The role of Bi-2212 in Bi-2223 Ag-sheathed tapes fabricated by a controlled melt process

We have studied the phase composition, transport current and flux pinning properties in Bi-2223 Ag-sheathed tapes fabricated by a controlled melt method (CM) and conventional thermo-mechanical process(CT), respectively. The highest J(c) (77K, 0T) value of 36.8 kA/cm(2) (I-c=27.5 A) was obtained in CM sample. The results of I-V curve showed a drastic voltage drop occurred at a certain current in CM samples, indicating that above a certain value of the self-field of the Ag-sheathed tape, Bi-2212 phase, which becomes a nonsuperconducting phase, might act as effective flux pinning centers.