract single nanoparticles reliably, and place them in a manner similar to automobile assembly - except this is at the nanoscale. This project is in close collaboration with Asylum Research of Santa Barbara USA, IBM Research - Zurich, Switzerland and the Microelectronics iNets with potential opportunities to travel to partner sites. 

The DPhil student working on this project will become an expert in advanced nanomanufacturing techniques, atomic force microscopy and nanoparticle assembly. All our projects allow for significant creative contributions and the right DPhil candidate will have the freedom to shape research directions.

Your Profile:
Your profile will be one of a highly motivated undergraduate (evidenced by previous stints in Research laboratories), first class honors degree (or equivalent) earning undergraduate in Physics, Materials, Engineering or a closely related field with a deep desire to carry out independent experimental research. You must like working on hands-on laboratory experiments and have the desire to try out many novel ideas. Evidence (via references) of initiative and ability to work collaboratively would be a plus, as this is an experimental project involving many collaborations.

Also see homepages: Harish Bhaskaran

Nanoscale patterning of graphene for electronic devices
J H Warner

One of the key challenges limiting 2D electronics is the ability to pattern features on the 10nm scale with high uniformity across a wafer. Field effect transistors comprised of graphene nanoribbons exhibit large on/off ratios only when their channel widths are sub-10nm. At this small size scale the structure of the edges plays a role in their transport properties. Developing methods to control the edge atomic structure is important and it will lead to uniform structures with tailored properties. This project aims to develop top-down lithographic approaches to achieving nanoscale structures in 2D sheets of graphene that are then incorporated into electronic devices. Graphene nanoribbon field effect transistors will be fabricated that are compatible with electron microscopy. Low-voltage aberration-corrected high resolution transmission electron microscopy will be used to characterize the atomic structure. The goal is to improve the performance of graphene nanoribbon field effect transistors by cleaning up the atomic disorder at the edges. Other methods to improve the atomic ordering at the edges such as Joule heating will be examined whilst inside the aberration-corrected HRTEM. The main focus of this project is to develop nanoscale patterning techniques that are scalable, rapid and provide uniformity across a large area.

Also see homepages: Jamie Warner

NanoSIMS analysis of nuclear materials
C R M Grovenor

The NanoSIMS is a very high resolution instrument for performing chemical analysis of dilute species and with an exceptional sensitivity for light elements.  The NanoSIMS group have developed novel techniques for the study of trace element distributions in zirconium fuel cladding alloys exposed to corrosion in isotopically labelled water in order to explore the fundamental mechanisms of hydrogen pick up in service.   This project will design and carry out experiments on both hydrogen pickup and the effect of water chemistry (Li and B in particular) on corosion processes on real ex-reactor materials provided by our project partners in Westinghouse and Canadian Nuclear Laboratories.  There will be opportunities for visiting both laboratories and to work closely with leading international nuclear companies.

Also see homepages: Chris Grovenor

Next generation of solid-state lithium batteries electrolytes
Prof M. Pasta

Rechargeable lithium-ion batteries have revolutionized the portable electronics industry because of their high energy density and efficiency. They may also prove valuable for a variety of other applications, including electrification of the transport system and grid-scale stationary energy storage. However, they still suffer from several significant safety and reliability issues, many of which are related to the use of electrolytes dissolved in organic solvent. Solid-state electrolytes could resolve all of these problems. However, most candidate materials have much lower ionic conductivity compared to that of liquid electrolytes, which reduces the power density of the cell and limits their practical applications. 

Prussian Blue analogues have recently demonstrated remarkable electrochemical performance that is enabled by rapid movement of ions through their open-framework crystal structure. 

The overarching goal of this project is to identify PBAs materials that function as a stable, high-power solid electrolyte for lithium-ion batteries. PBA materials have many tunable properties that affect their electronic and structural characteristics. In this project, the student will explore the effect of these parameters on the structural, electronic and electrochemical properties of PBA. Collaborations (both internal, external) are expected.

 

Also see homepages: Mauro Pasta

Nitride superconducting films for quantum device applications
S C Speller / C R M Grovenor

Many of the most exciting advances in quantum technologies rely on very high quality resonant circuits fabricated in superconducting materials. Simple Al or Nb films can be used, but many of the most impressive results have been achieved with nitride films as the superconducting material because they offer greater stability to atmospheric attack and oxidation and so are less lossy. Previous work on TiN films has shown that the stoichiometry uniformity, oxygen content, resistivity, texture and residual strain all have a significant impact on resonance performance, and that film uniformity over large areas will be an important issue in future more complex circuit designs. Although high quality VN and MoN thin films with excellent superconducting properties can be deposited, these materials have not been much tested for use in resonant circuits. The objective of this project is to explore a wider range of new superconducting compounds and alloys, (Nb,Mo,Ti,Re)N for example, for low loss resonant structures. The student, working closely with our industrial partners Oxford Instruments, will use the new thin film growth and characterisation facilities in the Centre for Applied Superconductivity (www.cfas.ox.ac.uk) to deposit and measure the properties of nitride thin films, and to assist in the testing of resonator performance with the quantum technology groups in both Physics and Materials Departments.

Also see homepages: Chris Grovenor Susannah Speller

NMR Crystallography: Exploring the use of J-couplings in Molecular Crystals
J Yates

Molecular crystals have a wide range of technological uses, from pharmaceuticals to electronic devices. Unfortunately, X-ray diffraction cannot always determine the structures of such materials. Solid-state NMR is an important technique for materials characterisation and could, in principle, be used for structure solution (so call 'NMR Crystallography'). However, there is no simple theory to link the observed NMR spectrum to the underlying atomic level structure (as Bragg's Law does for XRD).

In recent years we have developed computational techniques, based on quantum mechanics, to predict and interpret NMR spectra (see www.gipaw.net). Typically this has focused on the so-call NMR chemical shift, but, excitingly, it has recently become possible to both measure and compute the NMR J-coupling. J-coupling is an indirect interaction of the nuclear magnetic moments mediated by bonding electrons, and provides a direct measure of bond strength and a map of the connectivities of a system (hence its importance for crystallography).

The aim of this DPhil project is to study the nature of NMR J-coupling in molecular crystals - to interpret current experiments, understand the microscopic mechanisms, and guide the development of new experiments. The project is highly computational and will involve the use of large supercomputers, it may (optionally) include the development of new computational methods. The work will be carried out in close collaboration with experimental solid-state NMR studies performed in the group of Dr Steven Brown (University of Warwick).

