JPWO2020080279A1 - Method of manufacturing conductors, conductors, superconducting power transmission lines, superconducting magnet devices and superconducting magnetic shield devices - Google Patents

Abstract

(AE1-xAx) (Fe1-yTMy) in a method for producing a conductor in which a first layer containing the first compound represented by the following composition formula (Chemical Formula 1) is formed on at least the surface of a starting material containing iron. 2 (As1-zPz) 2 ... (Chemical formula 1) It has step S4 in which the starting material is brought into contact with a gas (G1) containing the first element E1 and the second element E2. AE is an alkaline earth metal element, A is an alkali metal element, and TM is a transition metal element. x satisfies 0 ≦ x <1, y satisfies 0 ≦ y <0.5, and z satisfies 0 ≦ z <0.8. The first element E1 contains AE and the second element E2 contains arsenic.

Description

The present invention relates to a method for manufacturing a conductor, a conductor, a superconducting power transmission line, a superconducting magnet device, and a superconducting magnetic shield device.

_{The critical temperature T c} of the iron-based superconductor is, for example, about 58 K, which is the second highest after the critical temperature of the copper oxide-based superconductor. Further, the upper critical magnetic field _Hc2 of the iron-based superconductor is larger than, for example, 100T, and is the second largest after the upper critical magnetic field of the copper oxide-based superconductor. Therefore, iron-based superconductors are expected to be applied to strong magnetic fields such as superconducting magnet devices that generate strong magnetic fields.

As such an iron-based superconductor, iron nickamide, which is a compound of iron (Fe) and a Group 15 element such as arsenic (As), is known, and as iron nickamide, (AE, A) (Fe, TM) ₂ (As, Pn) ₂ (AE is an alkaline earth metal element, A is an alkali metal element, TM is a transition metal element, and Pn is a nictogen element) are known. Of these, BaFe ₂ As ₂ is one composition of (AE, A) (Fe, TM) ₂ (As, Pn) ₂ described above, and is also referred to as Ba 122.

In Non-Patent Document 1, the anisotropy of the upper critical magnetic field H _c2 of the iron-based superconductor Ba (Fe _1-x Co _x ) ₂ As ₂ single crystal is about 2, and the cuprate superconductor It is described that it is smaller than the anisotropy of the conductor. Therefore, for a superconducting bulk body made of a sintered body of an iron-based superconductor, the two crystal grains are formed even if the orientation direction of each of the two adjacent crystal grains is separated from 0 °. The critical current density flowing across the interface between them does not decrease significantly. Therefore, for a superconducting bulk body made of a sintered body of an iron-based superconductor, it is not necessary to control the orientation direction of crystal grains when forming the superconducting bulk body, so that a large superconducting bulk body can be used. It can be easily formed.

In Japanese Patent Application Laid-Open No. 2017-82318 (Patent Document 1), in the _{iron-based compound represented by the chemical formula AA'Fe 4} As ₄ , A is Ca and A'is at least one selected from K, Rh and Cs. One element, or A is at least one element selected from Sr and Eu, A'is at least one element selected from Rb and Cs, AFe ₂ As ₂ layer and A'Fe ₂ As ₂ A technique is disclosed in which the layers have a crystal structure in which layers are alternately laminated, and the space group of the crystal structure is a simple square crystal P4 / mm.

Japanese Unexamined Patent Publication No. 2014-227329 (Patent Document 2) describes iron-based superconductors having a crystal structure of _{ThCr 2} Si _{2 and BaXO 3} (X is Zr, Sn, Hf, Ti) in iron-based superconducting materials. Disclosed is a technique in which nanoparticles having a particle size of 30 nm or less and having nanoparticles having a particle size of 30 nm or less and having nanoparticles ^{dispersed in a volume density of 1 × 10 21} m ^{-3 or more are disclosed.} There is.

Japanese Unexamined Patent Publication No. 2017-82318 Japanese Unexamined Patent Publication No. 2014-227329

A. Yamamoto et al., “Small anisotropy, weak thermal fluctuations, and high field superconductivity in Co-doped iron pnictide Ba (Fe1-xCox) 2As2”, Applied Physics Letters 94 (2009) 062511 A. S. Sefat et al., “Superconductivity at 22 K in Co-Doped BaFe2As2 Crystals”, Physical Review Letters 101 (2008) 117004

Such (AE, A) (Fe, TM) ₂ (As, Pn) ₂ (AE is an alkaline earth metal element, A is an alkali metal element, TM is a transition metal element, and Pn is a nictogen element) are generated. The mechanism has not been clarified. Therefore, for example, in an atmosphere where the pressure is not reduced below the atmospheric pressure, (AE, A) (Fe, TM) ₂ (As, P) ₂ (AE is an alkaline earth metal element, A) is placed on the surface layer of the base material. Is an alkali metal element, TM is a transition metal element) as a main component, and it is difficult to form a conductive layer made of a thick film-shaped superconductor.

Further, the above-mentioned problem is that (AE, A) (Fe, TM) ₂ (As, P) ₂ (AE is an alkaline earth metal element, A is an alkali metal element, and TM is a transition on the surface layer of the base material. It is also a common problem when forming a conductive layer containing (metal element) as a main component and having a thick film shape but not having superconductivity.

The present invention has been made to solve the above-mentioned problems of the prior art, and the (AE, A) (AE, A) ( Fe, TM) ₂ (As, P) ₂ (AE is an alkaline earth metal element, A is an alkali metal element, TM is a transition metal element) as the main component, and a conductor having a thick film-shaped conductive layer. It is an object of the present invention to provide a method for producing a conductor that can be formed.

A brief description of typical inventions disclosed in the present application is as follows.

The method for producing a conductor as one aspect of the present invention is to form a first layer containing the first compound represented by the following composition formula (Chemical Formula 1) on at least the surface of a starting material containing iron. It is a manufacturing method.
(AE _1-x A _x ) (Fe _1-y TM _y ) ₂ (As _1-z P _z ) ₂ ... (Chemical formula 1)
AE is at least one element selected from the group consisting of Ba and Sr, A is at least one element selected from the group consisting of K and Na, and TM is Cr, Mn, Co and Ni. It is at least one element selected from the group consisting of, x satisfies 0 ≦ x <1, y satisfies 0 ≦ y <0.5, and z satisfies 0 ≦ z <0.8. .. In the method for producing the conductor, the starting material is brought into contact with a first gas containing the first element and the second element, and iron contained in the starting material and the first element and the second element contained in the first gas are used. Has the step (a) of forming a first layer on at least the surface of the starting material by reacting. The first element contains AE, the second element contains arsenic, and when x satisfies 0 <x <1, the first element further contains A and y satisfies 0 <y <0.5. When the starting material further contains TM, and in step (a), the starting material is started by reacting TM and iron contained in the starting material with the first and second elements contained in the first gas. When a first layer is formed on at least the surface of the material and z satisfies 0 <z <0.8, the second element further comprises phosphorus.

Further, as another aspect, in the step (a), the solid raw material containing the first element and the second element and the starting material are heated, and the solid raw material is heated to generate the first gas, and the generated first gas is generated. 1 The starting material in a heated state may be brought into contact with the gas.

As another aspect, in the step (a), the solid raw material is heated to the first temperature, the starting material is heated to the second temperature, and the solid raw material is heated to the first temperature to generate the first gas. The generated first gas may be brought into contact with the starting material heated to the second temperature.

As another aspect, in the step (a), the solid raw material is heated to a third temperature of 700 ° C. or higher, the starting material is heated to a fourth temperature of 700 ° C. or higher, and the solid raw material is heated to a third temperature. By doing so, the first gas may be generated, and the generated first gas may be brought into contact with the starting material heated to the fourth temperature.

Further, as another aspect, in the method for producing the conductor, the starting material and the solid raw material are arranged in an airtight container before the step (a), and the step (b) and the step (b). After that, before the step (a), there may be a step (c) in which the inside of the container is evacuated or the atmosphere in the container is replaced with an inert gas.

Further, as another aspect, the method for producing the conductor is included in the first layer by bringing the first layer into contact with a second gas or a first liquid containing a third element after the step (a). It has the step (d) of substituting a part of the AE with a third element, and the third element may contain at least one element selected from the group consisting of K and Na.

Further, as another aspect, the method for producing the conductor is included in the first layer by bringing the first layer into contact with a third gas or a second liquid containing a fourth element after the step (a). It has a step (e) of substituting a part of arsenic with a fourth element, and the fourth element may contain phosphorus.

Further, in the method for producing a conductor as one aspect of the present invention, a conductor containing a first layer containing a first compound represented by the following composition formula (Chemical Formula 1) is formed on at least the surface of a starting material containing iron. It is a method of manufacturing a body.
(AE _1-x A _x ) (Fe _1-y TM _y ) ₂ (As _1-z P _z ) ₂ ... (Chemical formula 1)
AE is at least one element selected from the group consisting of Ba and Sr, A is at least one element selected from the group consisting of K and Na, and TM is Cr, Mn, Co and Ni. It is at least one element selected from the group consisting of, x satisfies 0 ≦ x <1, y satisfies 0 ≦ y <0.5, and z satisfies 0 ≦ z <0.8. .. In the method for producing the conductor, the starting material is brought into contact with a first gas containing the first element, and iron contained in the starting material is reacted with the first element contained in the first gas to cause the starting material. After the steps (a) and (a) of forming a second layer containing the second compound containing iron and arsenic on at least the surface of the above, the starting material is brought into contact with the second gas containing the second element. , The step (b) of forming the first layer on at least the surface of the starting material by reacting the second compound contained in the second layer with the second element contained in the second gas. The first element contains arsenic, the second element contains AE, and when x satisfies 0 <x <1, the second element further contains A and y satisfies 0 <y <0.5. When the starting material further contains TM, and in step (a), at least the surface of the starting material is formed by reacting TM and iron contained in the starting material with the first element contained in the first gas. A second layer containing TM and a second compound containing iron and arsenic is formed, and when z satisfies 0 <z <0.8, the first element further contains phosphorus.

As another aspect, in the step (a), the first solid raw material containing the first element and the starting material are heated, and the first solid raw material is heated to generate a first gas, and the generated first gas is generated. The heated starting material is brought into contact with the 1 gas, and in the step (b), the second solid raw material containing the second element and the starting material are heated, and the second solid raw material is heated to heat the second gas. The generated second gas may be brought into contact with the starting material in a heated state.

Further, as another aspect, the method for producing the conductor is included in the first layer by bringing the first layer into contact with a third gas or a first liquid containing a third element after the step (b). It has the step (c) of substituting a part of the AE with a third element, and the third element may contain at least one element selected from the group consisting of K and Na.

Further, as another aspect, the method for producing the conductor is included in the first layer by bringing the first layer into contact with a fourth gas or a second liquid containing a fourth element after the step (b). It has the step (d) of substituting a part of the arsenic with a fourth element, and the fourth element may contain phosphorus.

The conductor as one aspect of the present invention has a first layer containing metallic iron as a main component and a second layer laminated with the first layer, and the second layer has the following composition formula (formulation). Contains the first compound represented by 1).
(AE _1-x A _x ) (Fe _1-y TM _y ) ₂ (As _1-z P _z ) ₂ ... (Chemical formula 1)
AE is at least one element selected from the group consisting of Ba and Sr, A is at least one element selected from the group consisting of K and Na, and TM is Cr, Mn, Co and Ni. It is at least one element selected from the group consisting of, x satisfies 0 ≦ x <1, y satisfies 0 ≦ y <0.5, and z satisfies 0 ≦ z <0.8. ..

Further, as another aspect, the conductor has inclusions interposed between the first layer and the second layer, and the inclusions are a second compound represented by the _{composition formula Fe 2 As, or} , Iron in which arsenic is dissolved may be contained.

Further, as another aspect, the second layer may have superconductivity.

Further, as another aspect, the conductor has a linear shape or a plate shape composed of a first surface and a second surface opposite to the first surface, and is a base material containing metallic iron as a main component. The first layer may be the surface layer of the first surface or the second surface of the base material.

