High Jc's in just-rolled Tl-1223/Ag tapes prepared using(Tl,Pb,Bi)-(Sr,Ba)-Ca-Cu-O compositions

摘要

The grain morphology, the changes in microstructure and Jc during the thermo-mechanical treatment, and the field dependence of Jc in Tl-1223/Ag tapes of Tl0.8Pb0.2Bi0.2Sr1.6Ba 0.4Ca2Cu3Oz and Tl0.8 Pb0.2Bi0.2Sr1.8Ba0.2Ca 2.2Cu3Oz compositions were investigated, and then compared with each other. As a result, high Jc's near 25000 A/cm2 at 77 K and 0 T were obtained in the latter composition, in which plate-like Tl-1223 grains are directionally aligned, at least in local regions. The high Jc 's are attributed to enhanced grain-contact areas resulting from enhanced densification by a repetition of the TMT and the retarded decomposition of Tl-1223 phase in the latter composition. The strong field dependence of Jc indicates, however, that there still exist significant weak-links