SYNTHESIS OF TL-BASE HIGH-TC SUPERCONDUCTING OXIDES THROUGH A DIFFUSION PROCESS

In Tl-Ba-Ca-Cu-O (TBCCO) diffusion composites, the 2223 phase, which s hows an offset T(c) of 119 K, has been easily formed. Ag addition and F addition to the coating layer of the composites enhance the diffusio n reaction and decrease the optimum reaction temperature. F addition t o the coating layer of the TBCCO diffusion composite increases the cri tical current and reduces its degradation in magnetic field at 77 K. A fine dispersion of F is observed in the TBCCO diffusion layer. A crit ical current density of several thousand A/cm2 is obtained at 77 K and 0 T in the TBCCO diffusion layer without any mechanical fabrication p rocedure.