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Dr James Darnbrough
Career Development Fellow
Fellow of St Edmund Hall

Department of Materials
University of Oxford
16 Parks Road
Oxford OX1 3PH
UK

Tel: +44 1865 273777 (reception)
Fax: +44 1865 273789 (general fax)

OMG
MFFP

Summary of Interests

My main focus is on how materials and their mechanical properties evolve in working environments. This is a crucial question for a whole host of industries however I is particularly interested in  tackling the challenges in the energy sector via work on materials for nuclear applications and in new solid state battery technologies.

Current Interests:

• Investigating the role of applied pressure in suppressing solid state battery failure
• The mechanical properties of thin film solid electrolytes
• Battery Cycling Stresses: Investigating how to accommodate the volume expansion of cathode materials during charging without mechanical failure
• The fundamental mechanical and electrical properties of Lithium metal
• Advanced Microscopy for the observation of oxygen defects in irradiated uranium dioxide
• In-situ microscale cantilever testing of ion-irradiated tungsten

Research Publications

A Publications Full list can be found on ORCID

Selected Publications:

Interaction between U/UO2 bilayers and hydrogen studied by in-situ X-ray diffraction

J E Darnbrough, R M Harker, I Griffiths, D Wermeille, G H Lander and R S Springell (2018) Journal of Nuclear Materials 2018

This paper demonstrates a novel application of in-situ hydriding of uranium metal below an oxide in a thin film system monitored by synchrotron X-ray diffraction. These X-ray studies were supplemented by STEM-EELS characterisation of the uranium P absorption edge.

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Kinetics and Dynamics of Planar Abnormal Grain Growth in Nanocrystalline Nickel

J E Darnbrough, F Christien and P E J Flewitt Acta Materialia (2017) Acta Mat

This paper describes a novel in-situ observation of the abnormal growth of nanocrystalline nickel under heat treatment using backscatter electron diffraction.

Video shows the in-situ backscatter contrast SEM imaging of grain growth from which the abnormal grains can be analysed individually.  

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The influence of temperature and grain boundary volume on the resistivity of nanocrystalline nickel

J E Darnbrough, B Roebuck and P E J Flewitt Journal of Applied Physics (2015) J App Phys

In-situ observation of grain growth under heat treatment by measuring changes in the electrical resistivity of samples, deconvoluting the effect of temperature and scattering effects.

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Micro-scale testing of ductile and brittle cantilever beam specimens in-situ with a dual beam workstation

J E Darnbrough, D Liu and P E J Flewitt, Measurement Science and Technology (2013) ,  Meas Sci Tech

Novel micro-scale cantilever tests on nickel (ductile) and ceramic thermal barrier coating (brittle). This illustrates the versatility of the technique and the ability to observe failure modes in real time.  

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Projects Available

Mechanical properties of solid state lithium ion batteries
Supervisors: Professor David Armstrong & Dr Ed Darnbrough

The ceramic lithium ion conductor Li7La3Zr2O12 (LLZO) has been shown to be promising electrolyte materials for solid state lithium ion batteries. While its electrochemical properties have been well studied there is comparatively little information on the mechanical properties of these materials. This data is a key requirement for the development of a better model of the mechanical behaviour of the materials during the charge-discharge cycle.
This project will use a range of nano and mico-mechanical indentation methods to study, the hardness, elastic modulus, yield stress and fracture toughness of these materials processed in both bulk and thin film forms. These properties will be related to local microstructural features through the use of scanning electron microscopy (SEM), Electron back scattered diffraction (EBSD) and Raman Spectroscopy. Finally these micromechanical properties will be compared to bulk fracture properties obtained through four point bend flexure tests. The data produced in this way will not only be useful for seeding models but allow optimisation of processing routes for producing electrolytes with improved lifetimes.

Also see homepages: Ed Darnbrough

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