THERMAL-PROCESSING OF SPRAY-PYROLYZED AND ELECTRODEPOSITED TL SUPERCONDUCTOR FILMS AND OPTIMIZATION OF THE TRANSPORT CRITICAL-CURRENT DENSITY

Employing a flow-through ''two-zone'' thermal processing system to con trol thallous oxide vapor pressure, we have investigated two different types of precursors and explored their potential for producing open t ape conductors with high critical current densities. The two methods e xamined were: 1) precursor Pb-Sr-Ba-Ca-Cu-O(Ag) powders sprayed as a c olloidal ink onto a heated substrate; 2) precursor material deposited by electrodeposition from an electrolytic solution containing the meta l nitrates. Although both of these methods produce precursors with the proper stoichiometric ratios, vast differences in other properties su ch as reactivity, density, thickness, and morphology exist. The effect s of these precursor properties upon subsequent superconducting charac teristics such as phase development, final morphology, and electrical transport are characterized by XRD), SEM/optical microscopies, R vs. T and J(c) measurements, respectively. Both types of precursors have pr oduced superconducting films with high Jc's. Phase-pure textured films have been obtained on a variety of substrates.