MXPA06012908A - Method for manufacturing material for oxide superconductor, method for manufacturing oxide superconducting wire rod, and superconducting device - Google Patents

Abstract

A method for manufacturing a material for an oxide superconductor is provided with a step of ionizing a material, which includes atoms that compose the oxide superconductor, in a solution;a step of removing a solvent by jetting the solution in an atmosphere and manufacturing a material powder including the atoms which compose the oxide superconductor;and a step of cooling the material powder in the atmosphere to which cooling air is introduced. The concentration of carbon dioxide in the atmosphere is lower than that in the atmosphere including the ingredients of the removed solvent, the concentration of nitrogen oxide in the atmosphere is lower than that in the atmosphere including the ingredients of the removed solvent, and the concentration of water vapor in the atmosphere is lower than that in the atmosphere including the ingredients of the removed solvent. Thus, density and purity of the oxide superconductor can be improved.

Description

METHOD FOR MAKING MATERIAL FOR OXIDE SUPERCONDUCTOR, METHOD FOR MANUFACTURING SUPERCONDUCTOR WIRE ROD OXIDE AND SUPERCONDUCTOR DEVICE Field of the Invention The present invention relates to a method for producing a material of an oxide superconductor, a method for producing a superconducting oxide wire and a superconducting apparatus, in particular, a method for producing a material of an oxide superconductor. , the method is able to increase the density and purity of the oxide superconductor, a method to produce a superconducting oxide wire and a superconducting apparatus. BACKGROUND OF THE INVENTION [0002] Oxide superconductor wires are produced by the following procedures: (a) a metal tube is filled with a material (powder material) from an oxide superconductor; (b) the metal tube is processed by stretching or laminating to obtain a wire having a designated shape; (c) the wire obtained is heat treated to concrete the material of the oxide superconductor; and (d) therefore, an oxide superconductor is produced. A material of an oxide superconductor has been Ref.176217 produced by the following method: first, powders of starting materials of an oxide or carbonate of elements to constitute the superconductor are mixed with a specified ratio. Next, the mixed powder is treated a plurality of times with a heat treatment at 700 to 860 ° C or the like and with spraying. Therefore, the material of the oxide superconductor which is composed of a superconducting phase and a non-superconducting phase is obtained. That method of producing a material of an oxide superconductor has been described, for example, in the Japanese patent application published Tokukai 2004-119248 (patent literature 1). However, the above-described production method has a problem that heat treatment and pulverization have to be performed a plurality of times to make the powder of uniform material. Furthermore, even when heat treatment and spraying are performed a plurality of times, the uniformity of the material powder has a limitation. In view of the situation described above, for example, literatures that are not patent 1 and 2 have described a production method that can easily produce a material of an oxide superconductor having uniformly distributed elements that constitute the oxide superconductor. In the production methods described in literatures that are not patent 1 and 2, first the elements to form the oxide superconductor they are dissolved in a nitric acid solution to ionize the elements. Next, the nitrate solution is sprayed in a high temperature atmosphere to remove the solvent so that a powder can be obtained. Then, the temperature of the atmosphere is reduced to cool the powder. Therefore, the powder of material comprising the elements to constitute the oxide superconductor is produced. Patent Literature 1: the Japanese patent application published Tokukai 2004-119248. Literature that is not patent 1: M. Awano, et al., "Enhancement for Synthesis of Bi-PB-SR-Ca-Cu-0 superconductor by the Spray Drying and subsequent Calcination with Rapad Heating", Japanese Journal of Applied Physics, Vol. 30, No. 5A, (1991), pp. L806-L808. Literature that is not patent 2: N. Tohge, et al., "Preparation Conditions and Morphology of superconducting Fine Particles in the Bi-Ca-Sr-Cu-0 System Prepared by Spray Pyrolysis", J. Am. Ceram. Soc. , 74 (9), (1991), pp. 2117-2122. Brief Description of the Invention However, conventional oxide superconductor wires have a problem that the oxide superconductor has low density and low purity. The low density and low purity of the oxide superconductor creates a problem of a reduction in superconducting property such as, for example, a critical current value. In view of the situation described above, an object of the present invention is to provide a method for producing an oxide superconductor material, the method is capable of increasing the density and purity of the oxide superconductor and a method for producing a superconducting wire of rust Means for Solving the Problem The inventor of the present invention found that the problem of low density and low purity of the oxide superconductor in a superconducting oxide wire is attributable to the fact that the material of the oxide superconductor contains a large amount of waste such as as carbon, nitrogen and water. When the oxide superconductor material contains a large amount of these residues, the purity of the oxide superconductor is reduced. As a consequence, at the time of the heat treatment to produce an oxide superconductor in the oxide superconducting wire production process, the carbon is released as carbon dioxide and the nitrogen and water are released as gas. As a result, gaps are formed in the oxide superconductor, whereby the density of the oxide superconductor is reduced. The inventor of the present invention also found that there are residues contained in the material of the oxide superconductor at the time of the production of the material of the oxide superconductor. In particular, after removing the solvent, when the powder is cooled, carbon dioxide, nitrogen oxide and water vapor contained in the cooling atmosphere are adsorbed to the powder as waste. In conventional methods of producing the material of an oxide superconductor, the atmosphere containing the components of the removed solvent is used without being treated as the cooling atmosphere to cool the powder. The components of the solvent removed are contained in the atmosphere such as carbon dioxide, nitrogen oxide, water vapor and the like. These gases adhere to the dust at the time of cooling to form the waste. In view of the circumstances described above, in accordance with the present invention, a method for producing a material of an oxide superconductor comprises the following steps: (a) in a solution, ionizing a material containing an atom to constitute the superconductor of oxide; (b) removing the solvent by spraying the solution in a first atmosphere, thereby producing a powder containing the atom to constitute the oxide superconductor; and (c) cooling the powder in a second atmosphere in which a refrigerant gas is introduced. In this method, the concentration of dioxide carbon in the second atmosphere is lower than in the first atmosphere, which contains the solvent component removed. In addition, the concentration of nitrogen oxide in the second atmosphere is lower than in the first atmosphere, which contains the solvent component removed. In addition, the concentration of water vapor in the second atmosphere is lower than in the first atmosphere, which contains the solvent component removed. According to the present invention, in a method for producing the material of an oxide superconductor, the second atmosphere is an atmosphere that is produced by diluting the concentrations of carbon dioxide, nitrogen oxide and water vapor with the refrigerant gas. the first atmosphere, which contains the components of the solvent. The second atmosphere is used to cool the powder. Therefore, compared to conventional methods, carbon dioxide, nitrogen oxide and water vapor reduce the amounts of adhesion of the powder when it is cooled. In other words, the present invention can reduce the carbon, nitrogen and waste water contained in the oxide superconductor. As a result, the density and purity of the oxide superconductor can be increased. In the above description, the "first atmosphere" means an atmosphere containing the solvent removed by spraying the solution, and the "second atmosphere" means a atmosphere that is constituted by mixing a refrigerant gas with the first atmosphere. According to the present invention, in a method for producing the material of an oxide superconductor, it is desirable that the step of producing a powder comprises the following steps: (bl) spraying the solution together with a spray gas, and (b2) ) bring the solution of the first atmosphere to the second atmosphere by the use of a carrier gas. In addition to the above description, it is desirable that the volume flow rate of the entire gas formed by adding the spray gas, the carrier gas and the refrigerant gas is at least 10,000 times that of the solution. According to the present invention, in a method for producing the material of an oxide superconductor, it is desirable that the step of producing a powder comprises the following steps: (bl) spraying the solution together with a spray gas, and (b2) ) bring the solution of the first atmosphere to the second atmosphere by the use of a carrier gas. In addition to the above description, it is desirable that the concentration of water vapor in the second atmosphere be at most 10% by volume.

