Critical Current Properties and Microstructures of Ag-Sheathed Bi-Based Superconducting Wires

Since the first report of superconductivity in the Bi-Sr-Ca-Cu-O (BSCCO) system by Maeda et al., an enormous quantity of material work has been reported on the Bi system. The Bi-2223 phase exhibits a zero-resistivity temperature of around 110 K and this is the highest critical temperature outside the 125 K critical temperature found in the Tl-Ba-Ca-Cu-O system. The layered BSCCO phases cleave easily, making it possible to align grains by a deformation process.The powder-in-tube method is one of the fabrication processes that permits grain alignment and the achievement of high critical current density. This tendency is particularly strong for the 2223-BSCCO phase.In this paper, we report on the relation between the critical current density (Jc) and the microstructure in silver-sheathed Bi-Pb-Sr-Ca-Cu-0 (2223) wires produced by the powder-in-tube method.