Multi-core thin-film superconducting wire and method for manufacturing the same

Abstract

To provide a multifilamentary thin-film superconducting wire that can be manufactured without post-processing, and a method of manufacturing the same.SOLUTION: The multifilamentary thin-film superconducting wire of the present invention has a plurality of non-superconducting layers located on a substrate, and a rare earth based oxide thin film located above the substrate and the plurality of non-superconducting layers, where the rare earth based oxide thin film contains doped or undoped rare earth elements (RE), barium (Ba), copper (Cu) and oxygen (O), and satisfies the general formula REBa2Cu3O7-d (where 0≤d≤0.8), and where the substrate is a textured substrate of the rare earth based oxide thin film.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a multi-core thin film superconducting wire and a method for manufacturing the same.

Background Art

[0002] REBa2Cu3O 7-d (REBCO, RE is a rare element such as Y, Eu, Gd, Sm, RE:Ba:Cu = 1:2:3 composition ratio) superconductor is a material applicable to superconducting magnets and power equipment for power saving. In applying to superconducting magnets, it is essential to reduce AC loss and the influence of the shielding magnetic field. On the other hand, the so-called thin film superconducting wire expected for these applications can only produce a material with a high critical current density on a thin tape.

[0003] When considering the application of these wires to existing power systems including AC, etc., it is necessary to go through a process of thinning for the purpose of stably flowing current, preventing AC loss, and reducing the shielding magnetic field. So far, thinning has required post-processing such as mechanically cutting or creating a plurality of grooves with a laser called the laser scribing method.

[0004] In recent years, a thinning process that does not require post-processing has been developed (for example, see Patent Document 1). According to Patent Document 1, regarding a superconducting wire substrate used for manufacturing a superconducting wire by a coating pyrolysis method in which a metal organic compound solution is applied and then a predetermined heat treatment is performed to form an oxide superconducting thin film, it is disclosed that at least one or more coating non-forming portions that avoid the formation of a coating film of the metal organic compound solution are provided in the width direction along the length direction of the superconducting wire substrate.

[0005] According to Patent Document 1, in order to utilize the liquid repellency of the coating non-forming portion, the formation of the oxide superconducting thin film is limited to coating pyrolysis using a solution. Therefore, heat treatment is required for removing the coating non-forming portion and forming the oxide.

Prior Art Documents

Patent Document

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] From the above, an object of the present invention is to provide a multi-core thin film superconducting wire that can be manufactured without post-processing, and a method for manufacturing the same.

Means for Solving the Problems

[0008] The multi-core thin film superconducting wire according to the present invention includes a substrate, a plurality of non-superconducting layers located on the substrate, and a rare earth-based oxide thin film located on the substrate and the plurality of non-superconducting layers. The rare earth-based oxide thin film contains a doped or undoped rare earth element (RE), barium (Ba), copper (Cu), and oxygen (O), and has a general formula REBa2Cu3O 7-d (where 0 ≦ d ≦ 0.8). The substrate is an orientation substrate for the rare earth-based oxide thin film, thereby solving the above problems. The crystallinity of the rare earth-based oxide thin film located on the plurality of non-superconducting layers may be lower than that of the rare earth-based oxide thin film located on the substrate. The rare earth-based oxide thin film located on the plurality of non-superconducting layers may further contain an impurity phase. The impurity phase may be copper oxide and / or Y2BaCuO x (4 ≦ x ≦ 6). The plurality of non-superconducting layers may be a metal material or an oxide material having no superconductivity. The metal material or oxide material may have a melting point exceeding 800°C. The metal material may be selected from the group consisting of zirconium (Zr), silver (Ag), niobium (Nb), gold (Au), hafnium (Hf), cobalt (Co), germanium (Ge), platinum (Pt), and silicon (Si). The oxide may be a barium composite oxide (BaMO3, where M is selected from the group consisting of zirconium (Zr), hafnium (Hf), niobium (Nb), and tin (Sn)). The oxide may be selected from the group consisting of aluminum oxide (Al2O3), silicon oxide (SiO2), titanium oxide (TiO2), zinc oxide (ZnO), cerium oxide (CeO2), zirconium oxide (ZrO2), and hafnium oxide (HfO2). The width of the plurality of non-superconducting layers may satisfy the range of 100 nm or more and 20 μm or less. The width of the plurality of non-superconducting layers may satisfy the range of 1 μm or more and 20 μm or less. The thickness of the plurality of non-superconducting layers may satisfy the range of 100 nm or more and 1 μm or less. The thickness of the rare earth-based oxide thin film may satisfy the range of 100 nm or more and 500 nm or less. The substrate may be magnesium oxide (MgO), strontium titanate (SrTiO3), lanthanum aluminate (LaAlO3), strontium aluminum tantalate (SAT; Sr2AlTaO6), yttria-stabilized zirconia (YSZ), lanthanum gallate (LaGaO3), neodymium gallate (NdGaO3), praseodymium gallate (PrGaO3), yttrium aluminate (YAlO3), barium stannate (BaSnO3), barium zirconate (BaZrO3), barium neodymium tantalate (Ba2NdTaO6), strontium stannate (SrSnO3), calcium stannate (CaSnO3), strontium lanthanum gallate (LaSrGaO4), lanthanum strontium aluminate (LaSrAlO4), cerium oxide (CeO2), yttrium oxide (Y2O3), (LaAlO3) 0.3 -(SrAl 0.5 Ta 0.5 O3) 0.7 (LSAT), magnesium oxide (MgO), and an oxide selected from the group consisting of sapphire may also be used. The substrate may be a biaxially oriented substrate. The rare earth-based oxide thin film may be doped with nanorods made of a material selected from the group consisting of barium zirconate (BaZrO3), barium stannate (BaSnO3), barium hafnium oxide (BaHfO3), and gold (Au). The interval between the plurality of non-superconducting layers may satisfy the range of 100 nm or more and 1 mm or less. The method for manufacturing the multi-core thin film superconducting wire according to the present invention includes forming a plurality of non-superconducting layers on a substrate using a lithography technique or a printing technique, and forming a rare earth-based oxide thin film on the substrate and the plurality of non-superconducting layers, thereby solving the above problems. The forming of the plurality of non-superconducting layers may be performed at room temperature. The forming of the rare earth-based oxide thin film may use a method selected from the group consisting of physical vapor deposition, chemical vapor deposition, and liquid phase growth methods.