Further, as another aspect, the conductor has a plate-like shape composed of a third surface and a fourth surface opposite to the third surface, and a plurality of base materials each containing metallic iron as a main component. The first layer is the surface layer of the third surface or the fourth surface of each of the plurality of base materials, and the plurality of base materials are laminated in the thickness direction of each of the plurality of base materials. May be good.

The superconducting power transmission line as one aspect of the present invention includes the conductor, and the base material has a linear shape.

The superconducting magnet device as one aspect of the present invention includes the conductor.

The superconducting magnetic shield device as one aspect of the present invention includes the conductor.

_{By applying one aspect of the present invention, (AE, A) (Fe, TM) 2} (As, P) ₂ (AE) can be placed on the surface layer of the base material even in an atmosphere where the pressure is not reduced below the atmospheric pressure. Is an alkaline earth metal element, A is an alkali metal element, and TM is a transition metal element), and a conductor having a thick film-shaped conductive layer can be formed.

It is a perspective view which includes a partial cross section which shows an example of the conductor of an embodiment. It is sectional drawing which shows an example of the conductor of an embodiment. It is sectional drawing which shows the other example of the conductor of an embodiment. It is a perspective view which includes a partial cross section of the conductor of the 1st modification of embodiment. It is a perspective view which includes a partial cross section of the conductor of the 2nd modification of embodiment. It is a process flow diagram which shows a part of the manufacturing process of the conductor of an embodiment. It is a perspective view which includes a partial cross section in the manufacturing process of the conductor of an embodiment. It is sectional drawing in the manufacturing process of the conductor of an embodiment. It is sectional drawing in the manufacturing process of the conductor of an embodiment. It is sectional drawing in the manufacturing process of the conductor of an embodiment. It is a process flow diagram which shows a part of the manufacturing process of the conductor of the modification of embodiment. It is sectional drawing in the manufacturing process of the conductor of the modification of embodiment. It is sectional drawing in the manufacturing process of the conductor of the modification of embodiment. It is a graph which shows the θ-2θ spectrum by the XRD method of the surface of the conductor of the comparative example and Examples 1 to 3. It is a graph which shows the θ-2θ spectrum by the XRD method of the surface of the conductor of Examples 4 and 5. It is a graph which shows the temperature dependence of the electric resistance of the conductor of Example 4. It is a graph which shows the temperature dependence of the electric resistance of the conductor of Example 4. It is a graph which shows the temperature dependence of the electric resistance of the conductor of Example 5. It is a photograph which shows the reflected electron (BSE) image of the cross section in the vicinity of the surface of the conductor of Example 8. It is a photograph which shows the reflected electron (BSE) image of the cross section in the vicinity of the surface of another example of the conductor of Example 8. It is a photograph of the starting material made of pure Fe wire before forming the conductor of Example 9. It is a photograph of the starting material after contacting the starting material shown in FIG. 21 with a gas containing As. It is a photograph of the starting material after the starting material shown in FIG. 22 was brought into contact with a gas containing Ba to form the conductor of Example 9. It is a photograph which shows the reflected electron (BSE) image of the cross section in the vicinity of the surface of the conductor of Example 10. It is a figure which shows typically the cross section in the vicinity of the surface of the conductor of Example 10 by tracing the photograph of FIG. 24.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

It should be noted that the disclosure is merely an example, and those skilled in the art can easily conceive of appropriate changes while maintaining the gist of the invention are naturally included in the scope of the present invention. Further, in order to clarify the description, the drawings may schematically represent the width, thickness, shape, etc. of each part as compared with the embodiment, but this is just an example, and the interpretation of the present invention is used. It is not limited.

Further, in the present specification and each figure, the same elements as those described above with respect to the above-mentioned figures may be designated by the same reference numerals, and detailed description thereof may be omitted as appropriate.

Further, in the drawings used in the embodiments, hatching (shading) attached to distinguish the structures may be omitted depending on the drawings.

In the following embodiments, when the range is indicated as A to B, A or more and B or less are indicated unless otherwise specified.

(Embodiment)
<Conductor>
First, the conductor of the embodiment which is one embodiment of the present invention will be described.

FIG. 1 is a perspective view including a partial cross section showing an example of the conductor of the embodiment. In FIG. 1, a state in which a part of the conductor is removed and seen through is shown, and the removed part of the conductor is shown by a chain double-dashed line. FIG. 2 is a cross-sectional view showing an example of the conductor of the embodiment.

As shown in FIGS. 1 and 2, the conductor 10 of the present embodiment has a layer 11 and a layer 12 laminated with the layer 11.

The layer 11 contains metallic iron as a main component. Here, metallic iron is not a compound in which an iron atom and an atom of an element other than iron, such as iron oxide, are ion-bonded or covalently bonded, but a metal in which iron atoms are metal-bonded to each other, and iron. Means a metal containing as a main component, that is, iron containing 50% or more by weight. Further, the fact that the layer 11 contains metallic iron as a main component means that the layer 11 contains metallic iron in a weight fraction of 50% or more.

The layer 12 contains a compound represented by the following composition formula (Chemical formula 2).
(AE _1-x A _x ) (Fe _1-y TM _y ) ₂ (As _1-z P _z ) ₂ ... (Chemical formula 2)
AE is at least one element selected from the group consisting of Ba and Sr, A is at least one element selected from the group consisting of K and Na, and TM is Cr, Mn, Co and Ni. It is at least one element selected from the group consisting of. That is, AE is at least one element of alkaline earth metal elements, A is at least one element of alkali metal elements, and TM is at least one element of transition metal elements. Further, in the above composition formula (Formula 2), x satisfies 0 ≦ x <1, y satisfies 0 ≦ y <0.5, and z satisfies 0 ≦ z <0.8. The composition formula (Chemical formula 2) represents the same compound as the composition formula (Chemical formula 1).

In such a case, as will be described with reference to FIGS. 6 to 10 described later, a base material containing iron as a main component having various volumes and various shapes even in an atmosphere where the pressure is not reduced from atmospheric pressure. A layer 12 having a thick film shape of, for example, 10 μm or more can be easily formed on the layer 11 as a surface layer, and a conductor 10 having the layer 11 and the layer 12 can be easily formed.

In the compound represented by the above composition formula (Chemical formula 2), when x satisfies x = 0, y satisfies y = 0, and z satisfies z = 0, it is represented by the above composition formula (Chemical formula 2). The compound is represented by the following composition formula (Chemical Formula 3).
AEFe ₂ As ₂ ... (Chemical 3)
AE is at least one element selected from the group consisting of Ba and Sr.

Further, in the compound represented by the above composition formula (Chemical formula 3), when AE is Ba, the compound represented by the above composition formula (Chemical formula 3) is represented by the following composition formula (Chemical formula 4).
BaFe ₂ As ₂ ... (Chemical formula 4)

Hereinafter, the compound represented by the above composition formula (Chemical formula 4) is referred to as Ba122. The crystal structure of Ba122 has a plurality of Fe ₂ As ₂ layers and a plurality of Ba layers, and Fe ₂ As ₂ layers and Ba layers are alternately laminated.

For example, when x satisfies x> 0 or y satisfies y> 0 in the above composition formula (Chemical formula 2), that is, one of the AEs contained in the compound represented by the above composition formula (Chemical formula 3). When the part is replaced by A or a part of Fe contained in the compound represented by the above composition formula (Chemical formula 3) is replaced by TM, the compound represented by the above composition formula (Chemical formula 2) is It has superconductivity when cooled to a temperature lower than the critical temperature lower than room temperature. As a result, the conductor of the present embodiment can be used for various purposes as a superconductor.

When a part of Ba contained in the compound (Ba122) represented by the above composition formula (Chemical formula 4) is replaced by K, Ba122 becomes superconducting by introducing holes as charge carriers into Ba122. It has a critical temperature _{T c} of Ba122 having superconductivity, for example, about 38K. Further, when a part of Fe contained in the compound (Ba122) represented by the above composition formula (Chemical formula 4) is replaced by Co, Ba122 becomes superconducting by introducing an electron as a charge carrier into Ba122. having sex, the critical temperature _{T c} of Ba122 having superconductivity, for example, about 27K.

As shown in FIGS. 1 and 2, preferably, the conductor 10 of the present embodiment has a plate-like shape composed of a surface 13a and a surface 13b opposite to the surface 13a, or a linear shape such as a tape wire rod. It also has a base material 13 containing metallic iron as a main component, and the layer 11 is a surface layer of the surface 13a or the surface 13b of the base material 13.

As a result, various general-purpose iron plates can be used as the iron members having various volumes and various shapes, so that the manufacturing cost of the conductor can be reduced.

FIG. 3 is a cross-sectional view showing another example of the conductor of the embodiment. As shown in FIG. 3, the conductor 10 of the present embodiment may have an inclusion 14 interposed between the layer 11 and the layer 12, and the inclusion 14 has the following composition formula (Chemical formula 5). ), Or iron in which arsenic is dissolved may be contained.
Fe ₂ As ... (Chemical formula 5)

As will be described with reference to FIGS. 6 to 10 described later, in the case of producing the conductor 10 by the method for producing the conductor of the present embodiment, the gas containing arsenic is produced by heating the solid raw material containing arsenic. When the generated gas containing arsenic is brought into contact with the starting material containing heated iron, the iron contained in the starting material reacts with the arsenic contained in the gas to cause the layer 11 and the layer 11. An inclusion 14 containing the compound represented by the above composition formula (Chemical Formula 5) or iron in which arsenic is dissolved may be formed between the layer 12 and the layer 12. In other words, when an inclusion 14 containing the compound represented by the above composition formula (Chemical Formula 5) or iron in which arsenic is dissolved is formed between the layer 11 and the layer 12, the conductor 10 is formed. However, it can be seen that it was produced by the method for producing a conductor of the present embodiment.

As will be described with reference to FIGS. 24 and 25, which will be described later, preferably, the inclusion 14 interposed between the layer 11 and the layer 12 includes the layer 14b and the layer 14c. The layer 14c is arranged between the layer 14b and the layer 12. The layer 14b includes a layer body 14d and a plurality of particles 14e dispersed in the layer body 14d. The layer 14c contains iron in which arsenic is dissolved, the layer body 14d contains the compound represented by the above composition formula (Chemical Formula 5), and the particles 14e contain iron in which arsenic is dissolved. In such a case, since the layer 12 represented by the above composition formula (Chemical Formula 2) can be easily formed on the surface of the starting material 13c, for example, a long conductor can be easily manufactured.

When the conductor 10 of the present embodiment has superconductivity, a transmission line provided with the conductor 10 of the present embodiment as a superconducting wire can be used as the superconducting power transmission line 10a. That is, when the conductor 10 of the present embodiment has superconductivity, the superconducting power transmission line 10a provided with the conductor 10 of the present embodiment can be realized.

When the conductor 10 of the present embodiment has superconductivity, a superconducting coil formed by winding the conductor 10 of the present embodiment into a coil as a superconducting wire is used as the superconducting magnet device 10b. be able to. That is, when the conductor 10 of the present embodiment has superconductivity, the superconducting magnet device 10b provided with the conductor 10 of the present embodiment can be realized.

When the conductor 10 of the present embodiment has superconductivity, a superconducting coil formed by winding the conductor 10 of the present embodiment into a coil as a superconducting wire is used as a superconducting magnetic shield device 10c. Can be used. That is, when the conductor 10 of the present embodiment has superconductivity, the superconducting magnetic shield device 10c provided with the conductor 10 of the present embodiment can be realized.

<Modification example of conductor>
Next, various modifications of the conductor of the present embodiment will be described.

FIG. 4 is a perspective view including a partial cross section of the conductor of the first modification of the embodiment. In FIG. 4, a state in which a part of the conductor is removed and seen through is shown, and the removed part of the conductor is shown by a chain double-dashed line.