Also see homepages: Jonathan Yates

Novel manufacturing routes for solid state batteries
Prof Patrick Grant

New ideas for manufacturing the electrodes used in solid state Li ion batteries will be investigated in order to produce improvements in one or more of energy density, power density, cycle life, safety and reduced cost. The research involves developing new ideas and equipment for layer-by-layer, 3D printing, patterning and other types of fabrication for the various parts of a solid-state battery, with each layer optimised for its specific function and location in the device. For example, using layer-by-layer processing to adjust the electrode microstructure progressively during fabrication to improve ion mobility from place to place in the electrode, and to reduce charge and discharge times for electric vehicle applications. The project will involve a combination of novel processing and equipment development, modelling of battery behaviour, detailed microstructural characterisation and energy storage measurements.

 

Also see homepages: Patrick Grant

Novel Photon Capture Methods for Multicrystalline Silicon
Prof PR Wilshaw and Dr S Bonilla

In order to move to a low-carbon future, and avoid the worst effects of anthropogenic climate change, continuing reductions in the cost of renewable energy are required. The semiconductor group at Oxford Materials, in collaboration with international research partners at Fraunhofer ISE in Germany and the University of New South Wales in Australia as well as industry partners, is working to reduce the cost of photovoltaic cells. Graduate students would work as part of a dedicated group of researchers on state-of-the-art techniques for improving the performance of crystalline silicon solar cells, which account for over 90% of all currently manufactured solar cells. Texturing of multicrystalline silicon wafers for solar cell production has been an ongoing concern for cell manufacturers. While anisotropic texturing of mono-crystalline silicon can reduce the weighted average reflection (WAR) of bare silicon to below 10%, most approaches on multicrystalline materials yield WAR’s in excess of 25%. Furthermore the traditional approach of using acidic etching solutions to preferentially attack defect sites is incompatible with new wafer sawing techniques. In this project the graduate student will develop novel texturing approaches for multicrystalline silicon. These techniques will be evaluated in collaboration with international research institutions and industrial partners including cell manufactures and wafer suppliers. If successful this technology will reduce the cost of solar electricity by realizing superior optical performance with a reduced cost of production.

Also see homepages: Peter Wilshaw

Novel routes to manufacturing layered inorganic nanomaterials
Dr. F. Dillon, Dr. R. Nicholls, Professor N. Grobert

Cabon nanotubes, have attracted increasingly more attention due to their outstanding properties in recent years. Concurrently, other 1D nanomaterials such as, inorganic nanowires and nanotubes of other layered materials, such as MoS2, WS2, BN, have been explored. Recently, new techniques for the precise structural control of WS2 nanomaterials were developed in house. Larger laboratory scale production, however, is still scarce and needs to be developed in order to make these novel nanomaterials viable for further characterisation, manipulation and application. This project will be focusing on the development of novel routes to inorganic 1D nanomaterials using chemical vapour deposition techniques. In this project the student will work closely with other members of the group and the samples produced by the student will be an integral part of a collaborative project with Dr Michael B Johnston (Department of Physics) and Dr Kylie Vincent (Department of Chemistry). It is envisaged to publish the findings in a peer reviewed journal and conference participation will be encouraged.

Also see homepages: Nicole Grobert

Optical Quantum Control of Molecular States
L. Bogani

Several drawbacks have plagued the field of molecular electronics, up to now. For example the molecules cannot be placed into junctions in a controlled and reproducible way. Thus no control over the mutual direction of the electron flow and the magnetization is achieved. Reproducibility of the measurements is a long-lasting problem in single-molecule electronics, and doubts over what is really measured sometimes arise. Moreover we have no idea on what is the effect of the electron flow on the magnetic properties of a molecule, while one can easily imagine that the passage of electrons will strongly affect the magnetic properties. In this DPhil thesis the candidate will develop a new, original method of measuring interaction between one single spin and one flowing electron: Instead of using two bulk electrodes and place the molecule in between, we will grow two photoactive groups on the two sides of the molecule. When a light pulse is shone on the system electron flow from one group to the other occurs, and the effect can be detected via pulsed at GHz frequencies. This allows overcoming all the aforementioned problems, providing the candidate with an insuperably clean, time-resolved method to investigate electron-spin interactions. The thesis is strongly multidisciplinary and candidates from materials, chemistry and physics will be welcome. The work is developed in the context of national and European collaborations, so different aspects can be privileged depending on the interests and attitude of the candidate. Visits and learning periods to international laboratories can also be arranged. You will join an active and lively laboratory with an international atmosphere, and will be assisted in developing a personal vision and an autonomous scientific profile, as well as possible industrial links and scientific collaborations. Please refer directly to Lapo Bogani for details.

Also see homepages: Lapo Bogani

Phase separation and self-ordering in thin film polymers
Prof Hazel Assender

The project will examine phase separation and self-ordering processes and morphological changes in thin film polymers, comparing the processes and kinetics in thin film systems with those in the bulk. The work will consider the effect of substrate interactions as well as processing characteristics on the resulting structures.

Also see homepages: Hazel Assender

Predictive first-principles calculations of electronic and optical properties of semiconductors at finite temperature
Prof F Giustino

Density functional theory (DFT) is widely recognised as an enabling tool in modern materials modelling and design. DFT and its improvements allow us to calculate the properties of materials at the atomic scale with predictive accuracy, starting from the first principles of Quantum Mechanics. These calculations are referred to as “ab initio” because they do not require any empirical parameters, such as measured materials properties, and rely exclusively on universal physical constants, for example the electron mass and charge, the Planck constant, and so on.

Despite the enormous success of DFT in materials science, the vast majority of current DFT calculations of the electronic and optical properties of crystals are performed by describing the ionic nuclei as classical point charges, immobile in their equilibrium crystallographic sites. This approximation neglects two important effects, namely that at finite temperature the ions vibrate around their equilibrium sites, and that even at zero temperature there is a residual motion arising from so-called quantum zero-point fluctuations. Several research groups are currently trying to overcome this important limitation of standard DFT calculations.

In our group we recently discovered a powerful new method to incorporate temperature effects and zero-point quantum fluctuations in DFT calculations of electronic band structures and optical properties [1]. Using this new technique we succeeded to calculate temperature-dependent optical absorption spectra and band structures of common semiconductors (e.g. silicon and gallium arsenide), and we obtained a remarkable agreement with experiments. This technique is still under development, and much work needs to be done in order to understand its full potential and its range of applicability.

In this DPhil project we will explore in greater detail the formal properties of this new methodology, and we will explore its applicability to a number of optical properties, for example two-photon optical absorption spectra, photoluminescence spectra, and phonon-assisted Auger spectra. Target materials will be standard semiconductors for the optoelectronic industry, as well as novel solar cell materials such as halide perovskites, and two-dimensional semiconductors such as transition-metal dichalcogenides.

