A computational study of the geometric and electronic properties of oxide perovskites, and an investigation into the role of vacancies for surface stability.

A first principles study of surface energetics of the (001) surface terminations of nine oxide perovskites is presented. Additionally, investigation into the behaviour of vacancies as a function of depth from the surface in these perovskites is carried out, and results are compared to formation of the vacancies in bulk. Combining results from these investigations reveals a general trend for all nine perovskites – the AO surface is more energetically favourable to form than the BO2 surface. This dominance of the AO over the BO2 surface is further enforced by the phase diagrams of perovskite surfaces. However, A-site vacancies at the AO surface are far more favourable (1–2 eV lower in energy) than B-site vacancies at the BO2 surface. This result indicates that, whilst the AO surface is easier to form, the BO2 surface may have better long term stability, making it more suitable for use in potential applications. This study furthers the understanding of oxide perovskite (001)-terminated surface stability, which will aid in surface growth and manufac- turing.