Strain effects on formation and migration energies of oxygen vacancy in perovskite ferroelectrics: A first-principles study

Abstract

Oxygen vacancies (VO) and their migration and redistribution are believed to be the dominant factors resulting in the degradation of ferroelectrics. Thus, suppressing the formation and mobility of VO is quite crucial for the physical properties of ferroelectric materials. In this paper, the ab-biaxial strain effects on VO and their migration process in prototype perovskite ferroelectric BaTiO3 were studied by first principles total energy calculation. It is found that the formation energies for the two symmetrically inequivalent VO are enhanced under compressive strain. VO migration path between Vc (VO is located along the c-axis) and Vab (VO is located in the ab-plane) shows an “S” shape. The VO migration barrier between Vc and Vab is enhanced by the compressive strain while lowered by the tensile strain. These results suggest that the ferroelectricity degradation induced by VO and their migration can be effectively mitigated by applying compressive strain.