The prospective student is expected to have a strong background in Solid State Physics and Quantum Mechanics, aptitude for mathematical models, and knowledge of at least one major programming or scripting language. Previous experience with density-functional theory calculations and familiarity with supercomputing clusters is desirable but not essential, as appropriate training will be provided as needed.

[1] M. Zacharias and F. Giustino, One-shot calculation of temperature-dependent optical spectra and phonon-induced band-gap renormalization, Phys. Rev. B 94, 075125 (2016).

[2] M. Zacharias, C. E. Patrick, and F. Giustino, Stochastic Approach to Phonon-Assisted Optical Absorption, Phys. Rev. Lett. 115, 177401 (2015).

[3] C. E. Patrick and F. Giustino, Quantum nuclear dynamics in the photophysics of diamondoids, Nat. Commun. 4, 2006 (2013)

Also see homepages: Feliciano Giustino

Probing the atomic scale structure and dynamics of energy materials
J Yates

The aim of this project is to develop and apply computational techniques to interpret solid-state NMR spectra of materials used in solid-oxide fuel cells and battery materials. Determining the local atomic structure and material function of such materials has proved challenging using convention (diffraction based) techniques, due to the presence of long-range disorder and ionic motion.

Solid-state NMR is a powerful probe of atomic scale structure and dynamics. However, there is no simple theory to link the observed NMR spectrum to the underlying atomic level structure (as Bragg's Law does for diffraction). In recent years we have developed computational techniques, based on quantum mechanics, to predict and interpret NMR spectra (see www.gipaw.net).

There are several possible routes for this project, depending on the student's interest - either focusing on applying existing techniques to novel problems, or developing new computational methodologies. There will be close collaboration with experimental NMR groups, both international and within the UK.

Also see homepages: Jonathan Yates

Putting the mechanics into quantum mechanics: creating superpositions of motion using vibrating carbon nanotubes
Dr E. A. Laird / Dr N. Ares / Professor G. A . D. Briggs

The quantum mechanics of microscopic objects such as atoms and spins is well established. But what about larger objects? Can we verify true quantum behaviour for these?

As a first step to answering this question, we plan to create and measure quantum superpositions of nanoscale mechanical devices. Although tiny by everyday standards, even the smallest fabricated device contains thousands of atoms. We will make use of suspended vibrating carbon nanotubes. These possess many attractive features for creating mechanical quantum superpositions, including low mass, large quantum level spacing, and comparatively large zero-point motion. Our goal is to carry out a foundational test of quantum mechanics – the Leggett-Garg test – that falsifies the hypothesis of classical behaviour in this device. This project will focus on creating and probing so-called “macroscopically distinct” superpositions, such as a superposition of zero and ten phonons in the same device. These challenging experiments on tiny devices are the first step on a long road to discovering whether quantum mechanics applies to macroscopic objects.

Also see homepages: Natalia Ares Andrew Briggs

Quantitative atomic resolution imaging
A Kirkland

Almost all structural information derived from High Resolution Electron Microscopy relies on qualitative matching of observed and calculated images. This project aims to investigate the fundamental reasons as to why the calculated and measured image contrast differs by significant amounts and to develop new quantitative approaches to image matching that can be applied to a range of structural problems.

Also see homepages: Angus Kirkland

Quantum confinement in oxide nanostructures
Professor Martin Castell

Crystalline oxides such as SrTiO3 have vast potential as a material to be integrated in the next generation of microelectronic devices. It has recently been discovered in Oxford that certain surface treatments of SrTiO3 produce atomic scale nanostructures by subtly changing the ratio of Ti to Sr in the surface region. The aim of this DPhil project is to investigate the quantum confinement of electrons in these nanostructures, similar to the particle in a box problem in elementary quantum mechanics. Atomic resolution scanning tunneling microscopy will be used to determine the size and distribution of the nanostructures, and spectroscopy techniques will show the degree of quantum confinement. For this research a new state of the art microscopy/spectroscopy facility is available.

Also see homepages: Martin Castell

Quantum crystallography using electron ptychography
Prof P D Nellist, Dr R J Nicholls, Prof J R Yates

Electron ptychography is a newly available mode of imaging in the transmission electron microscope that is somewhat related to holography and can provide very precise measurements of the electrostatic potential in a crystal.  Recent work in Oxford has shown that it can provide a measurement of the charge transfer between boron and nitrogen in a hexagonal boron nitride monolayer. This work demonstrates the potential of ptychography for measuring the effect of bonding on wavefunctions and charge densities in crystals – a field now known as quantum crystallography.  The aim of this work is to develop this method to measure the effects of bonding in a range of different materials, such as compound nanomaterials and transition metal oxides.  It will involve developing the experimental and data processing approaches, and developing methods based on density functional theory modelling to interpret the experimental data.  Projects are available that have either a more experimental emphasis applying the method to a range of materials, or a greater emphasis on developing the theoretical modelling methods to improve how the experimental results can be interpreted.

Also see homepages: Peter Nellist Rebecca Nicholls Jonathan Yates

Quantum interference in single-molecule devices
Dr J. A. Mol, Professor G. A. D. Briggs and Professor H. L. Anderson*

Quantum interference offers a rich resource which could be exploited in molecular devices. If there are multiple pathways for energy transport through a molecule, or if electrical transport is subject to resonances within a molecule, then these effects could be exploited for practical technologies. For example, it may be possible to make transistors with much lower power consumption than current silicon CMOS, and it may be possible to develop improvement of thermovoltaic materials for scavenging heat that would otherwise be wasted. Understanding such phenomena may also shed light on postulated quantum coherent processes in biology, ranging from photosynthesis to bird navigation.

The project will require nanofabrication of carbon-based devices into which individual molecules can be inserted. The current through the molecules will be measured with a view to discovering mechanisms of quantum interference. A major challenge will be to devise and fabricate geometries with additional gates to control the quantum interference. The project will involve nanofabrication, chemical attachment of the molecules, and electrical measurements over a range of temperatures and frequencies, with especial regard to discovering the conditions under which quantum coherence can be found. A successful outcome will be to find regimes in which quantum coherence gives enhanced device performance.

* Department of Chemistry

Also see homepages: Andrew Briggs Jan Mol

Quantum theory and predictive computational modelling of carrier transport in two-dimensional materials
Prof F Giustino

One of the fundamental properties of semiconductors is their ability to sustain an electric current upon the application of an external electric field. The proportionality coefficient between the drift velocity of charge carriers and the applied field is called the carrier mobility, and is a key design parameter in every opto-electronic device, from transistors to light-emitting diodes, lasers, photo-detectors, and solar cells. For example the mobility sets the maximum theoretical switching speed of CMOS transistors, and ultimately tells us how fast a CPU can go.

