Rapid Furnace Annealing of YBa2Cu3Ox Thick Films on Ni/NiO and Inconel Substrates Prepared by Spray Pyrolysis of YBa2Cu3Ox Powder

A spray pyrolysis growth system has been employed for the formation of superconducting YBa₂Cu₃O_x (YBCO) thick films. YBCO films on polycrystalline Ni/NiO, Inconel 600, and Inconel X substrates ranging in thickness from 80-100 μm have been developed by a three-step process with observed T_{c zero} values up to 85 K. In the first step, the metallic substrates were examined with and without a preoxidation anneal to form a native oxide layer. Second, superconducting YBCO powder (0.2 μm particle size) was mixed with ethanol and sprayed onto the substrates. Third, the films were sintered at high temperature and oxygenated to form the superconducting phase. The effect of a native oxide buffer layer upon superconducting properties was evaluated as a function of the duration of the preoxidation anneal and the sintering anneal. X-ray diffraction (XRD) θ/2θ, variable temperature four-probe resistance, and Auger line scan characterization of these films will be discussed.