The fabrication and characterization of superconducting Tl-Pb-Ca-Pr-Sr-Cu-O compounds with Y1Ba2Cu3Oy-like structure and Tc (zero) up to 106 K

Abstract

Bulk superconductivity with Tc (zero) up to 106 K in a Tl0.5Pb0.5Ca0.8Pr0.2Sr2Cu2 oxide with Y1Ba2Cu3Oy-like structure was observed. A single phase, tetragonal structure with a = 0.382 ± 0.001 and c = 1.200 ± 0.001 nm and space group P4/mmm, was found in Tl0.5Pb0.5Ca0.8Pr0.2Sr2Cu2 oxide samples by X-ray diffraction. Tc (zero)'s were found to be 78, 96, 106, 98, 45 and 25 K for Tl0.5Pb0.5Ca1-xPrxSr2Cu2 oxide samples with x = 0, 0.1, 0.2, 0.3, 0.5 and 0.7, respectively. For x = 1, the samples exhibited semiconducting behavior. All sintered samples were found to be remarkably homogeneous both in composition and structure. They were also exceptionally regular in microstructure and highly reproducible and stable. Although the six-metal blend makes the system appear to be rather complicated composition-wise, it is compensated by the relatively simple crystal structure. Furthermore, the preparation conditions are much less stringent than those for other copper-based high-Tc superconductors. © 1989 Elsevier Science Publishers B.V. (North-Holland Physics Publishing Division).