As shown in FIG. 4, the conductor 10 of the first modification has a linear shape and has a base material 13 containing metallic iron as a main component, and the layer 11 is a surface layer of the base material 13. Is. Further, the layer 12 is laminated with the layer 11.

As a result, various general-purpose iron wires can be used as the iron members having various volumes and various shapes, so that the manufacturing cost of the conductor can be reduced.

When the conductor 10 of the first modification has superconductivity, a transmission line provided with the conductor 10 of the first modification as a superconducting wire can be used as the superconducting transmission line 10a. Further, when the conductor 10 of the first modification has superconductivity, the superconducting coil formed by winding the conductor 10 of the first modification into a coil as a superconducting wire is used as a superconducting magnet device 10b. Alternatively, it can be used as a superconducting magnetic shield device 10c.

FIG. 5 is a perspective view including a partial cross section of the conductor of the second modification of the embodiment. In FIG. 5, a state in which a part of the conductor is removed and seen through is shown, and the removed part of the conductor is shown by a chain double-dashed line.

As shown in FIG. 5, the conductor 10 of the second modification has a plate-like shape composed of a surface 13a (see FIG. 2) and a surface 13b (see FIG. 2) opposite to the surface 13a, respectively. It has a plurality of base materials 13 each containing metallic iron as a main component, the layer 11 is a surface layer of each surface 13a or surface 13b of the plurality of base materials 13, and the plurality of base materials 13 are a plurality of groups. The materials 13 are laminated in each thickness direction. Further, in each of the plurality of base materials 13, the layer 12 is laminated with the layer 11.

In such a case, by laminating a plurality of conductors having thin iron plates in the thickness direction, the layer 12 can be formed on the surface of the thick iron plate as the base material, which increases the manufacturing cost of the conductors. The volume of the base material can be easily increased without causing it.

When the conductor 10 of the second modification has superconductivity, the superconducting bulk body made of the conductor 10 of the second modification is used as the superconducting magnet device 10b or the superconducting magnetic shield device 10c. be able to. That is, when the conductor 10 of the second modification has superconductivity, the superconducting magnet device 10b or the superconducting magnetic shield device 10c provided with the conductor 10 of the second modification can be realized.

When the conductor 10 of the second modification has superconductivity, a transmission line provided with the conductor 10 of the second modification as a superconducting wire can be used as the superconducting transmission line 10a. When the conductor 10 of the second modification has superconductivity, a superconducting coil formed by winding the conductor 10 of the second modification into a coil as a superconducting wire is used as a superconducting magnet device 10b. Alternatively, it can be used as a superconducting magnetic shield device 10c.

<Manufacturing method of conductor>
Next, a method for manufacturing the conductor of the present embodiment will be described. In the method for producing a conductor of the present embodiment, a layer containing a compound represented by the above composition formula (Chemical Formula 2) is formed on at least the surface of a starting material containing iron. Further, in the above composition formula (Chemical formula 2), AE is at least one element selected from the group consisting of Ba and Sr, and A is at least one element selected from the group consisting of K and Na. , TM is at least one element selected from the group consisting of Cr, Mn, Co and Ni. That is, AE is at least one element of alkaline earth metal elements, A is at least one element of alkali metal elements, and TM is at least one element of transition metal elements. Further, in the above composition formula (Formula 2), x satisfies 0 ≦ x <1, y satisfies 0 ≦ y <0.5, and z satisfies 0 ≦ z <0.8.

In the method for producing a conductor of the present embodiment, iron and arsenic contained in the starting material are reacted at the same time, and iron and arsenic contained in the starting material are reacted to form iron and arsenic. This is different from the method for producing a conductor according to the embodiment in which Ba is reacted with a compound containing iron and arsenic after forming a compound containing.

FIG. 6 is a process flow diagram showing a part of the conductor manufacturing process of the embodiment. FIG. 7 is a perspective view including a partial cross section during the manufacturing process of the conductor of the embodiment. FIG. 7 shows a state in which a part of the starting material is removed and seen through, and the removed part of the starting material is shown by a chain double-dashed line. 8 to 10 are cross-sectional views of the conductor of the embodiment during the manufacturing process.

First, the starting material 13c and the solid raw material 15 are prepared (step S1 in FIG. 6).

In this step S1, as shown in FIG. 7, a starting material 13c containing iron is prepared. As the starting material 13c containing iron, a base material 13 having a plate-like shape composed of a surface 13a and a surface 13b opposite to the surface 13a (see FIG. 2) and containing metallic iron as a main component is prepared. When y satisfies 0 <y <0.5 in the above composition formula (Formula 2), the starting material 13c further contains TM. As described above, TM in the above composition formula (Chemical formula 2) is at least one element selected from the group consisting of Cr, Mn, Co and Ni.

Preferably, as the starting material 13c, pure iron having a low content of impurities such as carbon can be used. Thereby, the layer 12 (see FIG. 9 described later) containing the compound represented by the above composition formula (Chemical formula 2) can be easily formed.

Further, in this step S1, as shown in FIG. 8, a solid raw material 15 containing the first element E1 and the second element E2 is prepared. The first element E1 contains AE in the above composition formula (Chemical formula 2), and the second element E2 contains arsenic (As). As described above, AE in the above composition formula (Chemical formula 2) is at least one element selected from the group consisting of Ba and Sr.

When the first element E1 contains AE and the second element E2 contains arsenic, as the solid raw material 15, for example, a solid raw material represented by the _{composition formula BaAs 2 can be used. When a solid raw material represented by BaAs 2} is used as the solid raw material 15, the molar ratio of the second element E2 to the first element E1 is 2, which is equal to the composition of the compound represented by the above composition formula (Chemical formula 4). Therefore, the layer 12 including Ba122 can be easily formed. In the solid raw material 15, Ba and As may be reacting with each other, and Ba and As may not be reacting with each other.

Further, when x satisfies 0 <x <1 in the above composition formula (Chemical formula 2), the first element E1 further contains A in the above composition formula (Chemical formula 2), and z in the above composition formula (Chemical formula 2). When 0 <z <0.8 is satisfied, the second element E2 further contains phosphorus (P). As described above, A in the above composition formula (Chemical formula 2) is at least one element selected from the group consisting of K and Na.

Next, as shown in FIG. 8, the starting material 13c and the solid raw material 15 are placed in the airtight container 16 (step S2 in FIG. 6).

In this step S2, the solid raw material 15 is separated from the starting material 13c, or the solid raw material 15 is not separated from the starting material 13c and is in contact with the starting material 13c but is not mixed with the starting material 13c. The solid raw material 15 is not separated from the starting material 13c but is in contact with the starting material 13c, but is separated from the starting material 13c, or the region where the solid raw material 15 is arranged is separated from the region where the starting material 13c is arranged. In this state, the starting material 13c and the solid raw material 15 are arranged.

Next, as shown in FIG. 8, the inside of the container 16 is evacuated, or the atmosphere inside the container 16 is replaced with an inert gas (step S3 in FIG. 6). As the inert gas, a noble gas made of a Group 18 element such as argon (Ar) can be used.

Next, as shown in FIG. 9, the starting material 13c is brought into contact with the gas G1 containing the first element E1 and the second element E2 (step S4 in FIG. 6).

In this step S4, the solid raw material 15 containing the first element E1 and the second element E2 and the starting material 13c are heated, and the solid raw material 15 is heated to generate a gas G1 which is heated by the generated gas G1. As shown in FIG. 9, the starting material 13c is brought into contact with the starting material 13c in a fresh state, and the iron contained in the starting material 13c is reacted with the first element E1 and the second element E2 contained in the gas G1. The layer 12 is formed on the layer 11 which is at least the surface layer of the base material 13 as a base material. When y satisfies 0 <y <0.5 in the above composition formula (Chemical Formula 2), in step S4, TM and iron contained in the starting material 13c and the first elements E1 and 2 contained in the gas G1. By reacting with the element E2, the layer 12 is formed on the layer 11 which is at least the surface layer of the base material 13 as the starting material 13c.

In such a case, even in an atmosphere where the pressure is not reduced below the atmospheric pressure, the thickness of, for example, 10 μm or more is placed on the layer 11 as the surface layer of the base material 13 containing iron having various volumes and various shapes. The layer 12 having a film shape can be easily formed, and the conductor 10 having the layer 11 and the layer 12 can be easily formed.

As described above, after the step S2 and before the step S4, the solid raw material 15 is separated from the starting material 13c, or the solid raw material 15 is not separated from the starting material 13c and is in contact with the starting material 13. However, it is not mixed with the starting material 13c, or the solid raw material 15 is not separated from the starting material 13c but is in contact with the starting material 13c but separated from the starting material 13c, or the solid raw material 15 is arranged. The region is separated from the region where the starting material 13c is arranged. Therefore, in step S4, the first element E1 and the second element E2 diffused in the surface of the starting material 13c or diffused inward from the surface of the starting material 13c react with the iron contained in the starting material 13c. As a result, the layer 12 is formed for the first time. Therefore, in the method for producing a conductor of the present embodiment, the first element E1 and the second element contained in the gas generated from the powder are heated by heating the powder containing iron, the first element E1 and the second element E2. It is completely different from the method of reacting E2 with the iron contained in the powder. Further, as will be described later, when forming a conductor as a long wire, the method for producing a conductor according to the present embodiment is the first element E1 and the second element contained in the gas generated from the powder. Compared with the method of reacting E2 with iron contained in the powder, a conductor as a long wire can be formed extremely easily.

Preferably, in step S4, the solid raw material 15 is heated to the temperature T1 as the heat treatment temperature, the starting material 13c is heated to the temperature T2 as the heat treatment temperature, and the solid raw material 15 is heated to the temperature T1 to obtain a gas. G1 is generated, and the generated gas G1 is brought into contact with the starting material 13c heated to the temperature T2. The temperature T1 and the temperature T2 may be equal to each other or different from each other. Further, instead of the gas G1, a liquid may be generated, and the starting material 13c may be brought into contact with the generated liquid.

In such a case, even in an atmosphere where the pressure is not reduced below the atmospheric pressure, the thickness of, for example, 10 μm or more is placed on the layer 11 as the surface layer of the base material 13 containing iron having various volumes and various shapes. The layer 12 having a film shape can be formed more easily, and the conductor 10 having the layer 11 and the layer 12 can be formed more easily.

Alternatively, preferably, in step S4, the solid raw material 15 is heated to a temperature T1 of 700 ° C. or higher, the starting material 13c is heated to a temperature T2 of 700 ° C. or higher, and the solid raw material 15 is heated to a temperature T1 to obtain a gas. G1 is generated, and the generated gas G1 is brought into contact with the starting material 13c heated to the temperature T2. Even in such a case, even in an atmosphere where the pressure is not reduced below the atmospheric pressure, for example, 10 μm or more is placed on the layer 11 as the surface layer of the base material 13 containing iron having various volumes and various shapes. The layer 12 having a thick film shape can be formed more easily, and the conductor 10 having the layer 11 and the layer 12 can be formed more easily. The temperature T1 and the temperature T2 may be equal to each other or different from each other.

In step S4, since it is sufficient that the starting material 13c can be brought into contact with the gas G1 containing the first element E1 and the second element E2, for example, it is provided separately from the container 16 and the inside is inside the container 16. A solid raw material 15 is placed in a communicating container (not shown), gas G1 is generated by heating, for example, the solid raw material 15 in the container, and the generated gas G1 is supplied and supplied into the container 16. The heated starting material 13c may be brought into contact with the gas G1.

Further, in step S4, when the solid raw material 15 containing arsenic is heated to generate a gas G1 containing arsenic, and the generated gas G1 containing arsenic is brought into contact with the starting material 13c containing heated iron. In addition, depending on the temperature T2 at which the starting material 13c is heated, the iron contained in the starting material 13c reacts with the arsenic contained in the gas G1 to react between the layers 11 and 12 as shown in FIG. In some cases, inclusions 14 containing the compound represented by the above composition formula (Chemical Formula 5) or iron in which arsenic is dissolved may be formed. Therefore, when an inclusion 14 containing the compound represented by the above composition formula (Chemical Formula 5) or iron in which arsenic is dissolved is formed between the layer 11 and the layer 12, the conductor 10 is formed. It can be seen that it was produced by the method for producing a conductor of the present embodiment.

