The electrical and magnetic properties of lanthanide alkaline-earth transition-metal oxides

Five Ln(2)SrMCuO(6.5) oxides (M = Co, Ln = Y and Ho; M = Fe, Ln = Y, Ho, an d Dy) were synthesized, and their crystal structures, IR spectra, and physi cal properties were studied. They have almost the same structure and crysta llize in orthorhombic systems. Below room temperature, Y2SrFeCuO6.5, a know n layered oxide, shows antiferromagnetic behavior, but the four new oxides are paramagnetic. Y2SrFeCuO6.5 fits the Curie-Weiss law in the temperature range 300-100 K, but Y2SrCoCuO6.5 shows complex magnetic behavior because o f the disproportion of some Co+3 to Co+2 and Co+4 The five oxides are all p -type semiconductors in the measured temperature range and have large elect rical resistivities at room temperature. (C) 2000 Elsevier Science Ltd.