Studying Dynamics of Oxygen Vacancy Ordering in Epitaxial LaCoO3 / SrTiO3 Superlattice with Real-Time Observation

Oxygen vacancies in perovskite oxides are of great interest both from fundamental viewpoint due to their effect on electronic and magnetic properties of oxides – and from applications viewpoint due to their importance for solid oxide fuel cells. In the latter case, understanding the dynamic behavior of vacancies is crucial. Oxygen vacancy (Vo) ordering can substantially affect local structure and ionic conductivity of the oxide matrix. Recently, Kim et al. have reported that local oxygen content and thus vacancy ordering can be quantified using lattice expansion via atomic position mapping in high angle annular dark field (HAADF) images with unit cell resolution in the La0.5Sr0.5CoO3- system.[1] The composition studied in [1] is remarkably beam resistant, however, in other related compounds such as LaCoO3 (LCO) exposure to the electron beam can lead to the emergence of vacancy ordering in previously disordered matrix. Adapting Kim et al. approach to a dynamic setting, we explore Vo behavior in the PLD grown LaCoO3/SrTiO3 (LCO/STO) superlattices and LCO films by HAADF and annular bright field (ABF) STEM.