Abstract
Optimum composition was determined presisely on new oxide superconductor Bi-Sr-Cu-O system and substitution effects on Bi-Sr-Cu-O and Bi-Sr-Ca-Cu-O system were studied by electric and magnetic measurements. Maximum Tc (onset 10K) was observed at the composition ratio of Bi:Sr:Cu=1:1:1 (designated as BiSrCuOy) in the Bi2O3-SrCO3-CuO ternary system. Transition temperatures were increased with the substitution of light rare earth elements or Ca for Bi or Sr but were decreased with any other substitution. In the case of Bi-Sr-Ca-Cu-O system substitution with Pb, La, Nd, Yb or Lu for Bi or Sr are considered to be valuable for improvement of Tc and for obtaining single phase superconductor.