The use of the spray gas allows the easy spraying of the solution. The use of the carrier gas allows easy transportation of the powder to the second atmosphere. The above-described specification of the volume flow rate of the whole gas and the concentration of water vapor in the second atmosphere allows an increase in the critical current value. According to the present invention, in a method for producing the material of an oxide superconductor, it is desirable that the step of producing a powder comprises the following steps: (bl) spraying the solution together with a spray gas, and (b2) ) bring the solution of the first atmosphere to the second atmosphere by the use of a carrier gas. In addition to the above description, it is desirable to satisfy the ratio 0.1 (sec) = V / (q? + Q2) = 20 (sec), where i (liter / sec) is the flow rate in volume of the gas of the first atmosphere that is formed by adding the spray gas and the carrier gas, q2 (liter / sec) is the volume flow rate of the gas generated from the solution, and V (liter) is the volume of the first atmosphere. In the above description, the term V / (q? + Q2) means a period during which the solution remains in the first atmosphere. When the permanence period is set to be shorter than 20 (sec), the volume flow rate (ql + q2) of the total spray gas and the carrier gas can be increased, thereby reducing enough the concentration of water vapor in the first atmosphere. On the other hand, when the residence period is set to be longer than 0.1 (sec), the volume flow rate of the total spray gas and the carrier gas does not increase excessively. Therefore, the period during which the material (solution) remains in the heating zone does not become excessively short and the pyrolytic reaction becomes sufficient. Consequently, the specification of the above described range can further increase the critical current value. According to the present invention, in a method for producing the material of an oxide superconductor it is desirable that the step of producing a powder comprises the following steps: (bl) spraying the solution together with a spray gas, and (b2) ) bring the solution of the first atmosphere to the second atmosphere by the use of a carrier gas. In addition to the above description, it is desirable that each of the spray gas, the carrier gas and the refrigerant gas have a water vapor concentration of when much 1% in volume. When each of the spray gas, carrier gas and refrigerant gas is set to have a water vapor concentration of at most 1% by volume, the critical current value can be increased. In view of the reduction in water contained in the powder, it is desirable to reduce the concentration of water vapor to the lowest possible amount. In accordance with the present invention, in a method for producing material from an oxide superconductor, it is desirable that the step of producing a powder comprises the following steps: (bl) spraying the solution together with a spray gas, and (b2) bring the solution of the first atmosphere to the second atmosphere by using a carrier gas. In addition to the above description, it is desirable that each of the spray gas, the carrier gas and the refrigerant gas have a carbon dioxide concentration of at most 30 ppm by volume. When each of the spray gas, the carrier gas and the refrigerant gas is set to have a carbon dioxide concentration of at most 30 ppm by volume, the critical current value can be increased. In this case, at the time of solvent removal, carbon dioxide is generally generated from the solvent. In addition, the atmosphere generally contains carbon dioxide. Therefore, it is difficult to reduce the concentration of carbon dioxide to zero. As a result, the specified carbon dioxide concentration is greater than zero. According to the present invention, in a method for producing material from an oxide superconductor, it is desirable that the method further comprises a step of heat treating the powder after the cooling step of the powder. The heat treatment step removes residues such as carbon, nitrogen and water contained in the oxide superconductor material as gases. As a result, the residues in the oxide superconducting material can be further reduced. In accordance with the present invention, in a method for producing the material of an oxide superconductor, it is desirable that (a) an additional step be provided in which the powder is cooled immediately after heat treatment thereof, (b) both the heat treatment step of the powder and the cooling step of the powder immediately after the heat treatment thereof is carried out in a heat treatment apparatus, and (c) the concentration of water vapor is at most 1% by volume in each of the following atmospheres: (cl) the atmosphere in the heat treatment apparatus at the time of introduction of the powder into the heat treatment apparatus; (c2) the atmosphere in the heat treatment apparatus at the time of heat treatment of the powder; (c3) the atmosphere in the heat treatment apparatus during the cooling time of the powder; (c4) the atmosphere in the heat treatment apparatus at the time of removing the powder from the heat treatment apparatus. The inventor of the present invention found that the step of heat treatment of the powder, even at the time of introduction of the powder in the heat treatment apparatus, over time with heat treatment of the powder, at the time of cooling of the powder. powder, and at the time of dusting the heat treatment apparatus, the carbon dioxide, nitrogen and water vapor contained in the cooling atmosphere are adsorbed to the powder to remain in the powder as waste. Subsequently, the inventor of the present invention found that these operations are performed in an atmosphere having a water vapor concentration of at most 1% by volume, the adsorption of water vapor in the powder in the cooling time can be suppressed , thereby further reducing the residues contained in the material of the oxide superconductor. In this case, it is It is desirable to reduce the concentration of water vapor to the lowest possible amount. In accordance with the present invention, in a method for producing the material of an oxide superconductor, it is desirable that (a) an additional step be provided in which the powder is cooled immediately after heat treatment thereof, (b) both the heat treatment step of the powder and the cooling step of the powder immediately after the heat treatment thereof is carried out in a heat treatment apparatus, and (c) the concentration of carbon dioxide is at most 30 ppm by volume in each of the following atmospheres: (cl) the atmosphere in the heat treatment apparatus at the time of introduction of the powder into the heat treatment apparatus; (c2) the atmosphere in the heat treatment apparatus at the time of heat treatment of the powder; (c3) the atmosphere in the heat treatment apparatus during the cooling time of the powder; (c4) the atmosphere in the heat treatment apparatus at the time of removing the powder from the heat treatment apparatus. The inventor of the present invention found that the step of heat treatment of the powder, even at the time of introduction of the powder into the treatment apparatus with heat, over time with heat treatment of the powder, at the time of cooling of the powder, and at the time of removing the