Personal Homepages

• Atomic-scale behaviour of alloy catalyst materials in gaseous environments
• Catalytic core-shell nanoparticles
• Materials for nuclear power
• Instrument development for Atom Probe Tomography
• Gas-liquid interfacial scattering
• Molecular Dynamics simulations of liquid interfaces/particles

Reaction Cells for Atom Probe Tomography Instruments
Professor G.D.W. Smith, Dr P. Bagot, Dr T. Li
Custom-designed reaction cells are being developed as part of the Atom Probe Group's facilities, in order to permit the atomic-scale study of catalytic reaction processes (in collaboration with Johnson Matthey)

Atomic scale studies of oxide dispersion strengthened (ODS) steels
C.A. Williams, Dr P. Edmundson, Dr P. Bagot, Professor S.G. Roberts
Oxide dispersion strengthened steels have great potential for application in future nuclear fusion reactors, because of their high thermal stability and resistance to degradation under intense irradiation. This project involves atomic-scale studies of the microstructure, phase composition and solute segregation behaviour in a range of such steels, with the aim of optimising their overall design and performance.

2 public active projects

Catalytic Alloys/Nanoparticles

Li, T.; Marquis, E.A.; Bagot, P.A.J.; Tsang, S.C.E.; Smith, G.D.W. Characterization of oxidation and reduction of a platinum-rhodium alloy by atom-probe tomography, Catalysis Today, 2011, (corrected proof)

Bagot, P.A.J.; Kreuzer, H.J.; Cerezo, A.; Smith, G.D.W. A model for oxidation-driven surface segregation and transport on Pt-alloys studied by atom probe tomography, Surface Science, 605, 2011, 1541-1546

Tedsree, K.; Li, T.; Jones, S.; Chan, C.W.A.; Yu, K.M.K.; Bagot, P.A.J.; Marquis, E.A.; Smith, G.D.W.; Tsang, S.C.E. Hydrogen production from formic acid decomposition at room temperature using a Ag-Pd core-shell nanocatalyst, Nature Nanotechnology, 6, 2011, 302-307

Bagot, P.A.J.; Cerezo, A.; Smith, G.D.W. 3D atom probe study of gaseous adsorption on alloy catalyst surfaces III: Ternary Alloys- NO on Pt-Rh-Ru & Pt-Rh-Ir, Surface Science, 602, 2008, 1381-1391

Bagot, P.A.J.; Cerezo, A.; Smith, G.D.W. 3D atom probe study of gas adsorption and reaction on alloy catalyst surfaces II: Results on Pt and Pt-Rh, Surface Science, 601, 2007, 2245-2255

Bagot, P.A.J.; Cerezo, A.; Smith, G.D.W.; de Bocarmé, T.V.; Godfrey, T.J. Automobile exhaust catalysis at the atomic scale: atom-probe investigations on platinum alloys, Surface and Interface Analysis, 39, 2007, 172-177 (49th International Field Emission Symposium, 2004, Graz, Austria)

Bagot, P.A.J.; de Bocarmé, T.V.; Cerezo, A.; Smith, G.D.W. 3D atom probe study of gas adsorption and reaction on alloy catalyst surfaces I: Instrumentation, Surface Science, 600, 2006, 3028-3035

The Effects of Gaseous Adsorption on Pt-alloy Catalyst Surfaces studied with 3D Atom-Probe, University of Oxford, 2005, D.Phil Thesis

Bagot, P.A.J. Fundamental surface science studies of automobile exhaust catalysis, Materials Science and Technology, 20, 2004, 679-694

Scattering at Condensed Matter Surfaces

Waring, C.; King, K.L.; Bagot, P.A.J.; Costen, M.L.; McKendrick, K.G. Collision dynamics and reactive uptake of OH radicals at liquid surfaces of atmospheric interest, Physical Chemistry Chemical Physics, 13, 2011, 8457-8469

Waring, C.; Bagot, P.A.J.; Costen, M.L.; McKendrick, K.G. Reactive Scattering as a Chemically Specific Analytical Probe of Liquid Surfaces, Journal of Physical Chemistry Letters, 2, 2011, 12-18

Waring, C.; Bagot, P.A.J.; Bebbington W.M.P.; Räisänen, M.T.; Buck, M.; Costen, M.L.; McKendrick, K.G. How Penetrable Are Thioalkyl Self-Assembled Monolayers?, Journal of Physical Chemistry Letters, 1, 2010, 1917-1921

Waring, C.; Bagot, P.A.J.; Slattery, J.M.; Costen, M.L.; McKendrick, K.G. O(³P) Atoms as a Probe of Surface Ordering in 1-Alkyl-3-methylimidazolium-Based Ionic Liquids, Journal of Physical Chemistry Letters, 1, 2010, 429-433

