JP5739972B2 - Superconducting wire precursor and superconducting wire - Google Patents

Description

  The present invention relates to a precursor of a superconducting wire and a superconducting wire.

  Conventionally, a superconducting wire comprising a substrate, an intermediate layer formed on the substrate, and a superconducting layer formed on the intermediate layer has been used. As such a superconducting wire substrate, for example, Japanese Patent Application Laid-Open No. 2006-127847 (Patent Document 1) and Japanese Patent Publication No. 11-504612 (Patent Document 2) are used.

  Patent Document 1 includes a non-oriented, non-magnetic first metal layer, and a second metal layer having a texture in which the surface layer is oriented, the first metal layer being more than the second metal layer. A film-forming alignment substrate having high strength is disclosed. Patent Document 2 discloses a metal substrate having an alloyed biaxially oriented structure.

JP 2006-127847 A Japanese National Patent Publication No. 11-504612

  However, in order to manufacture a superconducting wire using the substrates of Patent Documents 1 and 2, it is necessary to form an intermediate layer and a superconducting layer after forming the substrate. When the first metal layer of Patent Document 1 and the metal substrate of Patent Document 2 are Ni (nickel) alloys, when an intermediate layer is formed on them, the first metal layer and the surface layer of the metal substrate are It will be oxidized. When the surface layer is oxidized, there is a problem that an intermediate layer cannot be formed on the surface layer.

  Moreover, when the 1st metal layer of the said patent document 1 is Ni, the oxidation of a 1st metal layer is suppressed. For this reason, since an intermediate | middle layer can be formed on Ni layer, a superconducting wire can be formed. However, since Ni is a ferromagnetic metal, the magnetic field at the end in the width direction of the superconducting wire is concentrated due to the hysteresis loss of Ni. For this reason, there has been a problem that the hysteresis loss of the superconducting wire is increased.

  Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to provide a superconducting wire precursor and a superconducting wire that can reduce hysteresis loss.

  The manufacturing method of the precursor of the superconducting wire of the present invention includes the following steps. A laminated metal having a first metal layer and a Ni layer formed on the first metal layer is prepared. An intermediate layer is formed on the Ni layer of the laminated metal. After the step of forming the intermediate layer, the laminated metal is heat-treated to form a nonmagnetic Ni alloy layer from the laminated metal.

  The precursor of the superconducting wire of the present invention includes a nonmagnetic Ni alloy layer and an intermediate layer formed on the nonmagnetic Ni alloy layer. In the nonmagnetic Ni alloy layer, the concentration of Ni monotonously decreases from the interface with the intermediate layer toward the surface opposite to the interface.

  According to the superconducting wire precursor manufacturing method and the superconducting wire precursor of the present invention, the intermediate layer is formed on the Ni layer. Ni is not easily oxidized and has good lattice matching with the intermediate layer. For this reason, an intermediate layer can be easily formed on the Ni layer. By heat-treating the laminated metal in this state, Ni constituting the Ni layer and the first metal constituting the first metal layer are alloyed, so that a Ni alloy can be formed. The magnetism of Ni alloy can be made smaller than that of Ni alone. That is, a nonmagnetic Ni alloy layer can be formed from a laminated metal. For this reason, when a superconducting wire is manufactured by forming a superconducting layer on the intermediate layer of the precursor, the concentration of the magnetic field on the end portion in the width direction of the superconducting wire can be reduced by the nonmagnetic Ni alloy layer. Therefore, a precursor capable of reducing hysteresis loss can be realized.

  In addition, the precursor manufactured with the said manufacturing method of the precursor forms the nonmagnetic Ni alloy layer from a laminated metal by heat-processing a laminated metal after the process of forming an intermediate | middle layer. For this reason, when Ni diffuses in the laminated metal, in the nonmagnetic Ni alloy layer, the concentration of Ni is monotonously decreased from the interface with the intermediate layer toward the surface opposite to the interface. Yes.

  Preferably, in the method for producing a precursor, in the step of preparing the laminated metal, a laminated metal in which a second metal layer having a higher strength than the first metal layer is formed below the first metal layer is prepared. .

