Compositional and physical changes on perovskite crystal surfaces

Abstract

The surface composition of BaTiO3, SrTiO3, and CaTiO3 perovskite (100) surface is determined by shell-model calculations. The TiO2-terminated surface is energetically favorable for BaTiO3 and SrTiO3, which is consistent with experimental observations on SrTiO3. On the other hand, the CaO-terminated surface is preferred for CaTiO3 where Ca2+ is the smallest 2+ cation in these titanates. Ions on (100) surface rumple and induce surface dipoles. The surface ferroelectric polarization stabilizes the surface and changes its sign as the surface composition changes from TiO2 to CaO. This phenomenon is expected to affect the stability and properties of epitaxial films on perovskite substrates.