Effects of Additional Elements (M=In, Al, Ga) on Superconductivity of Bi-Sr-Ca-Cu-O System

Abstract

The effects of additional elements on the superconductivity of a Bi-Sr-Ca-Cu-O system were studied by measuring the magnetic susceptibility and x-ray diffraction patterns of such a system. By observation of x-ray diffractions, a solid solution region in the low-and high-Tc (critical temperature) Bi-M-Sr-Ca-Cu-O phases were found to exist for O≤x≤1 (M=In, Ga) and for 0<x<0.5 (M=Al) in a Bi_4-xM_xSr₃Ca₃Cu₆O_y system (4-3-3-6 system). In a Bi_1-xM_xSrCaCu₂O_y system (1-1-1-2 system), a solid solution region in the low-and high-Tc phases were found to exist for 0≤x<0.3 (M=In, Ga, Al). Indium was found to be effective in raising the amount of both low-and high-Tc superconductivity phases and the critical current density. Aluminum and Gallium showed small effects on the formation of a high-Tc phase. Further addition of these elements broke the superconductivity of the Bi-Sr-Ca-Cu-0 system. These results suggest that the crystal of high-or low-Tc Bi-Sr-Ca-Cu-O phase was stabilized by the controlled addition of these elements.