powder from the heat treatment apparatus, the carbon dioxide, nitrogen and water vapor contained in the atmosphere of Cooling is adsorbed to the powder to remain in the dust as waste. Subsequently, the inventor of the present invention found that these operations are performed in an atmosphere having a carbon dioxide concentration of at most 30 ppm by volume, the adsorption of carbon dioxide in the powder in the cooling time can be suppressed , thereby further reducing the residues contained in the material of the oxide superconductor. In this case, at the time of heat treatment of the powder, carbon dioxide is generally generated from the powder. In addition, the atmosphere generally contains carbon dioxide. Therefore, it is difficult to reduce the concentration of carbon dioxide to zero. In accordance with the present invention, in a method for producing the material of an oxide superconductor, it is desirable that the solution for ionizing an atom-containing material to constitute the oxide superconductor is a nitric acid solution. The use of nitric acid allows a sufficient dissolution. In accordance with the present invention, a method for producing a superconducting oxide wire comprises the following steps: (a) producing a material of an oxide superconductor by using the above-described method of producing a material of an oxide superconductor; and (b) producing a superconducting oxide wire by using the material of the oxide superconductor. This specification allows an increase in the density and purity of the oxide superconductor. In accordance with the present invention, an oxide superconducting apparatus incorporates a superconducting oxide wire produced by using the above-described method of producing a superconducting oxide wire. The above specification allows the production of an oxide superconducting apparatus capable of increasing the density and purity. Effect of the Invention In accordance with the present invention, a method of a material of an oxide superconductor and a method for producing a superconducting oxide wire can increase the density and purity of the oxide superconductor. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a process diagram showing a method for producing the material of an oxide superconductor in mode 1 of the present invention.

Figure 2 is a diagram for explaining the method for producing the material of an oxide superconductor in mode 1 of the present invention. Figure 3 is a diagram schematically showing the structure of the heat treatment apparatus in mode 1 of the present invention. Figure 4 is a perspective view in partial cross-section showing schematically the structure of an oxide superconducting wire. Figure 5 is a diagram showing the process for producing an oxide superconductor wire in the mode 2 of the present invention. Figure 6 is a graph showing the critical current value of the oxide superconducting wires in the implementation example IV. Explanation of Reference Numbers 1, the: material powder, 2: oxide superconductor, 3: cover portion, 4: oxide superconductor wire, 11: solution, 12: spray, 13: electric oven, 14 to 16: atmosphere, 17: dust collector, 17a: container, 18: filter, 21: injection hole, 22: refrigerant gas inlet inlet, 23: outlet, 30: heat treatment apparatus, 31: heat treatment chamber , 32: cooling chamber, 33: heater, 34a: path of introduction path, 34b: connection path, 34c: path of departure. Detailed Description of the Invention The embodiments of the present invention are explained below with reference to the drawings. The relationships of dimension in the drawings do not necessarily coincide with those of the explanation. Modality 1 In this modality, a method for producing the material of an oxide superconductor based on bismuth is explained. Fig. 1 is a process diagram showing a method for producing the material of an oxide superconductor in mode 1 of the present invention. Figure 2 is a diagram for explaining a method for producing the material of an oxide superconductor in mode 1 of the present invention. As shown in Figures 1 and 2, first a material containing atoms to constitute the oxide superconductor is ionized in a solution. More specifically, for example, powders of starting materials of Bi203, PbO, SrC03, CaCO3, and CuO are dissolved in a nitric acid solution (step SI). When dissolved, Bi (bismuth), Pb (lead), Sr (strontium), Ca (calcium), and Cu (copper) are ionized in the nitric acid solution. In addition, when the powders of the starting materials dissolve, it is produced carbon dioxide, which allows the removal of carbon component from the powders of the starting materials. It is desirable that each of the powders of the starting materials contain the smallest possible amount of the carbon component. A nitrate solution in which the powders of the starting materials are dissolved is a solution 11 (see Figure 2). The solution for dissolving components such as bismuth is not limited to nitric acid. Sulfuric acid, hydrochloric acid, and other inorganic acid can be used. Furthermore, not only an acid but also an alkaline solution can be used as long as it has a component capable of dissolving the material. The temperature of the solution is not particularly limited. The temperature only needs to be a temperature capable of dissolving bismuth and similar enough. To achieve sufficient solubility, the solution can be red with a ring blade. Then, by removing the solvent by spraying the solution 11 in an atmosphere 14, a material of a powder is produced which contains the atom to replace the oxide superconductor (step S2). The production method is explained more specifically below. The solution 11 is sprayed from an injection orifice 21 together with a spray gas. An arrow "A" shows the injection of solution 11 and the spray gas. Therefore, a spray 12 is formed. On the other hand, a carrier gas is formed from the injection port 21 in a direction shown by arrow "B". The carrier gas conveys the spray 12 to an electric furnace 13. In the electric furnace 13, the solvent of the solution 11 included in the spray 12 is heated until evaporated. As described above, the solution is injected into an atmosphere 14 (first atmosphere), which is at an elevated temperature and is composed of the spray gas and the carrier gas. At this time, the solvent is removed. As a result, the powder of material is obtained which contains the atom to conute the oxide superconductor. An atmosphere 15 at the outlet of the electric furnace 13 contains the solvent component removed. As the method for the injection, not only the method in which the solution 11 is injected directly into the electric furnace 13 is used, but also another method can be used in which the solution 11 is injected in such a way that it can be produced swirl flow in the electric furnace 12. More specifically, the spray 12 can be formed in such a way that horizontal eddies or vertical eddies occur in the electric furnace 13. In addition, a spiral groove can be provided on the internal wall of the electric furnace 13 to form eddies at Supply the spray 12 along the groove. The temperature of the electric oven 13 is not particularly limited. When the nitrites are thermally decomposed in the electric furnace 13, the temperature of the electric furnace 13 can be set in the range of at least 700 ° C and at