ADVANCES IN THE DEVELOPMENT OF SILVER-SHEATHED (BI,PB)2223 COMPOSITE CONDUCTORS

Significant advances have been made in the critical current density of the technologically interesting (Bi,Pb)2223 composite conductors. Engineering current density, J(e), of 9,100 A/cm(2), corresponding to a filament current density, J(c), of 32,600 A/cm(2) (77 K, self field) has been achieved by increasing the fraction of oxide in the conductor and improving the thermomechanical processing of the conductor. The filament microstructure may be further optimized by decreasing the volume fraction of secondary phases and porosity. The strain tolerance of the higher oxide fraction conductors remains adequate for applications by increasing the number of filaments in the conductors. Composite tapes with twisted filaments have been produced that have promising electrical properties in applied magnetic fields.