Understanding mobilities at the atomic scale within the framework of Quantum Mechanics is challenging, because calculating this parameters requires a detailed knowledge of the electronic and vibrational properties of solids [1]. Very recently it has become possible to calculate carrier mobilities entirely ab initio, that is starting essentially from the Schrödinger equation, and without using any empirical parameters. In our group we have developed a cutting-edge computer code, EPW (epw.org.uk) that can now calculate carrier mobilities from first principles [2]. This code is distributed with the Quantum Espresso materials simulation suite (www.quantum-espresso.org).

In this DPhil project we are interested in applying these recent developments in algorithms and software to investigate electron and hole mobilities in two-dimensional materials. Target compounds include transition-metal dichalcogenide monolayers, silicene, phosphorene, and their heterostructures. The aim of the project is to establish the predictive power of our methods via direct comparison to experiments, and to design artificial heterostructures with superior electrical transport properties. Our group is the Oxford partner of the Graphene Flagship consortium, and close interactions with leading experimental groups working on two-dimensional materials are anticipated.

The prospective student is expected to have a strong background in Solid State Physics and Quantum Mechanics, aptitude for mathematical models, and knowledge of at least one major programming or scripting language. Previous experience with density-functional theory calculations and familiarity with supercomputing clusters is desirable but not essential, as appropriate training will be provided as needed. 

[1] F. Giustino, Electron-phonon interactions from first principles, Rev. Mod. Phys. 89, 015003 (2017).

[2] S. Poncé, E.R. Margine, C. Verdi and F. Giustino, EPW: Electron–phonon coupling, transport and superconducting properties using maximally localized Wannier functions, Comput. Phys. Commun. 209, 116 (2016).

 

Also see homepages: Feliciano Giustino

Recycling of Al alloys
K A Q O'Reilly

Reducing energy use is a major component of the UK’s policy for meeting its CO2 emission targets. Vehicle lightweighting, by replacing steel components with light alloy castings and wrought components, has been identified as one of the technologies with the greatest potential to contribute to this goal. Aluminium alloys are hence being used by the automotive and aerospace sectors. However, these industries are currently using primary grade aluminium, as recycled materials do not give adequate mechanical properties.  
A recent life cycle assessment for the Al industry showed that the production of 1kg of primary Al, when all the electricity generation and transmission losses were included, required 45kWh of energy and emitted 12kg CO2, whereas 1 kg of recycled Al required only 2.8kWh (5%) energy and emitted 0.6kg (5%) of CO2. Hence the use of recycled materials would considerably reduce the carbon footprint.
This project will investigate the ability of melt conditioning to improve the mechanical performance of recycled materials. Melt conditioning is defined as treatment of liquid metals by either chemical or physical means for the purpose of enhancing heterogeneous nucleation through manipulation of the chemical and physical nature of both intrinsic (naturally occurring) and extrinsic (externally added) nucleating particles prior to solidification processing. A prime aim of melt conditioning is to produce solidified metallic materials with fine and uniform microstructure, uniform composition and minimised cast defects and hence good mechanical properties.

Also see homepages: Keyna O'Reilly

Self-ordering in peptide thin films
Prof Hazel Assender

Peptides, typically 8 or 9 amino acid sequences long, can self-organise into helical and fibrillar structures, depending on the particular amino acid sequence. This of interest for a variety of hydrogel technologies for example.  The self ordering process is highly dependant on the charge on the amino acid sequences and hence the pH and salt concentration of the solution. Thus, when making thin films, the properties of the surface on which the film is cast and the drying process will also affect the resulting morphology and properties.  This project will seek to take a rather fundemental survey of these processes to better understand peptide ordering and hence how hydrogels can be tailed for materials properties both in the bulk and as thin films on a substrate.

Also see homepages: Hazel Assender

Sensing, characterisation and manipulation at the nanoscale using optical microcavities
Prof Jason Smith and Dr Aurelien Trichet

Optical sensing and spectroscopy are powerful tools for detecting and characterising nanoparticles at the single particle level. Pollutants and aerosols or microbiological organisms such as viruses have characteristic optical signatures based on their refractive index, size, and polarisability as well as spectral signatures that allow them to be identified and studied. This project will develop novel optical microcavities as means of confining light such that its interaction with nanoparticles is both strengthened and highly controlled. These microcavities show great potential for the trapping and manipulation of particles, and for particle identification using refractive index and spectroscopic methods. The project will involve fabrication of cavity devices and using them to perform some foundational experiments in this area. The student project is part of a larger effort within the group, in collaboration with Dr Claire Vallance in the Department of Chemistry. 

Also see homepages: Jason Smith

Sensor Technology Based on Large Area Synthetic Graphene
Jamie Warner

Sensor technology, such as touch screen displays and pressure/strain sensors, will be developed using graphene. The graphene will be synthetic and of large area, produced using metal catalyst assisted chemical vapour deposition. Processing methods for transferring the graphene onto transparent flexible polymer substrates will be developed. This project aims at bringing graphene into application and will utilize recent advances within the group for producing outstanding synthetic graphene material. Optical and electron beam lithography will be used to pattern the graphene and metal electrodes for devices. Interfacing with computer hardware will be undertaken to achieve functioning sensor technology.

Also see homepages: Jamie Warner

Silicon quantum electronics
Dr J. A. Mol and Professor G. A. D. Briggs

Quantum information embodied in spins in silicon can be manipulated very precisely, and can persist for over three hours. Quantum computers made from silicon materials would benefit from the great industrial development of silicon processing and nanofabrication. Much of previous research in silicon for quantum computing has used donor impurities in bulk crystals. The great challenges now are to learn how to measure the states and control the interactions of a small numbers of spins in silicon. This project will seek to develop control techniques that will be sufficiently precise to allow fault-tolerant error-correction in silicon devices with small numbers of spins. Scalable quantum technologies will need to meet and surpass certain accuracy thresholds to demonstrate quantum error correction. The goal of the project will be to exceed these thresholds using impurity and quantum dot spins in silicon devices. For this you will investigate magnetic resonance in both many-spin and single-spin regimes. You will need to have, or to acquire early in the project, good knowledge of physics, magnetic resonance, quantum information, and semiconductor materials.

