TOWARDS THE RAPID SYNTHESIS OF PURE 2223-POWDERS WITH BI2-XPBXSR2CA2CU3OY COMPOSITIONS BY SEMI-WET METHODS .2. OPTIMIZATION OF PB CONTENT USING PB-SR-CA CARBONATE PRECURSORS
D. Pandey et al., TOWARDS THE RAPID SYNTHESIS OF PURE 2223-POWDERS WITH BI2-XPBXSR2CA2CU3OY COMPOSITIONS BY SEMI-WET METHODS .2. OPTIMIZATION OF PB CONTENT USING PB-SR-CA CARBONATE PRECURSORS, Physica. C, Superconductivity, 241(3-4), 1995, pp. 279-291
The effect of Pb content on the formation of the 2223 phase in stoichi
ometric compositions Bi2-xPbxSr2Ca2Cu3Oy (0.1 less than or equal to x
less than or equal to 0.4) is reported for a semi-wet route using [xPb
CO(3) + 2SrCO(3) + 2CaCO(3)] precursors. Synthesis of high-purity 2223
phase free from Ca2PbO4 is reported for x = 0.3 within a total heat t
reatment duration of 44 h with several intermediate crushings and grin
dings. By studying the sequence of solid state thermochemical reaction
s, it is shown that in the absence of Ca2PbO4, which plays a crucial r
ole in accelerating the formation of 2223 phase, the conversion of 221
2 into 2223 gets slowed down unless one resorts to intermediate crushi
ng and grinding. The optimum Pb content for the formation of 2223 phas
e in Bi2-xPbxSr2Ca2Cu3Oy compositions has been estimated to be in the
range 0.3 less than or equal to x less than or equal to 0.4.