Oxygen non-stoichiometry and reducibility of B-site substituted lanthanum manganites

LaMn0.8B′0.2O3+δ (B′=Ni, Zn, Cu) and LaMn0.5Cu0.5O3+δ perovskites were studied by temperature programmed reduction (TPR). Oxygen non-stoichiometry of the perovskite samples calcined in air (PO2=0.21 bar) at 750°C decreased upon Zn2+ (δ=0.03), Cu2+ (δ=0.04) and Ni3+ (δ=0.08) substitution as compared to LaMnO3.16. LaMn0.5Cu0.5O3+δ had reductive non-stoichiometry and contained low amounts of La2CuO4 and CuO. The reducibility at low and mean temperatures (t<500°C) increased in the sequence (Mn, Ni)≈(Mn, Zn)