Also see homepages: Andrew Briggs Jan Mol

Spectroscopy and device applications of monolayer semiconductors coupled to optical microcavities
Prof Jamie Warner, Prof Jason Smith

Monolayer semiconductor materials such as WS2 and MoSe2 display strong optical transitions that are attractive for nanoscale optoelectronic devices. These properties can be both enhanced and harnessed by coupling the materials to optical microcavities, opening possibilities for fast optical switches, ultra-low threshold lasers, and advanced quantum light sources. This project brings together the expertise of two leading research groups in 2D materials (Prof Jamie Warner) and in microcavity photonics (Prof Jason Smith). The project will build on some preliminary work which provides first demonstrations of basic phenomena, and will develop the experiments further to investigate ‘strong coupling’ (ie the creation of polaritons - part electronic excitation, part photon) and the switching of polariton states to realise ambient temperature devices.

Also see homepages: Jason Smith Jamie Warner

Sputtered thin film electrodes for new battery designs
Supervisors: Professors Susannah Speller and Chris Grovenor

Rechargeable lithium-ion batteries have revolutionized the portable electronics industry because of their high energy density and efficiency, and are being widely deployed in electric vehicles. However, they suffer from significant safety and reliability issues, many of which are related to the use of flammable liquid electrolytes. There is a world-wide race to design and manufacture solid-state electrolyte materials that could resolve these problems.  Candidate Li+ ion conducting garnets like Li7La3Zr2O12 have lower conductivities than liquid electrolytes, but show promise for use in prototype all solid-state battery designs if the thickness of the electrolyte can be reduced.  However, a reliable growth process will have to be designed to give the necessary uniformity and electrochemical performance in thin films of these complex oxides.

This project will explore the deposition of Li-garnet thin films by both pulsed laser deposition and magnetron sputtering.  The influence of the deposition parameters on the phase, microstructure and mechanical properties of the films will be studied using XRD, electron microscopy and nano-indentation techniques to establish the optimised growth conditions and to compare the potential of the two deposition techniques.  The electrochemical performance of promising films will be measured in collaboration with the Pasta battery group in the department.  This project will be part of Oxford’s contribution to the UK Faraday Institution, and will give the student the opportunity to interact with this new national battery institute. 

Also see homepages: Chris Grovenor

Stabilization of world record surface passivation for high efficiency silicon solar cells
Supervisors Prof PR Wilshaw and Dr S Bonilla

In order to move to a low-carbon future, and avoid the worst effects of anthropogenic climate change, continuing reductions in the cost of renewable energy are required. The semiconductor group at Oxford Materials, in collaboration with international research partners at Fraunhofer ISE in Germany and the University of New South Wales in Australia as well as industry partners, is working to reduce the cost of photovoltaic cells. Graduate students would work as part of a dedicated group of researchers on state-of-the-art techniques for improving the performance of crystalline silicon solar cells, which account for over 90% of all currently manufactured solar cells.

Efficiency in the most advanced silicon solar cells is limited by recombination of photo-excited electron-hole pairs at surfaces and interfaces. Future generations of industrial high efficiency solar cells will require cost effective techniques for producing semiconductor/dielectric interfaces with very low rates of recombination. The process of creating these low recombination interfaces is known as surface passivation and its development is critical to the next generation solar cells. Existing work in the semiconductor group has produced record breaking surface passivation using charge extrinsically added to dielectric coatings. The problem, however, is that the passivation produced is not stable over a period of years as required for solar cells in the field. This project aims to develop new techniques that will stabilise the charge in dielectrics to produce superior and industrially relevant passivation of silicon surfaces.

The student performing the work will be involved in cleanroom processing and dielectric characterisation using electronic and optical techniques. They will have the opportunity to apply the passivation techniques to the most advanced silicon solar cell structures developed by research institutions around the world.

Also see homepages: Peter Wilshaw

Strains Induced by Hydride Formation in Zirconium
Prof Angus J Wilkinson, Dr Ed Tarleton, and Dr David E J Armstrong

In service temperature cycling of nuclear fuel cladding can lead to repeated sequences of precipitation and dissolution of hydrides in zirconium based alloys. During the transformation from hydrogen in solid solution to the hydride phase there is a considerable volume expansion. This project will explore the links between nucleation sites, hysteresis between temperatures for precipitation and dissolution, the stress field and local plasticity induced by the transformation strain and the precipitation morphology. The following techniques will be used: high resolution EBSD, digital image correlation of SEM images, in situ thermal cycling, finite element based-crystal plasticity simulations. This project will be carried out in close conjunction with Rolls Royce and other partner Universities within the HexMat flagship EPSRC programme (http://www3.imperial.ac.uk/hexmat).

Also see homepages: David Armstrong Edmund Tarleton Angus Wilkinson

Structural anisotropy properties correlations in materials for electronics and photonics
A Kirkland / K Borisenko

Chalcogenide phase change memory materials (for example, Ge2Sb2Te5, GST) find applications as electronic memory storage materials. In these materials the phase change, and therefore information storage, can be initiated by laser or electric pulses. It has recently been suggested that by using polarised light to initiate the phase change it may be possible to control the  anisotropic structures. In GST materials this could add an extra parameter  to increase the fundamental storage density. In the project we will prepare new chalcogenide-based phase-change memory materials with dopants that are likely to induce anisotropic properties and study their atomic structures .  The project will also involve measurements of the optical and electric properties of the prepared materials and the building of computed models describing structure – property correlations. The project will involve electron micrsoscopy, computer modelling and studies at the Diamond Synchrotron.

Also see homepages: Angus Kirkland

Structural studies of Graphene and other 2D crystals with single atom sensitivity
Jamie Warner, Angus Kirkland

Graphene is a 2D crystal only one atom thick and is ideal for studying individual atoms by transmission electron microscopy. This project will focus on understanding fundamental crystal defects in graphene and other 2D crystals such as boron nitride, MoS2 and WS2. Mono-vacancies and the other non-6 member ring structures that exist in the unique 2D crystal. It will also investigate the grain boundary interface between two graphene domains with the aim of mapping out the unique atomic stitching that occurs. Graphene will be grown by chemical vapour deposition. This project will use Oxford's state-of-the-art aberration-corrected high resolution transmission electron microscope, equipped with a monochromator for the electron beam to give unprecedent spatial resolution at a low accelerating voltage of 80 kV. Advanced image analysis techniques, including exit-wave reconstruction, and comparison to image simulations will be utilized for a deeper understanding of the atomic structure.