  Preferably, the precursor further includes a second metal layer formed under the nonmagnetic Ni alloy layer and having higher strength than the nonmagnetic Ni alloy layer.

  Since the second metal layer has higher strength than the first metal layer, the strength of the precursor can be improved as compared with the case of the first metal layer alone.

  In the precursor production method, preferably, in the step of preparing the laminated metal, the Ni layer has a thickness of 1 μm or more and 10 μm or less.

  When the thickness is 1 μm or more, Ni can be prevented from diffusing during the step of forming the intermediate layer, so that the Ni layer is hardly oxidized and the function of matching the lattice with the intermediate layer is effectively exhibited. When the thickness is 10 μm or less, Ni constituting the Ni layer is easily diffused into the first metal layer during the step of forming the nonmagnetic Ni diffusion layer, so that it can be effectively suppressed from remaining as Ni alone.

  The manufacturing method of the superconducting wire of the present invention includes the following steps. A laminated metal having a first metal layer and a Ni layer formed on the first metal layer is prepared. An intermediate layer is formed on the Ni layer of the laminated metal. A superconducting layer is formed on the intermediate layer. After at least one of the step of forming the intermediate layer and the step of forming the superconducting layer, the laminated metal is heat-treated to form a nonmagnetic Ni alloy layer from the laminated metal.

  The superconducting wire of the present invention includes the precursor and a superconducting layer formed on the intermediate layer.

  According to the superconducting wire manufacturing method and superconducting wire of the present invention, the intermediate layer is formed on the Ni layer. Ni is not easily oxidized and has good lattice matching with the intermediate layer. For this reason, an intermediate layer can be easily formed on the Ni layer. After at least one of this state and the state in which the superconducting layer is further formed, Ni constituting the Ni layer and the first metal constituting the first metal layer are obtained by heat-treating the laminated metal. Since it is alloyed, a Ni alloy can be formed. The magnetism of Ni alloy can be made smaller than that of Ni alone. That is, a nonmagnetic Ni alloy layer can be formed from a laminated metal. For this reason, the concentration of the magnetic field on the end portion in the width direction of the superconducting wire can be reduced by the nonmagnetic Ni alloy layer. Therefore, a superconducting wire that can reduce hysteresis loss can be realized.

  Preferably, in the method for manufacturing a superconducting wire, in the step of preparing a laminated metal, a laminated metal in which a second metal layer having a higher strength than the first metal layer is formed below the first metal layer is prepared. .

  Since the second metal layer has higher strength than the first metal layer, the strength of the superconducting wire can be improved as compared with the case of the first metal layer alone.

  Preferably, in the method for producing a superconducting wire, the Ni layer has a thickness of 1 μm or more and 10 μm or less in the step of preparing the laminated metal.

  When the thickness is 1 μm or more, Ni can be prevented from diffusing during the step of forming the intermediate layer, so that the Ni layer is hardly oxidized and the function of matching the lattice with the intermediate layer is effectively exhibited. When the thickness is 10 μm or less, Ni constituting the Ni layer easily diffuses into the first metal layer during the step of forming the nonmagnetic Ni alloy layer, so that it can be effectively suppressed from remaining as Ni alone.

  As described above, according to the superconducting wire precursor and superconducting wire of the present invention, hysteresis loss can be reduced.

It is sectional drawing which shows roughly the precursor in Embodiment 1 of this invention. It is a flowchart which shows the manufacturing method of the precursor in Embodiment 1 of this invention. It is sectional drawing which shows schematically the laminated substrate in Embodiment 1 of this invention. It is sectional drawing which shows roughly the state which formed the intermediate | middle layer on the laminated metal in Embodiment 1 of this invention. It is sectional drawing which shows schematically the superconducting wire in Embodiment 2 of this invention. It is a flowchart which shows the manufacturing method of the superconducting wire in Embodiment 2 of this invention. It is a flowchart which shows the manufacturing method of the superconducting wire in Embodiment 3 of this invention. It is sectional drawing which shows roughly the state in which the superconducting layer in Embodiment 3 of this invention was formed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is a cross-sectional view schematically showing a precursor in an embodiment of the present invention. The precursor of this Embodiment is demonstrated with reference to FIG. As shown in FIG. 1, the precursor includes a substrate 10 including a second metal layer 11 and a nonmagnetic Ni alloy layer 12 formed on the second metal layer 11, and a nonmagnetic Ni alloy layer 12. An intermediate layer 20 formed thereon is provided.

