Theoretical investigation of {1 1 0} generalized stacking faults and their relation to dislocation behavior in perovskite oxides

Abstract

Studies of generalized stacking fault energy surfaces, or γ-surfaces, provide a convenient and efficient source of information on possible dislocation dissociation mechanisms and favorable glide systems. We carried out an extensive theoretical investigation of the {1 1 0} γ-surface for three technologically important perovskite oxides SrTiO 3, BaTiO 3, and PbTiO 3. The calculations were performed using both a highly accurate first-principles density functional theory approach and simple empirical interatomic potentials. The main characteristic features common to all {1 1 0} γ-surfaces are the low energy path along the 〈 1 1 ¯ 0 〉 direction and the existence of a single local energy minimum along this path. This minimum corresponds to an antiphase boundary that has been observed experimentally in dissociated dislocation cores in various perovskites. The energy profiles obtained using the empirical potentials agree qualitatively well with the first-principles results but there are significant quantitative discrepancies. This comparison provides a valuable insight into the quality and limitations of empirical potentials for atomistic simulations of dislocations and other extended defects in these materials.