Cation diffusion in ionic conducting oxides was modelled by using molecular dynamics. As example systems LSGM (Sr- and Mg-doped LaGaO3; perovskite structure) and YSZ (Y-doped ZrO2; fluorite structure) were investigated. In both systems, cation diffusion was governed by diffusion via lattice vacancies and not via interstitials. In LSGM, the diffusion of all types of cations was correlated by the formation of a binary vacancy complex of two neighbouring vacancies on the A and B sites of the perovskite lattice, which were migrating together. This leads to very similar cation diffusion coefficients for all four cations. In YSZ, calculated diffusion coefficients of the two cations differ significantly (Y was five times faster than Zr), in good agreement with experiments. The calculated activation enthalpies were close to the experimental ones, indicating that cation diffusion was mainly governed by the migration enthalpy, while the formation enthalpy of a cation vacancy should be small.

Modeling of Cation Diffusion in Oxygen Ion Conductors using Molecular Dynamics. M.Kilo, M.A.Taylor, C.Argirusis, G.Borchardt, R.A.Jackson, O.Schulz, M.Martin, M.Weller: Solid State Ionics, 2004, 175[1-4], 823-7