  The substrate 10 has a long tape shape. The substrate 10 includes a second metal layer 11 and a nonmagnetic Ni alloy layer 12.

  The nonmagnetic Ni alloy layer 12 is a nonmagnetic metal. Although the Ni alloy which comprises the nonmagnetic Ni alloy layer 12 is not specifically limited, It is preferable that they are a Cu (copper) -Ni alloy and an Ag (silver) -Ni alloy. The nonmagnetic Ni alloy layer is preferably oriented.

The nonmagnetic Ni alloy layer 12 is lower than the magnetism of Ni alone. That is, the case where the magnetism is 0 J / m ^{3 and} the case where the magnetism exceeds 0 J / m ³ and has a magnetism lower than that of Ni alone are included.

  Within the nonmagnetic Ni alloy layer 12, there is a Ni concentration distribution. Specifically, in the nonmagnetic Ni alloy layer 12, the Ni concentration decreases monotonously from the interface with the intermediate layer 20 toward the surface opposite to the interface. The monotonic decrease means that the Ni concentration is constantly decreasing from the interface with the intermediate layer 20 toward the surface opposite to the interface, and the interface opposite to the interface is closer to the interface than the intermediate layer 20. It means that the Ni concentration is lower on the surface.

  The second metal layer 11 is formed under the nonmagnetic Ni alloy layer 12 and has higher mechanical strength than the nonmagnetic Ni alloy layer 12. The strength of the second metal layer 11 is preferably such that it does not stretch even when it is tensioned at a high temperature when the superconducting layer is formed. As such second metal layer 11, stainless steel is preferably used. Note that the second metal layer 11 may be omitted.

The intermediate layer 20 is a layer for forming a superconducting layer on this surface. The intermediate layer 20 includes one layer or two or more layers. When the intermediate layer 20 is composed of a plurality of layers, each layer constituting the intermediate layer 20 may be composed of different materials. The intermediate layer 20 may be, for example, an oxide having at least one crystal structure of a rock salt type, a fluorite type, a perovskite type, and a pyrochlore type. Examples of the material having such a crystal structure include rare earth element oxidation such as cerium oxide (CeO ₂ ), holmium oxide (Ho ₂ O ₃ ), yttrium oxide (Y ₂ O ₃ ), and ytterbium oxide (Yb ₂ O ₃ ). , Yttria-stabilized zirconia (YSZ), magnesium oxide (MgO), and strontium titanate (SrTiO ₃ ), BZO (BaZrO ₃ ), aluminum oxide (Al ₂ O ₃ ), and other Ln-MO compounds (Ln 1 or more lanthanoid elements, M is one or more elements selected from Sr, Zr, and Ga, and O is oxygen).

The intermediate layer 20 preferably has a good crystal orientation. The intermediate layer 20 is preferably a material that can prevent reaction and diffusion with the elements constituting the superconducting layer. Such materials include, for example, CeO _2. In addition, the material which comprises the intermediate | middle layer 20 is not specifically limited to said material.

  FIG. 2 is a flowchart showing a precursor manufacturing method in the present embodiment. Then, with reference to FIG. 2, the manufacturing method of the precursor in this Embodiment is demonstrated.

  FIG. 3 is a cross-sectional view schematically showing the multilayer substrate in the present embodiment. As shown in FIGS. 2 and 3, first, a laminated metal having a first metal layer 13 and a Ni layer 14 formed on the first metal layer 13 is prepared (step S10). In the present embodiment, a laminated metal is prepared in which a second metal layer 11 having a higher strength than the first metal layer 13 is further formed under the first metal layer 13.

