Microstructures in Tl-1223/Ag tapes with different chemical compositions and J(c)'s

The microstructures of a Tl0.8Pb0.2Bi0.2Sr1.6Ba0.4Ca2Cu3O9 + delta/Ag tape (tape I) with J(c) of 17,600 A/cm(2) at 77 K and 0 T and three Tl0.8Pb0.2Bi 0.2Sr1.8Ba0.4Ca2Cu3O9 + delta/Ag tapes with J(c)'s of 9300 (tape II), 16,70 0 (tape III) and 25200 A/cm(2) (tape IV) prepared using the powder-in-tube method and an in-situ reaction method, were investigated using high-resolut ion transmission electron microscopy. In the tape preparation, an intermedi ate rolling process was incorporated during final heat-treatment for the la st tape, but not for the rest of the tapes. Tl-1223 grains are in a thin pl ate-like shape. Tendency of directional grain-alignment increased in an ord er of tapes I, II, II and IV. In tape IV, Tl-1223 grains are clearly textur ed at least partly. In lattice defects, while stacking faults were prevalen t in the former composition, dislocations and holes were frequently observe d in the latter. Also impurity phases were appeared to be more abundant in the former than in the latter. The relationship between J(c) and the micros tructure in the tapes was explained in a term of grain-linking. (C) 2000 El sevier Science B.V. All rights reserved.