PREPARATION AND PROPERTIES OF BI(PB, SB)-SR-CA-CU-O SUPERCONDUCTORS

The influence of Pb and Sb dopants on the properties of Bi-based high- temperature superconductors was systematically investigated. The sampl es with nominal composition BiaPbbSbcSr4Ca5Cu7O (a + b + c = 3.6-4.4; b = 0.2-0.8; c = 0.1-0.6) were prepared and characterized by DTA, XRD analysis, resistivity and susceptibility measurements, Our results sho wed that the addition of a small amount of Sb for a constant or decrea sing concentration of Pb has little influence on T-c but suppresses T- o. The important characteristic of this system is the presence of a ne w phase for higher concentrations of Sb with strong reflections near 2 Theta = 35 degrees (Co K alpha) in the XRD pattern.