IMPROVEMENT OF CRITICAL-CURRENT DENSITY AND MICROSTRUCTURE OF TL-1223TAPES BY A 2-POWDER METHOD

Superconducting tapes of (TI,R)(Ba,Sr)(2)Ca2Cu3Ox (R = Bi or Ph) were prepared using a mixture of pre-reacted single phase powder and unreac ted precursor of identical or different stoichiometry. The effects of mechanical densification and sintering conditions on critical current (I-c) and microstructure of the tapes were investigated. Compared to t he tapes made with entirely unreacted powder or pre-reacted powder, th e tapes made with a mixture of the two showed a much improved microstr ucture, an improved self-field I-c at 77 K, as well as a smaller depen dence on sintering conditions and better reproducibility of I-c.