JP5273561B2 - Manufacturing method of superconducting film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat treatment process which is effective to improve the uniformity of the in-plane distribution of superconducting characteristics when a rare earth superconducting composite metal oxide film is produced by an application/thermal-decomposition method, in particular, a rare-earth superconducting film is produced on a large area substrate. <P>SOLUTION: In the heat treatment process, thin films of a metal-containing compound, applied on various supports or substrates, are calcined at a temperature of 200-650&deg;C in an atmosphere having oxygen partial pressure of 0.2-0.8 atm, and including water vapor and having a dew point of &ge;20&deg;C, thereby an organic component contained in the applied film is uniformly removed, and the uniformity of the in-plane distribution of superconducting characteristics is improved. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method for manufacturing a superconducting composite metal oxide film aimed at application to superconducting microwave devices, current limiters, wires, and the like.

Various methods have been developed to form a superconducting composite metal oxide film (hereinafter sometimes simply referred to as “superconducting film”).
In this method, a solution containing an organic compound containing an atomic species that forms a superconducting film on various supports is used as a raw material, and this is applied on a substrate and subjected to heat treatment to thermally decompose the coating film. There is a coating pyrolysis method for forming a superconducting film. In this method, an organic compound containing an atomic species is dissolved as uniformly as possible in a solvent to prepare a homogeneous mixed solution, the solution is uniformly coated on a support, and heat treatment is performed to remove an organic substance or the like. It is required to thermally decompose the component to remove only the organic component, to perform high-temperature heat treatment, and to form a superconducting film uniformly through a solid phase reaction or a liquid phase reaction. The present inventors have been actively involved in this method and proceeded with development. And the invention about the manufacturing method and coating solution of a superconducting film was performed (patent documents 1 and 2).
The invention of Kumagai et al. Is known for a method using a low oxygen partial pressure or reduced pressure during high-temperature heat treatment (Patent Documents 3 and 4). Compared with other methods such as vacuum deposition, this manufacturing method has the advantage that it is a low-cost film forming method because it does not require a vacuum device, and the film formation on a long, large-area substrate is possible. It has the feature of being easy. Also, from the viewpoint of the characteristics of the superconducting film produced by this method, it was highly evaluated as being better than other production methods.

Stimulated by the successful formation of the superconducting film by this coating pyrolysis method, research and development on superconducting film fabrication using a similar technique was promoted in various organizations around the world, and the following methods were announced.
The IBM Thomas Watson Laboratory, USA, and subsequently the Massachusetts Institute of Technology, said that a superconductor can be formed by applying a trifluoroacetate solution on a support and heat-treating it in a steam atmosphere. (Non-Patent Documents 1 and 2). After that, the Superconducting Engineering Laboratory announced that the process was improved and optimized to successfully produce a superconducting film having high critical current characteristics (Non-patent Document 3). Furthermore, Masabe et al. Invented a coating solution for producing a neutral superconducting material containing trifluoroacetic acid or pentafluoropropionic acid and a pyridine group and an acetylacetonato group as a ligand, and a method for forming a superconducting thin film using the same. (Patent Documents 5 and 6).
When these fluorine-containing organic compounds are used as a starting material, high critical current characteristics can be obtained, but toxic and environmentally friendly hydrogen fluoride is generated during heat treatment. In addition, since variations in characteristics occur depending on the direction of gas flowing in the main firing step, it is difficult to apply to large-area thin films such as superconducting current limiters and superconducting microwave devices (Non-Patent Document 4).

On the other hand, when a metal organic acid salt not containing fluorine and acetylacetonate are used as raw materials, there is a feature that hydrogen fluoride is not generated in the heat treatment. However, in this case as well, improvement of the uniformity and critical current density (Jc) is a problem in application to large-area thin films (Non-Patent Document 5).
Also, inspired by the hydrolysis of trifluoroacetate, a metal-free trimethylacetate solution containing no fluorine was applied to the substrate, and was temporarily placed in a humidified oxygen stream or a nitrogen stream with an oxygen partial pressure of 0.02 atm or less. It has also been proposed to perform firing (Non-Patent Documents 6 and 7), but large-area films have not been obtained.

