Effect of PO2 and Ag on the phase formation of the Bi(Pb)-2223 superconductor

Abstract

The chemical reactions and the compositional characteristics of liquids which lead to the phase formation of the Bi(Pb)-2223 [(Bi, Pb): Sr: Ca: Cu: O] superconductor have been studied for a precursor composition of Bi1.8Pb0.4Sr2Ca2.2Cu3Ox. The combined techniques of quenching, powder x-ray diffraction, differential thermal/thermogravimetric analysis (DTA/TGA), scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDS) were used to characterize the subsolidus phases and the presence of liquid. Samples were annealed under purified air and under a volume fraction mixture of 7.5% O2/92.5% Ar. The effects of Ag in both the pure air and the 7.5% O2/92.5% Ar experiments were also studied. Results are discussed with respect to their processing implications.