Effect of precursor powders on phase evolution and electromagnetic properties of controlled melting processed Bi-2223 Ag-sheathed tapes

The effect of precursor powder on the phase evolution and electromagnetic properties of Bi-2223 Ag-sheathed tapes prepared by a controlled melting (CM) process has been studied. It was found that during the CM process, the phase evolution is almost the same in tapes made from different precursors. Part of Bi-2223 is decomposed to Bi-2212 and nonsuperconducting phases due to a short time melting, and then can be recovered in the subsequent press-sinter cycles. The improved magnetic field dependence of critical current density suggests that the CM process is still effective in reducing the weak links and improving the flux pinning properties for the tapes made from highly reactive precursors.