Critical current in Tl-base high-Tc oxides synthesized through a diffusion process

In the TBCCO diffusion composites, the 2223 phase is easily formed within a short reaction time. The critical current at 77 K is significantly improved by the F addition to the coating layer. The F addition decreases the degradation of critical current under magnetic field at 77 K, and shifts the irreversibility line to higher temperature. The XRD study reveals that the F addition clearly promotes the phase transformation from 2223 to 1223. Meanwhile, the annealing in flowing O/sub 2/ at 550/spl deg/C-600/spl deg/C also increases the critical current at 71 K. A J/sub c/ of about 10,000 A/cm/sup 2/ is obtained at 77 K in the TBCCO diffusion layer by the F addition and the O/sub 2/ annealing.>