Also see homepages: Angus Kirkland Jamie Warner

Studies of rapid phase-change and resistive memory materials for information storage
Professor A I Kirkland / Dr K Borisenko

Phase change memory materials based on chalcogenide alloys and resistive memory materials based on metal oxides are an important class of industrial materials, which find applications in electronic storage and rewritable memory. The operation of phase-change memory is based on fast and reversible phase transformation between amorphous and crystalline forms which have different properties. Similarly, resistive memory operates by transition between states that have different resistivities. Despite their wide commercial applications the exact mechanism describing fast phase transitions or resistance changes remains unclear. To understand the ways in which performance of memory devises using such materials can be improved, accurate structure properties correlations are required. The project will involve preparation of new phase change and resistive memory materials and investigation of their atomic structures using advanced diffraction and imaging techniques as well as theoretical simulations. The electric and optical properties of the materials will be also measured and correlated with their structures

Also see homepages: Angus Kirkland

Surface structure characterisation of iron-based superconductors and topological insulators
Dr Susannah Speller/Professor Martin Castell

The unexpected discovery in 2008 of a new family of superconductors based on iron promises to lead to substantial progress in understanding the elusive mechanisms responsible for high-temperature superconductivity. However, worldwide efforts to understand the fundamental properties using a wide variety of experimental techniques have so far proved to be inconclusive and contradictory due to the lack of detailed understanding of the complex microstructures of even the best single crystal samples. This project involves using Scanning Tunnelling Microscopy (STM) to investigate the surface structure with atomic resolution in combination with High-Resolution Electron Backscatter Diffraction analysis for mapping local structural variations on the micron-scale.

Iron-based superconductors are only one of several novel quantum state materials of great interest in the scientific community. Another 'hot topic' are the so-called topological insulators, which exhibit bulk insulating properties with special conducting surface states, promising dissipation-less carrier transport at room temperature. There are a wide range of potential applications for these exciting new materials including dramatically faster, almost powerless computer chips. The experimental techniques developed in this project are ideally suited to studying the distribution of ferromagnetic additions needed to exploit the exciting properties of topological insulators in practical devices.

Also see homepages: Martin Castell

Synthesis and characterization of novel magnetic materials
L. Bogani / J. Le Roy / Prof. H. Anderson

The field of molecular magnetism is a playground where the desired functionalities can be inserted into magnetic materials by rationally tuning the molecular systems, using chemical synthesis. In this project you will play with the chemical possibilities of coordination chemistry compounds, creating molecular and extended structures with novel spin properties, long coherence times and an admixture of electronic and magnetic properties. The materials will be tailored by changing the topology, by introducing novel functionalities (e.g. pi-stacking groups, luminescent elements, etc…) and will be the basis for an in-depth exploration with electron paramagnetic resonance, magnetometry, and conduction experiments. Special attention will be placed on the quantum properties of the magnetic nanomaterials, and their inclusion into functional nanodevices. The thesis is rather synthesis (+characterization) oriented and suitable candidates from materials or chemistry background. The work is developed in the context of national and European collaborations, so different aspects can be privileged depending on the interests and attitude of the candidate. Visits and learning periods to international laboratories can also be arranged. You will join an active and lively laboratory with an international atmosphere, and will be assisted in developing a personal vision and an autonomous scientific profile, as well as possible industrial links and scientific collaborations. Please refer directly to Dr. Lapo Bogani for details.

Also see homepages: Lapo Bogani

Synthesis of large area graphene sheets using chemical vapour deposition
J H Warner

The 2D crystalline nature of graphene makes it suitable for large area transparent conducting electrodes. Recent advances in chemical vapour deposition (CVD) methods now permit a route to making large area sheets. This project will focus on understanding the growth mechanisms behind CVD grown graphene and then developing approaches to improve the atomic structure and electronic properties. Insights into the structure will be gained using atomic-resolution imaging with low-voltage aberration-corrected high resolution transmission electron microscopy. Techniques to transfer the sheets to transparent substrates, such as glass or flexible polymers will be examined and the sheet resistance determined. Methods to incorporate dopants into the CVD growth process will be pursued with the aim of improving conductivity. Controlling the number of graphene layers grown by CVD will be investigated.

Also see homepages: Jamie Warner

Tailored nanocrystal catalysts
Professor Martin Castell

Currently, industrial catalyst nanoparticles used for pollution control and chemical processing are randomly dispersed on their supports with a large variety of sizes and shapes. Within this multi-billion pound industry the main research driver is to find ways of increasing the catalytic efficiency of the precious metals used such as Pt, Pd, and Rh, or increasingly alloys of various metals. One method is to increase the surface to volume ratio of the particles, and much effort has been directed towards that goal. Another method, proposed here, is to recognise that the crystal facets of the catalyst particles all have different chemical properties. This means that highly efficient catalysts can be created by synthesising particles with particularly large fractions of highly active crystal facets. One of the central aims of this project is to develop new processing routes to allow large-scale manufacture of shape and size selected metal and oxide nanoparticles with high catalytic efficiency. The project will also involve the synthesis of core-shell nanocatalysts. Characterisation of the catalyst particles will be carried mainly with scannning tunnelling microscopy.

Also see homepages: Martin Castell

Three dimensional characterisation of CdTe solar cells
Supervisor: C R M Grovenor

More than 10 GW of installed solar cell capacity worldwide is based on thin film CdTe rather than the more well-known polycrystalline Si cells.   The microstructure and chemistry of CdTe cells is very complicated, and the cell performance is controlled by the 3D distribution of passivation and doping elements, often at very low concentrations.  We have recently shown that high resolution SIMS analysis can provide unique information on the distribution of key elements in these solar cell structures, and, when combined with results from other state of the art techniques, can provide the fundamental understanding needed to help design cells with improved performance.  This project will use our NanoSIMS instrument for the analysis of the 3D chemistry in prototype and commercial CdTe solar cells, including defining the analytical limits for dopant profiling and how variations in process variables can influence nanoscale chemistry and hence device performance.  The project student will work closely with the Centre for Renewable Energy Systems Technology (CREST) at Loughborough University and their collaborators at Colorado State University in the USA, and become an expert in advanced SIMS analysis techniques.  Please contact Professor Chris Grovenor for more information.

Also see homepages: Chris Grovenor

Three projects on the materials chemistry and electrochemistry of batteries: lithium-air, all solid state lithium and sodium-ion batteries
Prof Peter G Bruce (Wolfson Chair in Materials, Departments of Materials and Chemistry)

1. The materials chemistry and electrochemistry of the lithium-air battery

Energy storage represents one of the major scientific challenges of our time. Pioneering work in Oxford in the 1980s led to the introduction of the lithium-ion battery and the subsequent portable electronics revolution (iPad, mobile phone).

