Thermal Decomposition of Precursor and the Formation of Superconducting Phases in the Pb-Bi-Sr-Ca-Cu-O (Pb- BSCCO) System

Superconducting phases in the Pb-BSCCO system have been produced by ethylenediaminetetraacetic acid (EDTA)-gel processing using nitrate solutions. The decomposition of EDT A-gd precursor has been studied by thermo-analytical techniques in conjunction with X-ray dilTraction (XRD) method. The thermo-analytical data are discussed in relation to the sequence of phase formation necessary for the production of superconducting phases. The effect of Pb is shown to lower the temperature of formation of the Bi2Sr2Ca2Cu3o,. (2223) high Tc phase. The Bi2Sr2Ca,Cu20y (2212) low Tc phase was observed as a main product at 800°C along with the Bi2Sr2Cu2o,. (220 I) phase and Ca2PbO •. Sintering at higher temperature (845°C) led to the formation of the high Tc phase (2223). 11 is shown that liquid phase sintering of the samples assisted the fomlation of the 2223 phase. There is an optimum level of Pb addition above which the 2223 phase is not produced even when heated for up to 60 hours at 845°C.

N ARSHAD ,M ARSHAD ,F R SALE ,A H QURESHI ,S K DURRANI ,S U REHMAN ,