Oxygen vacancy defect migration at misfit dislocations in SrTiO₃/NiO heterostructures

Interfaces of oxide thin films and heterostructures are pivotal in enabling advanced energy applications, particularly through their influence on ionic transport. A significant factor in shaping these interfacial properties is lattice mismatch, which leads to the formation of misfit dislocations. These dislocations can strongly influence the formation and movement of oxygen vacancies, which are critical for the efficiency of thin film oxide electrolytes in solid oxide fuel cells. Yet, the mechanisms underlying these effects remain poorly understood. We employed a combination of molecular dynamics simulations and kinetic lattice Monte Carlo modeling to study ionic transport at misfit dislocations in SrTiO 3 /NiO heterostructures. We investigate the thermodynamic stability of misfit dislocations and predict the migration pathways of hundreds of oxygen vacancy defects in their vicinity. Our findings reveal how the atomic scale structure of misfit dislocations and the specific chemistry of interface layers influence defect transport. We further elucidate the atomic mechanisms that govern vacancy migration at misfit dislocations, offering new insights into strategies to optimize ionic transport in thin film oxide electrolytes.