most 850 ° C, for example. In addition, the length of the region in which the temperature is not in the range of at least 700 ° C and at most 850 ° C in the electric furnace 13 can be determined to be, for example, 300 mm. The reaction in the electric furnace 13 varies in the spray pyrolysis or the spray drying according to the temperature of the electric furnace 13. In the case of the spray pyrolysis, the temperature of the electric furnace 13 is at least about 700 ° C and at most 850 ° C. In the pyrolysis of aspersion, the water is evaporated from the particles (spray 12) of the mixed metal nitrate solution of Bi, Pb, Sr, Ca, and Cu, which conutes the solution. After the evaporation of the water, both the pyrolytic reaction of the nitrates and the reaction between metal oxides after the pyrolytic reaction are created instantaneously. In the case of spray pyrolysis, the reaction takes place instantaneously. Therefore, it is difficult to control the chemical reaction accurately. On the other hand, when the oven temperature electric 13 is changed to at least 200 ° C and at most 300 ° C, spray drying is carried out. In spray drying, although the water is evaporated which is the component of the solvent, the entire nitric acid component remains. The nitric acid component can be removed by heat treatment later. Subsequently, the powder is cooled by an atmosphere 16 into which a refrigerant gas is introduced (step S3). More specifically, the refrigerant gas is introduced from a refrigerant gas introduction inlet 22 in a direction shown by an arrow "C". The refrigerant gas is mixed with atmosphere 15 to form an atmosphere 16 (second atmosphere). Although it is cooled by the atmosphere 16, the powder of material is taken to a dust collector 17 by the carrier gas. In this embodiment, the concentration of carbon dioxide in atmosphere 16 is lower than in atmosphere 15, the concentration of nitrogen oxide in atmosphere 16 is lower than in atmosphere 15, and the concentration of water vapor in the atmosphere 16 is less than in atmosphere 15. Therefore, when the powder material is cooled in atmosphere 16, carbon dioxide, nitrogen and water reduce its tendency to adhere to the powder. Finally, the powder of material is cooled and housed in a container 17a placed in the lower part of the container. dust collector 17. Therefore, a powder of material 1 is obtained. The dust collector 17 is provided with an outlet 23 connected to a vacuum pump (not shown). After the material powder 1 is housed in the container 17a, the spray gas, carrier gas, refrigerant gas and components of the removed solvents are discharged from the outlet 23 through a filter 18. As the spray gas in this mode, dry air, nitrogen and the can be used. As the carrier gas, dry air and the can be used. The spraying gas and the carrier gas can be either a different gas or it can be the same type of gas. The flow rate relationship between the spray gas and the carrier gas can be varied as required. As the refrigerant gas, a gas is used which can reduce the concentration of carbon dioxide, nitrogen and water vapor from that in atmosphere 15 and which is lower in temperature than in atmosphere 15. It is desirable that the velocity of The volume flow of the whole gas formed by adding the spray gas, carrier gas and refrigerant gas is at least 10,000 times that of the solution 11. It is also desirable that the concentration of the water vapor in the atmosphere 16 is at most 10%. % in volume. It is desirable that the following relationship be satisfied: 0.1 (sec) = V / qi + q2) = 20 (sec), where qi (liter / sec) is the flow velocity of the atmosphere 14 's gas volume formed by adding the spray gas and the carrier gas, q2 (liter / sec) is the volume flow rate of the gas generated from solution 11, V (liter) is the volume of atmosphere 14, and V / qi + q2) means a period (sec) during which solution 11 remains in atmosphere 14. In addition, it is desirable that each of the spray gas, carrier gas and refrigerant gas have a water vapor concentration of at most 1% by volume. In addition, it is desirable that each of the spray gas, carrier gas and refrigerant gas have a carbon dioxide concentration of at most 30 ppm by volume. It is more desirable to combine a plurality of the desirable conditions described above, which this combination also increases the effects such as a critical current value. Subsequently, after cooling, the powder of material 1 is heat treated in a heat treatment apparatus (step S4). This heat treatment can further reduce the residues contained in the powder of material 1. More specifically, the heat treatment is conducted through the method described below. Figure 3 is a diagram showing schematically the structure of the heat treatment apparatus in the embodiment 1 of the present invention. As can be seen from Figure 3, a heat treatment apparatus 30 comprises a heat treatment chamber 31 and a cooling chamber 32. The heat treatment chamber 31 is connected in an introduction path 34a, the heat treatment chamber 31 and cooling chamber 32 are connected to each other through a connection path 34b, and cooling chamber 32 is connected to an output path 34c. The heat treatment chamber 31 is provided with a heater 33. Both the heat treatment of the powder material 1 and the cooling thereof immediately after the heat treatment are carried out in the heat treatment apparatus 30. In the 3, the atmosphere in the heat treatment chamber 30 at the time of introducing the powder of material 1 into the heat treatment chamber 30 is the atmosphere in the introduction path 34a. The atmosphere in the heat treatment chamber 30 at the heat treatment time of the powder of material 1 is the atmosphere in the heat treatment chamber 31. The atmosphere in the heat treatment chamber 30 at the time of cooling of the material powder 1 is the atmosphere in the cooling chamber 32. The atmosphere in the heat treatment chamber 30 at the time of the dust exit of material 1 of the heat treatment chamber 30 is the atmosphere in the exit path 34c. In this embodiment, it is desirable that each of the introduction paths 34a, the heat treatment chamber 31, the connection path 34b, the cooling chamber 32 and the exit path 34c have a water vapor concentration of when much a portion by volume and a carbon dioxide concentration of at most 30 ppm by volume. It is more desirable to combine the desirable conditions described above, because this combination also increases the effects such as further reduction of the residues contained in the powder material 1 of the oxide superconductor. The powder material 1 is taken to the heat treatment chamber 31 through the introduction path 34a. Then, the powder material 1 is heat treated in the heat treatment chamber 31 by the use of the heater 33. The heat treatment is carried out for example, for 5 to 10 hours at a temperature of 750 to 850 ° C in an atmosphere that has a partial oxygen pressure of 0.05 to 0.1 MPa. Subsequently, the powder material 1 is taken to the cooling chamber 32 through the connection path 34b. Then, the powder material 1 is cooled to room temperature in the cooling chamber 32. Finally, the powder material 1 is taken outside to the through exit 34c. The process described above can produce the powder of material 1 as the material of an oxide superconductor. In