Advantages of the Invention

[0009] The multi-core thin film superconducting wire according to the present invention includes a substrate, a plurality of non-superconducting layers located thereon, and a doped or undoped rare earth element (RE), barium (Ba), copper (Cu), and oxygen (O) located on the substrate and the plurality of non-superconducting layers, and has a rare earth-based oxide thin film satisfying the general formula REBa2Cu3O 7-d (where 0 ≦ d ≦ 0.8). Since the substrate is an orientation substrate for the rare earth-based oxide thin film, the rare earth-based oxide thin film located on the substrate is oriented with respect to the substrate and exhibits excellent superconductivity. On the other hand, the crystallinity of the rare earth-based oxide thin film located on the plurality of non-superconducting layers is lower than that of the rare earth-based oxide thin film located on the substrate. Due to such a disorder in the crystal orientation, it becomes difficult for a superconducting current to flow in the rare earth-based oxide thin film located on the plurality of non-superconducting layers. As a result, regions that exhibit superconductivity and in which a superconducting current easily flows and regions in which a superconducting current hardly flows are repeated, and the multi-core thin film superconducting wire can function.

[0010] The manufacturing method of the multi-core thin-film superconducting wire according to the present invention includes forming a plurality of non-superconducting layers on a substrate using lithography technology or printing technology, and forming a rare-earth-based oxide thin film on the substrate and the plurality of non-superconducting layers. Since it is only necessary to form a rare-earth-based oxide thin film on the substrate including the plurality of non-superconducting layers, there is no need to remove the plurality of non-superconducting layers, and post-processing is also unnecessary.

Brief Description of Drawings

[0011]

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Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same elements are given the same numbers, and the description thereof is omitted. FIG. 1 is a schematic diagram showing a multi-core thin film superconducting wire according to the present invention. FIG. 2 is a schematic diagram showing the details of the multi-core thin film superconducting wire according to the present invention. It is a schematic diagram showing a flexible porous body.

[0013] The multi-core thin film superconducting wire 100 of the present invention includes a substrate 110, a plurality of non-superconducting layers 120 located on the substrate 110, and a rare earth-based oxide thin film 130 located on the substrate 110 and the non-superconducting layers 120. Here, the rare earth-based oxide thin film 130 contains a doped or undoped rare earth element (RE), barium (Ba), copper (Cu), and oxygen (O), and has the general formula REBa2Cu3O 7-d (where 0 ≦ d ≦ 0.8). Further, since the substrate 110 is an orientation substrate for the rare earth-based oxide thin film 130, the rare earth-based oxide thin film 130 on the substrate 110 is oriented with respect to the substrate 110.

[0014] The general formula REBa2Cu3O 7-d (where 0 ≦ d ≦ 0.8) represents a rare earth-based oxide thin film having an oxygen-deficient type layered perovskite structure, and a superconducting layer composed of RE and CuO2 planes that exhibit superconductivity above and below it, and a block layer composed of BaO planes and CuO chains are alternately stacked to form a perovskite structure and are known as superconducting materials.

[0015] The rare earth element RE is preferably at least one selected from the group consisting of lutetium (Lu), ytterbium (Yb), thulium (Tm), erbium (Er), holmium (Ho), dysprosium (Dy), gadolinium (Gd), europium (Eu), and samarium (Sm). Since the critical temperature Tc can be changed by the selection of the rare earth element RE, it may be selected according to the application.

[0016] The rare earth-based oxide thin film 130 may have nanorods as pinning centers in order to improve the superconducting current. Such nanorods are preferably made of a material selected from the group consisting of barium zirconate (BaZrO3), barium stannate (BaSnO3), barium hafnium oxide (BaHfO3), and gold (Au). Among them, barium zirconate is preferable because it has the same perovskite structure as the rare earth-based oxide thin film 130 and does not reduce the superconducting properties.