Japanese Examined Patent Publication No. 4-76323 Japanese Examined Patent Publication No. 4-76324 Japanese Examined Patent Publication No. 7-10732 Japanese Patent Publication No. 7-106905 Japanese Patent No. 3548801 Japanese Patent No. 3548802

A. Gupta et al., Appl. Phys. Lett. 52 (1988) 2077 P. C. McIntyre et al. Mater. Res. 5 (1990) 2771 Araki et al., Cryogenic Engineering 35 (2000) 516 H. Fuji et al., Physica C 392-396 (2003) 905 T.A. Manabe et al., Physica C 412 (2004) 896 Y. Xu et al. J. et al. Mater. Res. 18 (2003) 677 B. Zhao et al. Physica C386 (2003) 348

As mentioned above, when manufacturing rare earth superconducting composite metal oxide films by coating pyrolysis method using metal organic compounds that do not contain fluorine, in applications to large area thin films such as superconducting current limiters and superconducting microwave devices, Improvement of the uniformity and critical current density is a challenge.
The present invention has been made in view of the current situation, and the uniformity of the large-area superconducting film produced when a superconducting composite metal oxide film is produced using a metal organic compound containing no fluorine as a raw material. It is an object of the present invention to provide a manufacturing method capable of improving the critical current density.

The cause of the non-uniformity is that the removal of the organic component is incomplete during the step of forming the temporary fired film by removing the organic component contained by pre-baking the metal-containing compound film at 200 to 650 ° C. It is conceivable that the pre-baking of the organic component occurs suddenly and the film surface is removed. In particular, when the area of the film becomes large, due to the influence of the windward and leeward when pre-firing is performed by circulating gas through the center and periphery of the film, the distance between the heating element and the film in the pre-firing process, or the like. Non-uniformity increases.
Therefore, the present inventors have conducted extensive research to achieve the above object, and the preliminary firing step of the metal-containing compound film at the time of producing a large-area superconducting film by a coating pyrolysis method, under controlled oxygen partial pressure. It was found that the uniformity and critical current density of the manufactured large-area superconducting film can be improved by carrying out in an atmosphere containing water vapor.

The present invention has been completed based on these findings, and according to the present invention, the following inventions are provided.
<1> In a method for producing a superconducting composite metal oxide film composed of rare earth elements, barium and copper,
(I) A metal-containing compound formulated using a metal-containing compound not containing fluorine selected from metal organic acid salts and metal acetylacetonates so as to have a metal seed composition corresponding to a superconducting composite metal oxide Preparing an organic solvent solution;
(Ii) applying and drying the solution on a support to form a film of the metal-containing compound on the support;
(Iii) The film of the metal-containing compound formed on the support is 200 to 650 ° C. in an atmosphere containing water vapor having an oxygen partial pressure of 0.2 to 0.8 atm and a dew point of 20 ° C. or higher. And (iv) subjecting the temporary fired film to main firing at 650 to 900 ° C. for crystallization, and further 900 to 400 ° C. A method for producing a superconducting composite metal oxide film, comprising the step of absorbing oxygen to form a superconducting composite metal oxide film.
<2> After performing the main firing step at an oxygen partial pressure of 0.01 to 100 Pa, the step of absorbing the oxygen is performed at an oxygen partial pressure of 0.2 to 1.2 atm. The method for producing a superconducting composite metal oxide film according to <1>.
<3> The step of preparing an organic solvent solution of the metal-containing compound containing no fluorine is a metal carboxylate having 1 to 8 carbon atoms and / or metal acetylacetate, which is a metal species containing rare earth elements, barium and copper. After adding pyridine and / or at least one tertiary amine and at least one carboxylic acid having 1 to 8 carbon atoms to the sodium powder mixture to produce a metal complex and volatilizing excess solvent, The superconducting composite metal oxide according to the above <1> or <2>, which is dissolved in a monovalent linear alcohol having 1 to 8 carbon atoms and / or water to form a uniform solution A method for producing a membrane.
<4> The superconducting composite metal according to <3>, wherein after dissolving in the linear alcohol having 1 to 8 carbon atoms and / or water, a polyhydric alcohol is added to obtain a homogeneous solution. Manufacturing method of oxide film.
<5> The method for producing a superconducting composite metal oxide film according to <4>, wherein the polyhydric alcohol is at least one selected from divalent alcohols and trivalent alcohols.