this embodiment, the case is explained in which the powder of material 1 is transmitted to the heat treatment (step S4). However, whenever the powder of material 1 housed in the container 17a has a intended composition, the heat treatment can be omitted. According to a method for producing the powder of material 1 of an oxide superconductor in this embodiment, the atmosphere 16 is an atmosphere that is produced by diluting the concentrations of carbon dioxide, nitrogen oxide and water vapor from the atmosphere. with the cooling gas. The atmosphere 16 is used to cool the powder of material 1. Therefore, compared to conventional methods, carbon dioxide, nitrogen oxide and water vapor reduce the amounts of adhesion to the powder of material when it is cooled. In other words, this mode can reduce the residual carbon, nitrogen and water contained in the oxide superconductor. As a result, the density and purity of the oxide superconductor can be increased. In this case, when the flow velocity of the carrier gas is simply increased, the concentrations of carbon dioxide, nitrogen oxide and water vapor will they can reduce. However, when the flow rate of the carrier gas is large, the period is shortened during which solution 11 passes through the electric furnace 13, thereby creating a problem of insufficient removal of the solvent. In this regard, the present invention has an advantageous effect. In the production method described above, it is desirable that the step of producing the powder of material comprises the steps of: (a) spraying solution 11 together with a spray gas; and (b) bringing solution 11 from atmosphere 15 to atmosphere 16 through the use of a carrier gas. It is desirable that the volume flow rate of the entire gas formed by adding the spray gas, the carrier gas and the refrigerant gas is at least 10,000 times that of the solution. It is also desirable that the concentration of water vapor in atmosphere 16 is at most 10% by volume. The use of the spray gas allows the easy spraying of the solution 11. The use of the carrier gas allows the easy supply of the material powder to the atmosphere 16. The specification described above of the volume flow rate of the whole gas and the concentration of water vapor in atmosphere 16 can increase the value of critical current. In addition, it is desirable to satisfy the 0.1 ratio (sec) = V / (q? + q2) = 20 (sec), where ql (liter / sec) is the flow velocity in volume of the atmosphere 14 's gas formed by adding the spray gas and the carrier gas, q2 (liter / sec) is the volume flow rate of the gas generated from solution 11, and V (liter) is the volume of atmosphere 14. When the period during which solution 11 remains in atmosphere 14 is set to be shorter than 20 seconds, the concentration of water vapor in atmosphere 14 can be reduced sufficiently. When the period during which the solution 11 remains in the atmosphere 14 is set to be longer than 0.1 second, the period during which the solution 11 remains in the heating zone does not become excessively short and the pyrolytic reaction is made enough. Consequently, the specification of the range described above can increase the critical current value. In addition, it is desirable that each of the spray gas, carrier gas and refrigerant gas have a water vapor concentration of at most 1% by volume.

In addition, it is desirable that each of the spray gas, carrier gas and refrigerant gas have a dioxide concentration of carbon at most 30 ppm in volume. The concentration of water vapor is when a lot of 1% by volume in each of the spray gas, carrier gas and refrigerant gas. In addition, the concentration of carbon dioxide is at most 30 ppm in volume in each of them. The conditions described above can increase the critical current value. In the production method described above, a heat treatment step of the material powder 1 is provided after the cooling step of the material powder 1. The heat treatment step removes residues such as carbon, nitrogen and water contained in the material powder 1 from the oxide superconductor as gases. As a result, the residues contained in the material powder 1 of the oxide superconductor can be further reduced. In the production method described above, it is desirable that both the heat treatment step of the material powder 1 and the cooling step immediately after the powder of material 1 is heat treated are carried out in the treatment apparatus with heat 30. It is also desirable that at the time of heat treatment the powder of material 1, the water vapor concentration is at most 1% in volume in each of the following atmospheres: (a) the atmosphere in the introduction path 34a, (b) the atmosphere in the heat treatment chamber 31, (c) the atmosphere in the connection path 34b, (d) the atmosphere in the cooling chamber 32, and (e) the atmosphere in the exit path 34c. It is also desirable that the concentration of carbon dioxide is at most 30 ppm by volume in each of the atmospheres described above. The above specification can suppress water vapor and carbon dioxide from being adsorbed to the material powder 1 of the cooling time, thereby further reducing the residues contained in the material powder 1 of the oxide superconductor. In the production method described above, it is desirable that the solution for dissolving the powder of the starting material be a nitric acid solution. The use of nitric acid allows complete dissolution without forming a passive state. In addition, the carbon content can be reduced to zero in theory. Modality 2 In this modality, a method to produce a superconducting oxide wire is explained, the method uses the material of the oxide superconductor produced in the modality 1. Figure 4 is a perspective view in partial cross-section showing schematically the structure of an oxide superconducting wire. Referring to Figure 4, as an example, a filament oxide superconducting wire is explained below. An oxide superconducting wire 4 comprises a plurality of longitudinally extending oxide superconductors (filaments) 2 and a cover portion 3 covering them. It is desirable that the material of each of the oxide superconductors have a structure based on, for example, Bi-Pb-Sr-Ca-Cu-O. In particular, a material containing a B2223 phase is more suitable, which approximately expresses the reactions of the bismuth and lead atoms to strontium to calcium to copper as 2: 2: 2: 3. The material of the cover portion 3 is composed, for example, of a metal such as silver or a silver alloy. In the above, the multiple filament wire is explained. However, an oxide superconductor wire having a structure of a single filament wire can be used in which a single oxide superconductor 2 is covered with a cover portion 3. Next, a method for producing the superconducting wire of The above described oxide is explained below. Figure 5 is a diagram showing the process of producing a superconducting oxide wire of the embodiment 2 of the present invention. As shown in Figure 5, first, the material powder 1 of the oxide superconductor is produced by using the method of mode 1 (step S10). Next, a metal tube is filled with the powder of material 1 (precursor) (step Sil). It is desirable that the metal tube be made of a metal such as silver or a silver alloy, having high thermal conductivity. By using this structure, the heat