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Reader in Computational Materials Science

BSc University of East Anglia
PhD University of Surrey

Materials Modelling at the Atomic Level

Our research is concerned with the atomistic modelling of defects, surfaces and interfaces in materials and their influence on physical properties. We apply and develop modern quantum-mechanical methods and focus on functional materials with electronic and optical applications.

Multilayer optical coatings

Multilayer thin-film coatings are widely used in many optical applications including UV and infra-red blockers, lighting filters, anti-reflective films on spectacle lenses, solar control films on windows and conductive films on flat-screen displays. The interfaces between the multilayers of the coatings have an important influence not only on the optical properties of the films but also on their mechanical properties. We are using quantum-mechanical density-functional calculations to predict the structure, energy, bonding and dielectric characteristics of various metal/oxide interfaces in these systems with the aim of developing coatings with improved properties.

Carbides for Future Fission Environments (MAX phases)

MAX phases are a group of layered ternary compounds with the general formula Mn+1AXn where M is an early transition metal, A is an A-group element (mainly IIIA and IVA), X is C or N and n =1-3. A well-known example is Ti3SiC2. MAX phases are unusual in that they exhibit both metallic and ceramic characteristics, e.g. good machinability and high temperature strength. Applications include surface coatings, heating elements and drilling tools. The mixed bonding characteristic also means that they can be tolerant to irradiation and resist amorphization. They could therefore be used as an in-core structural material or coating within the hostile environment of a nuclear reactor. We are using density functional methods to investigate the phase stability of these materials, the formation of point defects and the strength of internal interfaces and grain boundaries. The theoretical prediction of phases that have not yet been synthesized is also of interest.

Hybrid perovskites

Improving the cost and efficiency of current solar cell technology is an active area of sustainable energy research. Key to this objective is optimising the solar cell configuration so that the light absorbing material creates charge carriers (excitons) with large diffusion lengths, small effective masses and high mobilities. Organic-inorganic hybrid perovskites have recently shown significant promise in this regard with some device configurations achieving power conversion efficiencies exceeding 15%. Methylammonium lead iodide, CH3NH3PbI3, is an example of such a perovskite which has been studied extensively experimentally and theoretically. We are using density functional methods to investigate the atomic and electronic structure of these materials, particularly those which are Pb-free including double perovskites and perovskite-like structures.

Illustration of the rhombohedral to cubic phase transition in rare-earth hybrid double perovskites (Deng at al J. Phys. Chem. Lett. 8, 5015 (2017)).

 

  • Furnival, T; Leary, RK; Tyo, EC; Vajda, S; Ramasse, QM; Thomas, JM; Bristowe, PD; Midgley, PA, "Anomalous diffusion of single metal atoms on a graphene oxide support", Chemical Physics Letters 683, 370-374 (2017)
  • Milowska, KZ; Ghorbani-Asl, M; Burda, M; Wolanicka, L; Ćatić, N; Bristowe, PD; Koziol,KK, "Breaking the electrical barrier between copper and carbon nanotubes", Nanoscale 9, 8458 (2017)
  • Wei, F; Deng, Z; Sun, S; Xie, F; Kieslich, G; Evans, DM; Carpenter, MA; Bristowe, PD; Cheetham, AK, "The synthesis, structure and electronic properties of a lead-free hybrid inorganic-organic double perovskite (MA)2KBiCl6 (MA = methyl ammonium)", Materials Horizons 3, 328-332 (2016)
  • Lee, JH; Bristowe, NC; Lee, JH; Lee, SH; Bristowe, PD; Cheetham, AK; Jang, HM, "Resolving the physical origin of octahedral tilting in halide perovskites", Chemistry of Materials 28, 4259-4266 (2016)
  • Lee, JH; Bristowe, NC; Bristowe, PD; Cheetham, AK, "Role of hydrogen-bonding and its interplay with octahedral tilting in CH3NH3PbI3, Chemical Communications (Camb) 51, 6434-6437 (2015)
  • Kang, L; Munoz Ramo, D; Lin, Z; Bristowe, PD; Qin, J; and Chen, C, "First principles selection and design of mid-IR nonlinear optical halide crystals", Journal of Materials Chemistry C 1, 7363-7370 (2013)