  Specifically, first, the second metal layer 11 is prepared (step S11). The second metal layer 11 is a layer for imparting strength. For example, the above-described materials can be used as the second layer 11. The thickness of the second metal layer 11 is, for example, 100 μm.

  Next, the first metal layer 13 is formed on the second metal layer 11 (step S12). The first metal layer 13 is preferably a metal having good orientation such as Cu or Ag. The first metal layer 13 is preferably oriented. The thickness of the first metal layer 13 is, for example, 18 μm.

  The method for forming the first metal layer 13 is not particularly limited, and for example, a method of attaching the first metal layer 13 and the second metal layer 11 can be employed.

  Thereafter, the Ni layer 14 is formed on the first metal layer 13 (step S13). The Ni layer 14 is a layer for preventing oxidation when the intermediate layer is formed. When the first metal layer 13 is oriented, the Ni layer 14 formed thereon is also oriented. The thickness of the Ni layer 14 is, for example, 1 μm. The method for forming the Ni layer 14 is not particularly limited, and for example, a plating method can be adopted.

  The thickness of the Ni layer 14 is preferably 1 μm or more and 10 μm or less. In the case of 1 μm or more, even if heat of about 600 ° C. is applied during step S20 for forming the intermediate layer 20 described later, it is possible to suppress the diffusion of Ni. For this reason, it is possible to effectively exhibit the function that the Ni layer 14 is hardly oxidized and the lattice matching with the intermediate layer is good. In the case of 10 μm or less, Ni constituting the Ni layer 14 easily diffuses into the first metal layer 13 during step S30 for forming the nonmagnetic Ni alloy layer 12 to be described later. Can be suppressed.

  Through the above steps S11 to S13, the laminated metal shown in FIG. 3 can be prepared (step S10).

  FIG. 4 is a cross-sectional view schematically showing a state in which an intermediate layer is formed on the laminated metal in the present embodiment. As shown in FIGS. 2 and 4, next, an intermediate layer 20 is formed on the Ni layer 14 of the laminated metal (step S20). Since the Ni layer 14 is not easily oxidized, the intermediate layer 20 can be easily formed.

  When the first metal layer 13 is oriented, the Ni layer 14 formed thereon is oriented, so that the intermediate layer 20 formed on the Ni layer 14 is also oriented. For this reason, the intermediate layer 20 with good orientation can be formed.

  The method for forming the intermediate layer 20 is not particularly limited, and for example, a sputtering method can be employed. Further, for example, the intermediate layer 20 made of the above-described material is formed.

  As shown in FIG. 2, next, after the step of forming the intermediate layer 20 (step S20), the laminated metal is heat-treated to form the nonmagnetic Ni alloy layer 12 from the laminated metal (step S30). By this step S30, Ni in the Ni layer 14 is diffused into the first metal layer 13, and Ni and the first metal are alloyed to form the nonmagnetic Ni alloy layer 12. When the first metal constituting the first metal layer 13 is Cu or Ag, the nonmagnetic Ni alloy layer 12 is a Ni—Cu alloy or a Ni—Ag alloy.

  The heat treatment conditions are not particularly limited as long as Ni constituting the Ni layer 14 and the first metal constituting the first metal layer 13 are alloyed in the laminated metal. As an example of the heat treatment conditions, for example, a treatment time of about 1 hour at a temperature of 600 ° C. to 800 ° C. in an atmosphere containing Ar (argon) at a pressure of 10 Pa or less.

  When the first metal layer 13 is Cu, during alloying by heat treatment, Ni constituting the Ni layer 14 is 50% or less of non-magnetic Ni—Cu with respect to Cu constituting the first metal layer 13. An alloy layer can be formed.

  The precursor shown in FIG. 1 can be manufactured by performing the above steps S10 to S30. Note that the precursor to be manufactured includes a case where a part of the first metal layer 13 is not alloyed by the heat treatment in step S30. That is, the precursor of the present invention includes the second metal layer 11, the first metal layer 13 formed on the second metal layer 11, and the nonmagnetic Ni formed on the first metal layer 13. The alloy layer 12 and the intermediate layer 20 formed on the nonmagnetic Ni alloy layer 12 may be provided.

