EVOLUTION OF THE MICROSTRUCTURE IN (BI,PB)(2)SR2CA2CU3OX AG WIRES ANDITS INFLUENCE ON THE CRITICAL-CURRENT DENSITY/

Mono- and multifilamentary (Bi,Pb)(2)Sr2Ca2Cu3Ox-wire tapes were fabri cated by the oxide-powder-in-tube-technique (OPIT) using precursors wh ich were prepared by various methods. In order to get information abou t the kinetics of the BiPb-2223 phase formation, the microstructure an d the phase composition evolution were investigated during annealing b y SEM and XRD, respectively. In addition, DTA measurements were perfor med on precursor powder samples. From the results, it can be concluded that in dependence on the precursor parameters, the formation of BiPb -2223 can proceed by precipitation from a partial melted system as wel l as by formation from preexisting BiPb-2212 crystals. The microstruct ure and critical current densities j(c) of the tapes seem to be depend ent on its mechanism of formation. Maximum jc-values of 31 kA/cm(2) (7 7K, 0T) and about 22 kA/cm(2) were measured on multifilamentary wires with a length of 5 cm and 90 m, respectively, with precursors made by aerosol spray pyrolysis.