JP6801068B2 - Superconducting wire - Google Patents

Description

Embodiments of the present invention relates to a superconducting wire.

Most applications of superconducting equipment, except power transmission cables, are used in magnetic fields. In the case of a power transmission cable, if liquid helium is used for cooling at around 4K, the cooling cost becomes enormous. Therefore, the superconductor used for the power transmission cable is limited to the high temperature oxide superconductor.

The superconductor used for the power transmission cable is a Y (yttrium) -based wire rod. Most of the superconductors used for power transmission cables are Y-based wires made by the TFA-MOD (Metal Organic Deposition using TriFluoroActates) method.

When applying a superconductor to a coil, the superconductor is exposed to a magnetic field except in special cases such as a superconducting current limiter that suppresses the influence of magnetic field generation. The characteristics of superconductors deteriorate under a magnetic field due to Lorentz force and the like. Therefore, it is assumed that the metal superconductor has a temperature of 4K, the Bi superconductor has a temperature of 15 to 20K, and the Y superconductor has a temperature of 30 to 50K.

When applying superconductivity to a coil, it was mainly used at 4K using a metal-based superconductor. However, when the superconducting coil is used by immersing it in liquid helium, the amount of helium required at the initial stage of immersion is about four times the volume of the container. For example, the amount of helium required for immersion in a 400 L (liter) container is 1600 L.

The price of helium is soaring, and it is expected that it will continue to soar in the future. Helium is produced together with natural gas stored in the upper part of the bedrock. Therefore, it is not produced in the shale gas field located in the lower part of the bedrock. It is thought that the amount of helium produced with natural gas has already exceeded its peak, and it is thought that the depletion will continue and the price will rise.

The price of helium is still soaring to about 5,000 yen per liter. For example, if 1600 L is required for immersion in a 400 L container, a helium price of 8 million yen is required. Therefore, in recent years, a superconducting system that can be used for cooling a refrigerator is expected. It is expected that superconductors will be used at temperatures of 30K or higher, rather than 4K, which has a high cooling cost.

Superconducting coil is a technology that requires heat insulation by vacuum. When the degree of vacuum drops, it becomes difficult to maintain cooling in the refrigerator and the entire system stops. Therefore, maintaining the degree of vacuum is an important issue for superconducting application systems.

Indispensable for maintaining the degree of vacuum is the sealing of many metal welds. If the seal is weakened, vacuum insulation cannot be maintained, and maintenance such as evacuation is required again. In that case, the maintenance cost increases and the reliability of the system decreases.

As a general rule, metal welds deteriorate when vibration is applied at low temperatures, increasing the probability of leakage. A metal bond is a bond maintained by the movement of free electrons, and the mobility of free electrons decreases and the metal bond weakens when cooled to an extremely low temperature. In particular, it is considered that the damage is large when it receives vibration at 4K. Therefore, it is desirable to use a Bi-based superconductor at 15 to 20K or a Y-based superconductor at 30 to 50K for the superconducting coil.

Bi-based superconductors and Y-based superconductors, which are considered to be high-temperature metal oxide superconductors, are used at low temperatures below the liquid nitrogen temperature in a magnetic field. Of these, the Bi-based superconductor has a further problem. Bi-based superconductors have a high cost because the minimum silver ratio of the wire cross section is 60%. Oxygen permeation is required during heat treatment, and precious metals such as gold are required to improve strength, further increasing costs. Still, it is difficult to obtain sufficient strength. Therefore, it is difficult to use a Bi-based superconductor for a large-scale device in which a hoop force of several tens of tons is applied to the coil.

For the above reasons, the production of Bi-based wires has been withdrawn one after another, and the majority of superconducting wires used for superconducting coils are Y-based wires.

Not limited to Y-based wire rods, superconductors can generally coexist with magnetic flux wires if they are type 2 superconductors. Artificial pin technology is a technology that fixes a part of the magnetic flux line and makes it exhibit superconducting characteristics even in a magnetic field. The size of the artificial pin depends on the application temperature, but it is considered that a size of about 3 nm is required at around 30 K.