  As described above, according to the precursor and the manufacturing method thereof in the present embodiment, the nonmagnetic Ni alloy layer 12 is formed from the laminated metal by heat-treating the laminated metal after step S20 of forming the intermediate layer 20. (Step S30).

  Ni is not easily oxidized and has good lattice matching with the intermediate layer 20. For this reason, the intermediate layer 20 can be easily formed on the Ni layer 14. In this state, by heat-treating the laminated metal, Ni constituting the Ni layer 14 and the first metal constituting the first metal layer 13 are alloyed, so that a Ni alloy can be formed. . The magnetism of Ni alloy can be made smaller than that of Ni alone. That is, the nonmagnetic Ni alloy layer 12 can be formed from a laminated metal. For this reason, when a superconducting wire is manufactured by forming a superconducting layer on the precursor intermediate layer 20, the nonmagnetic Ni alloy layer 12 can alleviate the concentration of the magnetic field at the widthwise end of the superconducting wire. Therefore, a precursor capable of reducing hysteresis loss can be realized.

  Moreover, it can suppress that the surface layer of the Ni layer 14 is oxidized when forming the intermediate layer 20. For this reason, the fall of the orientation of the intermediate | middle layer formed on the surface layer by which oxidation was suppressed can be suppressed. That is, when the first metal layer 13 has a good orientation, the orientation of the intermediate layer 20 formed thereon is also good. Therefore, the favorable crystalline intermediate layer 20 and the superconducting layer can be formed. Therefore, when a superconducting wire is manufactured using this precursor, deterioration of superconducting characteristics can be suppressed.

(Embodiment 2)
FIG. 5 is a cross-sectional view schematically showing the superconducting wire in the present embodiment. With reference to FIG. 5, the superconducting wire in the present embodiment will be described. As shown in FIG. 5, the superconducting wire in the present embodiment includes the precursor in the first embodiment and the superconducting layer 30 formed on the intermediate layer 20 of the precursor. That is, the second metal layer 11, the nonmagnetic Ni alloy layer 12 formed on the second metal layer 11, the intermediate layer 20 formed on the nonmagnetic Ni alloy layer 12, and the intermediate layer 20 And the formed superconducting layer 30.

Superconducting layer 30 has a long tape-like shape. The superconducting layer 30 is made of REBa ₂ Cu ₃ O _y (y is 6 to 8, more preferably approximately 7, RE is Y (yttrium), Gd (gadolinium), Sm (samarium), Ho (holmium) or the like. A superconductor represented by (meaning an element), for example, preferably made of GdBCO. GdBCO is expressed as GdBa ₂ Cu ₃ O _y (y is 6 to 8, more preferably approximately 7).

  Note that the superconducting wire may further include a stabilizing layer (not shown) formed on the superconducting layer 30. The stabilization layer protects the superconducting layer 30 and is a contact portion with the external electrode. The material for the stabilization layer is not particularly limited, and for example, Ag (silver), Cu (copper), or the like can be used.

  FIG. 6 is a flowchart showing a method of manufacturing a superconducting wire in the present embodiment. Then, with reference to FIG. 6, the manufacturing method of the superconducting wire in this Embodiment is demonstrated.

  First, similarly to Embodiment 1, the precursor shown in FIG. 1 is manufactured (steps S10 to S30).

Next, as shown in FIG. 6, the superconducting layer 30 is formed on the intermediate layer 20 (step S40). The method for forming the superconducting layer 30 is not particularly limited, and for example, a PLD (Pulsed Laser Deposition) method, a MOD (Metal Organic Deposition) method, or the like can be employed. For example, the superconducting layer 30 made of the above-described material is formed.

  Next, a stabilization layer (not shown) of the above-described material may be formed on the superconducting layer 30. Note that this step may be omitted.

  By performing the above steps S10 to S40, the superconducting wire shown in FIG. 5 can be manufactured.

