Superconducting Tl2Ba2CaCu2O8 Thin Films Prepared by Post-Annealing in a Flow-Through Multiple-Zone Furnace

Tl2Ba2CaCu2O8 thin films were prepared for the first time by use of a multiple-zone flowthrough thallination process. Thallous oxide was volatilized from condensed thallium oxide in a low temperature source zone and convectively transported to a higher temperature thallination zone in which initially amorphous Ba2CaCu2O5precursor films were located. By careful control of the source temperature, film temperature, flow rate, anneal time, and rates of heat up and cool down, smooth Tl2Ba2CaCu2O8 thin films were prepared on (100) LaAlCO3with the following properties: inductive Tc of 107.6 K and 80% transition width of 1.3 K, transport Jc at 75 K of 1.3 X 105 A/cm2, and Rs at 10 GHz and 80 K of 1.3 mΩ. The scalability of the process to large area film processing was demonstrated by the preparation of Tl2Ba2CaCu2O8 thin films on LaAlO3three-inch diameter wafers.