Waring, C.; Bagot, P.A.J.; Slattery, J.M.; Costen, M.L.; McKendrick, K.G. O(³P) Atoms as a Chemical Probe of Surface Ordering in Ionic Liquids, Journal of Physical Chemistry A, 114, 2010, 4896-4904 (30th International Symposium on Free Radicals, 2009, Savonlinna, Finland)

Waring, C.; Bagot, P.A.J.; Räisänen, M.T.; Costen, M.L.; McKendrick, K.G. Dynamics of the Reaction of O(³P) Atoms with Alkylthiol Self-assembled Monolayers, Journal of Physical Chemistry A, 113, 2009, 4320-4329

Bagot, P.A.J.; Waring, C.; Costen, M.L.; McKendrick, K.G. Dynamics of inelastic scattering of OH radicals from reactive and inert liquid surfaces, Journal of Physical Chemistry C, 112, 2008, 10868-10877

Allan, M.; Bagot, P.A.J.; Westacott, R.E.; Costen, M.L.; McKendrick, K.G. Influence of molecular and supramolecular structure on the gas-liquid interfacial reactivity of hydrocarbon liquids with O(³P) atoms, Journal of Physical Chemistry C, 112, 2008, 1524-1532

Allan, M.; Bagot, P.A.J.; Costen, M.L.; McKendrick, K.G. Temperature dependence of OH yield, translational energy, and vibrational branching in the reaction of O(³P)(g) with liquid squalane, Journal of Physical Chemistry C, 111, 2007, 14833-14842

Allan, M.; Bagot, P.A.J.; Köhler, S.P.K.; Costen, M.L.; McKendrick, K.G. Dynamics of interfacial reactions between O(³P) atoms and long-chain liquid hydrocarbons, Physica Scripta, 76, 2007, C42-C47 (16th Biennial European Conference on Dynamics of Molecular Collisions, 2006, Levico, Italy)   

***4 studentships in nuclear materials
C.R.M. Grovenor / S. Lozano-Perez / P. Bagot / P. Edmondson

The Oxford Materials Department has established a major research effort in nuclear materials with funding from the Engineering and Physical Sciences Research Council and a number of global industrial partners. These new studentships are all externally funded and will offer the successful candidates the opportunity to join a very active team of 4 academic staff, 7 postdoctoral researchers and more than 20 students working on different aspects of materials design and materials degradation mechanisms critical to the nuclear industry, and to work closely with the funding companies.

***Studentships 1 and 2.  Atomic scale mechanisms of hydrogen pick up in nuclear fuel cladding
C.R.M. Grovenor/S. Lozano-Perez/P. Bagot/B. Comstock (Westinghouse)

These 2 studentships are part of a large international project on the mechanisms of hydrogen pick up in zirconium fuel cladding alloys, involving researchers and industrial partners in the USA, France, Sweden and the UK.  The detrimental impact of hydrogen on the performance of nuclear fuel is a serious issue for the efficient use of nuclear fuel in high burn-up applications. Understanding the mechanism of hydrogen pickup will provide a scientific basis for designing improved alloys.  Working on the same samples, the first studentship will concentrate on chemical analysis at the atom scale by state-of-the-art Atom Probe Tomography, and the second will work on transmission electron microscopy and high resolution SIMS analysis.  There will also be opportunities for undertaking experiments with the project partners, and spending time in their laboratories.

*Studentship 3.  Stability of Bubble Lattices in irradiated materials
C.R.M. Grovenor /S. Lozano-Perez/P. Edmondson

During the irradiation of nuclear reactor components in service, small voids or bubbles can be created that degrade the mechanical properties.  However, under certain conditions these bubbles can form stable lattices that are much less damaging to the macroscopic properties, and can allow the materials to have a much longer service life.  This project will use transmission electron microscopy and ion irradiation techniques to define in a range of nuclear alloys the dose, flux and temperature conditions under which stable bubble lattices can be developed using implanted ions to mimic neutron irradiation.

This project is only available to a citizen of the United Kingdom.

***Studentship 4.  Atom Probe Tomography studies of longterm ageing of nuclear pressure vessel steels
C.R.M. Grovenor /P. Bagot/ K. Wilford (Rolls Royce)

The Materials Department has a longstanding research partnership with Rolls Royce on the atomic scale changes of microstructure that occur in nuclear steels during thermal ageing which is intended to provide mechanistic understanding of similar changes during neutron irradiation.  These microstructural changes can strongly influence the mechanical properties of the steels and have implications on the service life of nuclear components.  This project will use state-of-the-art atom probe tomography techniques to study the precipitation processes in a unique set of nuclear steels thermally aged for more than 10 years, and there will be opportunity during the project for strong interaction with the sponsoring company.

