Effect of Sintering Temperature on the Glassy Precursor Synthesis of Superconducting Bi1.6Pb0.4Sr2Cu4Ca3O12+δ

Glassy route synthesis provides homogeneous and dense products of bismuth perovskite superconductors compared with the conventional solid-state sintering technique. Accordingly an attempt has been made here to synthesize Bi1.6Pb0.4Sr2Cu (n) Ca On-1 (w) , where n=4 through this route. Instead of varying Bi and Sr, the amount of Ca and Cu has been increased at their sites, in order to improve the superconducting phase assemblage and reduce the impurity. The activation energy for crystallization is evaluated and is found to be equal to 215 kJ/mol. The melt temperature is selected in such a way to reduce the evaporation of Bi and Pb. Analysis of the compositions revealed that the relative amount of Bi increased at the cost of Ca, which has shown a tendency to decrease. It is seen that the relative increase of bismuth in the quenched sample helped in reducing the processing temperature for the formation of superconducting phases. 540 cm(-1) observed in the Raman spectrum of bismuth cuprates has been assigned to the modulated non-superconducting grain through this study.