Preparation and properties of Pb-doped Bi-Sr-Ca-Cu-O superconductors

Electrical and magnetic properties of the superconducting oxides with nominal composition (Bi/sub 0.7/Pb/sub 0.3/)2Sr2Ca2Cu3O/sub x/ prepared from polymeric precursors have been investigated. Superconducting transition with zero-resistance temperature at T=108 K was achieved for a sample sintered at 840 degree C under a low oxygen pressure. The critical current density at 77 K in a zero magnetic field is similar to 400 A/cm2, which is much higher than that of the Pb-free sample. Variations of the superconducting transition temperature, the critical current density, and magnetic properties with heat treatment time are discussed in connection with the structural properties