Theoretically the Li-air battery can store more energy than any other device, as such it could revolutionise energy storage. The challenge is to understand the electrochemistry and materials chemistry of the Li-air battery and by advancing the science unlock the door to a practical device. The Li-air battery consists of a lithium metal negative electrode and a porous positive electrode, separated by an organic electrolyte. On discharge, at the positive electrode, O2 is reduced to O22- forming solid Li2O2, which is oxidised on subsequent charging. It is the organic analogue of the oxygen reduction/oxygen evolution reaction in aqueous electrochemistry. The project will involve understanding the electrochemistry of O2 reduction in Li+ containing organic electrolytes to form Li2O2 and its reversal on charging. The use for redox mediators to facilitate the O2 reduction and evolution. The exploration of new electrolyte solutions and their influence of the reversibility of the reaction. The project will use a range of electrochemical, spectroscopic (Raman, FTIR, XPS, in situ mass spec.) and microscopic (AFM, TEM) methods to determine the mechanism of O2 reduction (presence and nature of intermediates e.g. superoxide) and its kinetics. Our aim is not to build devices but to understand the underlying science. We seek highly qualified, ambitious, imaginative, hard-working and self-motivated candidates. Further details may be obtained by contacting simultaneously Dr Lee Johnson at lee.johnson@materials.ox.ac.uk and Zsofia Lazar at zsofia.lazar@materials.ox.ac.uk.

2. Challenges facing all-solid-state batteries

There is increasing worldwide motivation to research and develop all-solid-state batteries in order to achieve better safety, higher energy density, as well as wider operating temperature energy storages, as compared to conventional Li-ion batteries using liquid electrolytes. All solid state batteries consist of a solid electrolyte as the main component, an intercalation cathode, e.g. LiCoO2, and an anode with the ultimate goal of implementing a lithium metal anode. The project will involve advancing the fundamental understanding from material to cell level. Synthesis of new Li+ conducting solid electrolytes and characterisation of their structural, electrochemical, electrical, and mechanical properties will be required. The work will include investigation of phenomena at solid electrode/solid electrolyte interfaces, something that is central to progressing solid state batteries but is not well understood, e.g. charge transfer, parasitic reactions, occurring at the interfaces of the electrolytes with both cathodes and anodes. Further parameters affecting the cycleability of the all-solid-state batteries will need to be identified. A range of characterisation techniques will be used, including X-ray and neutron diffraction, electron microscopy, NMR, Raman and IR spectroscopy, X-ray tomography, as well as several electrochemical techniques such as EIS and cycling. We seek highly qualified, ambitious, imaginative, hard-working and self-motivated candidates. Further details may be obtained by contacting simultaneously Dr Christian Kuss at  christian.kuss@materials.ox.ac.uk and Zsofia Lazar at zsofia.lazar@materials.ox.ac.uk.

3. The materials chemistry and electrochemistry of lithium and sodium-ion batteries

Lithium-ion batteries have revolutionised portable electronics and are now used in electric vehicles. However new generations are required for future applications in transport and storing electricity from renewable sources (wind, wave, solar). Such advances are vital to mitigating climate change. Sodium is more abundant than lithium and so attractive especially for applications on the electricity grid. Lithium and sodium ion batteries both consist of intercalation compounds as the negative and positive electrodes. The charge and discharge involves shuttling Li+ or Na+ ions between the two intercalation hosts (electrodes) across the electrolyte. In the case of Li-ion batteries currently the most common technology is still graphite (anode) and LiCoO2 (cathode). However, the development of increased energy storage in Li ion systems drives research to discover new materials. In the case of Na-ion batteries whilst the principles are analogous to that of the Li-ion battery, as yet there are no preferred candidates as electrodes, which provides excellent motivation for further work.

The project will involve synthesising and characterising a number of Na/Li containing transition metal oxides. This will utilise synthesis methods such as sol-gel, hydrothermal and solid state, characterisation will involve X-ray and Neutron diffraction, solid state NMR, XPS, FTIR, TEM and SEM. Additionally it is important to understand the processes at the interfaces between the intercalation oxides and the organic electrolyte. For such the interfacial studies FTIR, Raman, in situ mass spec and XPS will be the main techniques. We seek highly qualified, ambitious, imaginative, hard-working and self-motivated candidates. Further details may be obtained by contacting simultaneously Dr Christian Kuss at christian.kuss@materials.ox.ac.uk and Zsofia Lazar at zsofia.lazar@materials.ox.ac.uk.

Also see homepages: Peter Bruce

Three-Dimensional Deformation and Fracture Mechanics
James Marrow

The mechanical properties and fracture resistance of engineering materials are measured using standard test specimens; real cracks and engineering components are three-dimensional and more complex, so approximations and adjustments are needed to reliably assess their structural integrity.  There is also an increasing need to miniaturized test specimens, to monitor the degradation of structural material properties in fission and fusion energy generating power plants.  Material properties can be extracted from small volumes by indentation tests, but generally we have no knowledge of what actually happens under the surface, and this requires assumptions to be made.

One way to address this is to use 3D digital correlation image analysis, combined with X-ray computed tomography techniques (laboratory and synchrotron), to obtain precise, in-situ, measurements of the material displacements inside solid samples, such as deformation and cracking. (e.g. http://dx.doi.org/10.1038/srep34346, http://dx.doi.org/10.1016/j.actamat.2014.08.046 and http://dx.doi.org/10.1016/j.jeurceramsoc.2014.04.002)

The aim of this project is to investigate, by experiment and finite element modelling, the propagation of three-dimensional cracks and deformation under indentations with the objective of developing novel test methods to assess strain hardening and fracture resistance.  You will use high resolution X-ray tomography and digital volume correlation to measure the displacement field under indentations, and you will also study and model the development of cracks in brittle materials.

The project is suitable for graduates with an engineering, mathematical or physics background.

Also see homepages: James Marrow

Tissue engineering of scaffolds
J T Czernuszka

§ Tissue engineering is a rapidly expanding commercial and research area. To date, skin and articular cartilage have been tissue engineered and are available for clinical use. Other larger structures have been more difficult to produce. The major reason for this is the diffusion constraints imposed on the scaffold. We have developed a novel and unique method for producing three dimensional scaffolds from collagen, either by itself or as a composite with hydroxyapatite or other biopolymers. The technique involves rapid prototyping by solid freeform fabrication combined with CT/MRI data scanned directly from patients. Because we use SFF we can create a microvasculature within the scaffold ensuring that nutrients are kept supplied to cells deep within the structure. This is termed a 'platform technology' and the following examples show the breadth of tissues which can now be fabricated: bone, meniscal cartilage, heart valves, smooth muscle and arteries. We have a range of collaborations with leaders in their field both within the UK and abroad. There is scope for several projects within this general theme, depending on the interests and experience of the applicants.

