Effect of barrier configuration on the superconducting properties of Bi2223 multifilamentary tapes with Sr-V-O oxide barriers

We prepared Ag-sheathed Bi2223 multifilamentary tapes having 19 filaments with three different barrier configurations by using the powder-in-tube method. The layers of Sr-V-O (SVO) barrier are arranged inside and/or outside of each filament. For the tapes with barriers the transport critical current I_c and its density J_c at 77 K are higher than those of the nonbarrier tapes for all the barrier configurations. This can be due to the reduction in oxygen partial pressure during the heat-treatment and the enhancement of Bi2223 phase formation by the reaction of the inside-coated SVO with a Bi-based oxide core in the inside-barrier tapes. Furthermore, for all the barrier tapes the transport AC losses at 77 K in self-field are lower than those of the nonbarrier tapes. This results suggest that SVO will be one of the most important candidates for resistive barriers with a view to AC applications, in particular, the inside-barrier tapes give us an excellent possibility to improve the overall J_c and ease the fabrication of tape. For the tapes, however, SrCO₃ contaminated in the process of SVO preparation must be eliminated