Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x//Ag multilayer tapes with J/sub c/ (4.2 K, 10 T) of 500,000 A/cm/sup 2/ by using PAIR process

We developed PAIR (pre-annealing and intermediate rolling) process, which is a fabrication procedure for Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/(Bi-2212)/Ag composite tapes, in order to improve their superconducting properties. PAIR process is the combination of pre-annealing (PA) and subsequent intermediate rolling (IR) processes and is performed prior to a melt-solidification process. By performing the PAIR process, Bi-2212 grain alignment and intergrain connectivity are much improved and a large J/sub c/ enhancement can be expected for Bi-2212/Ag conductors. We study the effects of pre-annealing and intermediate rolling processes on microstructure and superconducting properties of the Bi-2212/Ag multilayer tapes fabricated by the oxide-painting and lamination method. The results show that J/sub c/ has been increased strongly by performing pre-annealing at 1133 K in oxygen (1 atm) and intermediate rolling with 25% deformation. PAIR processed samples have transport J/sub c/-oxide (4.2 K, 10 T) exceeding 5.0/spl times/10/sup 5/ A/cm/sup 2/. Whereas J/sub c/-oxide for the samples melt-solidified without PAIR process remains 3.0/spl times/10/sup 5/ A/cm/sup 2/. The enhancement of J/sub c/ is assigned to the microstructure with high grain alignment and uniformity, as well as the improvement in grain connectivity achieved by the PAIR process.