SYNTHESIS OF TlBa_2Ca_2Cu_3O_x THICK LAYER ON METAL TAPES THROUGH THE DIFFUSION REACTION

摘要

Tl-based high-T_c oxide layers have been synthesized through the reaction between a Tl-free substrate and a coating layer containing Tl. The T1F substitution for Tl_2O_3 in the coating layer promotes the formation of the Tl-1223 phase, which significantly improves the I_c-B performance at higher temperatures. The behavior of our F during the reaction and the mechanism of the enhancement of the synthesis of Tl-1223 phase by the T1F substitution have been studied. Meanwhile, thick Tl-1223 layers, a few hundred μm in thickness, have been formed on Ni tape with good bonding through the diffusion reaction. The same reaction condition can be applied for the synthesis of Tl-1223 phase on Ni tape as that for the bulk specimen with almost no degradation in superconducting performance.