Low temperature synthesis, structure and properties of La4BaCu5-xMxO13+delta (M=Ni, Co and Fe)

Oxygen deficient defect perovskite oxides having the general formula La4BaCu5âxMxO13+ (M=Ni or Co, 0x1.0, Fe, x=0.5) have been synthesized from NaOH-KOH fluxes at 450�°C. Structures of these materials have been refined by the Rietveld method and confirmed by electron diffraction studies. Ni3+, Co3+ and Fe3+ ions are shown to occupy the octahedral 1(a) site in the La4BaCu5O13+ structure. While the Ni substituted compound is metallic, composition controlled metal to insulator (M-I) like behaviour is observed for Co and Fe substituted compounds. While temperature independent magnetic susceptibility in the case of the Ni substituted compound indicated Pauli paramagnetic behaviour, Co and Fe substituted oxides were weakly paramagnetic