Regarding the formation of artificial pins in Y-based superconducting wires, the TFA-MOD method, which has dominated the power transmission cable market, has not obtained good results in magnetic field applications so far. An effective artificial pin cannot be formed, and there is no trial production of a coil used in a magnetic field. In this system, artificial pins such as Dy ₂ O ₃ are formed inside, but the size is very large at 20-30 nm, and it is considered that they do not function as artificial pins.

Huge size artificial pins are ineffective in two ways. One is that the pinning effect is reduced by reducing the number of artificial pins. Assuming that the volume of the artificial pin in the wire rod is constant in order to maintain the amount of current, the number of artificial pins at 30 nm is 1/1000 of the number of artificial pins at 3 nm. Therefore, the magnetic flux line may not be sufficiently fixed.

The other is that the size of the artificial pin is too large, which reduces the pinning effect. If the size of the artificial pin is large, many magnetic flux lines will enter inside. The force that holds the magnetic flux of the artificial pin acts only at the interface between superconducting and non-superconducting. Therefore, if a plurality of magnetic flux lines enter the artificial pin, stress corresponding to the total Lorentz force is applied, and the magnetic flux crosses the interface. Therefore, the magnetic flux line may not be sufficiently fixed.

Under these circumstances, physical vapor deposition methods such as the Pulsed Laser Deposition (PLD) method and the Metalorganic Chemical Vapor Deposition (MOCVD) method have been developed in advance as magnetic field applications. In the physical vapor deposition method, artificial pins are easily introduced, and BaZrO ₃ (BZO) artificial pins are actively introduced. Much effort has been made to control the size of the artificial pin to 3 nm. In recent years, even artificial pins with a size of about 5 nm have been developed.

Although this BZO artificial pin has a lot of quench burnout accidents in coil application, it seems that there is no successful example. Moreover, it is said that the quench burnout accident occurs at a current lower than half of the current value that can be energized. For example, in a superconducting wire material capable of energizing 200 A, when the manufacturer enables energization up to 100 A, it is said that a quench burnout accident occurs when energized at 80 A. In extreme cases, it has been reported that it becomes unstable at about 25% of the maximum current value.

The cause of this quench burnout accident is not always clear. It is expected that a superconducting coil with suppressed quench burnout accidents will be realized.

In addition, even if a quench burnout accident does not occur, the uniformity of the generated magnetic field is inferior, and the result of not satisfying the specifications is also reported. It is also expected to realize a superconducting coil that can generate a stable magnetic field.

M. Rupich, et al., Supercond. Sci. Technol. 23 (2010) 014015 (9pp) P. Mele, et al., Physica C, 468, (2008), 1631-1634

An object to be solved by the present invention is to provide a superconducting wire material capable of suppressing quench burnout.

The superconducting wire of the embodiment includes an oxide superconducting layer. The oxide superconducting layer has a continuous perovskite structure containing a rare earth element, barium (Ba), and copper (Cu), and the rare earth element is a first element, neodium (Nd), which is a placeodium (Pr). , At least one second element in the group Samarium (Sm), Europium (Eu) and Gadrinium (Gd), at least in the group Ittrium (Y), Terbium (Tb), Dysprosium (Dy) and Hormium (Ho). It contains one kind of third element and at least one kind of fourth element in the group of elbium (Er), turium (Tm), itterbium (Yb) and lutetium (Lu).

