Oxygen non-stoichiometry and oxide ion diffusion constant of La0.6Sr0.4Co0.8Fe0.2O3-δ were gravimetrically studied with a thermal balance, at 973 to 1073K, with PO2 between 1 and 105Pa. The weight relaxation was mainly determined by bulk diffusion, but also influenced by surface exchange reaction. Diffusion coefficients were obtained by fitting the experimental data to the solution of the diffusion equation. For log (PO2/P0)>-2 (P0 = 101325Pa), it was found that the O vacancy diffusion constant had almost a constant value (1.0 x 10-5) for log (PO2/P0)<-2; however, a rapid decrease was observed.

High Temperature Properties of La0.6Sr0.4Co0.8Fe0.2O3-δ Oxygen Nonstoichiometry and Chemical Diffusion Constant. M.Katsuki, S.Wang, M.Dokiya, T.Hashimoto: Solid State Ionics, 2003, 156[3-4], 453-61