Abstract
We have undertaken a study of the formation process of Bi,Pb(2223) starting from different precursors, and established that all the precursors studied transformed with a similar process as the coprecipitated calcined powder used in the preparation of high current carrying Bi,Pb(2223) Ag sheathed tapes. The different types of precursors that have been studied are the following: (a) The coprecipitated calcined powder, (b) Bi,Pb(2212) based mixtures and (c) a mixture of PbO and Pb-free calcined powder. The kinetic analysis for the first 24 hours of heat treatment at 855°C revealed that the reaction order parameter n as defined by the Avrami equation is 1.4. In addition, we have confirmed our previous formation mechanism from Bi(2212) to Bi,Pb(2223). There the formation of the solid solution Bi,Pb(2212) occurs first. The maximum T c value of the solid solution is 94.5 K. Subsequently, within a slower reaction, one forms Bi,Pb(2223). We have also established that the Bi,Pb(2223) formation is the same regardless of the precursor powder type studied.
Published Version
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