  According to the present invention, the characteristics, stability, and reliability of the superconducting fault current limiter and the microwave device are greatly improved, so that resource saving, energy saving, and cost reduction are realized.

The manufacturing method of the superconducting film of this invention is demonstrated in order.
[Preparation process of organic solvent solution of metal-containing compound]
The organic solvent solution of the metal-containing compound used in the method of the present invention contains each metal component composed of rare earth metal, barium (Ba), and copper (Cu) as an essential component. This solution is used to form an oxide superconducting film, and can be used to synthesize an inorganic compound containing these metal components by performing a heat treatment.

  The essential rare earth metal elements include yttrium (Y) and lanthanoid elements, lanthanum (La), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), dysprosium (Dy). , Holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). These rare earth metals can also use a plurality of metals selected from these.

For the purpose of producing a superconducting film, in addition to the above-mentioned rare earth metal, barium and copper essential metal components, other rare earth metals such as cerium (Ce) and praseodymium (Pr), calcium, Alternatively, by including a small amount of other components such as strontium, the electrical characteristics of the resulting superconducting film can be changed.
In addition, any metal species that can be used as a metal species that can be used when forming a superconducting film can be used as appropriate.

When a superconducting film made of rare earth metal, barium, and copper is to be formed, the ratio of rare earth metal, barium, and copper is a rare earth 123 system having a ratio of 1: 2: 3 (hereinafter, for example, when the rare earth metal is yttrium, A superconducting film having a ratio of 1: 2: 4 (hereinafter referred to as Y124 when the rare earth metal is yttrium, for example). Therefore, the mixing ratio of the element species in the raw material solution is preferably a molar ratio of 1: 2: 3 to 1: 2: 4. However, for example, a preferable result can be obtained even in a composition lacking barium. , This ratio is not something that can be tied.
In addition, monovalent metals such as silver, divalent metals such as calcium and strontium, trivalent metals such as rare earth metals other than the essential rare earth metals constituting the superconducting phase, and tetravalent metals such as zirconium and hafnium are added to the above solution. Thus, it is possible to form a superconductor containing an additive element or a compound thereof. Superconductors containing additive elements such as calcium and strontium or their compounds have different electrical characteristics from superconductors that do not contain them, so by controlling the ratio of metals in the solution, It is possible to control various characteristics such as critical temperature and critical current density.

  The solution used in the production method of the present invention is pyridine and / or at least one tertiary amine and at least one carbon number of 1 to 1 with respect to a metal ion of a metal species containing rare earth elements, barium and copper. A metal complex in which a carboxylic acid group of 8 and an acetylacetonato group are coordinated as necessary is dissolved in a linear alcohol having 1 to 8 carbon atoms and / or water to form a uniform solution.

As the “tertiary amine” which is one of the ligands in the metal complex, for example, trimethylamine, triethylamine, tripropylamine, tributylamine and the like are used, and “a carboxylic acid group having 1 to 8 carbon atoms” is used. Examples of the carboxylic acid include 2-ethylhexanoic acid, caprylic acid, butyric acid, propionic acid, acetic acid, oxalic acid, citric acid, lactic acid, benzoic acid, and salicylic acid.
Moreover, as said C1-C8 monovalent | monohydric linear alcohol, methanol, ethanol, n-propanol, n-butanol, n-pentanol etc. are raised, These mixtures can also be used.
Further, water can be used to dissolve the metal complex, and a mixture of one or more kinds of the monovalent linear alcohol having 1 to 8 carbon atoms and water can also be used.