produced by the extinction phenomenon located in the superconductor can be removed promptly from the metal tube. Subsequently, the wire is processed by stretching until a target diameter is achieved. Therefore, a single filament wire is produced in which the precursor with the filament material is covered with a metal such as silver (step S12). A multitude of single filament wires are joined together and inserted into a metal tube made of a metal such as silver without a space (insertion of multiple filaments without space: step S13). Therefore, a structured member with multiple filaments is obtained which has a multitude of filament member each of which has a powder of material. Next, the structured member with multiple filaments is processed by stretching until it is achieves a designated diameter. Therefore, a multi-filament wire is produced in which a plurality of the powders of material 1 are embedded in the cover portion 3 made for example as silver (step S14). This step produces a multi-filament wire having the structure in which the powder material of the oxide superconducting wire is covered with a metal. The wire is processed by rolling to obtain a wire in ribbon form (step S15). The rolling operation increases the density of the powder material 1. Next, the ribbon-shaped wire is heat treated (step S16). The heat treatment is carried out at a temperature of, for example, approximately 830 ° C. This heat treatment produces an oxide superconductor phase from the powder of material 1. Therefore, the oxide superconductor 2 is produced (see figure 4). The heat treatment and the rolling operation can be performed a plurality of times on the ribbon-shaped wire. In this case, the powder of material 1 obtained through the production method shown in mode 1 has only a small amount of waste such as carbon. Consequently, when the wire is treated with heat, the waste releases only a small amount of gas into the air. As a result, the oxide superconductor 2 reduces the tendency to form gaps in the crystal, which allows the increase in the density and purity of the oxide superconductor 2. Through the production methods described above, the superconducting oxide wire shown in Figure 4 is obtained. The method for producing the oxide superconducting wire 4 in this mode comprises (a) a step for producing the powder of material 1 of the oxide superconductor 2 by using the method to produce the powder of material shown in mode 1 (step S10) and (b) steps for producing the superconducting oxide wire 4 through the use of powder material 1 (steps Sil to S16). As a result, the density of the oxide superconductor 2 can be increased. An oxide superconducting wire of the present invention can be used, for example, in a superconducting wire, a superconducting transformer, a superconducting fault current limiter, an apparatus of power storage and other superconducting devices. Examples of the present invention are explained below. Implementation Example I In this implementation example, the effect of introducing the refrigerant gas was studied. More specifically, powders of starting materials Bi, Pb, Sr, Ca, and Cu were dissolved in a nitric acid solution. The nitrate solution was filtered to remove impurities. The powders of starting materials were dissolved in such a way that the Bi: PB: Sr: Ca: Cu ratio became 1.7: 0.4: 1.9: 2.0: 3.0. The nitrate solution was mixed with a spray gas. A solution sprinkler was used to form a spray composed of tiny drops of liquid of several tens of microns. The flow velocity "q" of the nitrate solution was set to be 20 mL / min. When using a carrier gas, the spraying was introduced in an electric oven heated to a maximum temperature of 800 ° C. The total flow rate Ql of the spray gas and the carrier gas was 50 NL / min (NL: one volume at 0 ° C and 1 atm). Under these conditions, the drying and pyrolysis of the spray were conducted in an atmosphere (first atmosphere) composed of the spray gas and the carrier gas. Therefore, a powder of material at high temperature was obtained. Subsequently, when using the carrier gas, the high temperature material powder was taken out of the electric furnace. The powder of material was cooled in an atmosphere (second atmosphere) having an introduced refrigerant gas. As the refrigerant gas, air was used in which the concentrations of carbon dioxide, nitrogen oxide and water vapor were controlled. As the spray gas, carrier gas and refrigerant gas, a gas having a water vapor concentration of 0.01% by volume. The concentration of carbon dioxide contained in the refrigerant gas was set to be 10 ppm volume. In this implementation example, the flow rate (velocity of the entered quantity) Q2 of the refrigerant gas was varied in the range of 0 to 300 NL / min to cool the material powder. In Comparative Example 1, the material powder was cooled in an untreated atmosphere containing the removed solvent components without introducing the refrigerant gas. Subsequently, when using the carrier gas, the material powder was taken to a dust collector. The dust collector separated the dust from the gas. Therefore, the composite powder of mixed metal oxides was collected. Subsequently, the material powder was brought into a heat treatment apparatus to be heat treated for 10 hours at a temperature of 800 ° C in an atmosphere having an oxygen partial pressure of 0.02 MPa. Therefore, the material of the oxide superconductor was produced. Each of the operations of the introduction to the heat treatment apparatus, heating, cooling and the exit from the heat treatment apparatus was carried out in an atmosphere containing at most 1% by volume of water and at most 30 ppm in volume of carbon dioxide. Next, the material powder was loaded into the tube silver. The powder was heat treated for 10 hours at a temperature of 600 ° C under a vacuum to remove the gas. The end of the silver tube was welded to seal the powder material under a vacuum. Therefore, a single filament wire was produced. With its two sealed ends, the single filament wire was processed by stretching. The stretched wire was cut into 55 wires. The 55 wires were packed together to be inserted into a silver tube. The silver tube with 55 wires was heat treated for 10 hours at a temperature of 600 ° C under a vacuum to remove the gas again. The avocado tube end was welded to seal the material powder under a vacuum. Therefore, a multiple filament wire was produced. With its two sealed ends, the multi-filament wire was processed by stretching and rolling to obtain a tape-shaped wire having a width of 4 mm and a thickness of 0.2 mm. The ribbon-shaped wire was heat treated for 30 hours at a temperature of 820 ° C in an atmosphere having an oxygen partial pressure of 0.008 MPa to produce a B2223 phase. Subsequently, after undergoing an intermediate rolling operation, the wire was further heat treated for 50 hours at a temperature of 810 to 820 ° C in an atmosphere having an oxygen partial pressure of 0.008 MPa to produce a superconducting wire of oxide. The critical current value of the obtained oxide superconducting wire was measured in its own magnetic field at 77K. Table I shows the production conditions of the material powder, such as the flow rate Q2 of the refrigerant gas and the critical current value Jc of the obtained oxide superconducting wires.

