Abstract: Provided is a coating solution where, upon producing a rare-earth superconductive composite metal oxide film by means of a coating-pyrolysis method, cracks are not generated in the heat treatment process for eliminating organic components, even when the thickness of the rare-earth superconductive film produced in a single coating is 500 nm or more, and without having to repeat the coating and annealing process. A solution for producing a rare-earth superconductive film which is made into a homogeneous solution by dissolving, in a solvent formed by adding a polyhydric alcohol to a univalent linear alcohol having a carbon number of 1 to 8 and/or water, a metal complex coordinated, relative to metal ions of a metallic species containing rare-earth elements, barium and copper, with pyridine and/or at least one type of tertiary amine, at least one type of carboxylic acid having a carbon number of 1 to 8, and, as needed, an acetylacetonato group.

Abstract: Provided is a coating solution where, upon producing a rare-earth superconductive composite metal oxide film by means of a coating-pyrolysis method, cracks are not generated in the heat treatment process for eliminating organic components, even when the thickness of the rare-earth superconductive film produced in a single coating is 500 nm or more, and without having to repeat the coating and annealing process. A solution for producing a rare-earth superconductive film which is made into a homogeneous solution by dissolving, in a solvent formed by adding a polyhydric alcohol to a univalent linear alcohol having a carbon number of 1 to 8 and/or water, a metal complex coordinated, relative to metal ions of a metallic species containing rare-earth elements, barium and copper, with pyridine and/or at least one type of tertiary amine, at least one type of carboxylic acid having a carbon number of 1 to 8, and, as needed, an acetylacetonato group.