The homogeneous solution used in the production of the present invention is preferably made into a uniform solution by further adding polyhydric alcohols after dissolving in the linear alcohol having 1 to 8 carbon atoms. Things are used. This is because the addition of polyhydric alcohols can prevent the occurrence of cracks in the above-described preliminary firing step and main firing step.
Examples of the polyhydric alcohols include ethylene glycol, hexylene glycol, octylene glycol, glycerin, diethylene glycol, triethylene glycol, tetraethylene glycol, and propylene glycol.

  Specifically, the preparation of the superconducting film manufacturing solution of the present invention is performed on a metal carboxylate having 1 to 8 carbon atoms and / or a metal acetylacetonate powder mixture of rare earth elements, barium and copper. , Pyridine and / or at least one tertiary amine and at least one carboxylic acid having 1 to 8 carbon atoms to produce a metal complex and volatilizing an excess solvent, It is prepared by dissolving in 8 monovalent linear alcohol and / or water, and preferably adding a polyhydric alcohol to obtain a uniform solution.

[Raw material solution coating process]
In this step, the solution is applied onto a substrate to form a solution coating film of a metal-containing compound. In this case, as the solution coating method, conventionally known methods, for example, various methods such as a dipping method, a spin coating method, a spray method, and a brush coating method can be used.
As the substrate, various materials and shapes can be used. In this case, as materials, metals and alloys such as nickel, copper, gold, silver, stainless steel, hastelloy, alumina, zirconia, titania, strontium titanate, lanthanum aluminate, neodymium gallate, yttrium aluminate, etc., Ceramics such as silicon carbide are used, and any shape such as a curved surface or a flat surface can be used. For example, any shape such as a plate shape, a wire shape, a coil shape, a fiber shape, a woven fabric shape, and a tubular shape can be adopted. The The support may be porous. Further, in order to prevent the reaction between the composite metal oxide and the base material and / or to relax the lattice mismatch between the two, a metal film or a metal oxide film such as zirconia or ceria is previously formed on the surface of the base material as an intermediate layer. Can be formed.

[Drying process]
The solution coating film formed on the substrate as described above is dried under normal pressure or reduced pressure at room temperature or under heating. Since the drying can be completed at the initial stage of the pre-baking process following the drying process, the coating film does not have to be completely dried in the drying process. Further, since the subsequent pre-baking step can be used as the drying step, this drying step can be omitted.

[Temporary firing process]
This step is a step of heating and baking the metal-containing compound film formed on the substrate as described above, and converting the film into a film made of barium carbonate, rare earth metal oxide, and copper oxide. . As the maximum firing temperature, a temperature of 400 to 650 ° C., preferably 450 to 550 ° C. is adopted. When the temperature is gradually raised to this temperature and this temperature is 20 to 600 minutes, the equivalent film thickness is preferably 500 nm or more. The temperature is lowered after holding for 150 to 300 minutes.
As the pre-baking atmosphere, an atmosphere including water vapor having an oxygen partial pressure of 0.2 to 0.8 atm and a dew point of 20 ° C. or higher is used.
When the oxygen partial pressure is not more than the above range, the supply of oxygen is insufficient, so that an organic component rich in carbon tends to remain in the film after pre-baking. The carbon-rich organic component in the pre-fired film partially makes the film reducible when the main calcination is carried out under a low oxygen partial pressure, so that Y123 is generated non-uniformly and the critical current density is also lowered. . On the other hand, if the oxygen partial pressure is above the above range, the supply of oxygen becomes excessive and the combustion of organic components and the generation of gas occur rapidly, so that the surface texture is disturbed and irregularities are formed, and the critical current density of the Y123 film after the main firing Is high, but its distribution is non-uniform.
Similarly, when the dew point of water vapor is 20 ° C. or lower, an organic component rich in carbon is likely to remain in the film after calcination, and Y123 is generated unevenly after calcination, resulting in a low critical current density. Become. In the calcination step, water vapor is considered to promote the removal of the carbon component in the film by the same mechanism as the gasification of the carbon component by the water gas reaction represented by the formula (1).
C + H ₂ O → CO + H ₂ (1)