Preferably, after step S4, the layer 12 is included in the layer 12 by contacting the layer 12 with a gas G2 containing the third element E3 (see FIG. 9) or a liquid L1 containing the third element E3 (see FIG. 9). A part of AE is replaced with the third element E3 (step S5 in FIG. 6). The third element E3 contains at least one element selected from the group consisting of K and Na.

In the compound contained in the layer 12 formed in step S4 and represented by the above composition formula (Chemical formula 2), even when the first element E1 does not contain A and x satisfies x = 0. By performing step S5 after step S4, x can satisfy 0 <x <1 in the compound represented by the above composition formula (Chemical formula 2). In the compound contained in the layer 12 formed in step S4 and represented by the above composition formula (Chemical formula 2), the first element E1 contains A and x is 0 <x <1. Even if it is satisfied, step S5 can be performed.

Preferably, after step S4, the layer 12 is included in the layer 12 by contacting the layer 12 with a gas G3 containing the fourth element E4 (see FIG. 9) or a liquid L2 containing the fourth element E4 (see FIG. 9). A part of arsenic is replaced with the fourth element E4 (step S6 in FIG. 6). The fourth element E4 contains phosphorus.

By performing step S6 after step S4 even when z satisfies z = 0 in the compound contained in the layer 12 formed in step S4 and represented by the above composition formula (Chemical formula 2). , In the compound represented by the above composition formula (Chemical formula 2), z can satisfy 0 <z <0.8. In the compound contained in the layer 12 formed in step S4 and represented by the above composition formula (Formula 2), step S6 is performed even when z satisfies 0 <z <0.8. Can be done.

Further, in FIG. 6, a case where step S5 and step S6 are sequentially performed after step S4 is illustrated, but the order in which step S5 and step S6 are performed after step S4 is arbitrary, or step S5. And step S6 may be performed at the same time.

For example, as the base material 13, a base material 13 having a linear shape or a plate shape and containing metallic iron as a main component is used, and a delivery reel around which the base material 13 is wound and a base material 13 are wound up. The take-up reel to be used is provided in the container 16, or the container 16 is provided between the delivery reel and the take-up reel, and the delivery reel and the take-up reel are rotated at a constant speed to deliver the base from the delivery reel. When the material 13 passes through a fixed position in the container 16 at a constant speed, a layer 12 is formed on the surface of the base material 13, and the base material 13 having the layer 12 formed on the surface is wound on a take-up reel. To be able to. In this way, for example, as described in the first modification of the conductor of the embodiment, the base material 13 has a linear shape and contains metallic iron as a main component, and the layer 11 is a base. It is possible to form a conductor as a long wire, such as the surface layer of the material 13.

<Modification example of conductor manufacturing method>
Next, a modified example of the method for manufacturing the conductor of the present embodiment will be described. The method for producing the conductor of this modification is to form a compound containing iron and arsenic by reacting iron contained in the starting material with arsenic, and then using a compound containing iron and arsenic and Ba. Is different from the method for producing a conductor in which iron, arsenic, and Ba contained in the starting material are reacted at the same time in that the layer 12 is formed by reacting with the above.

As will be described with reference to Example 8 described later, in the process of producing the conductor of the embodiment, formation of Ba122 when the starting material 13c is brought into contact with the gas G1 containing Ba and As (see FIG. 9). In the process, in the first step, iron contained in the starting material 13c and arsenic contained in the gas G1 react to form iron in which arsenic is solid-dissolved, that is, (Fe, As), and the second step. in iron arsenic in a solid solution i.e. (Fe, as) and the arsenic contained in the gas G1, by react, formed mainly _Fe 2 as, a third step, _Fe 2 as the Ba and as It is _{considered that BaFe 2} As ₂ (Ba122) is formed by the reaction with and. That is, it is considered that Ba does not contribute much to the reaction in the first half of the process of forming Ba122. Therefore, instead of contacting the starting material 13c with the gas G1 containing Ba and As (see FIG. 9), the starting material 13c is first brought into contact with the gas containing As, and iron and arsenic contained in the starting material. It is considered that the layer 12 can also be formed by reacting Ba with the compound containing iron and arsenic after forming the compound containing iron and arsenic by reacting with. As a result, the number of parameters to be controlled at the same time during the manufacturing process of the conductor can be reduced, so that the conductor including the layer 12 represented by the composition formula (Chemical formula 2) can be manufactured with good reproducibility. ..

In the method for producing the conductor of this modification, similarly to the method for producing the conductor of the embodiment, a layer containing the compound represented by the above composition formula (Chemical Formula 2) is formed on at least the surface of the starting material containing iron. It is what forms. Further, in the above composition formula (Chemical formula 2), AE is at least one element selected from the group consisting of Ba and Sr, and A is at least one element selected from the group consisting of K and Na. , TM is at least one element selected from the group consisting of Cr, Mn, Co and Ni. That is, AE is at least one element of alkaline earth metal elements, A is at least one element of alkali metal elements, and TM is at least one element of transition metal elements. Further, in the above composition formula (Formula 2), x satisfies 0 ≦ x <1, y satisfies 0 ≦ y <0.5, and z satisfies 0 ≦ z <0.8.

FIG. 11 is a process flow diagram showing a part of the manufacturing process of the conductor of the modified example of the embodiment. 12 and 13 are cross-sectional views during the manufacturing process of the conductor of the modified example of the embodiment.

First, the starting material 13c, the solid raw material 15a, and the solid raw material 15b are prepared (step S11 in FIG. 11).

In this step S11, as shown in FIG. 12, a starting material 13c containing iron is prepared. As the starting material 13c containing iron, for example, a base material 13 having a linear shape including a side peripheral surface 13d and containing metallic iron as a main component is prepared. When y satisfies 0 <y <0.5 in the above composition formula (Formula 2), the starting material 13c further contains TM. As described above, TM in the above composition formula (Chemical formula 2) is at least one element selected from the group consisting of Cr, Mn, Co and Ni.

Preferably, as the starting material 13c, pure iron having a low content of impurities such as carbon can be used. Thereby, as described in step S14 described later, the layer 14a (see FIG. 12) containing the compound containing iron and arsenic contained in the starting material 13c can be easily formed.

Further, in this step S11, as shown in FIG. 12, a solid raw material 15a containing at least the fifth element E5 containing arsenic (As) is prepared. That is, the solid raw material 15a contains at least arsenic.

Since the solid raw material 15a may contain at least arsenic, the solid raw material 15a containing the fifth element E5 and the sixth element E6 containing AE in the above composition formula (Chemical Formula 2) described later as the solid raw material 15a. In such a case, for example, a solid raw material represented by the _{composition formula BaAs 2 can be used.} When the solid raw material _{represented by BaAs 2} is used as the solid raw material 15a, the layer 14a containing the compound containing iron contained in the starting material 13c and arsenic contained in the solid raw material 15a can be easily formed. .. In the solid raw material 15a, Ba and As may be reacting with each other, and Ba and As may not be reacting with each other.

Further, in this step S11, as shown in FIG. 13, a solid raw material 15b containing at least the sixth element E6 containing AE in the above composition formula (Chemical Formula 2) is prepared. As described above, AE in the above composition formula (Chemical formula 2) is at least one element selected from the group consisting of Ba and Sr. When the sixth element E6 contains AE, as the solid raw material 15b, for example, a solid raw material containing Ba such as elemental metal barium (Ba) can be used. When potassium (K) is added, a solid raw material containing an alloy of barium and potassium, or a solid raw material in which barium as a metal and potassium as a metal are placed together can be used.

Further, when x satisfies 0 <x <1 in the above composition formula (Chemical formula 2), the sixth element E6 further contains A in the above composition formula (Chemical formula 2), and z in the above composition formula (Chemical formula 2). When 0 <z <0.8 is satisfied, the fifth element E5 further contains phosphorus (P). As described above, A in the above composition formula (Chemical formula 2) is at least one element selected from the group consisting of K and Na.

Next, as shown in FIG. 12, the same steps as in step S2 of FIG. 6 are performed to arrange the starting material 13c and the solid raw material 15a in the airtight container 16 (step S12 of FIG. 11).

In this step S12, the solid raw material 15a is separated from the starting material 13c, or the solid raw material 15a is not separated from the starting material 13c and is in contact with the starting material 13c but is not mixed with the starting material 13c. The solid raw material 15a is not separated from the starting material 13c but is in contact with the starting material 13c, but is separated from the starting material 13c, or the region where the solid raw material 15a is arranged is the region where the starting material 13c is arranged. In the separated state, the starting material 13c and the solid raw material 15a are arranged.

Next, although not shown, the same steps as in step S3 of FIG. 6 are performed to create a vacuum inside the container 16 or to replace the atmosphere inside the container 16 with an inert gas (FIG. 11). Step S13). As the inert gas, a noble gas made of a Group 18 element such as argon (Ar) can be used.

Next, as shown in FIG. 12, the starting material 13c is brought into contact with the gas G4 containing the fifth element E5 (step S14 in FIG. 6).

In this step S14, the solid raw material 15a containing the fifth element E5 and the starting material 13c are heated, and the solid raw material 15a is heated to generate the gas G4, and the generated gas G4 is used as the starting material in a heated state. By contacting 13c and reacting the iron contained in the starting material 13c with the fifth element E5 contained in the gas G4, as shown in FIG. 12, at least on the surface layer of the base material 13 as the starting material 13c. On a certain layer 11, iron contained in the starting material 13c and arsenic contained in the solid raw material 15a are contained, and the compound represented by the above composition formula (Chemical Formula 5) or iron in which arsenic is solid-dissolved. , To form a layer 14a containing. When y satisfies 0 <y <0.5 in the above composition formula (Chemical formula 2), in step S14, TM and iron contained in the starting material 13c are reacted with the fifth element E5 contained in the gas G4. By doing so, a compound containing TM and iron and arsenic is formed on the layer 11 which is at least the surface layer of the base material 13 as the starting material 13c.

In such a case, even in an atmosphere where the pressure is not reduced below the atmospheric pressure, the thickness of, for example, 10 μm or more is placed on the layer 11 as the surface layer of the base material 13 containing iron having various volumes and various shapes. The layer 12 having a film shape can be easily formed, and the conductor 10 having the layer 11 and the layer 12 (see FIG. 13) can be easily formed.

As described above, after the step S12 and before the step S14, the solid raw material 15a is separated from the starting material 13c, or the solid raw material 15a is not separated from the starting material 13c and is in contact with the starting material 13c. However, it is not mixed with the starting material 13c, or the solid raw material 15a is not separated from the starting material 13c but is in contact with the starting material 13c but separated from the starting material 13c, or the solid raw material 15a is arranged. The region is separated from the region where the starting material 13c is arranged. Therefore, in step S14, the layer is formed for the first time when the surface of the starting material 13c is diffused or the fifth element E5 diffused from the surface of the starting material 13c to the inside reacts with the iron contained in the starting material 13c. 14a will be formed. Therefore, in the method for producing a conductor of this modification, the powder containing iron and the fifth element E5 is heated to react the fifth element E5 contained in the gas generated from the powder with the iron contained in the powder. It's completely different from the method.

Next, as shown in FIG. 13, the starting material 13c is brought into contact with the gas G5 containing the sixth element E6 (step S15 in FIG. 6).

