Complex susceptibility of bi, pb-sr-ca-cu-o superconductors

In terms of complex susceptibility χ=χ-iχ, we measured the superconducting transition of the Bi, Pb-Sr-Ca-Cu-O systems, which were prepared by partial substitution of Pb for Bi. The observed χ of the disk samples shows that they contain both the bulk phase and the Josephson-like coupling phase, being similar to other oxide superconductors. From measurements of the powdered samples, we find that the system mostly consists of the high-T_c phase, of which the onset temperature lies in the range of 115–120 K. The low-T_c phase (80 K) is still involved, but the amount is roughly estimated to be 5% or less.