[0017] The doping amount of such nanorods is preferably in the range of 5 mol% or more and 15 mol% or less. Within this range, the crystal structure of the rare earth-based oxide thin film 130 can be maintained, and the superconducting current can be improved without degrading the superconductivity.

[0018] Thus, the rare earth-based oxide thin film 130 located on the substrate 110 is oriented with respect to the substrate 110 and exhibits excellent superconductivity. On the other hand, the rare earth-based oxide thin film 130 located on the plurality of non-superconducting layers 120 makes it difficult for the superconducting current to flow and is less likely to exhibit superconductivity. As a result, without physically cutting the rare earth-based oxide thin film 130, regions where the superconducting current easily flows and regions where the superconducting current hardly flows are repeated, so that it can function as a multi-core and fine-wire multi-core thin film superconducting wire.

[0019] The substrate 110 is not particularly limited as long as it is a substrate for orienting the rare earth-based oxide thin film 130. Exemplarily, magnesium oxide (MgO), strontium titanate (SrTiO3), lanthanum aluminate (LaAlO3), strontium aluminum tantalate (SAT; Sr2AlTaO6), yttria-stabilized zirconia (YSZ), lanthanum gallate (LaGaO3), neodymium gallate (NdGaO3), praseodymium gallate (PrGaO3), yttrium aluminate (YAlO3), barium stannate (BaSnO3), barium zirconate (BaZrO3), barium neodymium tantalate (Ba2NdTaO6), strontium stannate (SrSnO3), calcium stannate (CaSnO3), lanthanum strontium gallate (LaSrGaO4), lanthanum strontium aluminate (LaSrAlO4), cerium oxide (CeO2), yttrium oxide (Y2O3), (LaAlO3) 0.3 -(SrAl 0.5 Ta 0.5 O3) 0.7 (LSAT), magnesium oxide (MgO), and an oxide selected from the group consisting of sapphire. These are known as orientation substrates for the rare earth-based oxide thin film 130.

[0020] For example, when using MgO as the substrate, if a MgO single crystal substrate with a plane orientation {100} is used, the rare earth-based oxide thin film 130 can be c-axis oriented. The rare earth-based oxide thin film 130 has no limitation on the crystal orientation as long as it is oriented, and is not limited to c-axis orientation. A person skilled in the art can appropriately select the single crystal substrate made of the above-described oxide and the plane orientation of s according to the crystal orientation of the rare earth-based oxide thin film 130.

[0021] Alternatively, the substrate 110 may be a biaxially oriented substrate. The biaxially oriented substrate is a substrate in which an in-plane oriented intermediate layer is formed on a metal substrate, and is known to be used for the rare earth-based oxide thin film 130.

[0022] Hereafter, for the sake of clarity, the rare earth-based oxide thin film 130 located on the substrate 110 is simply referred to as the rare earth-based oxide thin film 210 (FIG. 2), and the rare earth-based oxide thin film 130 located on the plurality of non-superconducting layers 120 is simply referred to as the rare earth-based oxide thin film 220 (FIG. 2).

[0023] The crystallinity of the rare earth-based oxide thin film 220 is preferably lower than that of the rare earth-based oxide thin film 210. The difference in crystallinity is based on the disorder of the crystal orientation. In the rare earth-based oxide thin film 220 with a disordered crystal orientation, the superconducting current is less likely to flow compared to the oriented rare earth-based oxide thin film 210. Such a disorder of the crystal orientation, that is, the difference in crystallinity, can be confirmed by electron backscatter diffraction (EBSD) using a scanning electron microscope, and the rare earth-based oxide thin film 220 may have a plane with a crystal orientation different from that of the rare earth-based oxide thin film 210. Referring to the EBSD image, it can be discriminated simply by the difference in color.

[0024] Note that there is no particular limitation if there is a difference between the crystallinity of the rare earth-based oxide thin film 210 and that of the rare earth-based oxide thin film 220. Preferably, if the average inclination of adjacent crystal orientations in the ab plane in the rare earth-based oxide thin film 220 is 4° or more, the superconducting current is less likely to flow, and the formation of a multi-core wire can be promoted. In this specification, the inclination of the crystal orientation is calculated and averaged for the inclination of the crystal orientations of adjacent crystal grains with respect to 100 crystal grains.

[0025] For simplicity, if the rare earth-based oxide thin film 220 contains crystal grains having a crystal orientation different from the main crystal orientation of the crystal of the rare earth-based oxide thin film 210 in the range of 10% or more and 80% or less with respect to 100 crystal grains, the average inclination can be regarded as 4° or more. More preferably, the rare earth-based oxide thin film 220 may contain crystal grains having a crystal orientation different from the main crystal orientation of the crystal of the rare earth-based oxide thin film 210 in the range of 35% or more and 45% or less with respect to 100 crystal grains.

[0026] The rare earth-based oxide thin film 220 preferably contains an impurity phase 230. The impurity phase 230 contained in the rare earth-based oxide thin film 220 does not exhibit superconductivity. Therefore, without physically cutting the rare earth-based oxide thin film 130, regions showing superconductivity and regions not showing superconductivity / hardly showing superconductivity are repeated, so that it can function as a multi-core thin film superconducting wire.

