Growth kinetics of high-Tc and low-Tc phases in Bi2-xPbxCa2Sr2Cu3Oy superconducting compounds

Superconducting samples of the composition Bi2-xPbxCa2Sr2Cu3Oy (x 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) are prepared by co-decomposition of metal nitrates. DTA, TGA, density, and porosity studies have been performed on these samples. Characterisation techniques like XRD, SEM, EDXA, d.c. resistance, and a.c. magnetic susceptibility have been employed to study the growth of High-Tc (HTP) and Low-Tc (LTP) phases upon lead substitution for bismuth. Results have revealed the growth of HTP with increase in Pb conc. up to x = 0.3. Further increase in Pb appears to result in the deterioration of HTP resulting in the formation of LTP and Ca2PbO4 impurity phase. Transport critical current density (Jc) measurements performed on the samples indicate that Pb doping followed by densification remarkably improves the current carrying capacity of the materials. (orig.)