GROWTH-KINETICS OF HIGH-TC AND LOW-TC PHASES IN BI2-XPBXCA2SR2CU3OY SUPERCONDUCTING COMPOUNDS

Superconducting samples of the composition Bi, PbxCa2Sr2Cu3Oy (x = 0.0 , 0.1, 0.2, 0.3, 0.4, and 0.5) are prepared by co-decomposition of met al nitrates. DTA, TGA. density, and porosity studies have been perform ed on these samples. Characterisation techniques like XRD, SEM, EDXA, d.c. resistance, and a.c. magnetic susceptibility have been employed t o study the growth of High-T(c) (HTP) and Low-T(c) (LTP) phases upon l ead substitution for bismuth. Results have revealed the growth of HTP with increase in Pb conc. up to x = 0.3. Further increase in Pb appear s to result in the deterioration of HTP resulting in the formation of LTP and Ca2PbO4 impurity phase. Transport critical current density (J( c)) measurements performed on the samples indicate that Pb doping foll owed by densification remarkably improves the current carrying capacit y of the materials.