Table 1 15 or fifteen In Table I, the term "whole gas (Ql + Q2)" means the atmosphere after the refrigerant gas was introduced (atmosphere 16 in Figure 2 (second atmosphere)). In Comparative Example 1, in which the refrigerant gas was not introduced, the whole gas had a concentration of N02 of 3.7% by volume, a concentration of H20 of 32% by volume and a dew point of 71 ° C, all which show high values. The oxide superconducting wire of Comparative Example 1 had a critical current value of 18 kA / cm2. On the other hand, in example 1 of the present invention, in which the refrigerant gas was introduced at a flow rate of 50 NL / min, the whole gas had a N02 concentration of 2.3% by volume, a concentration of H20. 20% by volume, and a dew point of 60 ° C, all of which show lower values than those of comparative example 1. In addition, the concentration of carbon dioxide contained in the refrigerant gas was introduced at 10 ppm by volume . Consequently, it is believed that the concentration of carbon dioxide obtained in the whole gas was also lower than in the case of comparative example 1. The critical current value of the oxide superconducting wire of example 1 of the present invention was 20 k / A / cm2. The results described above show that when the flow rate of the refrigerant gas is increased to reduce the concentrations of carbon dioxide, the Nitrogen and water vapor contained in the whole gas, the critical current value of a superconducting oxide wire can be increased. As can be seen from the comparison of the data of Examples 1 to 4 of the present invention, Examples 3 and 5 of the present invention had a critical current value as high as 40 kA / cm2 or more. More specifically, in Example 3 the flow velocity of the entire gas (Q1 + Q2) was 10,000 times the flow velocity of the nitrate solution (q). In example 4, the flow velocity of the whole gas (Ql + Q2) was greater than 10,000 times the flow velocity of the nitrate solution (q) and the concentration of H20 contained in the whole gas (Ql + Q2) was less than 10% in volume. The results show that when the volume flow rate of the whole gas formed by adding the spray gas, carrier gas and refrigerant gas is at least 10,000 times the flow velocity of the nitrate solution or when the concentration of water vapor in the second atmosphere is at most 10% by volume, the critical current value can be increased. Example of I plementation II In this implementation example, the relationship between the concentration of carbon dioxide contained in each of the spray gas, carrier gas and refrigerant gas and the critical current value was studied. More In particular, the material of the oxide superconductor was produced by almost the same method as that of the implementation example I. The material was used to produce superconducting oxide wires. However, in this case the spray gas, carrier gas and refrigerant gas were introduced by varying their carbon dioxide concentrations in the range of 1 to 300 ppm by volume. Table II shows the critical current value of the oxide superconductor wires obtained.

Table II -P- 10 fifteen As can be seen from Table II, Examples 6 to 8 of the present invention had a critical current value as high as 40 kA / cm2 or more. More specifically, in these examples, the concentration of carbon dioxide contained in each of the spray gas, carrier gas and refrigerant gas was 30 ppm by volume or less. The results show that when the concentration of carbon dioxide contained in each of the spray gas, carrier gas and refrigerant gas is at most 30 ppm by volume, the critical current value can be increased. Implementation Example III In this implementation example, the effect of the concentration of water vapor contained in each of the spray gas, carrier gas and refrigerant gas and the atmosphere in the heat treatment apparatus on the current value was studied. critical. More specifically, the material of the oxide superconductor was produced by almost the same method as that of the implementation example I. The material was used to produce superconducting oxide wires. In this case, however, the spray gas, carrier gas and refrigerant gas were introduced by varying their water vapor concentrations in the range of 0.0004 to 2% by volume. In addition, the material powder was heat treated by varying the concentration of water vapor in the heat treatment apparatus in the range of 1 to 4% by volume and the concentration of carbon dioxide in the heat treatment apparatus in the range of 30 to 300 ppm by volume. Table III shows the critical current value of the superconducting oxide wires obtained.

Table ni Example 9 of Example 10 Example 11 Example 12 Example 13 Example 14 Example 15 present one of the one of the one of the present invention present present present invention present invention invention invention invention invention invention Flow velocity of nitrate solution "q" (ml / min) Total flow velocity of gas 50 of spray and carrier gas O1"(NL / min) 10 Gas flow rate 300 refrigerant O2" (NIJmin) Concentration of water 2 1 0.4 0.01 0.0004 0.0004 0.0004 contained in each of the spray gas, carrier gas and refrigerant gas (vol%) 15 Concentration of H20 8.4 7.6 6.9 6.6 6.6 6.6 6.6 content of whole gas (Q1 + Q2) (vol. %) -P- oo As can be seen from Table III, Examples 10 to 13 of the present invention had a critical current value as high as 39 kA / cm2 or more. More specifically, in these examples, the concentration of water vapor contained in each of the spray gas, carrier gas and refrigerant gas was 1% by volume or less; the water vapor concentrations in the heat treatment apparatus was 1% by volume; and the concentrations of carbon dioxide in the heat treatment apparatus was 30 ppm by volume. The results show that when the concentration of water vapor contained in each of the spray gas, carrier gas and refrigerant gas is at most 1% by volume, the critical current value can be increased. Implementation Example IV In this implementation example, the relationship between the volume of the first atmosphere and the critical current value was studied. More specifically, the oxide superconductor material was produced by almost the same method as implementation example I. The material was used to produce superconducting oxide wires. However, the volume of the first atmosphere was set to be 100 (liters), and the total volume flow rate of the gas in the first atmosphere and the volume flow rate of the gas generated from the solution was varied in the range from 3.3 to 1.199 (liters / sec). Table IV and Figure 6 show the critical current value of the obtained oxide superconducting wires.

Table IV I? fifteen As can be seen from Table IV and Figure 6, Examples 17 and 21 of the present invention had a critical current value as high as 35 kA / cm2 or more. More specifically, in these examples, the value V / (q? + Q2) satisfied the condition of at least 0.1 (sec) and at most 20 (sec). The results show that when the volume of the first atmosphere satisfies the relation 0.1 (sec) = V / (q? + Q2) = 20 (sec), the critical current value can be increased. It should be considered that the modalities described above and the examples are illustrative and not restrictive in all aspects. The scope of the present invention is shown by the scope of the appended claims and not by the modalities and examples described above. Accordingly, the present invention is designed to cover all revisions and modifications included within the meaning and scope equivalent to the scope of the claims. Field of Industrial Application It is desirable that the method of the present invention for producing a material of an oxide superconductor and the method of the present invention for producing a superconducting oxide wire are applied to a method for producing a material of an oxide superconductor. based on bismuth and a method to produce superconducting oxide wire based on bismuth, and in particular to a method to produce an oxide superconductor material based on Bi-Pb-Sr-Ca-Cu-0 that not only contains bismuth, lead, strontium, calcium and copper but also contains a phase of B2223, which expresses approximately the ratios of the bismuth and lead atoms to strontium to calcium to copper as 2: 2: 2: 3, and to a method for producing superconducting oxide wire by using the material. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (12)

1. Having described the invention as above, the content of the following claims is claimed as property. A method for producing a material of an oxide superconductor, characterized in that it comprises the following steps: (a) in a solution, ionizing a material containing an atom to constitute the oxide superconductor; (b) removing a solvent by spraying the solution in a first atmosphere, thereby producing a powder containing the atom to constitute the oxide superconductor; and (c) cooling the powder in a second atmosphere in which a refrigerant gas is introduced; the concentration of carbon dioxide in the second atmosphere is lower than in the first atmosphere, which contains the solvent component removed; the concentration of nitrogen oxide in the second atmosphere is lower than in the first atmosphere, which contains the solvent component removed; the concentration of water vapor in the second atmosphere is lower than in the first atmosphere, which contains the solvent component removed.
