Effect of sintering temperature on phase composition and J/sub c/ of Ag-sheathed Bi-2223 single and multifilamentary tapes

The sintering temperature window of Ag sheathed Bi-2223 tapes was studied by a temperature gradient method for fabrication of tapes. The I/sub c/ of the tapes was found to be very sensitive to the sintering temperature. For the single filament tapes, the I/sub c/ reaches the maximum value at a temperature higher than that at which the 2212 percentage reaches the minimum. Around 6.5% of 2212 still exists in the best single filamentary tapes, while just a half of this 2212 fraction (about 3.5%) remains in the best 19 filamentary tapes. The J/sub c/ was found to be more sensitive to Bi-2212 phase content in the multifilamentary tapes than that in the single core tapes. A J/sub c/ of 4.5/spl times/10/sup 4/ A/cm/sup 2/ (J/sub c/ 1/spl times/10/sup 4/ A/cm/sup 2/) for single core tapes and of 3.3/spl times/10/sup 4/ A/cm/sup 2/ (J/sub c/ 0.65/spl times/10/sup 4/ A/cm/sup 2/) for 19 core multifilament tapes were achieved reproducibly with sintering time of 100 hours and one intermediate pressing. 70% of maximum I/sub c/ can be retained within 4 degrees sintering temperature window for both single and 19 filamentary tapes.