Fabrication and characterization of micro-structural evolution and properties of twisted Bi(Pb)-Sr-Ca-Cu-O superconductor tape

We Fabricated 37 multi-filament Bi-2223 (BSCCO) superconductor tapes and ev aluated the effect of twisting on the microstructural evolution such as gra in size, grain alignment, and interface morphology, and on the resulting cr itical current. Twist pitches of the BSCCO tapes are in the range of 70 to 8 mm and uniformly deformed. It was observed that the grain size and the de gree of texture decreased with decreasing pitch, probably due to the format ion of the irregular interface between the Ag and the filaments. In additio n, the critical current of the tapes decreased with decreasing pitch. For t he tape having a twist pitch of 8 mm, approximately 50% of the critical cur rent was maintained compared to that of the untwisted tape. The reduction o f critical current may be related to the interface irregularity, smaller gr ain size, poorer texture and presence of creeks due to the induced strain d uring the twisting processing.