The schematic diagram of the superconducting coil of 1st Embodiment. The schematic sectional view of the superconducting wire material of 1st Embodiment. A transmission electron microscope image of the oxide superconducting layer of the first embodiment. The figure which shows the result of the X-ray diffraction measurement of the oxide superconducting layer of the 1st Embodiment. The figure which shows the result of the X-ray diffraction measurement of the oxide superconducting layer of the 1st Embodiment. The flowchart which shows an example of the coating solution preparation of 1st Embodiment. The flowchart which shows an example of the method of forming a superconductor from the coating solution of 1st Embodiment. The figure which shows the typical calcining profile of 1st Embodiment. The figure which shows the typical main firing profile of 1st Embodiment. The flowchart which shows an example of the method of manufacturing the superconducting coil of 1st Embodiment. Explanatory drawing of operation and effect of 1st Embodiment. Explanatory drawing of operation and effect of 1st Embodiment. Explanatory drawing of operation and effect of 1st Embodiment. Explanatory drawing of operation and effect of 1st Embodiment. Explanatory drawing of operation and effect of 1st Embodiment. Explanatory drawing of operation and effect of 2nd Embodiment. Explanatory drawing of operation and effect of 2nd Embodiment. The block diagram of the superconducting apparatus of 4th Embodiment. The graph which shows the current-voltage characteristic of Comparative Example 1. The graph which shows the current-voltage characteristic of Comparative Example 1. The graph which shows the current-voltage characteristic of Comparative Example 1. The graph which shows the current-voltage characteristic of Comparative Example 1. The graph which shows the current-voltage characteristic of Comparative Example 1. The graph which shows the current-voltage characteristic of Comparative Example 1. The graph which shows the current-voltage characteristic of the comparative example 2. The graph which shows the current-voltage characteristic of the comparative example 2. The graph which shows the current-voltage characteristic of the comparative example 2. The graph which shows the current-voltage characteristic of the comparative example 2. The graph which shows the current-voltage characteristic of Example 1. The graph which shows the current-voltage characteristic of Example 1. The graph which shows the current-voltage characteristic of Example 1. The graph which shows the current-voltage characteristic of Example 1. The graph which shows the current-voltage characteristic of Example 1. The graph which shows the current-voltage characteristic of Example 1. The graph which shows the current-voltage characteristic of Example 5. The graph which shows the current-voltage characteristic of Example 5. The graph which shows the current-voltage characteristic of Example 5. The graph which shows the current-voltage characteristic of Example 5. The graph which shows the current-voltage characteristic of Example 5. The graph which shows the current-voltage characteristic of Example 5.

In the present specification, a crystallographically continuous structure is regarded as a "single crystal". Further, a crystal containing a low tilt angle grain boundary having a difference in the c-axis direction of 1.0 degree or less is also regarded as a “single crystal”.

In the present specification, PA (Pinning Atom) is a rare earth element that serves as an artificial pin of an oxide superconducting layer. PA forms a non-superconducting unit cell. PA is praseodymium (Pr) only.

In the present specification, SA (Supporting Atom) is a rare earth element that promotes clustering of artificial pins. The trivalent ionic radius of SA is smaller than the trivalent ionic radius of PA and larger than the trivalent ionic radius of MA, which will be described later.

In the present specification, MA (Matrix Atom) is a rare earth element that forms a matrix phase of an oxide superconducting layer.

In the present specification, CA (Counter Atom) is a rare earth element that forms a cluster with PA or SA. The trivalent ionic radius of CA is smaller than the trivalent ionic radius of MA.

In the present specification, the first-generation atomically substituted artificial pin (1st-ARP: 1st-Atom Distributed Pin) is the ultimate non-superconducting unit cell containing PA in the matrix phase of the superconducting unit cell containing MA. It means an artificial pin in a dispersed form. Ultimate dispersion is a form in which a non-superconducting unit cell exists alone in the matrix phase.

In the present specification, the second generation clustered atomic substitution type artificial pin (2nd-CARP: 2nd generation-clustered atom replicated pin) is a unit cell containing PA in the matrix phase of the superconducting unit cell containing MA. , A unit cell containing SA and a unit cell containing CA means an artificial pin in a clustered form. The size of the artificial pin is larger than that of 1st-ARP.

In the present specification, a 3rd generation clustered atomic substitution type artificial pin (3rd-CARP: 3rd generation-clustered atom replicated pin) is a unit cell containing PA in the matrix phase of a superconducting unit cell containing MA. And a unit cell containing CA means an artificial pin in a clustered form. It differs from 2nd-CARP in that it does not contain SA.

In the present specification, "superconducting equipment" is a general term for equipment using a superconductor.

Hereinafter, the superconducting coil of the embodiment will be described with reference to the drawings.