In this step S15, the starting material 13c and the solid raw material 15b are placed in the airtight container 16 as in step S12 of FIG. 11, and then the inside of the container 16 is in a vacuum state as in step S13 of FIG. Or, the atmosphere in the container 16 is replaced with an inert gas. Then, the solid raw material 15b containing the sixth element E6 and the starting material 13c are heated, and the solid raw material 15b is heated to generate a gas G5, and the generated gas G5 is brought into contact with the heated starting material 13c. The compound contained in the layer 14a (see FIG. 12) and represented by the above composition formula (Chemical formula 5) or iron in which arsenic is solid-dissolved and the sixth element E6 contained in the gas G5 are formed. By reacting, as shown in FIG. 13, a layer 12 containing the compound represented by the above composition formula (Chemical Formula 2) is formed on the layer 11 which is at least the surface layer of the base material 13 as the starting material 13c. ..

In such a case, even in an atmosphere where the pressure is not reduced below the atmospheric pressure, the thickness of, for example, 10 μm or more is placed on the layer 11 as the surface layer of the base material 13 containing iron having various volumes and various shapes. The layer 12 having a film shape can be easily formed, and the conductor 10 having the layer 11 and the layer 12 can be easily formed.

Preferably, in step S14, the solid raw material 15a is heated to the temperature T3 as the heat treatment temperature, the starting material 13c is heated to the temperature T4 as the heat treatment temperature, and the solid raw material 15a is heated to the temperature T3 to obtain a gas. G4 is generated, and the generated gas G4 is brought into contact with the starting material 13c heated to the temperature T4. The temperature T3 and the temperature T4 may be equal to each other or different from each other. Further, instead of the gas G4, a liquid may be generated, and the starting material 13c may be brought into contact with the generated liquid.

In such a case, the layer 14a can be further easily formed on the layer 11 as the surface layer of the base material 13 containing iron having various volumes and various shapes even in an atmosphere where the pressure is not reduced below the atmospheric pressure. Can be formed into.

Further, preferably, in step S15, the solid raw material 15b is heated to the temperature T5 as the heat treatment temperature, the starting material 13c is heated to the temperature T6 as the heat treatment temperature, and the solid raw material 15b is heated to the temperature T5. The gas G5 is generated by the above method, and the generated gas G5 is brought into contact with the starting material 13c heated to the temperature T6. The temperature T5 and the temperature T6 may be equal to each other or different from each other. Further, instead of the gas G5, a liquid may be generated, and the starting material 13c may be brought into contact with the generated liquid.

In such a case, even in an atmosphere where the pressure is not reduced below the atmospheric pressure, the thickness of, for example, 10 μm or more is placed on the layer 11 as the surface layer of the base material 13 containing iron having various volumes and various shapes. The layer 12 having a film shape can be formed more easily, and the conductor 10 having the layer 11 and the layer 12 can be easily formed. Further, conditions such as the temperature at which the starting material 13c is brought into contact with the gas G4 containing As (see FIG. 12) and the temperature at which the starting material 13c is brought into contact with the gas G5 containing Ba (see FIG. 13). Since the conditions such as the above can be individually controlled, the conductor 10 having the layer 12 can be manufactured with good reproducibility.

Alternatively, preferably, in step S14, the solid raw material 15a is heated to a temperature T3 of 840 to 900 ° C., the starting material 13c is heated to a temperature T4 of 840 to 900 ° C., and the solid raw material 15a is heated to a temperature T3. Gas G4 is generated by the above method, and the generated gas G4 is brought into contact with the starting material 13c heated to the temperature T4. When the temperature T3 and the temperature T4 are 840 ° C. or higher, a melt containing iron and arsenic is more likely to be generated on the layer 11 as compared with the case where the temperature T3 and the temperature T4 are lower than 840 ° C. The adhesion with the layer 14a is improved, and the quality of the layer 14a is improved. Further, when the temperature T3 and the temperature T4 are 900 ° C. or lower, the arsenic contained in the layer 14a is less likely to vaporize or iron and arsenic are separated on the layer 11 as compared with the case where the temperature T3 and the temperature T4 exceed 900 ° C. The quality of the layer 14a is improved by not increasing the amount of the melt contained in the layer too much. Therefore, the layer 14a is more easily formed on the layer 11 as the surface layer of the base material 13 containing iron having various volumes and various shapes even in an atmosphere where the pressure is not reduced below the atmospheric pressure. be able to. The temperature T3 and the temperature T4 may be equal to each other or different from each other.

Alternatively, preferably, in step S15, the solid raw material 15b is heated to a temperature T5 of 700 to 840 ° C., the starting material 13c is heated to a temperature T6 of 700 to 840 ° C., and the solid raw material 15b is heated to a temperature T5. The gas G5 is generated by the above method, and the generated gas G5 is brought into contact with the starting material 13c heated to the temperature T6. When the temperature T5 and the temperature T6 are 700 ° C. or higher, the AE contained in the solid raw material 15b is more easily vaporized than when the temperature T5 and the temperature T6 are lower than 700 ° C., so that the layer 12 can be easily formed. Can be done. Further, when the temperature T5 and the temperature T6 are 840 ° C. or lower, the melt containing iron and arsenic is less likely to be generated as compared with the case where the temperature T5 and the temperature T6 exceed 840 ° C., and are contained in the layers 14a and 12. The layer 12 can be easily formed because arsenic is less likely to vaporize. Therefore, even in an atmosphere where the pressure is not reduced below the atmospheric pressure, a thick film shape of, for example, 10 μm or more is formed on the layer 11 as the surface layer of the base material 13 containing iron having various volumes and various shapes. The layer 12 having the layer 12 can be formed more easily, and the conductor 10 having the layer 11 and the layer 12 can be formed more easily. The temperature T5 and the temperature T6 may be equal to each other or different from each other.

Further, in step S14 or step S15, it is sufficient that the starting material 13c can be brought into contact with the gas G4 containing the fifth element E5 or the gas G5 containing the sixth element E6. Gas G4 or gas G5 by arranging the solid raw material 15a or the solid raw material 15b in a container (not shown) whose inside communicates with the inside of the container 16 and heating, for example, the solid raw material 15a or the solid raw material 15b in the container. May be generated, the generated gas G4 or the gas G5 is supplied into the container 16, and the supplied starting material 13c may be brought into contact with the supplied gas G4 or the gas G5.

Further, in step S15, depending on the temperature T6 for heating the starting material 13c, as shown in FIG. 13, between the layer 11 and the layer 12, the compound represented by the above composition formula (Chemical formula 5) or arsenic The layer 14a containing the solid-dissolved iron may remain as inclusions 14. Therefore, when an inclusion 14 containing the compound represented by the above composition formula (Chemical Formula 5) or iron in which arsenic is dissolved is formed between the layer 11 and the layer 12, the conductor 10 is formed. It can be seen that it was manufactured by the method for manufacturing the conductor of this modification or the method for manufacturing the conductor of the embodiment.

As will be described later with reference to FIGS. 24 and 25, preferably, in step S15, the layer 12 is formed and the layer 14a is left as an inclusion 14 between the layer 11 and the layer 12. The arranged layer 14b is formed, and the layer 14c arranged between the layer 14b and the layer 12 is formed. Layer 14c contains iron in which arsenic is dissolved. In such a case, since the layer 12 represented by the above composition formula (Chemical Formula 2) can be easily formed on the surface of the starting material 13c, for example, a long conductor can be easily manufactured.

Further, as described later with reference to FIGS. 24 and 25, preferably, the layer 14b formed in step S15 is the layer body 14d and a plurality of particles 14e dispersedly arranged in the layer body 14d. And, including. The layer body 14d contains the compound represented by the above composition formula (Chemical Formula 5), and the particles 14e contain iron in which arsenic is dissolved. In such a case, since the layer 12 represented by the above composition formula (Chemical Formula 2) can be easily formed on the surface of the starting material 13c, for example, a long conductor can be easily manufactured.

Preferably, after step S15, the layer 12 is brought into contact with the gas G2 containing the third element E3 (see FIG. 13) or the liquid L1 containing the third element E3 (see FIG. 13) in the same manner as in step S5 of FIG. By doing so, a part of the AE contained in the layer 12 is replaced with the third element E3 (step S16 in FIG. 11). The third element E3 contains at least one element selected from the group consisting of K and Na.

Even when the sixth element E6 does not contain A and x satisfies x = 0 in the compound contained in the layer 12 formed in step S15 and represented by the above composition formula (Formula 2). By performing step S16 after step S15, x can satisfy 0 <x <1 in the compound represented by the above composition formula (Chemical formula 2). In the compound contained in the layer 12 formed in step S15 and represented by the above composition formula (Chemical formula 2), the sixth element E6 contains A and x is 0 <x <1. Even if it is satisfied, step S16 can be performed.

Preferably, after step S15, the layer 12 is brought into contact with the gas G3 containing the fourth element E4 (see FIG. 13) or the liquid L2 containing the fourth element E4 (see FIG. 13), as in step S6 of FIG. By doing so, a part of the arsenic contained in the layer 12 is replaced with the fourth element E4 (step S17 in FIG. 11). The fourth element E4 contains phosphorus.

By performing step S17 after step S15 even when z satisfies z = 0 in the compound contained in the layer 12 formed in step S15 and represented by the above composition formula (Chemical formula 2). , In the compound represented by the above composition formula (Chemical formula 2), z can satisfy 0 <z <0.8. In the compound contained in the layer 12 formed in step S15 and represented by the above composition formula (Formula 2), step S17 is performed even when z satisfies 0 <z <0.8. Can be done.

Further, in FIG. 6, a case where step S16 and step S17 are sequentially performed after step S15 is illustrated, but the order in which step S16 and step S17 are performed after step S15 is arbitrary, or step S16. And step S17 may be performed at the same time.

In the conductor manufacturing method of the present modification, as in the conductor manufacturing method of the embodiment, when the base material 13 fed from the feeding reel passes through a fixed position in the container 16 at a constant speed, A conductor 12 as a long wire is formed by forming a layer 12 on the surface of the base material 13 and allowing the base material 13 having the layer 12 formed on the surface to be wound on a take-up reel. Can be done.

Hereinafter, the present embodiment will be described in more detail based on the examples. The present invention is not limited to the following examples.

(Comparative Examples and Examples 1 to 3)
The conductors of Comparative Examples and Examples 1 to 3 were formed. Table 1 shows whether or not the compound represented by the above composition formula (Chemical formula 2), that is, the above composition formula (Chemical formula 4) was formed in the conductors of Comparative Examples and Examples 1 to 3. In Table 1, the case where the compound represented by the above composition formula (Chemical Formula 4) is formed is indicated by ◯, and the case where the compound represented by the above composition formula (Chemical Formula 4) is not formed is indicated by ×. .. The conductors of Examples 1 to 3 were formed by the method for producing a conductor of the embodiment, and iron, arsenic, and Ba contained in the starting material were reacted at the same time.

As shown in Table 1, the conductor of Comparative Example could not form the compound represented by the above composition formula (Chemical formula 4), that is, Ba122, but the conductors of Examples 1 to 3 had the above composition formula (Chemical formula). The compound represented by 4) could be formed. The details will be described below.

[Formation of conductor]
First, a starting material 13c (see FIG. 7) and a solid raw material 15 (see FIG. 8) were prepared.

As the starting material 13c, a base material having a plate-like shape and containing metallic iron as a main component, that is, a pure Fe plate was prepared. Specifically, as a pure Fe plate, a plate obtained by processing a pure Fe plate into a plate shape having a length of 10 mm, a width of 3 mm, and a thickness of 0.5 mm using a laser processing machine is used. board.

Further, as the solid raw material 15, a solid raw material made of BaAs ₂ was prepared. Specifically, the elemental metals were weighed so that the molar ratio was Ba: As = 1: 2 under an argon (Ar) atmosphere, and mixed using a ball mill. Then, the mixed simple substance metal was molded into pellets to obtain a solid raw material 15.

Next, the starting material 13c and the solid raw material 15 were placed in an airtight container 16 (see FIG. 8), and the inside of the container 16 was evacuated.

Specifically, the _{solid raw material 15 made of BaAs 2} and the starting material 13c made of pure Fe plate are arranged in a pipe made of stainless steel (stainless steel pipe), and the solid raw material 15 and the starting material 13c are placed inside. The arranged stainless steel tube was sealed in a quartz tube in a vacuum state.