These 3.5 year studentships will provide full fees and maintenance for a citizen of the UK or EU (the stipend is expected to be £15,500 per year, tax free).  Funding is available to all applicants, but the fees are covered only at the home/EU rate.  Therefore, overseas students would have to provide the difference between home/EU and overseas student fees from some other source such as a scholarship or personal funds.  For students who commence their studies in October 2012 this difference is expected to be in the region of £40,000 over three years.  Please see http://www.ox.ac.uk/admissions/postgraduate_courses /finance/index.html for a statement of the actual fees.

Any questions concerning the project can be addressed to Professor Chris Grovenor (chris.grovenor@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 and 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: Paul Bagot Chris Grovenor Sergio Lozano-Perez

Atomic-scale Characterization of Catalytic Alloys
P Bagot / C Grovenor

Many industrial processes and chemical reactions rely heavily on the use of active metals as catalysts. For example, the key ingredients of automobile exhausts and fuel-cells are expensive metals including Pt, Rh, Ru and Pd. Maximising the efficiency of these is crucial for cost-effective catalysts. However a proper understanding how different metals behave in reactive environments has yet to be achieved; the surface composition of alloy catalysts can alter markedly from the as-prepared state under high temperatures/pressures. This project will use Atom Probe Tomography (APT), a unique facility in the UK, to investigate structural and chemical changes at the atomic scale on the surfaces of a range of alloys using a fully integrated reaction cell. The student will become an expert user of these advanced facilities, and be a member of the Oxford Catalysis Network.

Also see homepages: Paul Bagot Chris Grovenor

Materials for fission and fusion power
S G Roberts / A J Wilkinson / P Bagot / P S Grant

Do you want to help to solve the future energy crisis? Are you interested in doing novel and exciting experimental work? Would you like opportunities for international collaborations and travel?

Fusion reactors potentially offer a complete solution to the problem of future energy supply, and are environmentally friendly: they emit no greenhouse gases, and so would not contribute to global warming. The recent success of the JET project at Culham in the south of Oxfordshire, which proved that plasma could be heated and controlled to produce fusion, has demonstrated the feasibility of the concept. The next step is to construct a prototype reactor (ITER) which is now the focus of a major international project. This will be followed by a prototype commercial reactor (DEMO).

So far relatively little demand has been made on the properties of the materials used for JET and other prototype reactors, since they had only to contain an operating plasma for very short times. For actual fusion power plants, materials issues will be crucial to success.

In the closer future, advanced fission reactors will be needed to meet some at least of the world energy demand, as fossil stocks dwindle and as their use become less environmentally acceptable. Materials degradation by radiation damage is a serious issue in current-generation reactors, and the new “generation IV” reactors currently being proposed will place even heavier demands on materials.

The materials needed will operate at temperatures of 600ºC or more, will need to withstand stresses up to 300MPa, and will accumulate over their lifetime radiation damage from fast neutrons amounting to ~100 displacements per atom. In fusion reactors, an additional problem will arise due to the high levels of helium and hydrogen produced in transmutation reactions. It is essential that any material used maintains adequate strength and toughness, while suffering minimal dimensional change through swelling and creep. These are very demanding requirements, which cannot be met by conventional structural materials. It will be necessary to develop and evaluate new materials.

Ion irradiation is currently the only non-activating method of mimicking the fast neutron damage produced in nuclear fission and fusion reactors (with or without co-implantation with He or H, to mimic the effects of fusion by-products). Implanted layers are ~2-3 microns deep or less.  We have developed micromechanical test methods, using ion beam machining to make specimens only a few microns in size, for determination of the elastic, plastic and fracture properties of candidate materials. This is linked with parallel electron microscopy and atom-probe microscopy studies of the development and nature of the radiation damage, and of the interactions between radiation damage and mobile dislocations which give rise to hardening and embrittlement.The experimental work is closely linked to the development and verification of computer models of radiation defects and their interactions.

A new large research project in this area, an EPSRC programme grant centred at Oxford University, started in early 2010. It involves UK and European partners (especially Liverpool University, CCFE Culham laboratory, the Commissariat à l'Énergie Atomique (CEA), and Rolls Royce). It aims at providing a thorough understanding of the mechanical properties and irradiation response of materials with potential for fusion and advanced fission reactor applications, including low-activation ferritic-martensitic steels, oxide-dispersion strengthened steels, model Fe-Cr alloys and tungsten alloys.

Individual research student projects started in 2009, 2010 and 2011 in the areas of:

• Tungsten-based alloys,
• Radiation hardening and embrittlement, 
• Grain boundary irradation embrittlement,
• Grain boundary stress-corrosion cracking,
• Processing & properties of Oxide Dispersion Strengthened alloys

Further projects will be available, to start October 2012. Applications for studentships in these areas from well-qualified applicants of all nationalities are welcome, but the note that available funding covers fees and stipend of UK and EU nationals only.

Also see homepages: Paul Bagot Patrick Grant Steve Roberts Angus Wilkinson

Also see a full listing of New projects available within the Department of Materials.