(First Embodiment)
The superconducting coil of the present embodiment includes a superconducting wire material. The superconducting wire has an oxide superconducting layer. The oxide superconducting layer has a continuous perovskite structure containing rare earth elements, barium (Ba), and copper (Cu). The rare earth element is ytterbium (Y), which is at least one kind of second element in the group of first element which is placeodium (Pr), neodymium (Nd), samarium (Sm), europium (Eu) and gadolinium (Gd). ), Terbium (Tb), dysprosium (Dy) and holmium (Ho), as well as at least one third element of the group, as well as erbium (Er), turium (Tm), ytterbium (Yb) and lutetium (Lu). Contains at least one fourth element of the group

FIG. 1 is a schematic view of the superconducting coil of the present embodiment. FIG. 1A is a cross-sectional view, and FIG. 1B is a perspective view of a pancake coil which is a part of a superconducting coil.

As shown in FIG. 1A, the superconducting coil 100 has four pancake coils 14a, 14b, 14c, and 14d as shown in FIG. 1B around the axis of the bobbin (winding frame) 12. It is in a laminated state. The pancake coils 14a, 14b, 14c, and 14d are formed by winding the superconducting wire 20 in a spiral shape. Around the pancake coils 14a, 14b, 14c, and 14d, for example, an impregnated resin layer 15 such as an epoxy resin is covered.

The superconducting coil 100 of the present embodiment can take various shapes such as a saddle shape. Further, the superconducting coil 100 of the present embodiment can be used for various purposes such as a heavy particle beam therapy device, a superconducting magnetic levitation type railway vehicle, or a test coil for fusion.

FIG. 2 is a schematic cross-sectional view of the superconducting wire rod of the present embodiment. FIG. 2A is an overall view, and FIG. 2B is an enlarged schematic cross-sectional view of the superconducting wire.

As shown in FIG. 2A, the superconducting wire 20 includes a tape-shaped base material 22, an intermediate layer 24, an oxide superconducting layer 30, and a metal layer 40. The base material 22 enhances the mechanical strength of the oxide superconducting layer 30. The intermediate layer 24 is a so-called oriented intermediate layer. The intermediate layer 24 is provided to orient the oxide superconducting layer 30 to form a single crystal when the oxide superconducting layer 30 is formed. The metal layer 40 is a so-called stabilizing layer. The metal layer 40 protects the oxide superconducting layer 30. Further, the metal layer 40 has a function of bypassing the current even when the superconducting state becomes partially unstable during the actual use of the superconducting wire 20.

The tape-shaped base material 22 is, for example, a metal tape such as a nickel-tungsten alloy. The intermediate layer 24 is, for example, yttrium oxide (Y ₂ O ₃ ), yttria-stabilized zirconia (YSZ), and cerium oxide (CeO ₂ ) from the base material 22 side. The layer structure of the base material 22 and the intermediate layer 24 is, for example, nickel-tungsten alloy / yttrium oxide / yttria-stabilized zirconia / cerium oxide. In this case, the oxide superconducting layer 30 is formed on the cerium oxide.

Further, as the base material 22 and the intermediate layer 24, for example, an IBAD (Ion Beam Assisted Deposition) substrate can be used. In the case of the IBAD substrate, the base material 22 is a non-oriented layer. Further, the intermediate layer 24 has, for example, a five-layer structure. For example, the lower two layers are an unoriented layer, an orientation origin layer produced by the IBAD method is formed on the lower layer, and two layers of a metal oxide oriented layer are formed on the oriented origin layer. In this case, the uppermost oriented layer is lattice-matched with the oxide superconducting layer 30.

The oxide superconducting layer 30 has a continuous perovskite structure containing rare earth elements, barium (Ba), and copper (Cu). The rare earth element is ytterbium (Y), which is at least one kind of second element in the group of first element which is placeodium (Pr), neodymium (Nd), samarium (Sm), europium (Eu) and gadolinium (Gd). ), Terbium (Tb), dysprosium (Dy) and holmium (Ho), as well as at least one third element of the group, as well as erbium (Er), turium (Tm), ytterbium (Yb) and lutetium (Lu). Includes at least one fourth element of the group.

Hereinafter, the first element is referred to as PA (Pinning Atom), the second element is referred to as SA (Supporting Atom), the third element is referred to as MA (Matrix Atom), and the fourth element is referred to as CA (Counter Atom).

The oxide superconducting layer 30 of the present embodiment includes a second generation clustered atomic substitution type artificial pin (2nd-CARP).

