Effect of Po-2 and Ag on the phase formation of the Bi(Pb)-2223 superconductor

The chemical reactions and the compositional characteristics of liquids whi ch 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 Bi1.8Pb0.4 Sr2Ca2.2Cu3Ox The combined techniques of quenching, powder x-ray diffractio n, differential thermal/thermogravimetric analysis (DTA/TGA), scanning elec tron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDS) were used to characterize the subsolidus phases and the presence of liquid. Samp les were annealed under purified air and under a volume fraction mixture of 7.5% O-2/92.5% Ar. The effects of Ag in both the pure air and the 7.5% O-2 /92.5% Ar experiments were also studied. Results are discussed with respect to their processing implications.