The effect of Ag on the superconductivity of Bi_2-xPb_xSr₂Ca₂Cu₃O_y superconductors prepared by an optimum thermal procedure

The effect of Ag addition (0-100 wt%) to Bi_2-xPb_xSr₂Ca₂Cu₃O_y (x=0.1-1.0) was systematically studied using differential thermal analysis (DTA), electrical resistivity, change in inductance, scanning electron microscopy (SEM) and X-ray diffraction (XRD) studies. The sample was prepared by the optimum thermal procedure in which the sintering was done at the endothermic peak temperature judging from the DTA curve. It was found that the 110 K phase was produced with good reproducibility by the lowering of the melting temperature due to the addition of Ag. It was also found that high-T_c (end) corresponded well to the high-T_c fraction m= Sigma H/( Sigma H+ Sigma L+ Sigma l) (H: 2223, L: 2212, l: Ca₂PbO₄, Ca₂CuO₃) defined from the result of XRD measurements.