Oxygen diffusion in Sr0.75 Y0.25 CoO2.625: A molecular dynamics study

Oxygen diffusion in ${\text{Sr}}_{0.75}{\text{Y}}_{0.25}{\text{CoO}}_{2.625}$ is investigated using molecular dynamics simulations in conjunction with an established set of Born model potentials. We predict an activation energy of diffusion for 1.56 eV in the temperature range of 1000\char21{}1400 K. We observe extensive disordering of the oxygen ions over a subset of lattice sites. Furthermore, oxygen ion diffusion both in the $a\text{\ensuremath{-}}b$ plane and along the $c$ axis requires the same set of rate-limiting ion hops. It is predicted that oxygen transport in ${\text{Sr}}_{0.75}{\text{Y}}_{0.25}{\text{CoO}}_{2.625}$ is therefore isotropic.