DEVELOPMENT AND PERFORMANCE CHARACTERISTICS OF Bi-2212/Ag SUPERCONDUCTING WIRES

A series of Bi-2212/Ag composite wires have been fabricated by the "powder in tube" method. Heat treatment studies have been performed to investigate their effect on superconducting properties. The critical current density was found to be strongly influenced by the phase composition of the calcined powder. The wires with T-c of 85 K reached at 4.2 K j(c) values up to 66500 A/cm(2) (0 T) and 22500 A/cm(2) at 12 T. At 77 K j(c) falls to 1800 A/cm(2) (0 T). The index of resistive transition n was found to correlate with the critical current density, suggesting that n could be useful as an indicator of microstructural inhomogeneities. Since practical applications require stability of the superconducting phase, measurements of the effect of ageing and thermal shocks on j(c) were made and are discussed.