Superconductivity in the system CaLaBaCu3−X(PO4)XO7−δ with X=0.1, 0.3, 0.5

Abstract

Abstract In this work, we present X-ray diffraction, Raman spectroscopy and magnetizations measurement of the system CaLaBaCu 3− X (PO 4 ) X O 7− δ with X =0.1, 0.3, 0.5 which is superconductor with the critical temperatures: T c =20 K to X =0.1, T c =14 K to X =0.3 and T c =20 K to X =0.5. Samples were prepared by the solid-state reaction method under normal conditions of pressure and temperature, replacing 0.1, 0.3 and 0.5 of phosphate (PO 4 ) 3− in the Cu(1) site of CaLaBaCu 3 O 7−δ (La1113). The X-ray diffraction patterns revel the presence of BaCuO 2 and CuO as secondary phases, BaCuO 2 increases as phosphate increases in the samples. Rietveld refinements suggest orthorhombic crystalline structures, belonging to Pmmm spatial group, for all the samples; nevertheless there are variations in the cell parameters. T c 's were determinate by measurements of magnetization using a SQUID detection system, which indicate variation of T c according with phosphate concentrations. An study by Raman spectroscopy is added. Finally, the chemical analysis by EDX of a scanning electronic microscope (Phillips XL30) indicates the appropriates amounts of phosphorus in the samples.