Superconducting properties of Bi2? xPbxSr2Ca2Cu3Oy system derived via sol?gel and solid state routes

Bulk Pb doped Bi2?xPbxSr2Ca2Cu3Oy(x=0.4 and 0.5) superconductors have been prepared via sol?gel route (SGR) using pure metal acetate precursors and solid state route (SSR) using conventional carbonate-oxide compounds. Variation of the percentage of high-TC phase (2223-phase) for samples prepared by different routes were observed from XRD data and it was found that SGR samples have higher percentage of (2223) phase than the SSR samples. It was ?75% and ?78% for SSR samples and ?85% and ?95% in SGR samples for doping composition of x=0.4 and x=0.5, respectively. The highest zero bulk resistance temperature (TC(R=0)) of 104K was found in SGR sample (x=0.5), while the lowest TC(R=0) value of 98K was measured in SSR sample (x=0.4). Complex ac susceptibility measurements showed that the nature of the grains, grain boundaries and coupling associated to the