Diffusion of oxide ion vacancies in perovskite-type oxides

Abstract

In order to elucidate the diffusion of oxide ion vacancies in perovskite-type oxides, we determined the tracer diffusion coefficient of oxide ions, D∗ O , in La 1− x Sr x CoO 3− δ ( x = 0.1) and La 1− x Sr x FeO 3− δ ( x = 0.1, 0.25, and 0.4) single crystals. The correlation factor, f, for a vacancy diffusion mechanism in a perovskite-type anion sublattice was calculated to be f = 0.69. Using this value and the nonstoichiometry data, the diffusion coefficient of oxide ion vacancies, D V, was estimated. It was found that D V in La 1− x Sr x MO 3− δ ( M = Co, Fe) take similar values in their magnitude and activation energy. It was concluded that a point defect model holds for the vacancy diffusion in these oxides. The diffusivity of oxide ions in the perovskite-type oxides was comparable to that in fluorite-type oxides.