[Main firing process]
This step is a step of reacting barium carbonate, rare earth metal oxide, and copper oxide while baking the film formed in the preliminary baking step to remove carbon dioxide from the barium carbonate. In the present invention, this firing step is preferably carried out at an oxygen partial pressure of 0.01 to 100 Pa, particularly 1 to 20 Pa.
By adopting such firing conditions, decomposition of barium carbonate in the film formed in the preliminary firing step is promoted, and a composite metal oxide film is formed. Further, in this firing step, since the conditions of low oxygen concentration or low oxygen partial pressure are adopted as described above, the decomposition of barium carbonate can be carried out smoothly at a reduced temperature. Alternatively, the reaction between the intermediate layer and the composite metal oxide can be substantially avoided. The general firing temperature in this step is 650 to 900 ° C. According to the firing conditions as described above in the present invention, it is possible to substantially prevent the reaction between the base material and / or the intermediate layer and the composite metal oxide as conventionally observed.

[Oxidation process]
This step is a step in which the composite metal oxide film formed in the main firing step is oxidized using molecular oxygen to absorb oxygen to form a composite metal oxide film having superconductivity.
In the main firing step, since the oxygen partial pressure in the atmosphere is maintained at 0.01 to 100 Pa, the superconducting properties of the obtained composite metal oxide film are unsatisfactory. It can be converted into an excellent composite metal oxide film.
The oxidation step for absorbing oxygen is preferably performed at an oxygen partial pressure of 0.2 to 1.2 atm.
As the molecular oxygen, pure oxygen or air is used. When air is used as the oxidant, the superconducting properties of the film are adversely affected by the carbon dioxide contained therein, so the carbon dioxide partial pressure in the air is reduced to 1 Pa or less, preferably 0.5 Pa or less by decarboxylation. It is good to adjust.
This oxidation step is performed at a medium to high temperature, and the reaction between the substrate and / or the intermediate layer and the composite metal oxide can be substantially avoided. The temperature of this oxidation process is generally 400 to 900 ° C. When implementing the method of this invention, the said temporary baking process, this baking process, and an oxidation process can be continuously implemented in the same apparatus.

EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to this Example.
(Examples 1-3)
A commercially available product (manufactured by Nippon Kagaku Sangyo Co., Ltd.) acetylacetonate powder of yttrium, barium and copper is weighed so that the molar ratio of metal components is 1: 2: 3, and these are mixed to obtain a powder mixture. Obtained. To this mixture, pyridine and propionic acid were added in amounts until the powder mixture was completely dissolved. This was heat-treated to remove excess solvent components (pyridine and propionic acid) to obtain an amorphous dry solid acetylacetonate group-propionic acid group-pyridine coordination metal complex. Next, this is dissolved in methanol, and a liquid metal complex in which the ratio of the metal element is Y: Ba: Cu = 1: 2: 3 (3 of acetylacetonato group, pyridine, propionic acid group as a ligand) A coating solution comprising the above was obtained. The concentration of the solution was such that 0.1 to 0.2 mmol of rare earth metal species was contained per 1 g of the solution.

This solution was applied by spin coating on a disk-shaped sapphire substrate having a diameter of 5 cm, on which cerium oxide had been previously deposited. This coating film was heated to 500 ° C. in an air stream containing water vapor having a dew point of 24 ° C. with oxygen partial pressures of 0.2, 0.5, and 0.7 atm, respectively, to remove organic components. Firing was performed.
All of the temporarily fired films were light brown and transparent and had good smoothness.
About these temporary baking films | membranes, after performing this baking process in 720 degreeC for 2 hours in the airflow of oxygen partial pressure 10Pa, oxygen was absorbed at atmospheric pressure and the Y123 superconductor film | membrane with a film thickness of 100 nm was produced.

