Thermomechanical treatment, structure and transport currents in multicore Bi(2223)/Ag tapes

A set of 19 filament Bi(2223)/Ag tapes differing in thermomechanical treatment were analyzed structurally (XRD, SEM and TEM) and electrically by transport I-c measurement in self field, in external magnetic field up to 1.2 T, and by I-c-angular dependence, all at 77 K. The results obtained show that the optimal state for the application of a roll-sinter step is at the 2223/2212 phase ratio near to 1 (50% of 2223). The structural results (2223 phase content, grains morphology and texture) were studied, and they were related to the transport currents. I-c(0 T), I-c(B) and I-c(alpha) as well as the n-exponent of current-voltage characteristics and its relation to I-c are studied and discussed in connection with the structure induced by the thermomechanical treatment applied. (C) 1999 Elsevier Science B.V. All rights reserved.