Vacancy and interstitial oxide ion migration in heavily doped La2−xSrxCoO4±δ

Abstract

La_2−xSr_xCoO_4±δ, a K₂NiF₄-type structured oxide, is currently under investigation for its possible application as a cathode material in solid oxide fuel cells operating at intermediate temperature (IT-SOFCs). Here we report a combined energy minimization and molecular dynamics study of oxygen migration mechanisms in the La_2−xSr_xCoO_4±δ material for high Sr levels (x > 0.8). In the oxygen-deficient composition La_0.8Sr_1.2CoO_3.9 the oxide-ion transport mainly occurs through the migration of oxygen vacancies within the perovskite layer of the structure, with possible vacancy paths between adjacent layers. In the oxygen-rich composition La_1.2Sr_0.8CoO_4.1 interstitial oxygen transport is via an interstitialcy mechanism and within the ab plane.