Joint computational and experimental study of Brownmillerites for novel renewable energy applications

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Brownmillerite phases, oxide-deficient perovskite structures, have previously gained interest as high temperatures oxide-ion conductors, and more recently as photocatalysts. However, their wider energy applications are relatively underexplored. The flexibility of the structure to host a range of p-block and transition metals indicates promise to engineer suitable band gaps to match the solar spectrum, and hence also be suitable photovoltaics. In addition to their promising electronic structure, they can be tailored to adopt polar crystal structures, which could lead to the design of the elusive photoferroic - a polar material that generates spontaneous shift currents and reduces photo-induced carrier recombination and therefore enhances photovoltaic (and photocatalytic) properties. To date, this has been overlooked in brownmillerite energy materials research. The complementary expertise of the supervisory team in the study of ferroic materials from both theory and experiment is well suited to the design and optimisation of brownmillerite materials for photoferroic applications.This research project is interdisciplinary, providing the student with the opportunity to develop expertise in both theory and computation (density functional theory) and experimental techniques (materials synthesis, structural and properties measurements).The PhD will consist of three work strands:1) DFT to identify known and proposed brownmillerite phases likely to adopt polar crystal structures with appropriate band gaps.2) Results from this first strand will form synthetic targets. Samples will be synthesised by solid state reactions and structural characterisation will be carried out by diffraction and microscopy.3) Property measurements will be performed by collaborators on promising photoferroic candidates.