  As described above, the superconducting wire and the manufacturing method thereof in the present embodiment form the nonmagnetic Ni alloy layer 12 from the laminated metal by heat-treating the laminated metal after step S40 of forming the superconducting layer. (Step S40).

  As described above, the intermediate layer 20 can be easily formed on the Ni layer 14. After forming the intermediate layer 20 (step S20), the nonmagnetic Ni alloy layer 12 can be formed by heat-treating the laminated metal (step S30). Since the superconducting layer 30 is formed in this state (step S40), the superconducting layer 30 can be easily formed. For this reason, the nonmagnetic Ni alloy layer 12 can alleviate the concentration of the magnetic field on the end portion in the width direction of the superconducting wire. Therefore, a superconducting wire that can reduce hysteresis loss can be realized.

(Embodiment 3)
Since the superconducting wire in the present embodiment is the same as the superconducting wire in the second embodiment shown in FIG. 5, the description thereof will not be repeated.

  FIG. 7 is a flowchart showing a method of manufacturing a superconducting wire in the present embodiment. Next, with reference to FIG. 7, a method for manufacturing a superconducting wire in the present embodiment will be described.

  As shown in FIG. 7, first, a laminated metal having a first metal layer 13 and a Ni layer 14 formed on the first metal layer 13 is prepared (step S10). Next, the intermediate layer 20 is formed on the Ni layer 14 of the laminated metal (step S20). Since steps S10 and S20 are the same as those in the first embodiment, description thereof will not be repeated.

  FIG. 8 is a cross-sectional view schematically showing a state in which the superconducting layer in the present embodiment is formed. As shown in FIGS. 7 and 8, next, the superconducting layer 30 is formed on the intermediate layer 20 (step S40). Since this step S40 is the same as that of Embodiment 2, the description thereof will not be repeated.

  Next, after step S40 for forming the superconducting layer 30, the laminated metal is heat-treated to form the nonmagnetic Ni alloy layer 12 from the laminated metal (step S30). Since step S30 is the same as that of the first embodiment, description thereof will not be repeated.

  By performing the above steps S10 to S50, the superconducting wire shown in FIG. 5 can be manufactured.

  In addition, after forming the intermediate | middle layer 20, you may heat-process a laminated metal. That is, after step S20 for forming the intermediate layer 20 and step S40 for forming the superconducting layer 30, step S30 for heat treatment may be performed.

  As described above, the superconducting wire and the manufacturing method thereof in the present embodiment form the nonmagnetic Ni alloy layer 12 from the laminated metal by heat-treating the laminated metal after step S20 of forming the intermediate layer. (Step S40).

  As described above, the intermediate layer 20 can be easily formed on the Ni layer 14. Therefore, the superconducting layer 30 can be easily formed on the intermediate layer 20. After forming the superconducting layer 30 (step S40), the laminated metal is heat-treated (step S30), whereby the nonmagnetic Ni alloy layer 12 can be formed. For this reason, the nonmagnetic Ni alloy layer 12 can alleviate the concentration of the magnetic field on the end portion in the width direction of the superconducting wire. Therefore, a superconducting wire that can reduce hysteresis loss can be realized.

  In this embodiment, after at least one of the step of forming the intermediate layer and the step of forming the superconducting layer, a step of forming a nonmagnetic Ni alloy layer from the stacked metal by heat-treating the stacked metal is provided. The effect of was investigated.

(Invention Example 1)
A superconducting wire of Example 1 of the present invention was manufactured according to the second embodiment. Specifically, first, a Cu substrate having a thickness of 18 μm was prepared as the first metal layer 13 (step S12). An Ni layer 14 having a thickness of 1 μm was formed on the first metal layer 13 by plating (step S13). As a result, a laminated metal in which the Cu substrate as the first metal layer 13 and the Ni layer 14 were laminated was formed.

Next, CeO ₂ was formed as an intermediate layer 20 on the Ni layer 14 by sputtering (step S20).

  Next, the laminated substrate was heat-treated in an atmosphere containing Ar at a temperature of 700 ° C. under a pressure of 10 Pa or less (Step S30). This formed the nonmagnetic Ni-Cu alloy layer from the laminated metal.

