A point defect model was used to describe the O non-stoichiometry of the perovskites, La0.75Sr0.25CrO3, La0.9Sr0.1FeO3, La0.9Sr0.1CoO3, and La0.8Sr0.2MnO3, as a function of the O partial pressure. On the basis of the O vacancy concentration which was predicted by the point defect model, the ionic conductivity was deduced by assuming a vacancy diffusion mechanism. The ionic conductivity was combined with the Wagner model for the oxidation of metals in order to obtain an analytical expression for the O permeation current density as a function of the O partial pressure gradient.

B.A.Van Hassel, T.Kawada, N.Sakai, H.Yokokawa, M.Dokiya, H.J.M.Bouwmeester: Solid State Ionics, 1993, 66, 295-305