Cation inter-diffusion between LaMnO 3 and LaCoO 3 materials

Abstract

Cation inter-diffusion between polycrystalline LaMnO 3 and LaCoO 3 pellets has been studied at 1373–1673 K in air by electron microprobe analysis. Inter-diffusion coefficients were evaluated by the Boltzman–Matano method from Mn 3+ to Co 3+ concentration profiles. The cation inter-diffusion is thermally activated and follows Arrhenius behaviour. The activation energies have been calculated and the mechanism for the B-site cation diffusion in La(Mn,Co)O 3 solid solution suggested. Cation diffusion coefficients in the end members LaMnO 3 and LaCoO 3 were estimated. Cation mobility in LaMnO 3 is higher than in LaCoO 3. It is suggested that higher cation diffusion in LaMnO 3 is due to the specific defect chemistry of this material, caused by the relative stability of manganese in a higher oxidation state (Mn 4+). The results are compared to previous reports on cation diffusion in perovskite oxides.