Effect of precursor phase composition on 2223 phase formation in Ag-sheathed tapes

Metastable phase states of BPSCCO 2223 precursor were studied as a function of annealing temperature, time, and oxygen partial pressure. Reproducible, but path-dependent changes in precursor phase composition during annealing are mostly governed by changes in Pb solubility in the (Bi,Pb)2212 phase. Studying phase formation upon heat treatment of tapes made by Nexans customers, we found that BPSCCO phase composition affects melting behavior of (Bi,Pb)2223/Ag tapes, phase recrystallization upon heating, and early stages of Bi2223 phase formation.