Computer simulation techniques were applied to perovskite materials in order to clarify the mechanisms and energetics of O ion migration. A common set of interatomic potentials was derived which correctly reproduced the structure. The results supported suggestions that diffusion was mediated by O ion vacancies. An analysis of the potential energy surface demonstrated that vacancy migration took place along the anion octahedron edge, via a curved path rather than a straight one. The calculated migration energies ranged from 0.5 to 0.9eV, and were in accord with available experimental data. The relationship between cation size and migration energy was investigated by modifying the interatomic potential function so as to relate the ionic radii directly to the short-range repulsive term. A study was also made of the energy of solution of an alkaline-earth dopant at the La site, with O vacancy compensation. It was found that ion size effects were important, with Sr being calculated to have the highest solubility.

Oxygen Ion Migration in Perovskite-Type Oxides. M.Cherry, M.S.Islam, C.R.A.Catlow: Journal of Solid State Chemistry, 1995, 118[1], 125-32