Fabrication and properties of Bi2223 tapes with high resistive barrier formed by the in situ oxidation method

Abstract

Ag sheathed Bi2223 tapes have the performances of I c values over 100 A and length of 1000 m which are enough for prototype applications. However, their AC loss is still too high for practical applications. To reduce the AC coupling loss, the introduction of high resistive barrier between filaments and the filament twisting are effective. In this study, the Bi2223 tapes with CuO and NiO barriers between filaments were fabricated through the in situ oxidation method, and the effect of 2223 addition in precursor on the formation of Bi2223 was also investigated. Mono-core wires covered with metal Cu or Ni were stacked and deformed to form 7-filamentary tapes. These tapes were sintered, and the metal Cu and Ni layer were oxidized to form CuO and NiO barrier layer, respectively. The continuity of CuO and NiO barriers were kept well in the final tapes, although the CuO grains in barrier layer easily agglomerated during sintering compared to NiO. The formation speed of Bi2223 phase was increased by the addition of Bi2223 in precursor. However, the formation speed of the tape with barrier was slower than that without barrier. This difference should be considered to control the processing for high J c value.