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 Bi2Sr2Ca1Cu2Ox(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 mum showed good superconducting properties. The highest J(c)(4.2K, 10T) value was 1.7x10(5)A/cm(2), which is comparable to those of Bi-2212 tape fabricated using pure Ag tape. However, when the thickness of Ag layer was reduced to 5 mum, 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 epsilon = 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.