[0027] Such an impurity phase 230 is preferably copper oxide and / or Y2BaCuO x (4 ≦ x ≦ 6). None of these exhibit superconductivity. The content of the impurity phase 230 may preferably be in the range of 5 vol% or more and less than 100 vol%. Within this range, since it does not exhibit superconductivity, multi-core wire formation can be promoted. Note that having the impurity phase 230, the content is measured by elemental mapping etc. attached to a scanning electron microscope etc. Even if most of the rare earth-based oxide thin film 220 consists of the impurity phase, since the ratio of the rare earth-based oxide thin film 220 in the whole rare earth-based oxide thin film 130 is extremely small, according to X-ray diffraction, the whole rare earth-based oxide thin film 130 satisfies the general formula REBa2Cu3O 7-d (where 0 ≦ d ≦ 0.8), and the present invention includes such cases. The content of the impurity phase 230 may more preferably be in the range of 5 vol% or more and 20 vol% or less. It enables multi-core wire formation with a small amount of impurities.

[0028] The ratio of the width of the rare earth-based oxide thin film 210 to the width of the rare earth-based oxide thin film 220 is preferably 1 or more and 1000 or less. Thereby, it functions as a multi-core thin film superconducting wire. The ratio of the width of the rare earth-based oxide thin film 210 to the width of the rare earth-based oxide thin film 220 may more preferably be 10 or more and 500 or less.

[0029] The plurality of non-superconducting layers 120 are not particularly limited as long as they are made of a material having no superconductivity, but are preferably a non-superconducting metal material or an oxide material.

[0030] The metal material or oxide material without superconductivity preferably consists of a material having a melting point exceeding 800°C. Thereby, in the manufacturing process described later, it is possible to prevent the rare-earth oxide thin film 130 and the non-superconducting layer 120 from reacting. Note that the upper limit of the melting point is not particularly limited. For example, it may be 2000°C or lower for a metal material and 3000°C or lower for an oxide material.

[0031] The metal material without superconductivity is, for example, selected from the group consisting of zirconium (Zr), silver (Ag), niobium (Nb), gold (Au), hafnium (Hf), cobalt (Co), germanium (Ge), platinum (Pt), and silicon (Si). These metal materials can be formed into a film on a substrate at room temperature and have a melting point exceeding 800°C. On these metal materials, the rare-earth oxide thin film 230 becomes polycrystalline or has low orientation even if it is oriented.

[0032] The oxide material without superconductivity is, for example, a barium composite oxide (BaMO3, where M is selected from the group consisting of zirconium (Zr), hafnium (Hf), niobium (Nb), and tin (Sn)). This composite oxide can be formed into a film on a substrate at room temperature and has a melting point exceeding 800°C. Since such a composite oxide has low reactivity with the rare-earth oxide thin film, it promotes the formation of the rare-earth oxide thin film 230.

[0033] Alternatively, the oxide material without superconductivity may be selected from the group consisting of aluminum oxide (Al2O3), silicon oxide (SiO2), titanium oxide (TiO2), zinc oxide (ZnO), cerium oxide (CeO2), zirconium oxide (ZrO2), and hafnium oxide (HfO2). These oxides can be formed into a film on a substrate at room temperature and have a melting point exceeding 800°C. On these oxides, the rare-earth oxide thin film 220 becomes polycrystalline or has low orientation even if it is oriented.

[0034] The width of the non-superconducting layer 120 is not particularly limited as long as the above-described rare earth oxide thin film 220 can be formed, but preferably satisfies the range of 100 nm or more and 20 μm or less. If it is 100 nm or more, lithography technology or printing technology described orally can be adopted, which is preferable. Considering the size of the wire, the upper limit is preferably 20 μm.

[0035] More preferably, the width of the non-superconducting layer 120 satisfies the range of 1 μm or more and 20 μm or less. In this range, the rare earth oxide thin film 220 on the non-superconducting layer 20 may have low crystallinity and an impurity phase 230.

[0036] The interval of the non-superconducting layers 120 preferably satisfies the range of 100 nm or more and 1 mm or less. Thereby, it functions as a multi-core thin film superconducting wire. More preferably, the interval of the non-superconducting layers 120 satisfies the range of 10 μm or more and 500 μm or less. Still more preferably, the interval of the non-superconducting layers 120 satisfies the range of 30 μm or more and 100 μm or less. Thereby, a multi-core thin film superconducting wire capable of efficiently suppressing AC loss and reducing the influence of the shielding magnetic field can be provided.

[0037] The thickness of the non-superconducting layer 120 is not particularly limited, but preferably is in the range of 100 nm or more and 1 μm or less. In this range, the rare earth oxide thin film 220 on the non-superconducting layer 20 may have low crystallinity and an impurity phase 230. More preferably, the thickness of the non-superconducting layer 120 is in the range of 100 nm or more and 500 nm or less.

