MECHANICALLY INDUCED FLUX-PINNING IN (BI,PB)(2)SR-2,CA2CU3OX TAPES

It is shown that mechanical deformation enhances intragrain flux pinni ng in silver-sheathed tapes ofthe (Bi,Pb)(2)Sr2Ca2Cu(3)O(x) (2223) mat erial. Tapes with zero transport critical current density (J(ct)) - bu t nonzero magnetic hysteresis - were produced with prereacted 2223 pow ders. Comparisons ofthe hysteresis in tapes directly after a heat trea tment and after a subsequent pressing step show a clear increase of th e hysteresis, almost a factor of three at 20K and 3T, corresponding to a five-fold increase in J(c). The J(c) values can be lowered again by an additional heat treatment. Bent platelets can be observed in the m icrostructure after, but not before, pressing, suggesting that disloca tions that could have been introduced in the pressing step may act as pinning centers.