Oxygen vacancy-assisted high ionic conductivity in perovskite LaCoO3−δ (δ = 1/3) thin film: A first-principles-based study

Abstract

Synthesising a solid state material with high oxygen-ionic conductivity is a challenge. In this work, an integrated method of density functional theory and first-principles molecular dynamics (FPMD) simulations has been performed to investigate the oxygen-ionic conductivity in the LaCoO3−δ films. We demonstrated that, in the strained epitaxial LaCoO3−δ films, O vacancy superstructures release strain and produce the high oxygen-ionic conductivity with an activation barrier of 0.65±0.1 eV. We found that the oxygen hopping occurs in the oxygen-deficient regions of CoO mainly. We proposed a possible oxygen-ionic diffusion highway with an energy barrier of 0.55 eV by using the transition state calculations. Thus, the oxygen-deficient regions are the keys to the high oxygen-ionic conductivity in the LaCoO3−δ thin films.