Fabrication, processing and properties of Tl-1223 conductors

Fabrication of Tl-1223 conductors in two geometries is reported. Powder-in-tube (PIT) tapes were fabricated using aerosol generated precursor powders mixed with Tl/sub 2/O/sub 3/. Effect of processing variables such as temperature, time and uniaxial pressure were studied. Under optimum processing conditions the tapes have sharp transitions (widths /spl sim/1 K) and zero-field J/sub c//spl sim/0.9/spl times/10/sup 4/ A/cm/sup 2/ at 77 K, However the tapes lack any detectable grain orientation texture and are severely weak-linked. On the other hand, thick films (3-30 /spl mu/m) of Tl-1223 on Ag made using a variety of precursor deposition techniques followed by thallination in a two-zone flow reactor, show significantly reduced weak-link behavior and high zero-field J/sub c/'s (>10/sup 4/ A/cm/sup 2/). It is found that these films are c-axis aligned (rocking curve FWHM/spl sim/3-11/spl deg/) and also possess varying degrees of local in-plane texture. Microstructural development in these thick films is found to be similar to that observed previously for films on polycrystalline YSZ. Such thick films present a working model of a practical Tl-1223 conductor. >