The influence of precursor preparation on the superconducting properties of Bi(2223) tapes

The effect of preparation of precursor powders on the formation of Bi-2223 phase and critical current density (J/sub c/) of OPIT tapes, was studied. The precursors were prepared by "one-powder" and "two-powder" methods. The results indicate that a sufficiently large fraction of second phases in the precursors is crucial for obtaining pure 2223 phase and high J/sub c/ values. It is also revealed that the (Sr,Ca)/sub 2/CuO/sub 3/ second phase promotes a faster phase transformation of 2212 to 2223 than other second phases in the precursors. Tapes prepared with "one-powder" precursor achieved J/sub c/ of 25.5 kA/cm/sup 2/, while the J/sub c/ for the tapes made from "two-powder" precursors had values of about 12 kA/cm/sup 2/.