In addition, when an experiment was repeated on the same substrate by repeating the spin coat coating process and the pre-baking process three times at maximum (maximum film thickness of 300 nm as a manufactured Y123 film), the film thickness increased in proportion to the number of coatings. It was confirmed. Moreover, it was confirmed that the film after repeating the process also has good smoothness.
That is, it was confirmed that the coating solution did not dissolve the base pre-baked film, and that a thick film could be formed by repeating the spin coat coating process and the pre-baking process.
The obtained film sample after film firing (film thickness 200 nm) was analyzed by an X-ray diffraction method using an X-ray diffractometer MXP3 manufactured by MacScience, and it was found that the film was a superconductor single phase having a Y123 structure. confirmed. Next, when the in-plane orientation of Y123 was examined by X-ray pole measurement using the same apparatus, it was confirmed that it was epitaxially grown on the single crystal substrate. Furthermore, when the superconducting property of this film was evaluated by an induction method using a cryoscan manufactured by Teva, a high characteristic of an average of 4 MA / cm ² was obtained as a critical current density (Jc) at a liquid nitrogen temperature. In addition, the in-plane Jc distribution in a disk size of 5 cm in diameter was within ± 10% of the average value, and the uniformity was high.
These results are listed in the table below.

(Comparative Example 1)
A pre-fired film was prepared in the same manner as in Example 1 except that the oxygen partial pressure in the pre-baking step was 0.02 atm.
The obtained pre-baked film was brown and the surface smoothness was slightly lowered.
The calcined film produced by performing the same calcining process as in Example 1 for this temporarily calcined film contained Y123 superconductor, but the critical current density at the liquid nitrogen temperature averaged 0.5 MA / cm ^2. And low characteristics. However, the in-plane Jc distribution in a disk size of 5 cm in diameter was within ± 10% of the average value, and the uniformity was high. The results are listed in the table below.

(Comparative Example 2)
A pre-fired film was prepared in the same manner as in Example 1 except that the oxygen partial pressure in the pre-baking step was 0.95 atm.
The obtained pre-baked film was brown and the surface smoothness was lowered.
With respect to this temporarily fired film, the fired film produced by performing the same firing process as in Example 1 includes the Y123 superconductor, and the critical current density at the liquid nitrogen temperature has a high average characteristic of ² MA / cm ^2. It was. However, the in-plane Jc distribution in a disk size of 5 cm in diameter was slightly different from the average value in some places, and the uniformity was slightly low.
The results are listed in the table below.

(Comparative Examples 3 and 4)
A pre-fired film was produced in the same manner as in Example 2 except that the dew point was changed to an air stream containing water vapor at -10 ° C and 14 ° C.
The obtained pre-fired films were all brown, and the surface smoothness was also lowered.
With respect to these temporarily fired films, the fired films produced by performing the same firing process as in Example 1 included the Y123 superconductor, and the critical current density at the liquid nitrogen temperature was an average of 2 MA / cm ² . In-plane Jc distribution in a disk size of 5 cm in diameter was non-uniform, with some differences from the average value by 30% or more.
These results are listed in the table below.

Example 4
In order to investigate the effects of raw materials, the starting materials were commercial products (Wako Pure Chemical Industries, Ltd.) yttrium, barium and copper acetate powder, trimethylamine instead of pyridine, n-butanol and water instead of methanol. A pre-fired film was produced in the same manner as in Example 2 except for the above. All of the temporarily fired films were light brown and transparent and had good smoothness.
It was confirmed that these temporarily fired films were produced by performing the same firing process as in Example 2 and that the fired film was a superconductor single phase having a Y123 structure and was epitaxially grown on a single crystal substrate. As a critical current density (Jc) at liquid nitrogen temperature, a high characteristic of an average of 3.5 MA / cm ² was obtained. In addition, the in-plane Jc distribution in a disk size of 5 cm in diameter was within ± 10% of the average value, and the uniformity was high.
The results are listed in the table below.

