Irreversibility lines for Ag/(Bi, Pb)2Sr2Ca2Cu3O{sub y}(2223) wires prepared through a phase formation- decomposition-recovery (PFDR) process and normal annealing process were determined using both AC susceptibility measurements under DC fields and magnetisation measurements. It was found that flux pinning was enhanced in the PFDR processed samples over the normal processed samples, in particular at temperature above 77 K. The PFDR process results in high mass density, grain alignment, uniform distribution of impurity precipitates and high density of defects. The irreversibility temperatures scaled with the applied field according to H13, which is in contrast to H23 law for YBa2Cu3O{sub 7-x} and conventional superconductors. The irreversibility lines for PFDR processed tapes showed a crossover with those for normal processed tapes at temperature below {Tc} of the (Bi, Pb)2Sr2CaCu2O{sub 8+x} (2212), suggesting that at temperature above {Tc} of the 2212 phase, the 2212 as nonsuperconducting region, may serve as effective pinning sites for fluxoids.

A significant enhancement of the in-field J{sub c} of Ag-clad (Bi, Pb)-Sr-Ca-Cu-0 (BPSCCO:2223) wires has been achieved using a controlled melt procedure. The greatly reduced weak linking has resulted in an extended plateau regime in the J{sub c}-H curve. J{sub c}s of 40,000 A/cm2 at 77 K (self field) and 9,000 A/cm2 at 77 K (1 T) have been achieved. The improved J.H characteristics may be attributed to microstructures consisting of uniform grain alignment throughout the entire cross section, intimate connection between grains, impurities within the grains, and an optimal level of dispersed 2212 phase. Irreversibility line measurements using both AC susceptibility in DC fields (reported elsewhere), and magnetization measurements, have indicated that flux pinning can be enhanced in the melt-processed samples over the results of normal solid-state processing with its less-than optimal 2212-phase content. But sufficiently long annealing times during the ''normal'' route may achieve 2212-phase content and J{sub c}s which are comparable to those of melt-processed samples.

Proceedings of the Tenth International Cryogenic Materials Conference (ICMC) held in Albuquerque, New Mexico, July 12-16, 1993.

This book covers all research fields in high Tc Superconductivity. Breakthrougs in the single crystal growth of a monolithic device leads to a new technology.