Fabrication of Bi 2Sr 2Ca 1Cu 2O x superconductor using metallic substrate tape clad with Ag

Abstract

With the intentions of the reduction of material cost and the improvement of mechanical properties, Ag/Ni and Ag/Stainless Steel (SUS) clad tapes were prepared as substrate materials for the fabrication of Bi 2Sr 2Ca 1Cu 2O x (Bi-2212) superconducting tape. Bi-2212 formed on the Ag/Ni clad tape with a 10 μm Ag layer thickness showed good superconducting properties of T c=88 K and J c (4.2 K, 10 T)=1.7×10 5 A/cm 2, comparable to those of Bi-2212 tape fabricated using pure Ag tape. However, Bi-2212 formed on the Ag/Ni clad tape with a 5 μm Ag layer thickness showed deteriorated properties due to the transfer of Cu and Ni across the Ag layer. The Ag/SUS clad tape did not work as a substrate material, because the Ag layer was eroded, forming many holes, and hence could not prevent a severe reaction between Bi-2212 and SUS. The J c of the Bi-2212/Ag/Ni tape started to degrade at ε=0.2–0.3% in the bending test. A tensile test indicated that the Ag/Ni clad tape had about three times larger yield strength than pure Ag tape. From these results, it is expected that the Bi-2212/Ag/Ni tape has a much improved stress tolerance over the conventional Bi-2212/Ag tape.