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

Five Ln2SrMCuO6.5 oxides (M = Co, Ln = Y and Ho; M = Fe, Ln = Y, Ho, and Dy) were synthesized, and their crystal structures, IR spectra, and physical properties were studied. They have almost the same structure and crystallize in orthorhombic systems. Below room temperature, Y2SrFeCuO6.5, a known 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 of 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 electrical resistivities at room temperature.