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

褐铁矿相是一种缺氧钙钛矿结构，以前作为高温氧化物离子导体而备受关注，最近又作为光催化剂受到关注。然而，它们在更广泛的能源应用中的开发相对较少。这种结构的灵活性可以容纳一系列p-块和过渡金属，这表明有希望设计合适的带隙来匹配太阳光谱，从而也适用于光伏。除了前景看好的电子结构外，它们还可以定制为采用极性晶体结构，这可能导致难以捉摸的光铁材料的设计--一种产生自发移位电流并减少光致载流子复合的极性材料，从而增强光伏(和光催化)性能。到目前为止，这一点在褐磨石能源材料研究中一直被忽视。在铁性材料的理论和实验研究方面，监督团队的互补专业知识非常适合用于光铁应用的褐铁矿材料的设计和优化。这项研究项目是跨学科的，为学生提供了在理论和计算(密度泛函理论)和实验技术(材料合成、结构和性能测量)方面发展专业知识的机会。PHD将由三个工作链组成：1)DFT识别可能采用具有适当带隙的极性晶体结构的已知和建议的褐铁矿相。2)第一个链的结果将形成合成目标。样品将通过固相反应合成，结构表征将通过衍射和显微镜进行。3)性能测量将由合作者对有希望的光铁素体候选材料进行。

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.