The influence of starting precursors on grain growth, microstructure evolution and J/sub c/ property of Bi-2223/Ag tapes

The grain growth, microstructure evolution and J/sub c/ properties of Bi-2223/Ag tapes, fabricated from precursor powders with different lead contents (Pb=0.2-0.4) and particle size distributions, were compared. The experimental results show that the variations of lead content and particle sizes extremely influence the reactivity of precursor powders, consequently, the formation rate of the 2223 phase, microstructure and J/sub c/ values of Bi-2223/Ag tapes. In addition, these variables also affect the formation and distribution of the nonsuperconducting secondary phases, hence the grain connectivity and texture, which are of vital importance to the current transport. By optimizing these powder parameters, J/sub c/ values above 60 kA/cm/sup 2/ (77 K, 0 T) in short tapes were achieved with high reproducibility.