Fabrication of low cost Bi-2212 superconductors using Ag/Ni clad tape

With the intentions of the reduction of material cost and the improvement of mechanical properties of Bi₂Sr₂Ca ₁Cu₂O_x(Bi-2212) superconducting tape, Ag/Ni and Ag/Ni/Ag clad tapes were successfully prepared by a diffusion and deformation process and used as substrates for the fabrication of Bi-2212 tape. The clad tape has extremely good adhesion between Ag and Ni layers. Bi-2212 powder precursor mixed with organic binder was mounted on the Ag layer of the clad tape and subjected to a heat treatment of melting and solidification. Bi-2212 formed on the Ag layer whose average thickness was more than 10 μm showed good superconducting properties. The highest J_c (4.2 K, 10 T) value was 1.7×10⁵ A/cm², which is comparable to the Bi-2212 tape fabricated using pure Ag tape. However, when the thickness of the Ag layer was reduced to 5 μm, the tape showed deteriorated properties due to the transfer of Cu and Ni elements across the Ag layer. 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 3 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