Effect of Ca Starting Materials of Bi-2223 System on Superconducting Characteristics

Abstract

As well-known that partial substitution of a Pb for Bi in the Bi-Sr-Ca-Cu-O system has been found to sharply increase the volume fraction of the high-Tc phase when both the starting material and the heating process are appropriate. This paper discusses the influence, in this case of the CaCO₃ or CaO used as a raw material of Ca and the cold isostatic pressing (CIP) method on the superconducting properties of Bi_1.8Pb_0.4Sr₂Ca_2+xCu_3.2O_y prepared by the solid-atate reaction. The superconducting characteristic obtained from the electrical resistance for the specimens sintered at 850°C for 200h, became gradually lower from 105K to 70K with increasing a Ca content from O to 0.8 mol. The Jc value increase with x was a maximum of 1820A/cm² at x=0.4 sintered at 850°C to 200h.