PREPARATION AND SUPERCONDUCTING PROPERTIES OF BI-PB-SR-CA-CU-O FILMS (TC=106-K) BY THE DIPPING-PYROLYSIS PROCESS

Superconducting Bi-Pb-Sr-Ca-Cu-O (2223 as the major phase) films were prepared by the dipping-pyrolysis process on MgO(100) substrates using a metal naphthenate solution. From the XRD and SEM-EDX analyses, the formation of the 2223 phase with well-developed platelike grains was facilitated in the films by placing a Pb-containing BSCCO pellet on the surface of the prefired films during the heat treatment (850-degrees-C in air) and by the use of a nominal composition of Bi:Pb:Sr:Ca:Cu = 1.8:0.4:2.0:2.4:3.6 in molar ratio, i.e., a Ca-and-Cu-rich composition compared to the 2223 phase. The values of T(c, zero) and J(c)(77 K) were 106 K and 2 x 10(3) A/cm2 , respectively. The dependence of critical current densities on temperature showed that J(c) was approximately proportional to (1 - T/T(c))3/2, which corresponds to the results of the proximity junction tunneling (SNIS) model.