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 control thallous oxide vapor pressure, we have investigated two different types of precursors and explored their potential for producing open tape conductors with high critical current densities. The two methods examined were: 1) precursor Pb-Sr-Ba-Ca-Cu-O(Ag) powders sprayed as a colloidal ink onto a heated substrate; 2) precursor material deposited by electrodeposition from an electrolytic solution containing the metal nitrates. Although both of these methods produce precursors with the proper stoichiometric ratios, vast differences in other properties such as reactivity, density, thickness, and morphology exist. The effects of these precursor properties upon subsequent superconducting characteristics such as phase development, final morphology, and electrical transport are characterized by XRD, SEM/optical microscopies, R vs. T and Jc measurements, respectively. Both types of precursors have produced superconducting films with high Jc’s. Phase-pure textured films have been obtained on a variety of substrates.