High-temperature chemistry of doped lanthanum manganites

Information concerning the phase composition of La2O3-MO-manganese oxides ( M = Mg, Ca, Sr, Ba. Cd, Pb) systems is surveyed. Perovskite-related solid s olutions produced by heterosubstitutions of M2+ for lanthanum or vice versa and categorized as Raddlesden-Popper (RP) phases are characteristic of the se systems, as well as undoped manganites. Illustrations are given of the d ependence of the phase composition of the system and of the homogeneity ran ges and structures of solid solutions on both the synthesis parameters (pro cess, temperature, po,) and La/M and (La,M)/Mn ratios. Phase diagrams refer red to identical conditions (air, 1440-1500 degreesC for M = Mn, Ca, Sr, Ba ; 900 degreesC for M = Cd, Pb) were mapped in the La2O3-MO-Mn3O4(MnO2, Mn2O 3) space and discussed.