Next, the starting material 13c and the solid raw material 15 were heat-treated to bring the starting material 13c into contact with the gas G1 containing Ba and As (see FIG. 9). Specifically, the solid raw material 15 containing Ba and As is heated at the temperature T1 as the heat treatment temperature, the starting material 13c is heated at the temperature T2 as the heat treatment temperature, and the solid raw material 15 is heated at the temperature T1. Gas G1 was generated by the above method, and the generated gas G1 was brought into contact with the starting material 13c heated at the temperature T2. Then, by reacting the iron contained in the starting material 13c with Ba and As contained in the gas G1, the layer 11 (see FIG. 9), which is at least the surface layer of the base material 13 as the starting material 13c, is subjected to the reaction. Layer 12 (see FIG. 9) was formed.

Here, the cases where the temperature T2 is equal to the temperature T1 and the temperatures T1 are 600 ° C., 700 ° C., 800 ° C., and 900 ° C., respectively, are referred to as Comparative Example, Example 1, Example 2, and Example 3.

[Evaluation by X-ray diffraction method]
The formed comparative examples and the conductors of Examples 1 to 3 were evaluated by the X-ray diffraction (XRD) method. FIG. 14 is a graph showing θ-2θ spectra of the surfaces of the conductors of Comparative Examples and Examples 1 to 3 by the XRD method. In FIG. 14, in addition to the measured θ-2θ spectrum, what is known as the θ-2θ spectrum of Ba122 is displayed.

As shown in FIG. 14, in the θ-2θ spectrum of the conductor of the comparative example in which the temperature T1 as the heat treatment temperature is 600 ° C. by the XRD method, _{a peak due to Fe 2} As was observed, but it was caused by Ba122. No peak was observed. Therefore, it was clarified that when the temperature T1 is 600 ° C., iron contained in the base material 13 reacts with arsenic contained in the gas G1 to _{generate Fe 2} As, but Ba 122 is not produced.

On the other hand, in the θ-2θ spectra of the conductors of Example 1, Example 2, and Example 3 in which the temperatures T1 as the heat treatment temperatures are 700 ° C., 800 ° C., and 900 ° C., respectively, the peaks are caused by Ba122. Was observed. Therefore, it was clarified that Ba122 was produced when the temperature T1 was 700 to 900 ° C.

That is, in step S4, the solid raw material 15 is heated to a temperature T1 of 700 ° C. or higher, the starting material 13c is heated to a temperature T2 of 700 ° C. or higher, and the solid raw material 15 is heated to a temperature T1 to generate gas G1. It has been clarified that the layer 12 containing the compound represented by the above composition formula (Chemical Formula 2) is formed by contacting the generated gas G1 with the starting material 13c in a state of being heated to the temperature T2. ..

Further, when the temperature T1 is in the range of 700 to 900 ° C., _{the intensity of the peak caused by Fe 2} As decreases and the intensity of the peak caused by Ba122 increases as the temperature T1 rises, so that the temperature T1 becomes higher. At 900 ° C., no _{peak caused by Fe 2} As was observed, and the intensity of the peak caused by Ba122 became maximum. Therefore, when the temperature T1 is in the range of 700 to 900 ° C., the ratio of the content of Fe ₂ As to the content of Ba122 decreases as the temperature T1 rises, and when the temperature T1 is 900 ° C., it is substantially single-phase. Ba122 was obtained.

Further, as shown in FIG. 14, in the θ-2θ spectrum of the conductor of Example 3 (900 ° C.), the θ-2θ spectrum of the conductor of Example 2 (800 ° C.) and Example 1 (700 ° C.) The intensity of the peak corresponding to the (110) plane of Ba122 was stronger than that of the θ-2θ spectrum of the conductor (° C.). Therefore, it is considered that the crystal grains of Ba122 have grown preferentially in the c-axis direction, for example.

Regarding the lattice constant of Ba122, in all of Example 1 (700 ° C.), Example 2 (800 ° C.) and Example 3 (900 ° C.), when the temperature T1 as the heat treatment temperature is 700 to 900 ° C. Regarding the measured lattice constants a and c, values substantially close to 0.3963 nm and 1.3022 nm, which are the values of the lattice constants a and c described in Non-Patent Document 2, respectively, were obtained. Therefore, it is considered that Ba122 was obtained in Examples 1 to 3 from the measured values of the lattice constants a and c.

From the above results, it was clarified that Ba122 can be formed in the conductors of Examples 1 to 3 by bringing a gas containing barium and arsenic into contact with the Fe plate.

(Examples 4 and 5 and Examples 6 to 8)
The conductors of Examples 4 and 5 were formed. Table 2 shows whether or not the compound represented by the above composition formula (Chemical Formula 2) was formed in the conductors of Examples 4 and 5. In Table 2, the case where the compound represented by the above composition formula (Chemical Formula 2) is formed is indicated by ◯. The conductors of Examples 4 and 5 are also those in which iron, arsenic, and Ba contained in the starting material are reacted at the same time, similarly to the conductors of Examples 1 to 3.

First, the conductor of Example 4 was formed under the same conditions as in Example 3 except that _{Ba 0.6} K _0.4 As ₂ was used as the solid raw material. _{As a result, Ba 0.6} K _0.4 Fe ₂ As ₂ (denoted as “(Ba, K) Fe ₂ As ₂ ” in Table 2) is formed as the compound represented by the above composition formula (Chemical formula 2). I was able to.

In Example 4, as the solid raw material 15, a solid raw material made of Ba _0.6 K _0.4 As ₂ was prepared. Specifically, the elemental metals were weighed so that the molar ratio was Ba: K: As = 0.6: 0.4: 2 under an argon (Ar) atmosphere, and mixed using a ball mill. Then, the mixed simple substance metal was molded into pellets to obtain a solid raw material 15.

The composition ratio of Ba and K in the solid raw material is 6: 4, but since it becomes steam and reacts with the iron plate, the composition ratio of solid-dissolved Ba and K is strictly 6: 4. May be different. Therefore, in Table 2, it is described as "(Ba, K) Fe ₂ As ₂ ".

Further, although detailed description will be omitted, in the above composition formula (Chemical Formula 2), AE is at least one element selected from the group consisting of Ba and Sr, and A is selected from the group consisting of K and Na. Similarly, when the above composition formula (Chemical formula 2) is used in the case where x is at least one kind of element, x satisfies 0 <x <1, and the first element E1 further contains A. The compound represented could be formed.

On the other hand, the conductor of Example 5 was formed under the same conditions as in Example 3 except that _{Fe 0.92} Co _{0.08 was used as the starting material. As a result, Ba (Fe 0.92} Co _0.08 ) ₂ As ₂ could be formed as the compound represented by the above composition formula (Chemical formula 2).

In Example 5, as the starting material 13c, a base material having a disk-like shape and containing metallic iron as a main component, that is, Fe and Co mixed pellets was prepared. Specifically, as Fe and Co mixed pellets, a simple substance metal is weighed so that the molar ratio is Fe: Co = 0.92: 0.08 under an argon (Ar) atmosphere, and a tablet molding machine is used. , 7 mm in diameter and 0.5 mm in thickness, processed into a disk-like shape was used. In Example 5, the solid raw material remained _{BaAs 2.}

Although detailed description will be omitted, in the above composition formula (Chemical Formula 2), TM is at least one element selected from the group consisting of Cr, Mn, Co and Ni, and y is 0 <y <. Similarly, when 0.5 was satisfied and the starting material had various compositions including TM, the compound represented by the above composition formula (Chemical Formula 2) could be formed in the same manner.

[Evaluation by X-ray diffraction method]
The formed conductors of Examples 4 and 5 were evaluated by the XRD method. FIG. 15 is a graph showing the θ-2θ spectra of the surfaces of the conductors of Examples 4 and 5 by the XRD method. In FIG. 15, in addition to the measured θ-2θ spectrum, the same conditions as in Examples 4 and 5 (same conditions as in Example 3) and containing neither K nor Co (referred to as Example 6 for convenience). ), And what is known as the θ-2θ spectrum of Ba122 is displayed. In FIG. 15, the θ-2θ spectrum of Example 6 is referred to as “Non-doped”, and what is known as the θ-2θ spectrum of Ba122 is referred to as “BaFe ₂ As ₂ data”.

As shown in FIG. 15, in Example 4, similarly to Example 3 (Example 6), substantially single-phase Ba122, that is, (Ba, K) Fe ₂ As _2, was obtained. Further, as shown in FIG. 15, in Example 5, similarly to Example 3 (Example 6), a substantially single-phase Ba 122, that is, Ba (Fe _0.92 Co _0.08 ) ₂ As _2, was obtained. Was done.

[Evaluation by measuring electrical resistance]
The formed conductors of Examples 4 and 5 were evaluated by measuring electrical resistance. 16 and 17 are graphs showing the temperature dependence of the electrical resistance of the conductor of Example 4. FIG. 18 is a graph showing the temperature dependence of the electrical resistance of the conductor of Example 5. The horizontal axis of FIGS. 16 to 18 indicates the temperature, and the vertical axis of FIGS. 16 to 18 indicates a value obtained by normalizing the electric resistance with the electric resistance at 300K. FIG. 17 shows a temperature range of 35 to 40 K, which is a temperature range near the superconducting transition in the graph of FIG. 16 showing a temperature range of 0 to 300 K, and FIG. 18 shows a temperature range near the superconducting transition. The temperature range of ~ 30K is shown.

As shown in FIGS. 16 and 17, a clear superconducting transition was observed at about 38 K for the conductor of Example 4. Although not shown, the temperature dependence of magnetization when a magnetic field of 1 Oe is applied at 5 K to the conductor of Example 4 that has been subjected to zero-field cooling (ZFC) and the temperature is raised to 40 K. Was measured, and an onset of superconducting transition was observed at about 37K. Therefore, it was revealed that the conductor of Example 4, that is, (Ba, K) Fe ₂ As _{2, has superconductivity.}

Further, as shown in FIG. 18, a clear superconducting transition was observed at about 25 K for the conductor of Example 5. Therefore, it was revealed that the conductor of Example 5, that is, Ba (Fe _0.92 Co _0.08 ) ₂ As _{2, has superconductivity.}

Here, the composition of a plurality of Ba and K different from each other under the same conditions as in any of Examples 1 to 3 except that the composition ratio of Ba and K in the solid raw material is set to a composition other than 6: 4. The conductor of Example 7, which is a conductor having a ratio, was formed. Therefore, the conductors of Examples 6 and 7 are also those in which iron, arsenic, and Ba contained in the starting material are reacted at the same time, similarly to the conductors of Examples 1 to 3. Then, the lengths of the crystal axes of the conductors of Examples 4 and 7 were analyzed by the XRD method, and Ba and K in the conductors of Examples 4 and 7 were obtained from the analyzed crystal axis lengths. The composition ratio of was estimated. As a result, it was found that the composition ratio of Ba and K differed depending on the synthesis conditions, and the K-doping amount, which is the number of atoms of K with respect to the sum of the number of atoms of Ba and K, was 20 to 60%. That is, when A is K, it is clear that the suitable range of x in which the compound represented by the above composition formula (Chemical Formula 2) is easily synthesized is 0.2 ≦ x ≦ 0.6. became.

[Evaluation by scanning electron microscope]
The conductor of Example 8 formed under the same conditions as in Example 4 except that the temperature T1 is 800 ° C. was evaluated by a scanning electron microscope (SEM), and energy dispersive X-rays were evaluated. Element mapping by analysis (Energy Dispersive X-ray microscopy: EDX) and composition analysis of the superconductor part were performed. Therefore, the conductor of Example 8 is also the same as the conductors of Examples 1 to 3, in which iron, arsenic, and Ba contained in the starting material are reacted at the same time.

