Anisotropic oxygen diffusion in tetragonal La2NiO4+δ: molecular dynamics calculations

Abstract

Molecular dynamics simulations, used in conjunction with a set of Born model potentials, have been employed to study oxygen transport in tetragonal La₂NiO_4+δ. We predict an interstitialcy mechanism with an activation energy of migration of 0.51 eV in the temperature range 800–1100 K. The simulations are consistent with the most recent experiments. The prevalence of oxygen diffusion in the a–b plane accounts for the anisotropy observed in measurements of diffusivity in tetragonal La₂NiO_4+δ.