Influence of sintering temperature and lead content on the formation of the high temperature superconducting phase in Bi 2− x Pb xSr 2Ca 2Cu 3O y

Abstract

The formation of the high temperature superconducting phase in Bi 2− x Pb x Sr 2Ca 2Cu 3O y ( x = 0, 0.2, 0.4, 0.6, 0.8) with a superconducting transition temperature ( T c near 110 K is studied as a function of sintering temperature and lead content. The optimum range of sintering temperature is based on differential thermal analysis (DTA) results. DTA shows two endothermic peaks near 1135 and 1155 K. The temperature difference between these two peaks varies with lead content and is maximum at x = 0.4. The x = 0.4 sample also shows the highest fraction of high t c phase based on X-ray diffraction (XRD) and resistance measurements. Thus DTA, XRD and resistance measurements all independently support the x = 0.4 composition as having a unique response which seems characteristic of the high t c phase. XRD and DTA results also suggest that the high t c phase is formed by a reaction between the low T c phase and the products of decomposition of Ca 2PbO 4 which is produced during the synthesis.