Also see homepages: Jan Czernuszka

Tissue expanders
J T Czernuszka

§ Tissue expanders are widely used by plastic surgeons in reconstructive surgery. These are of the 'balloon' type which involves sequentially injecting fluid into the device to expand the overlying tissue. This tissue is then used elsewhere in the patient. We are developing an in situ anisotropic tissue expander for the treatment of severe cleft palates, syndactyly and tissue reconstruction following major burns. We are collaborating with plastic surgeons at the John Radcliffe Hospital and at the Radcliffe Infirmary and with colleagues at Georgia Tech in the US.

Also see homepages: Jan Czernuszka

Two dimensional conducting metal-organic frameworks (MOFs)
Prof Martin Castell

This project will be to grow and characterise 2D conducting metal-organic frameworks (MOFs) using scanning tunnelling microscopy (STM). Conductive 2D MOF networks are a recently discovered materials, resulting from square planar complexation of late transition metals and some simple polyaromatic hydrocarbon ligands. The MOFs will also be grown on insulating substrates and used for high sensitivity gas sensing. A correlation can then be drawn between the quality of the film structure with its use for chemiresistive sensing of volatile organic compounds. This project will form part of the WAFT collaboration, involving a number of UK Universities (www.waftcollaboration.org).

Also see homepages: Martin Castell

Ultimate microscopy without lenses
A Kirkland

All Transmission Electron Microscope Images are resolution limited by the aberrations of the objective lens. This project aims to develop radical new approaches to overcoming these limitations by processing diffraction data thus avoiding the need for a good (or even any) lens. The approaches developed will form part of a multi University program and the Diamond Synchrotron investigating imaging and diffraction using a variety of radiation sources.

Also see homepages: Angus Kirkland

Ultra high resolution imaging of soft (biological) materials
A Kirkland

This project aims to extend many of the ultra high resolution imaging techniques that have been developed for imaging hard (radiation resistant) materials to soft materials including biological structures. This is an entirely new area and projects will be available in experimental, theoretical and computational areas or combinations of these. Part of this work may involve collaboration with the MRC laboratories in Oxford.

Also see homepages: Angus Kirkland

Ultra low resistance joints for high temperature superconducting magnets
S C Speller / C R M Grovenor

The next generation of ultra high field magnets are starting to require the use of high temperature superconducting materials. These magnets will require several kinds of very low resistance (persistent) joints between superconducting wires that can operate reliably in high magnetic fields. So far few potential solutions to overcoming the serious materials challenges in manufacturing these joints have been reported.  The student, working closely with our industrial partners Oxford Instruments, will use new facilities in the Centre for Applied Superconductivity (cfas.ox.ac.uk) to design novel processes to form joints between commercial wires, and measure their performance.  The initial focus of the work will be on the state-of-the-art multifilamentary wires from Oxford Superconducting Technology. There will be opportunities for the student to spend time in the laboratories of Oxford Instruments, and to become an expert in the correlation of microstructure with superconducting properties of materials critical for future magnet designs.

Also see homepages: Chris Grovenor Susannah Speller

Ultrafast Electron Microscopy
A Kirkland

Modern electron microscope can provide information at the atomic scale in the spatial dimemsion. The next generation of instruments will also provide temporal resolutions in the fs regime. This project will investigate solutions to providng temporal resoltuions from the ms to micro s timescale to bridge the gap between the limits imposed by current detectors and possible future pulsed electron sources.

Also see homepages: Angus Kirkland

Understanding High Temperature Small Scale Mechanical Performance of Materials for Nuclear Fusion
Dr D.E.J. Armstrong, Dr E. Tarleton, Professor A.J. Wilkinson,

Future nuclear power systems, both fission and fusion, rely on the development of materials which can withstand some of the most extreme engineering environments. These include temperatures up to 1500oC, high fluxes of high energy neutrons and effects of gaseous elements produced by transmutation and implantation from the plasmas. Due to efforts to minimise the production of nuclear waste by such reactors the elements which may be used in structural components is limited and in many cases there is a lack of understanding of the basic deformation processes occur in ether pure materials or alloys and importantly how these are affected by temperature, radiation damage and gas content. This project will build upon the expertise in the MFFP and Micromechanics groups on high temperature mechanical testing at the micro and nano-scale. Facilities include two high temperature nanoindenters (-50oC to 950oC), high temperature microhardness (RT to 1500oC) and dedicated FIB-SEM and FEG-SEM with EBSD as well as state of the art computer codes for strain gradient crystal plasticity finite element modelling and discrete dislocation plasticity modelling. Both nanoindentation, micro-compression and micro-bend experiments will be used to study plastic deformation, fracture and creep in a range of novel high temperature materials (likely Fe, SiC or Zr based) with potential for use in future fusion reactors. HR-EBSD and AFM will be used to study deformation structures produced during testing and to inform strain gradient crystal plasticity finite element and discrete dislocation models. This will allow for a fuller understanding of the underlying physics of deformation in these materials both before and after irradiation or gas implantation. Strong links will be made to activities within the Science and Technology of Fusion Energy (EPSRC Centre for Doctoral Training) and the Culham Centre for Fusion Energy.

Also see homepages: David Armstrong Edmund Tarleton Angus Wilkinson

Understanding Zeolite Catalysts
Professor A I Kirkland

Zeolites are one of the worlds most important catalysts but their structures are still relatively poorly understood. This project which is co-sponsored by Johnson Matthey aims to understand how these catalysts evolve and degrade. The project will involve advanced electron microscopy under low dose conditions and possibly X-Ray synchrotron studies and computer modelling. There may be opportinities for direct placement with the Industrial partner.

Also see homepages: Angus Kirkland

Up-scaling graphene manufacturing to meet target device specifications
Dr. A.A. Koos, Professor N. Grobert

For graphene to become industrially viable und useful for technological applications large scale production of high-quality graphene must be developed. This project will investigate different routes to manufacturing highest grade graphene and the feasibility of up-scaling production. State of the art characterisation techniques will be employed for quality control, and close collaboration with internationally leading industries will form an integral part of the project.

Also see homepages: Nicole Grobert

Vacuum Deposited Organic Photovoltaics
Andrew Watt

In the last 3 years there has been a surge in the power conversion efficiency of organic photovoltaic devices to over 10% . This has been brought about by the development of new materials with improved electronic structure and molecular co-doping to create graded p-i-n structures. This project aims to build on this work and start from a first device operation principles to determine what the key metrics are for a good organic photovoltaic device. From here we will assess the conjugated molecules available and build devices using a new deposition tool that will be built as part of the project. Particular attention will be paid to using materials which are stable, low cost, environmentally friendly and amenable to large volume production.

Also see homepages: Andrew Watt

128 projects

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