Complementary evaluation of structure stability of perovskite oxides using bond-valence and density-functional-theory calculations

Abstract

Estimation of structure stability is an essential issue in materials design and synthesis. Global instability index (<i>GII</i>) based on bond-valence method is applied as a simple indication, while density functional theory calculation is adopted for accurate evaluation of formation energy. We compare the <i>GII</i> and total energy of typical <i>AB</i>O₃-type perovskite oxides and rationalize their relationship, proposing that the criteria for empirically unstable structures (<i>GII</i> > 0.2 valence unit) correspond to the difference in total energy of 50-200 meV per formula unit.