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

摘要： 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.