[0038] In the multi-core thin film superconducting wire 100 of the present invention, since the rare earth oxide thin film is multi-core without physically cutting, AC loss is suppressed and the shielding magnetic field is reduced. Such a multi-core thin film superconducting wire 100 is applied to power equipment, medical accelerators, fusion reactors, and the like.

[0039] Next, a method for manufacturing the multi-core thin film superconducting wire 100 of the present invention will be described. FIG. 3 is a flowchart showing the manufacturing process of the multi-core thin film superconducting wire according to the present invention.

[0040] The multi-core thin film superconducting wire 100 of the present invention includes the following manufacturing steps. Step S310: Forming a plurality of non-superconducting layers on a substrate using lithography technology or printing technology. Step S320: Forming a rare earth-based oxide thin film on the substrate and the plurality of non-superconducting layers.

[0041] In this way, by simply forming a plurality of non-superconducting layers on the substrate and then forming a rare earth-based oxide thin film thereon, post-processing such as physical cutting of the rare earth-based oxide thin film is not required, and there is no need to remove the non-superconducting layer, thus manufacturing the multi-core thin film superconducting wire of the present invention.

[0042] Each step will be described in detail. Since the substrate, the non-superconducting layer, and the rare earth-based oxide thin film are as described with reference to FIGS. 1 and 2, the description thereof will be omitted.

[0043] In step S310, a resist is patterned on the substrate using lithography technology or printing technology. The resist may be a composition whose solubility in a developer changes by light, an electron beam, or the like. For example, a plurality of linear patterns are drawn in the longitudinal direction of the substrate on the resist by a laser exposure apparatus and then developed, and only the irradiated portion irradiated with light is removed.

[0044] The lithography technology may be either existing photolithography or electron beam lithography. As the printing technology, existing nanoimprint can be adopted.

[0045] On a substrate with a patterned resist, a non-superconducting layer is formed by a physical vapor deposition method (such as vacuum evaporation, molecular beam epitaxy, PLD (Physical Laser Deposition) method by laser ablation, molecular beam epitaxy, various sputtering, etc.). Considering the process using the resist, the non-superconducting layer is formed at room temperature (in the range of 8 °C or more and 35 °C or less). Then, by removing the resist using a solvent or the like, a plurality of non-superconducting layers can be formed on the substrate in the longitudinal direction of the substrate.

[0046] In step S320, a rare earth oxide thin film is formed on a substrate on which a plurality of non-superconducting layers are formed by the above-described physical vapor deposition method, chemical vapor deposition method (such as various CVD methods including MOCVD method and flash CVD method), chemical liquid phase growth method (such as sol-gel method, metalorganic compound decomposition (MOD) method, liquid phase mist chemical deposition (LSMCD method), etc.).

[0047] In step S320, by simply forming a rare earth oxide thin film on a substrate on which a plurality of non-superconducting layers are formed, the rare earth oxide thin film directly above the substrate grows so as to be oriented with respect to the substrate by the oriented substrate, and the rare earth oxide thin film directly above the non-superconducting layer may have low crystallinity and may have an impurity phase. As a result, the multi-core thin film superconducting wire 100 of the present invention shown in FIGS. 1 and 2 is obtained.

[0048] Next, the present invention will be described in detail using specific examples, but it should be noted that the present invention is not limited to these examples.

Example

[0049] [Examples 1 to 3] In Examples 1 to 3, a multi-core thin film superconducting wire including a substrate, a plurality of non-superconducting layers with various widths thereon, and a rare earth oxide thin film thereon was manufactured using photolithography technology. A (001)STiO3 single crystal substrate (STO substrate) was used as the substrate, a Zr film or an Ag film was used as the non-superconducting layer, and a 10% BaZrO3 nanorod-doped or undoped YBa2Cu3O7 film was used as the rare earth oxide thin film.

[0050] Figure 4 is a procedure showing the process of manufacturing the multi-core thin film superconducting wire for Examples 1 to 3.

[0051] A resist 420 (OFPR800LB, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied to an STO substrate 410 (5 mm × 5 mm), and the resist 420 was patterned using a maskless exposure apparatus (Nano System Solutions Co., Ltd., DL-1000). As a result, the resist in the exposed portion was removed, and a plurality of linear resists 420a were formed in the longitudinal direction of the STO substrate 410.

[0052] In Figure 4, for clarity, three linear resists 420a located at equal intervals are schematically shown. Actually, there were five linear resists, and the intervals between them were 2 μm, 5 μm, 10 μm, and 15 μm in that order.

[0053] Next, a non-superconducting layer 430, which is a Zr film (300 nm) or an Ag film (300 nm), was formed using an RF magnetron sputtering apparatus (manufactured by Shibaura Mechatronics Co., Ltd., CFD-4EP-LL(4G)). The sputtering conditions are shown in Table 1.

[0054]

Table 1

[0055] This was immersed in a resist remover (RemoverPG, manufactured by MicroChem) to remove the resist 420a. As a result, a plurality of linear non-superconducting layers 430a were formed on the STO substrate 410.

