Abstract: The present invention relates to a method of preparing an oxide superconducting film, the method includes reacting a metal acetate containing metal M selected from the group consisting of lanthanum, neodymium and samarium with fluorocarboxylic acid having not less than three carbon atoms, reacting barium acetate with fluorocarboxylic acid having two carbon atoms, reacting copper acetate with fluorocarboxylic acid having not less than two carbon atoms, respectively, followed by refining reaction products, dissolving the reaction products in methanol such that a molar ratio of the metal M, barium and copper is 1:2:3 to prepare a coating solution, and coating a substrate with the coating solution to form a gel film, followed by calcining and firing the gel film to prepare an oxide superconducting film.

Abstract: A metal substrate for an oxide superconducting wire, which comprises a polycrystalline metal substrate with a rolled aggregate structure having a {100} plane which is parallel to the rolled surface and a <001> axis which is parallel to the rolling direction, and an oxide crystal layer comprising an oxide of the polycrystalline metal and formed on a surface of the polycrystalline metal substrate, wherein at least 90% of grain boundaries in the oxide crystal layer have an inclination of 10° or less, and at least 90% of the {100} plane of the oxide crystal layer make an angle of 10° or less with the surface of the polycrystalline metal substrate.

Abstract: A superconducting device has a substrate and a superconducting film formed on the substrate. A surface of the substrate has a first surface portion of which a curvature is constant or changes continuously, a second surface portion of which a curvature is constant or changes continuously, and a third surface portion at which the first and second surface portions meet and at which the curvatures of the first and second surface portions become discontinuous. The superconducting film formed on the surface of said substrate has a grain boundary serving as a junction only in a portion corresponding to the third surface portion of the substrate.