FIG. 19 is a photograph showing a backscattered electron (BSE) image of a cross section near the surface of the conductor of Example 8. The right side portion in FIG. 19 is the iron-based layer 11, and the left side portion in FIG. 19 is the layer 12 represented by the above composition formula (Chemical formula 2). In FIG. 19, for convenience, the layer 11 is referred to as "iron", the layer 12, that is, the superconductor portion is referred to as "reaction layer", and the boundary between "iron" and "reaction layer" is white. It is shown by a broken line.

Although the element mapping is omitted, Ba, As and K are distributed in the "reaction layer" part, and Ba 122 to which K is added, that is, (Ba, K) Fe ₂ As ₂ is generated. It was confirmed that there was.

Next, in FIG. 19, composition analysis was performed at three measurement points labeled "No. 1", "No. 2" and "No. 3". The results are shown in Table 3. The measurement points of "No. 1" and "No. 2" are arranged in the "reaction layer", that is, the superconductor portion, and the measurement points of "No. 3" are arranged in "iron". Further, the composition analysis results in Table 3 are displayed so that the total content of each element of Ba, K, Fe and As is 100.

As shown in Table 3, all of Ba, K, Fe and As were detected at the measurement points arranged in "No. 1" and "No. 2", that is, the "reaction layer", and approximately (Ba + K). : Fe: A = 1: 2: 2 relationship holds. Therefore, it was confirmed that the portion of the "reaction layer" was Ba122. In addition, neither Ba nor K was detected at all and only a small amount of As was detected at the measurement point arranged on the "iron" side beyond the white broken line from "No. 3", that is, the "reaction layer". , Fe is mainly detected. Therefore, it was confirmed that the "iron" part was iron.

From the above results, it was clarified that Ba122 to which K was added can be formed by contacting the Fe plate with a gas containing Ba, K and As.

Although detailed description will be omitted, in the above composition formula (Chemical formula 2), z may satisfy 0 <z <0.8, and the second element E2 may further contain phosphorus in various compositions. Similarly, the compound represented by the above composition formula (Chemical Formula 2) could be formed.

FIG. 20 is a photograph showing a reflected electron (BSE) image of a cross section near the surface of another example of the conductor of Example 8. The bottom layer (part marked with 1) in FIG. 20 is a layer containing iron in which arsenic is solid-solved, and the intermediate layer (part _{marked with 2} ) in FIG. 20 is a layer containing Fe 2 As and Ba 122. Yes, the uppermost layer (the portion marked with 3) in FIG. 20 is the layer 12 containing Ba122. Although detailed description is omitted, the composition of each layer was confirmed by EDX as in the case described with reference to FIG.

In FIG. 20, for convenience, the bottom layer is described as "(Fe, As)", the intermediate layer is described as "Fe ₂ As &Ba122", the top layer is described as "Ba122", and the bottom layer and the intermediate layer are used. The boundary between the layers and the boundary between the intermediate layer and the uppermost layer are shown by a solid white line. Further, the uppermost layer side of FIG. 20 is the surface side of the starting material 13c, the lowermost layer side of FIG. 20 is the central side of the starting material 13c, and As and Ba are from the uppermost layer side of FIG. 20 to the outermost layer of FIG. 20. It means that it diffused toward the lower layer side. In such a case, regarding the process of forming Ba122 when the starting material 13c is brought into contact with the gas G1 containing Ba and As (see FIG. 9), the lowermost layer of FIG. 20 is the first stage of the process of forming Ba122. It is considered that the middle layer of FIG. 20 shows the second stage of the formation process of Ba122, and the uppermost layer of FIG. 20 shows the third stage of the formation process of Ba122.

That is, in the process of forming Ba122 when the starting material 13c is brought into contact with the gas G1 (see FIG. 9) containing Ba and As, the bottom layer (the portion marked with 1) of FIG. 20 is "(Fe, As). In the first stage, iron contained in the starting material 13c and arsenic contained in the gas G1 react to form iron in which arsenic is solid-dissolved, that is, (Fe, As). It is thought that it was. Further, in the second stage, as described as "Fe ₂ As & Ba 122" in the intermediate layer (the portion marked with 2) in FIG. 20, arsenic-dissolved iron, that is, (Fe, As) and gas G1 It is considered that _{Fe 2} As was mainly formed by the reaction with the contained arsenic. Further, in the third stage, as described as "Ba122" in the uppermost layer (the portion marked with 3) in FIG. 20, Fe ₂ As, Ba, and As react with each other to cause BaFe ₂ As ₂ (Ba122). Is considered to have been formed.

(Examples 9 and 10)
The conductors of Examples 9 and 10 were formed. In the conductors of Examples 9 and 10, the compound represented by the above composition formula (Chemical Formula 4) could be formed. The conductors of Examples 9 and 10 were produced by the method for producing a conductor of a modified example of the embodiment, and by reacting iron contained in a starting material with arsenic, iron and iron were produced. After forming a compound containing arsenic, a compound containing iron and arsenic is reacted with Ba. The details will be described below.

[Formation of conductor]
First, a starting material 13c (see FIG. 12), a solid raw material 15a (see FIG. 12), and a solid raw material 15b (see FIG. 13) were prepared.

As the starting material 13c, a base material having a linear shape and containing metallic iron as a main component, that is, a pure Fe wire was prepared. Specifically, as a pure Fe wire, a wire having a diameter of 1.45 mm and a length of 20 mm was used.

Further, as the solid raw material 15a, a solid raw material made of BaAs ₂ was prepared. Specifically, the elemental metals were weighed so that the molar ratio was Ba: As = 1: 2 under an argon (Ar) atmosphere, and mixed using a ball mill. Then, the mixed simple substance metal was molded into pellets to obtain a solid raw material 15a. Further, as the solid raw material 15b, a solid raw material made of elemental metal barium (Ba) was prepared.

Next, the starting material 13c and the solid raw material 15a were placed in an airtight container 16 (see FIG. 8), and the inside of the container 16 was evacuated.

Specifically, the _{solid raw material 15a made of BaAs 2} and the starting material 13c made of pure Fe wire are arranged in a pipe made of stainless steel (stainless steel pipe), and the solid raw material 15a and the starting material 13c are placed inside. The arranged stainless steel tube was sealed in a quartz tube in a vacuum state.

Next, the starting material 13c and the solid raw material 15a were heat-treated to bring the starting material 13c into contact with the gas G4 containing As (see FIG. 12). Specifically, the solid raw material 15a containing Ba and As is heated at the temperature T3 as the heat treatment temperature, the starting material 13c is heated at the temperature T4 as the heat treatment temperature, and the solid raw material 15a is heated at the temperature T3. Gas G4 was generated by the above method, and the generated gas G4 was brought into contact with the starting material 13c heated at the temperature T4. Then, by reacting the iron contained in the starting material 13c with the As contained in the gas G4, iron and iron are formed on the layer 11 (see FIG. 12) which is at least the surface layer of the base material 13 as the starting material 13c. A layer 14a (see FIG. 12) containing a compound containing arsenic was formed.

Next, the starting material 13c and the solid raw material 15b were heat-treated to bring the starting material 13c into contact with the gas G5 containing Ba (see FIG. 13). Specifically, the starting material 13c and the solid raw material 15b were placed in an airtight container 16, and the inside of the container 16 was evacuated. Next, the solid raw material 15b containing Ba is heated at the temperature T5 as the heat treatment temperature, the starting material 13c is heated at the temperature T6 as the heat treatment temperature, and the solid raw material 15b is heated at the temperature T5 to obtain the gas G5. The generated gas G5 was brought into contact with the starting material 13c heated at the temperature T6. Then, by reacting the compound contained in the layer 14a with the Ba contained in the gas G5, the layer 12 (see FIG. 13) is placed on the layer 11 (see FIG. 13) which is at least the surface layer of the base material 13 as the starting material 13c. (See FIG. 13) was formed.

Here, the cases where the temperature T4 is equal to the temperature T3, the temperature T6 is equal to the temperature T5, the temperature T5 is 800 ° C., and the temperature T3 is 750 ° C. and 900 ° C., respectively, are referred to as Example 9 and Example 10. bottom.

A photograph of the starting material made of pure Fe wire before forming the conductor of Example 9 is shown in FIG. A photograph of the starting material after contacting the starting material shown in FIG. 21 with a gas containing As is shown in FIG. FIG. 23 shows a photograph of the starting material after the starting material shown in FIG. 22 was brought into contact with a gas containing Ba to form the conductor of Example 9. The minimum scale of the graph paper photographed together with the starting material in FIGS. 21 to 23 is 1 mm.

As shown in FIG. 21, the pure Fe wire before forming the conductor of Example 9 had a metallic luster. Next, by bringing a gas containing As into contact with the pure Fe wire, Fe ₂ As or Fe in which As was dissolved was formed on the surface of the pure Fe wire. It had a metallic luster. Next, by bringing a gas containing Ba into contact with the pure Fe wire, Ba122 was formed on the surface of the pure Fe wire, but as shown in FIG. 23, a black layer was formed. Further, although detailed description will be omitted, it was confirmed by EDX that the layer of FIG. 23 contains Ba122, as in the case described with reference to FIGS. 24 and 25 described later.

On the other hand, the conductor of Example 10 was evaluated by SEM, element mapping by EDX, and composition analysis of the superconductor portion were performed. FIG. 24 is a photograph showing a reflected electron (BSE) image of a cross section near the surface of the conductor of Example 10. The left side of FIG. 24 is the surface side of the starting material, and the right side of FIG. 24 is the center side of the starting material. FIG. 25 is a diagram schematically showing a cross section of the conductor of Example 10 near the surface by tracing the photograph of FIG. 24. The area RG1 in FIG. 25 corresponds to the area displayed in the photograph of FIG. 24. Further, in FIG. 25, hatching of the layer main body 14d is omitted for easy understanding.

As shown in FIGS. 24 and 25, the conductor of Example 10 had a four-layer structure including a layer 11, a layer 14b, a layer 14c, and a layer 12. The layer 14b was arranged between the layers 11 and 12, and the layer 14c was arranged between the layers 14b and 12. Further, the layer 14b contained a layer body 14d as a matrix phase and a plurality of particles 14e dispersedly arranged in the layer body 14d. In addition, it is considered that the layer 14a described with reference to FIG. 12 described above remains in the layer 14b. Further, the inclusions 14 described with reference to FIGS. 10 and 13 described above include the layer 14b and the layer 14c.

When the composition was analyzed by EDX, all of Ba, Fe and As were detected in the layer 12, and the abundance ratio (atomic number ratio) of these elements was a percentage, Ba: Fe: As = 13.3. %: 52.0%: 34.7%, which is close to the relationship of Ba: Fe: A = 1: 2: 2, and it is considered that _{the layer 12 contains Ba122, that is, BaFe 2} As _2. Further, Fe and As were detected in the layer 14c, and the abundance ratio (atomic number ratio) of these elements was Fe: As = 92.5%: 7.5% in percentage, and Fe: As = 2 Since it is far from the 1: 1 relationship, it is considered that the layer 14c contains Fe in which As is dissolved.

Further, Fe and As were detected in the layer body 14d contained in the layer 14b, and the abundance ratio (atomic number ratio) of these elements was Fe: As = 67.8%: 32.2% in percentage. Since the relationship is close to Fe: As = 2: 1, it is considered that _{the layer body 14d contains Fe 2 As.} Further, Fe and As were detected in the particles 14e contained in the layer 14b, and the abundance ratio (atomic number ratio) of these elements was Fe: As = 92.1%: 7.9% in percentage. Since it is far from the relationship of Fe: As = 2: 1, it is considered that the particles 14e contain Fe in which As is dissolved.

Although not shown, it is after the starting material 13c is brought into contact with the gas G4 containing As (see FIG. 12) and before the starting material 13c is brought into contact with the gas containing Ba (see FIG. 13). The conductor of Example 10 has a three-layer structure including a layer 11, a layer 14c, and a layer 14b including a layer body 14d and a plurality of particles 14e dispersed in the layer body 14d. Was there. The layer 14c was arranged between the layer 11 and the layer 14b. That is, the layer 14a shown in FIG. 12 included the layer 14c and the layer 14b.