[0056] The non-superconducting layer 430a on the obtained STO substrate 410 was observed using an optical microscope (manufactured by Keyence Corporation, VHX-1000), a scanning electron microscope (SEM, manufactured by Hitachi High-Technologies Corporation, SU-70), and a laser microscope (manufactured by Keyence Corporation, VK-X1100). The results are shown in Figures 5 to 7.

[0057] On an STO substrate 410 formed with a plurality of non-superconducting layers 430a, a rare-earth oxide thin film 440 which is undoped or 10% BaZrO3 nanorod-doped YBa2Cu3O7 was formed using a pulse laser deposition apparatus (manufactured by ULVAC, Inc.). The PLD conditions are shown in Table 2. The target was obtained from TEP Co., Ltd.

[0058]

Table 2

[0059] For simplicity, the experimental conditions of the multi-core thin film superconducting wires of Examples 1 to 3 are shown in Table 3.

Table 3

[0060] The surfaces of the multi-core thin film superconducting wires of Examples 1 to 3 obtained in this way were observed by SEM. The results are shown in Fig. 8. X-ray diffraction was performed on the rare-earth oxide thin films of the multi-core thin film superconducting wires of Examples 1 to 3 using an X-ray diffractometer (manufactured by Rigaku Corporation, TRY-HA). The results are shown in Fig. 9. The temperature dependence of the electrical resistance was measured for the rare-earth oxide thin films of the multi-core thin film superconducting wires of Examples 1 to 3. The results are shown in Fig. 10.

[0061] The surfaces of the multi-core thin film superconducting wires of Examples 1 to 3 were observed by a magnetic deflection observation apparatus. The results are shown in Fig. 11. The cross-sectional states of the multi-core thin film superconducting wires of Examples 1 to 3 were observed by a scanning transmission electron microscope (STEM, manufactured by JEOL Ltd., JEM-ARM200F-G) equipped with an energy dispersive X-ray spectrometer (EDX). These results are shown in Figs. 12 to 13. The EBSD images of the surfaces of the multi-core thin film superconducting wires of Examples 1 to 3 were examined by the above-mentioned SEM. The results are shown in Figs. 14 and 15. Furthermore, elemental analysis of the details of the multi-core thin film superconducting wires of Examples 1 to 3 was performed by EDX. The results are shown in Fig. 16.

[0062] The above results will be collectively explained. Figure 5 is a diagram showing an optical microscope image of the surface of an STO substrate including a plurality of non-superconducting layers used in Example 1 and Example 2. Figure 6 is a diagram showing an SEM image of the surface of an STO substrate including a plurality of non-superconducting layers used in Example 1 and Example 2. Figure 7 is a diagram showing a laser microscope image of the surface of an STO substrate including a plurality of non-superconducting layers used in Example 1 and Example 2.

[0063] In Figure 5, the region shown in dark gray scale is a non-superconducting layer which is a Zr film, and it was confirmed that a plurality of linear non-superconducting layers were formed on the STO substrate. From the left in Figure 5, the widths of the non-superconducting layers were in the order of 2 μm, 5 μm, 10 μm, and 15 μm.

[0064] Figure 6 shows an enlarged view of the non-superconducting layer which is a Zr film with a width of 15 μm. The boundary of the non-superconducting layer was clear by the lithography technique. Figure 7(B) is a measurement image of the surface unevenness of the main image (Figure 7(A)) of the non-superconducting layer which is a Zr film with a width of 15 μm. In Figure 7(B), the region shown in dark gray scale corresponds to a height of 300 nm, and the thickness of the non-superconducting layer which is a Zr film was 300 nm. Although not shown, the non-superconducting layer which is an Ag film in Example 3 also showed a similar state and had a thickness of 300 nm.

[0065] Figure 8 is a diagram showing an SEM image of the surface of the multi-core thin film superconducting wire of Example 1 to Example 3.

[0066] Figures 8(A) to (C) show the surfaces of the multi-core thin film superconducting wires of Example 1 to Example 3, respectively, and for clarity, the regions corresponding to the non-superconducting layers are indicated by dotted lines.

[0067] According to Figures 8(A) and (B), both the rare earth oxide thin film directly on the STO substrate and the rare earth oxide thin film directly on the non-superconducting layer were in a uniform state. The presence of nanorods was confirmed in Figure 8(B). On the other hand, Figure 8(C) shows different states between the rare earth oxide thin film directly on the STO substrate and the rare earth oxide thin film directly on the non-superconducting layer because of different integration times.

[0068] Figure 9 is a diagram showing the XRD pattern of the surface of the multi-core thin film superconducting wire of Example 1.

[0069] According to Figure 9, only the diffraction peaks of 00L were observed, and the rare earth oxide thin film was identified as YBa2Cu3O7 with c-axis orientation as a whole. Although not shown, it was also confirmed that in Examples 2 and 3, it was c-axis oriented 10% BaZrO3 nanorod-doped YBa2Cu3O7 or undoped YBa2Cu3O7.

[0070] Figure 10 is a diagram showing the temperature dependence of the electrical resistance of the multi-core thin film superconducting wire of Example 1.

