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

LaMn0.8B'O-0.2(3+delta) (B'=Ni, Zn, Cu) and LaMn0.5Cu0.5O3+delta perovskite s were studied by temperature programmed reduction (TPR). Oxygen non-stoich iometry of the perovskite samples calcined in air (Po-2=0.21 bar) at 750 de grees C decreased upon Zn2+ (delta=0.03), Cu2+ (delta=0.04) and Ni-3 (delta =0.08) substitution as compared to LaMnO3.16. LaMn0.5Cu0.5O3+delta had redu ctive non-stoichiometry and contained low amounts of La2CuO4 and CuO. The r educibility at low and mean temperatures (t<500 degrees C) increased in the sequence (Mn, Ni)approximate to(Mn, Zn)<Mn<(Mn, Cu). (C) 2000 Elsevier Sci ence B.V. All rights reserved.