First-principles structural stability study of nonstoichiometry-related planar defects in SrTiO3 and BaTiO3

First principles (ab initio) pseudopotential total energy calculations have been made to theoretically interpret the structural stability of various planar defects appearing in the perovskite oxide compounds SrTiO3 and BaTiO3. The defects are a consequence of nonstoichiometric chemical compositions occurring during conventional high-temperature sintering or low-temperature thin-film deposition. The calculations, based on the density functional theory using wave functions expanded by a plane wave basis set, were applied to newly found defect structures in the perovskite materials and have been successfully used to interpret these structures. The results showed the applicability of first principles-based calculations to the theoretical interpretation of the stability of perovskite lattices containing defect structures, comparable to the use of the conventional empirical shell model. (C) 2001 American Institute of Physics.