  Next, GdBCO was formed as the superconducting layer 30 on the intermediate layer 20 by the PLD method (step S40).

  By performing the above steps S10 to S40, in the nonmagnetic Ni alloy layer of Example 1 of the present invention, the Ni concentration monotonously decreases from the interface with the intermediate layer toward the surface opposite to the interface. A superconducting wire was manufactured.

(Invention Example 2)
The manufacturing method of the superconducting wire of Example 2 of the present invention was basically the same as the manufacturing method of the superconducting wire of Example 1 of the present invention, but differed in that it was manufactured according to the manufacturing method of the superconducting wire in Embodiment 3. It was. That is, the manufacturing method of the superconducting wire of Example 2 of the present invention was different from Example 1 of the present invention in that Step S30 for heat treatment was performed after Step S40 for forming the superconducting layer 30.

(Comparative Example 1)
The manufacturing method of the superconducting wire of Comparative Example 1 was basically the same as the manufacturing method of the superconducting wire of Example 1 of the present invention, but differed in that the heat treatment step S30 was not performed.

(Measuring method)
For the superconducting wires of Invention Examples 1 and 2 and Comparative Example 1, hysteresis loss and critical current value Ic were measured. The results are shown in Table 1.

Specifically, the critical current value Ic of the superconducting wires of Invention Examples 1 and 2 and Comparative Example 1 was measured in a self-magnetic field at a temperature of 77K. The critical current value Ic was the energization current value when an electric field of 10 ⁻⁶ V / cm was generated.

  The hysteresis loss when the magnetic field was applied to the superconducting wires of Invention Examples 1 and 2 and Comparative Example 1 at room temperature in the direction parallel to the tape surface of the superconducting wire was measured using a vibration magnetometer (VSM). Measured.

(Measurement result)
In Invention Examples 1 and 2 and Comparative Example 1, since the intermediate layer was formed on the Ni layer, oxidation of the Ni layer could be suppressed. For this reason, the intermediate layer could be easily formed.

Further, as shown in Table 1, the superconducting wire of the present invention example 1 in which the heat treatment was performed after forming the intermediate layer and the heat treatment example 2 in which the heat treatment was performed after forming the superconducting layer was made of an alloy of Ni and Cu. To form a non-magnetic Ni—Cu alloy layer. For this reason, the hysteresis loss of the superconducting wires of Invention Examples 1 and 2 was 0 J / m ³ . On the other hand, the comparative example 1 which did not heat-process
The hysteresis loss of the superconducting wire was 52 J / m ³ . From this, it was confirmed that the hysteresis loss can be reduced by heat-treating the laminated metal after at least one of step S20 for forming the intermediate layer and step S40 for forming the superconducting layer.

  Moreover, as shown in Table 1, the critical current value Ic of the superconducting wires of Invention Examples 1 and 2 was 250 A / cm, the same as the critical current value Ic of the superconducting wire of Comparative Example 1. From this, it was confirmed that the superconducting properties of the superconducting layer were not deteriorated even if heat treatment was performed after at least one of step S20 for forming the intermediate layer and step S40 for forming the superconducting layer.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is shown not by the above-described embodiment but by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

  10 substrate, 11 second metal layer, 12 nonmagnetic Ni alloy layer, 13 first metal layer, 14 Ni layer, 20 intermediate layer, 30 superconducting layer.

Claims (3)

A non-magnetic nickel alloy layer;
An intermediate layer formed on the nonmagnetic nickel alloy layer,
A precursor of a superconducting wire, wherein the nonmagnetic nickel alloy layer monotonously decreases so that the concentration of nickel always decreases from the interface with the intermediate layer toward the surface opposite to the interface.   The superconducting wire precursor according to claim 1, further comprising a second metal layer formed under the nonmagnetic nickel alloy layer and having a higher strength than the nonmagnetic nickel alloy layer. The precursor of the superconducting wire according to claim 1 or 2,
A superconducting wire comprising a superconducting layer formed on an intermediate layer.

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