Therefore, when the starting material 13c is brought into contact with the gas G4 containing As (see FIG. 12) at a temperature of 900 ° C., the Fe contained in the layer 11 reacts with the As contained in the gas G4 to cause As. The solid-melted Fe is formed and melted, and the melted As is phase-separated when the temperature is lowered from 900 ° C., so that the _{layer body 14d containing Fe 2} As and As are solid-dissolved. It is considered that the particles 14e containing Fe and the layer 14b containing the same Fe were formed. Next, when the starting material 13c is brought into contact with the gas G5 containing Ba (see FIG. 13) at a temperature of 800 ° C., Fe ₂ As contained in the layer body 14d of the layer 14b and Ba contained in the gas G5. It is considered that Ba122, that is, BaFe ₂ As _2, was formed by the reaction of and, and a part of Fe ₂ As was reduced to Fe in which As was dissolved.

Although detailed description is omitted, the starting material 13c is also started when the temperature at the time of contacting the starting material 13c with the gas G4 containing As (see FIG. 12) is within the range of 840 to 900 ° C. and other than 900 ° C. Similar results were obtained when the temperature at which the material 13c was brought into contact with the gas G4 containing As was 900 ° C. Next, when the temperature at which the starting material 13c is brought into contact with the gas G5 containing Ba (see FIG. 13) is within the range of 700 to 840 ° C and other than 800 ° C, the starting material 13c is also provided with Ba. The same result as when the temperature at the time of contacting with the gas G5 containing the above was 800 ° C. was obtained.

From the above results, in the conductors of Examples 9 and 10, iron and arsenic are contained after forming a compound containing iron and arsenic by reacting iron contained in the starting material 13c with arsenic. It has been clarified that even when the compound and Ba are reacted, Ba122 can be formed in the same manner as when iron, arsenic and Ba contained in the starting material are reacted at the same time.

Further, in Examples 9 and 10, the conditions such as the temperature at which the starting material 13c is brought into contact with the gas G4 containing As (see FIG. 12) and the starting material 13c are referred to the gas G5 containing Ba (see FIG. 13). ) Can be individually controlled, and the number of parameters to be controlled at the same time during the conductor manufacturing process can be reduced, so that the conductor 10 having the layer 12 can be reproduced. It can be manufactured with good properties.

Although detailed description will be omitted, in the above composition formula (Chemical Formula 2), AE is at least one element selected from the group consisting of Ba and Sr, and x satisfies 0 <x <1. Similarly, when A is at least one element selected from the group consisting of K and Na and the sixth element E6 has various compositions further containing A, the compound contained in the layer 12 is similarly selected. The compound represented by the above composition formula (Chemical formula 2) could be formed. Further, in the above composition formula (Chemical Formula 2), y satisfies 0 <y <0.5, the starting material further contains TM, and TM is selected from the group consisting of Cr, Mn, Co and Ni. Similarly, in the case of various compositions, which are at least one kind of element, the compound represented by the above composition formula (Chemical Formula 2) could be formed. Further, in the above composition formula (Chemical formula 2), when z satisfies 0 <z <0.8 and the fifth element E5 further contains phosphorus, the layer 12 is similarly contained. As the compound to be used, the compound represented by the above composition formula (Chemical Formula 2) could be formed.

Although the invention made by the present inventor has been specifically described above based on the embodiment thereof, the present invention is not limited to the embodiment and can be variously modified without departing from the gist thereof. Needless to say.

Within the scope of the idea of the present invention, those skilled in the art can come up with various modified examples and modified examples, and it is understood that these modified examples and modified examples also belong to the scope of the present invention.

For example, a person skilled in the art appropriately adds, deletes, or changes the design of each of the above-described embodiments, or adds, omits, or changes the conditions of the process of the present invention. As long as it has a gist, it is included in the scope of the present invention.

The present invention is effective when applied to a method for manufacturing a conductor, a conductor, a superconducting power transmission line, a superconducting magnet device, and a superconducting magnetic shield device.

10 Conductor 10a Superconducting transmission line 10b Superconducting magnet device 10c Superconducting magnetic shield device 11, 12 Layer 13 Base material 13a, 13b Surface 13c Starting material 13d Side peripheral surface 14 inclusions 14a, 14b, 14c Layer 14d Layer body 14e Particles 15, 15a, 15b Solid raw material 16 Container G1, G2, G3, G4, G5 Gas L1, L2 Liquid

Claims (19)

In a method for producing a conductor, which forms a first layer containing a first compound represented by the following composition formula (Chemical formula 1) on at least the surface of a starting material containing iron.
(AE _1-x A _x ) (Fe _1-y TM _y ) ₂ (As _1-z P _z ) ₂ ... (Chemical formula 1)
(A) The starting material is brought into contact with a first gas containing the first element and the second element, and iron contained in the starting material and the first element and the second element contained in the first gas are combined with each other. To form the first layer on at least the surface of the starting material,
Have,
The AE is at least one element selected from the group consisting of Ba and Sr.
A is at least one element selected from the group consisting of K and Na.
The TM is at least one element selected from the group consisting of Cr, Mn, Co and Ni.
The x satisfies 0 ≦ x <1 and
The y satisfies 0 ≦ y <0.5, and
The z satisfies 0 ≦ z <0.8, and
The first element contains the AE and
The second element contains arsenic and
When the x satisfies 0 <x <1, the first element further comprises the A.
When the y satisfies 0 <y <0.5, the starting material further contains the TM, and in the step (a), the TM and iron contained in the starting material and the first gas. By reacting the first element and the second element contained in the above, the first layer is formed on at least the surface of the starting material.
A method for producing a conductor, wherein when z satisfies 0 <z <0.8, the second element further contains phosphorus. In the method for producing a conductor according to claim 1,
In the step (a), the solid raw material containing the first element and the second element and the starting material are heated, and the solid raw material is heated to generate the first gas, and the generated first gas is generated. A method for producing a conductor, in which the starting material in a heated state is brought into contact with a gas. In the method for producing a conductor according to claim 2,
In the step (a), the solid raw material is heated to a first temperature, the starting material is heated to a second temperature, and the solid raw material is heated to the first temperature to generate the first gas. A method for producing a conductor, in which the starting material heated to the second temperature is brought into contact with the generated first gas. In the method for producing a conductor according to claim 2,
In the step (a), the solid raw material is heated to a third temperature of 700 ° C. or higher, the starting material is heated to a fourth temperature of 700 ° C. or higher, and the solid raw material is heated to the third temperature. A method for producing a conductor, in which the first gas is generated and the generated first gas is brought into contact with the starting material in a state of being heated to the fourth temperature. In the method for producing a conductor according to claim 2,
(B) A step of arranging the starting material and the solid raw material in an airtight container before the step (a).
(C) After the step (b) and before the step (a), the step of evacuating the inside of the container or replacing the atmosphere in the container with an inert gas.
A method for producing a conductor. In the method for producing a conductor according to any one of claims 2 to 5,
(D) After the step (a), by bringing the first layer into contact with a second gas or a first liquid containing a third element, a part of the AE contained in the first layer is made into the third layer. The process of substituting with elements,
Have,
A method for producing a conductor, wherein the third element contains at least one element selected from the group consisting of K and Na. In the method for producing a conductor according to any one of claims 2 to 6.
(E) After the step (a), by bringing the first layer into contact with a third gas or a second liquid containing the fourth element, a part of arsenic contained in the first layer is made into the fourth element. Replacing with,
Have,
A method for producing a conductor, wherein the fourth element contains phosphorus. In a method for producing a conductor, which forms a first layer containing a first compound represented by the following composition formula (Chemical formula 1) on at least the surface of a starting material containing iron.
(AE _1-x A _x ) (Fe _1-y TM _y ) ₂ (As _1-z P _z ) ₂ ... (Chemical formula 1)
(A) The starting material is brought into contact with a first gas containing the first element, and iron contained in the starting material is reacted with the first element contained in the first gas to cause the starting material. A step of forming a second layer containing a second compound containing iron and arsenic, at least on the surface of the
(B) After the step (a), the starting material is brought into contact with a second gas containing a second element, and the second compound contained in the second layer and the second gas contained in the second gas. A step of forming the first layer on at least the surface of the starting material by reacting the two elements.
Have,
The AE is at least one element selected from the group consisting of Ba and Sr.
A is at least one element selected from the group consisting of K and Na.
The TM is at least one element selected from the group consisting of Cr, Mn, Co and Ni.
The x satisfies 0 ≦ x <1 and
The y satisfies 0 ≦ y <0.5, and
The z satisfies 0 ≦ z <0.8, and
The first element contains arsenic and
The second element contains the AE and
When the x satisfies 0 <x <1, the second element further contains the A.
When the y satisfies 0 <y <0.5, the starting material further contains the TM, and in the step (a), the TM and iron contained in the starting material and the first gas. By reacting with the first element contained in the above, the second layer containing the second compound containing TM and iron and arsenic is formed on at least the surface of the starting material.
A method for producing a conductor, wherein when z satisfies 0 <z <0.8, the first element further contains phosphorus. In the method for producing a conductor according to claim 8,
In the step (a), the first solid raw material containing the first element and the starting material are heated, and the first solid raw material is heated to generate the first gas, and the generated first gas is generated. In contact with the heated starting material,
In the step (b), the second solid raw material containing the second element and the starting material are heated, and the second solid raw material is heated to generate the second gas, and the generated second gas is generated. A method for producing a conductor, in which the starting material in a heated state is brought into contact with the starting material. In the method for producing a conductor according to claim 9,
(C) After the step (b), by bringing the first layer into contact with a third gas or a first liquid containing a third element, a part of the AE contained in the first layer is made into the third layer. The process of substituting with elements,
Have,
A method for producing a conductor, wherein the third element contains at least one element selected from the group consisting of K and Na. In the method for producing a conductor according to claim 9 or 10.
(D) After the step (b), by bringing the first layer into contact with a fourth gas or a second liquid containing the fourth element, a part of arsenic contained in the first layer is made into the fourth element. Replacing with,
Have,
A method for producing a conductor, wherein the fourth element contains phosphorus. The first layer containing metallic iron as the main component and
The second layer laminated with the first layer and
Have,
The second layer contains the first compound represented by the following composition formula (Chemical formula 1).
(AE _1-x A _x ) (Fe _1-y TM _y ) ₂ (As _1-z P _z ) ₂ ... (Chemical formula 1)
The AE is at least one element selected from the group consisting of Ba and Sr.
A is at least one element selected from the group consisting of K and Na.
The TM is at least one element selected from the group consisting of Cr, Mn, Co and Ni.
The x satisfies 0 ≦ x <1 and
The y satisfies 0 ≦ y <0.5, and
The z is a conductor satisfying 0 ≦ z <0.8. In the conductor according to claim 12,
It has inclusions intervening between the first layer and the second layer.
The inclusion is a conductor containing a second compound represented by the _{composition formula Fe 2 As or iron in which arsenic is dissolved.} In the conductor according to claim 12 or 13,
The second layer is a conductor having superconductivity. In the conductor according to claim 14,
It has a linear or plate shape consisting of a first surface and a second surface opposite to the first surface, and has a base material containing metallic iron as a main component.
The first layer is a conductor which is a surface layer of the first surface or the second surface of the base material. In the conductor according to claim 14,
It has a plate-like shape consisting of a third surface and a fourth surface opposite to the third surface, and has a plurality of base materials each containing metallic iron as a main component.
The first layer is a surface layer of the third surface or the fourth surface of each of the plurality of base materials.
The plurality of base materials are conductors in which the plurality of base materials are laminated in the thickness direction of each of the plurality of base materials. In the superconducting power transmission line provided with the conductor according to claim 15.
The base material is a superconducting power transmission line having a linear shape. A superconducting magnet device comprising the conductor according to claim 15 or 16. A superconducting magnetic shield device comprising the conductor according to claim 15 or 16.

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