(Example 5)
In order to investigate the effect of thick film, on the disk-like yttria-stabilized zirconia single crystal substrate having a diameter of 5 cm, on which cerium oxide was vapor-deposited in advance, the concentration of the solution in Example 2 was adjusted per gram of solution. In order to make the amount of the rare earth metal species 0.2 to 0.3 mmol and to make a uniform solution, the thickness of the Y123 superconductor film to be produced was set to 550 nm using a solution to which octylene glycol was added. It was confirmed that the fired film produced in the same manner was a superconductor single phase having a Y123 structure and was epitaxially grown on a single crystal substrate. The critical current density (Jc) at the liquid nitrogen temperature was ² MA / cm ² on average. In-plane Jc distribution in a disk size of 5 cm in diameter was within ± 10% of the average value, and the uniformity was high.
The results are listed in the table below.

(Comparative Example 5)
A pre-fired film was prepared in the same manner as in Example 5 except that the oxygen partial pressure in the pre-baking step was 0.95 atm.
The obtained calcined film was dark brown and the surface smoothness was also lowered.
For these temporarily fired films, the fired films produced by performing the same firing process as in Examples 1 to 5 included Y123 superconductor, and the critical current density at the liquid nitrogen temperature was 1 MA / cm ^{2 on} average. It was. In-plane Jc distribution in a disk size of 5 cm in diameter was non-uniform, with some differences from the average value by 30% or more.
The results are listed in the table below.

Claims (5)

In a method for producing a superconducting composite metal oxide film comprising a rare earth element, barium and copper, at least,
(I) A metal-containing compound formulated using a metal-containing compound not containing fluorine selected from metal organic acid salts and metal acetylacetonates so as to have a metal seed composition corresponding to a superconducting composite metal oxide Preparing an organic solvent solution;
(Ii) applying and drying the solution on a support to form a film of the metal-containing compound on the support;
(Iii) The film of the metal-containing compound formed on the support is 200 to 650 ° C. in an atmosphere containing water vapor having an oxygen partial pressure of 0.2 to 0.8 atm and a dew point of 20 ° C. or higher. And (iv) subjecting the temporary fired film to main firing at 650 to 900 ° C. for crystallization, and further 900 to 400 ° C. A method for producing a superconducting composite metal oxide film, comprising the step of absorbing oxygen to form a superconducting composite metal oxide film.   The main firing step is performed at an oxygen partial pressure of 0.01 to 100 Pa, and then the step of absorbing oxygen is performed at an oxygen partial pressure of 0.2 to 1.2 atm. A process for producing a superconducting composite metal oxide film as described in 1). The step of preparing the organic solvent solution of the metal-containing compound containing no fluorine is a metal carboxylate having 1 to 8 carbon atoms and / or a metal acetylacetonate powder mixture of a metal species containing rare earth elements, barium and copper. After adding pyridine and / or at least one tertiary amine and at least one carboxylic acid having 1 to 8 carbon atoms to produce a metal complex and volatilizing an excess solvent, carbon 1 is added. The method for producing a superconducting composite metal oxide film according to claim 1 or 2, wherein the solution is dissolved in a monovalent linear alcohol and / or water of 8 to 8 to form a uniform solution.   The method for producing a superconducting composite metal oxide film according to claim 3, wherein after dissolving in the linear alcohol having 1 to 8 carbon atoms, a polyhydric alcohol is added to obtain a uniform solution. .   The method for producing a superconducting composite metal oxide film according to claim 4, wherein the polyhydric alcohol is at least one selected from divalent alcohols and trivalent alcohols.