Effect of Cooling Rate on Critical Current Density for Bi2Sr2CaCu2O8+δ/Ag Composite Tapes

Bi2Sr2CaCu2O8+?(Bi-2212)/Ag composite tapes were prepared by melt-solidifying method and the relationship between cooling conditions after the melt-solidification and superconducting properties were investigated. A high cooling rate was found to be effective in suppressing the decomposition of Bi-2212 and in increasing Jc. A tape with high Jc of 2.4?105 A/cm2 at 4.2 K in 12 T was obtained by fast cooling. With annealing of this tape in N2 atmosphere, Jc of 3.1?104 A/cm2 at 77.3 K in 0 T was attained due to the enhancement of Tc.