[0071] According to Figure 10, it was found that the rare earth oxide thin film, which is undoped YBa2Cu3O7 in Example 1, becomes superconducting at the critical temperature Tc = 85.9K. This critical temperature was the same as the critical temperature reported for YBa2Cu3O7 so far. Although not shown, it was also found that the rare earth oxide thin films of Examples 2 and 3 also become superconducting in the same manner.

[0072] Figure 11 is a diagram showing the magnetic deflection image of the multi-core thin film superconducting wire of Example 1.

[0073] According to Figure 11, the region is clearly magnetically divided with four lines where the gray scale is brightly shown, and it was found that the rare earth oxide thin film is multi-core. These four lines are non-superconducting layers that are Zr films, suggesting that it is difficult for superconducting current to flow in YBa2Cu3O7 on the Zr film. Although not shown, the multi-core thin film superconducting wires of Examples 2 to 3 also showed similar magnetic deflection images.

[0074] From the above, it includes a substrate, a plurality of non-superconducting layers located on the substrate, and a rare earth oxide thin film located on these, and the rare earth oxide thin film contains a doped or undoped rare earth element (RE), barium (Ba), copper (Cu), and oxygen (O), and the general formula REBa2Cu3O 7-d(Here, 0 ≤ d ≤ 0.8) is satisfied, and it has been shown that for a multi-core thin film superconducting wire in which the substrate is an oriented substrate of a rare earth-based oxide thin film, the rare earth-based oxide thin film can be multi-core without physically cutting.

[0075] FIG. 12 is a STEM image of a cross-section of the multi-core thin film superconducting wire of Example 1. FIG. 13 is a TEM image of a cross-section of the multi-core thin film superconducting wire of Example 1.

[0076] According to FIGS. 12 and 13, a non-superconducting layer which is a Zr film on the STO substrate, a region where there is a rare earth-based oxide thin film which is YBa2Cu3O7 thereon, and a region where there is a rare earth-based oxide thin film which is YBa2Cu3O7 directly above the STO substrate were confirmed.

[0077] FIG. 14 is an EBSD image of the surface of the multi-core thin film superconducting wire of Example 1.

[0078] Although shown in grayscale in FIG. 14, it is actually a color image, and the same brightness indicates the same crystal orientation. In FIG. 14, the crystal orientations of the rare earth oxide thin film 210 directly above the STO substrate were substantially aligned in the 100 orientation. On the other hand, the crystal orientations of the rare earth oxide thin film 220 directly above the Zr film were clearly random. From this, it was found that the crystallinity of the rare earth oxide thin film 220 directly above the Zr film was lower than that of the rare earth oxide thin film 210 directly above the STO substrate. Although not shown, the cross-sections of the multi-core thin film superconducting wires of Examples 2 to 3 were in a similar state.

[0079] FIG. 15 is a diagram showing the distribution of the inclination of the crystal orientation calculated from the EBSD image of the rare earth oxide thin film on the Zr film of FIG. 14.

[0080] According to FIG. 15, more than 60% of the crystal grains in the rare earth oxide thin film 220 on the Zr film have the same crystal orientation, while the remaining 40% of the crystal grains have variations in crystal orientation and are widely inclined and distributed from 5° to 80° with respect to the main crystal orientation. Although not shown, the inclination of the adjacent crystal orientations in the ab plane of the rare earth oxide thin film 210 directly above the STO substrate is 2° or less, and substantially 100% of the crystal grains have the same crystal orientation, which is the same as the crystal orientation of the above-mentioned 60% of the crystal grains.

[0081] FIG. 16 is an EDX mapping of the cross-section of the multi-core thin film superconducting wire of Example 1.

[0082] FIG. 16(A) is an EDX mapping of YBa2Cu3O7 directly above the Zr film, and FIG. 16(B) is an EDX mapping of YBa2Cu3O7 directly above the STO substrate. Comparing FIG. 16(A) and FIG. 16(B), it can be seen that the compositions of Y, Ba, and Cu are different, especially. From this, it can also be seen that the crystallinity of the rare earth oxide thin film directly above the Zr film can be lower than that of the rare earth oxide thin film directly above the STO substrate and can have an impurity phase. Furthermore, according to the EDX mapping, the rare earth oxide thin film directly above the Zr film contains copper oxide (CuO) as an impurity phase, and it has been found that the content is 5 vol% or more. Even if the measurement region is simply converted to the entire rare earth oxide thin film directly above the Zr film, it is considered that the content of the impurity phase is 20 vol% or less. Although not shown, the cross-sections of the multi-core thin film superconducting wires of Examples 2 to 3 were in the same state.

Industrial Applicability

[0083] The manufacturing method of the multi-core thin film superconducting wire of the present invention can be multi-core without post-processing, which is advantageous for practical application. The multi-core thin film superconducting wire of the present invention is thinned without physical cutting or the like, so that the AC loss is suppressed and the shielding magnetic field is reduced. Such a multi-core thin film superconducting wire is applied to power equipment, medical accelerators, fusion reactors, etc.

