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

It is shown that mechanical deformation enhances intragrain flux pinning in silver-sheathed tapes ofthe (Bi,Pb)(2)Sr2Ca2Cu(3)O(x) (2223) material. Tapes with zero transport critical current density (J(ct)) - but nonzero magnetic hysteresis - were produced with prereacted 2223 powders. Comparisons ofthe hysteresis in tapes directly after a heat treatment and after a subsequent pressing step show a clear increase of the 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 microstructure after, but not before, pressing, suggesting that dislocations that could have been introduced in the pressing step may act as pinning centers.