Double B perovskite-type series in the system La0.6Ca0.4Mn1−xMxO3−δ with M = Fe, Co, Ni and x = 0 to 0.6 were synthesized in air by solid state reactions at 1200C from simple oxides and CaCO3. Almost single phase compositions with small impurities (3 to 5%) were formed. Replacement of Mn with Me-cations was accompanied by a considerable decrease of electrical conductivity of the prepared ceramics. Lower conductivities of the Me containing compositions compared to La0.6Ca0.4MnO3−δ were explained by stronger polarization of the -Mn(α+γ)+-Oα−-Me(α−γ)+-Oα−- fragments of the –Oα−-Mnα+–Oα−-Mnα+–Oα−-Mn(α+γ)+-Oα−-M(α−γ)+-Oα−- chains in comparison with the -Oα−-Mnα+-Oα−-Mnα+-Oα−- chains without M-cations, because of different electronegativity of M and Mn. The double exchange theory gives strong explanation for this phenomenon. Type and level of the electrical conductivity of the La0.6Ca0.4Mn1−xMxO3−δ series were the functions of the [Mn4+]/[Mn3+] and [M3+]/[M2+] ratios. Mn4+ and M2+-cations were possible point defects which determine the p- and n-type conductivity of compositions, respectively.

Electrical Conductivity and Oxygen Non-Stoichiometry of the Double B Mixed Perovskite Series La0.6Ca0.4Mn1−yMeyO3−δ with Me = Fe, Co, Ni and x = 0–0.6. V.Vashook, D.Franke, L.Vasylechko, J.Zosel, J.Rebello, K.Ahlborn, W.Fichtner, M.Schmidt, T.L.Wen, U.Guth: Solid State Ionics, 2008, 179[21-26], 1101-7