Explanation of Signs

[0084] 100 Multi-core thin film superconducting wire 110 Substrate 120, 430, 430a Non-superconducting layer 130, 210, 220, 440 Rare earth-based oxide thin film 230 Impurity phase 410 STO substrate 420, 420a Resist

Claims

1. A substrate, a plurality of linear non-superconducting layers located on the substrate, and a rare-earth oxide thin film located on the substrate and the plurality of non-superconducting layers are provided, The rare earth-based oxide thin film contains a doped or undoped rare earth element (RE), barium (Ba), copper (Cu), and oxygen (O), and has the general formula REBa ２ Cu ３ O ７－ｄ (where 0 ≦ d ≦ 0.8), and wherein the substrate is an orientation substrate for the rare-earth oxide thin film, The plurality of non-superconducting layers are a metallic material selected from the group consisting of zirconium (Zr), silver (Ag), niobium (Nb), gold (Au), hafnium (Hf), cobalt (Co), germanium (Ge), platinum (Pt), and silicon (Si), or a barium composite oxide (BaMO ３ , provided that M is an oxide material selected from the group consisting of zirconium (Zr), hafnium (Hf), niobium (Nb), and tin (Sn)), a multi-core thin film superconducting wire.

2. The crystallinity of the rare-earth oxide thin film located on the plurality of non-superconducting layers is lower than that of the rare-earth oxide thin film located on the substrate. The multi-core thin film superconducting wire according to Claim 1.

3. The rare-earth oxide thin film located on the plurality of non-superconducting layers further contains an impurity phase. The multi-core thin film superconducting wire according to Claim 1 or 2.

4. The impurity phase is copper oxide and / or Y ２ BaCuO ｘ (4 ≤ x ≤ 6), the multi-core thin film superconducting wire according to claim 3.

5. The width of the plurality of non-superconducting layers satisfies the range of 100 nm or more and 20 μm or less. The multi-core thin film superconducting wire according to any one of Claims 1 to 4.

6. The width of the plurality of non-superconducting layers satisfies the range of 1 μm or more and 20 μm or less. The multi-core thin film superconducting wire according to Claim 5.

7. The thickness of the plurality of non-superconducting layers satisfies the range of 100 nm or more and 1 μm or less. The multi-core thin film superconducting wire according to any one of Claims 1 to 6.

8. The thickness of the rare-earth oxide thin film satisfies the range of 100 nm or more and 500 nm or less. The multi-core thin film superconducting wire according to any one of Claims 1 to 7.

9. The substrate is an oxide selected from the group consisting of magnesium oxide (MgO), strontium titanate (SrTiO ３ ), lanthanum aluminate (LaAlO ３ ), strontium aluminum tantalate (SAT; Sr ２ AlTaO ６ ), yttria-stabilized zirconia (YSZ), lanthanum gallate (LaGaO ３ ), neodymium gallate (NdGaO ３ ), praseodymium gallate (PrGaO ３ ), yttrium aluminate (YAlO ３ ), barium stannate (BaSnO ３ ), barium zirconate (BaZrO ３ ), barium neodymium tantalate (Ba ２ NdTaO ６ ), strontium stannate (SrSnO ３ ), calcium stannate (CaSnO ３ ), lanthanum strontium gallate (LaSrGaO ４ ), lanthanum strontium aluminate (LaSrAlO ４ ), cerium oxide (CeO ２ ), yttrium oxide (Y ２ O ３ ), (LaAlO ３ ), ０．３ -(SrAl ０．５ Ta ０．５ O ３ ), ０．７ (LSAT), magnesium oxide (MgO), and sapphire, the multi-core thin film superconducting wire according to any one of claims 1 to 8.

10. The substrate is a biaxially oriented substrate. The multi-core thin film superconducting wire according to any one of Claims 1 to 9.

11. The rare earth-based oxide thin film is doped with nanorods made of a material selected from the group consisting of barium zirconate (BaZrO ３ ), barium stannate (BaSnO ３ ), barium hafnium oxide (BaHfO ３ ), and gold (Au). The multi-core thin film superconducting wire according to any one of claims 1 to 10.

12. The interval between the plurality of non-superconducting layers satisfies the range of 100 nm or more and 1 mm or less. The multi-core thin film superconducting wire according to any one of Claims 1 to 11.

13. forming a plurality of linear non-superconducting layers on a substrate using a lithography technique or a printing technique, and forming a rare-earth oxide thin film on the substrate and the plurality of non-superconducting layers are included, The plurality of non-superconducting layers are a metal material selected from the group consisting of zirconium (Zr), silver (Ag), niobium (Nb), gold (Au), hafnium (Hf), cobalt (Co), germanium (Ge), platinum (Pt), and silicon (Si), or a barium composite oxide (BaMO ３ , provided that M is an oxide material selected from the group consisting of zirconium (Zr), hafnium (Hf), niobium (Nb), and tin (Sn)), the method for manufacturing a multi-core thin film superconducting wire according to any one of claims 1 to 12.

14. The forming of the plurality of non-superconducting layers is performed at room temperature. The method according to Claim 13.

15. The forming of the rare-earth oxide thin film uses a technique selected from the group consisting of physical vapor deposition, chemical vapor deposition, and liquid phase growth. The method according to Claim 13 or 14.

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