A-site deficiency was introduced intentionally into the mixed conducting perovskite ABO3-type oxide, La0.6Sr0.4Co0.2Fe0.8O3–δ (LSCF = 6/4/2/8), in order to create additional O vacancies. With increasing Sr-deficiency, z in La0.6Sr0.4–zCo0.2Fe0.8O3–δ, its lattice parameters and O content gradually increased and decreased, respectively, which strongly suggested that additional O vacancies were created in the lattice. It was expected that these additional O vacancies improve its oxide ionic conductivity and catalytic property for O reduction. Further increase in z, however, led the LSCF system into a coexistence region with transition metal oxides. Over a wide range of PO2, electrical property of samples 0 ≤ z ≤ 0.025 was p-type semi-conducting regardless of the z value, whereas its conductivity was strongly affected by a subtle change in z.

Introduction of A-site Deficiency into La0.6Sr0.4Co0.2Fe0.8O3–δ and its Effect on Structure and Conductivity. A.Mineshige, J.Izutsu, M.Nakamura, K.Nigaki, J.Abe, M.Kobune, S.Fujii, T.Yazawa: Solid State Ionics, 2005, 176[11-12], 1145-9