We have recently published our work exploring the effects of vacancies on the stability of surfaces for a set of oxide perovskites.
Article: https://doi.org/10.1103/w683-tvc4
Within the article, we use density functional theory (DFT) to explore energetics of surfaces, vacancies, and charged defects. Energetics are calculated using the PBE GGA functional, whilst charge states are corrected for using the HSE06 hybrid functional. Vacancy and surface energetics are modelled for nine ABO3 perovskites (A=Ca,Sr,Ba; B=Ti,Zr,Sn), whilst charged defects are studied for SrSnO3 only.
We explore the relative energetic stability of two (001) oxide perovskite (ABO3) surfaces and identify that, theoretically, the AO surface is more energetically favourable than the BO2 surface. However, through exploration of A-site, B-site, and O-site vacancy formation as a function of depth, we identify that the AO surface is more prone to vacancy formation, thus reducing its long-term stability.
Modelling of charged vacancies within SrSnO3 bulk and slabs (as a function of distance from the surface) highlights the further instability of the AO surface due to vacancies, especially under oxygen rich environments.