Mechanisms for oxygen vacancy defect migration in SrTiO3/NiO heterostructures

Perovskite-based oxide heterostructures display promising properties resulting from interface phenomena, making them good candidates for next-generation solid oxide fuel cell electrolytes. Amongst the different features exhibited by these interfaces, misfit dislocations play an important role in influencing ionic transport, yet their role remains poorly understood, which is the case in rock salt-perovskite interfaces too. In SrTiO3/NiO heterostructures, to comprehend interface ionic transport, we investigate oxygen vacancy migration near misfit dislocations. To this end, we developed a high-throughput framework that integrates atomistic simulations with nudged elastic band method to predict migration energy barriers across disparate interface atomic environments. By comprehensively mapping activation energy barriers across different interfacial chemistries and asymmetric structural features, we explore how the dislocation structure, which is dependent on the local interfacial chemistry, modulates vacancy migration. This study aims to shed light on the role of dopants, oxygen vacancies, interfacial chemistry, and extended defects in shaping ionic migration at the atomic scale. Misfit dislocations are often considered thermodynamic sinks for oxygen vacancies, oftentimes hindering ionic conductivity at such interfaces. We report dynamic behavior at interfaces that are largely dependent on the local coordination environment, challenging this conventional perspective. The study further attempts to bridge the crucial gap in understanding interface-governed ionic transport mechanisms in complex oxide heterostructures while exploring novel computational techniques for characterization of misfit dislocations.