Fabrication, current density and strain dependence of sintered, Ag-sheathed BiSrCaCuO (2212) single filament and multifilamentary tape superconductors

Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/ (2212) superconductors have been fabricated into silver (Ag)-sheathed single-filament, multifilament, and wire-in-tube (WIT) tapes. Calcining, annealing and sintering conditions have been studied to improve the critical current density J/sub c/(B, 4.2 K) at high magnetic field (B). The optimization is discussed, and resulting properties are related to the microstructure of the superconductor. Superconductor J/sub c/ approximately 1-5*10/sup 4/ A/cm/sup 2/ has been obtained in fields >20 T at 4.2 K in both single and multifilamentary tapes. The dependence of J/sub c/ upon mechanical strain ( in ) has been investigated. No prestraining of the superconductor occurred in any of the samples, most likely due to yielding of the Ag sheath. Although strain resistance was good in all samples, the WIT tapes were significantly more resistant than the single-filament tapes. For the single-filament tapes, in /sub irr/ approximately 0.24%, while for the WIT tapes, in /sub irr/ approximately 0.36%, where in /sub irr/ is the irreversible strain limit.