Promotion of high-Tc phase in doped Bi/sub 1.6/Pb/sub 0.4/M/sub 0.1/Ca/sub 2/Cu/sub 3/O/sub y/ conductors prepared by melt quenching

Superconductors with a variety of dopants (m=Nb, Ag, Ba and Zn) were prepared by the heat treatment of quenched glass precursors. The peritectic transition of Bi-2223 superconductors with a nominal composition of Bi/sub 1.6/Pb/sub 0.4/M/sub 0.1/Ca/sub 2/Cu/sub 3/O/sub y/ were studied kinetically under different atmospheres and temperature gradients. It was found that both peritectic transition and reaction were dependent on the ambient atmosphere. Kinetic studies under different atmospheres revealed that the thermal stability of Bi-2223 was greatly enhanced under oxygen atmosphere. Systematic investigations of the effect of sintering time on the J/sub c/ of Ag cladded BPSCCO taped and wires showed that J/sub c/ increases initially but subsequently decreases for longer sintering times. Formation of low temperature eutectic by silver addition was observed to accelerate the rate of evaporation. Lower temperature processing was required for fabrication of high quality Ag sheathed BPSCCO tapes. (author)