2. 2. The method for producing a material of an oxide superconductor according to claim 1, characterized in that the step of producing a powder comprises the steps of: (bl) spraying the solution together with a spray gas, and (b2) carrying the solution of the first atmosphere to the second atmosphere by the use of a carrier gas; The volume flow rate of the entire gas formed by adding the spray gas, the carrier gas and the refrigerant gas is at least 10,000 times that of the solution.
3. 3. The method for producing a material of an oxide superconductor according to claim 1, characterized in that the step of producing a powder comprises the steps of: (bl) spraying the solution together with a spray gas, and (b2) bring the solution of the first atmosphere to the second atmosphere by the use of a carrier gas; the concentration of water vapor in the second atmosphere is at most 10% by volume.
4. 4. The method for producing a material of an oxide superconductor according to claim 1, characterized in that the step of producing a powder comprising the steps of: (bl) spraying the solution together with a spray gas, and (b2) bringing the solution of the first atmosphere to the second atmosphere by the use of a carrier gas; the ratio 0.1 (sec) = V / (qi + q2) = 20 (sec) is satisfied, where qi (liter / sec) is the flow velocity in volume of the gas of the first atmosphere that is formed when the gas is added of spray and carrier gas, q2 (liter / sec) is the volume flow rate of the gas generated from the solution, and V (liter) is the volume of the first atmosphere. The method for producing a material of an oxide superconductor according to claim 1, characterized in that the step of producing a powder comprises the steps of: (bl) spraying the solution together with a spray gas, and (b2) bring the solution of the first atmosphere to the second atmosphere by the use of a carrier gas; each of the spray gas, the carrier gas and the refrigerant gas has a water vapor concentration of at most 1% by volume. 6. The method to produce a material from a oxide superconductor according to claim 1, characterized in that the step of producing a powder comprises the steps of: (bl) spraying the solution together with a spray gas, and (b2) bringing the solution from the first atmosphere to the second atmosphere by the use of a carrier gas; each of the spray gas, the carrier gas and the refrigerant gas has a carbon dioxide concentration of at most 30 ppm by volume. A method for producing a material of an oxide superconductor according to claim 1, characterized in that it further comprises a step of heat treatment of the powder after the cooling step of the powder. 8. The method for producing a material of an oxide superconductor according to claim 7, characterized in that: (a) an additional step is provided in which the powder is cooled immediately after heat treatment thereof, (b) both the heat treatment step of the powder and the cooling step of the powder immediately after the heat treatment thereof is carried out in a heat treatment apparatus, and (c) the concentration of water vapor is at most 1% by volume in each of the following atmospheres: (cl) the atmosphere in the heat treatment apparatus at the time of introduction of the powder into the treatment apparatus with heat; (c2) the atmosphere in the heat treatment apparatus at the time of heat treatment of the powder; (c3) the atmosphere in the heat treatment apparatus during the cooling time of the powder; and (c4) the atmosphere in the heat treatment apparatus at the time of removing the powder from the heat treatment apparatus. The method for producing a material of an oxide superconductor according to claim 7, characterized in that: (a) an additional step is provided in which the powder is cooled immediately after heat treatment thereof, (b) both the heat treatment step of the powder and the cooling step of the powder immediately after the heat treatment thereof is carried out in a heat treatment apparatus, and (c) the concentration of carbon dioxide is at the very 30 ppm in volume in each of the following atmospheres: (cl) the atmosphere in the heat treatment apparatus at the time of introduction of the powder into the heat treatment apparatus; (c2) the atmosphere in the heat treatment apparatus at the time of heat treatment of the powder; (c3) the atmosphere in the heat treatment apparatus during the cooling time of the powder; (c4) the atmosphere in the heat treatment apparatus at the time of removing the powder from the heat treatment apparatus. A method for producing a material of an oxide superconductor according to claim 1, characterized in that the solution is a nitric acid solution. A method for producing a superconducting oxide wire, characterized in that it comprises the steps of: (a) producing a material of an oxide superconductor using a method for producing a material of an oxide superconductor comprising the steps of: ) in a solution, ionize a material that contains an atom to constitute the oxide superconductor; (a2) removing a solvent by spraying the solution in a first atmosphere, which produces a powder that it contains the atom to constitute the oxide superconductor; and (a3) cooling the powder in a second atmosphere in which a refrigerant gas is introduced; the concentration of carbon dioxide in the second atmosphere is lower than in the first atmosphere, which contains the solvent component removed; the concentration of nitrogen oxide in the second atmosphere is lower than in the first atmosphere, which contains the solvent component removed; the concentration of water vapor in the second atmosphere is lower than in the first atmosphere, which contains the solvent component removed; and (b) producing a superconducting oxide wire using the oxide superconductor material. 12. An oxide superconducting apparatus, characterized in that it incorporates an oxide superconductor wire produced by a method for producing a superconducting oxide wire, the method comprising the steps of: (a) producing a material of an oxide superconductor using a method for producing a material of an oxide superconductor, comprising the steps of: (a) in a solution, ionizing a material containing an atom to constitute the oxide superconductor; (a2) removing a solvent by spraying the solution in a first atmosphere, thereby producing a powder containing the atom to constitute the oxide superconductor; and (a3) cooling the powder in a second atmosphere in which a refrigerant gas is introduced; the concentration of carbon dioxide in the second atmosphere is lower than in the first atmosphere, which contains the solvent component removed; the concentration of nitrogen oxide in the second atmosphere is lower than in the first atmosphere, which contains the solvent component removed; the concentration of water vapor in the second atmosphere is lower than in the first atmosphere, which contains the solvent component removed; and (b) producing a superconducting oxide wire using the oxide superconductor material.