The type of rare earth element contained in the oxide superconducting layer 30 can be identified by using SIMS (Seconday Ion Mass Spectrometry).

The oxide superconducting layer 30 is a single crystal having a continuous perovskite structure. The perovskite structure is described by, for example, REBa ₂ Cu ₃ O _7-y (−0.2 ≦ y ≦ 1) (hereinafter, REBCO). RE is a rare earth site.

The layer thickness of the oxide superconducting layer 30 is, for example, 0.1 μm or more and 10 μm or less. The oxide superconducting layer 30 is, for example, all single crystals in the layer thickness direction.

Further, the single crystal exists, for example, in the oxide superconducting layer 30 within a range of 50 nm or more from the base material 22 side of the oxide superconducting layer 30 and 70% or less of the average layer thickness of the oxide superconducting layer 30. To do. The single crystal has a size of, for example, 500 nm × 100 nm or more in the cross section of the oxide superconducting layer 30 in the layer thickness direction.

The oxide superconducting layer 30 includes, for example, fluorine of 2.0 × 10 ¹⁵ atoms / cc or more and 5.0 × 10 ¹⁹ atoms / cc or less, and 1.0 × 10 ¹⁷ atoms / cc or more and 5.0 × 10 ²⁰ atoms. Contains carbon of / cc or less. Fluorine and carbon contained in the oxide superconducting layer 30 are residual elements resulting from the film formation of the oxide superconducting layer 30 by the TFA-MOD method. Fluorine and carbon in the oxide superconducting layer 30 are present at, for example, the grain boundaries of a single crystal.

The concentration of fluorine contained in the oxide superconducting layer 30 is, for example, 2.0 × 10 ¹⁶ atoms / cc or more. The concentration of carbon contained in the oxide superconducting layer 30 is, for example, 1.0 × 10 ¹⁸ atoms / cc or more.

The concentrations of fluorine and carbon in the oxide superconducting layer 30 can be measured using, for example, SIMS.

The metal layer 40 is, for example, a metal whose base material is silver (Ag) or copper (Cu), and may be an alloy. It may also contain a small amount of precious metal such as gold (Au).

FIG. 2B is an enlarged schematic cross-sectional view of the oxide superconducting layer 30 as viewed from above the membrane, that is, from the c-axis direction. Each rectangle represents a unit cell in a single crystal.

In FIG. 2B, PA is praseodymium (Pr), SA is samarium (Sm), MA is yttrium (Y), and CA is lutetium (Lu). The oxide superconducting layer 30 is composed of a unit cell of PBCO containing praseodymium (Pr), SmBCO containing samarium (Sm), YBCO containing yttrium (Y), and LuBCO containing lutetium (Lu).

The squares indicating the PrBCO, SmBCO, and LuBCO unit cells are marked with Pr, Sm, and Lu, respectively. The blank quadrangle in the figure is a unit cell of YBCO which is a matrix phase.

In the oxide superconducting layer 30, the unit cells of PrBCO, SmBCO, and LuBCO form an aggregate in YBCO, which is a matrix phase. This aggregate is called a cluster. In FIG. 2B, the area surrounded by the thick solid line is the cluster.

PrBCO is a non-superconductor. The cluster containing PrBCO functions as an artificial pin of the oxide superconducting layer 30.

The relationship between the trivalent ionic radii of praseodymium (Pr), samarium (Sm), yttrium (Y), and lutetium (Lu) is Pr> Sm> Y> Lu. In the cluster, PrBCO and SmBCO containing rare earth elements larger than YBCO, which is a matrix phase, and LuBCO containing rare earth elements smaller than YBCO are aggregated. Hereinafter, a unit cell containing a rare earth element larger than the matrix phase is referred to as a large unit cell, and a unit cell containing a rare earth element smaller than the matrix phase is referred to as a small unit cell.

The unit cell containing MA is in the matrix phase. Among the rare earth elements contained in the oxide superconducting layer 30, the amount of MA is the largest. For example, when the number of atoms of the rare earth element is N (RE) and the number of atoms of MA, which is the third element, is N (MA), N (MA) / N (RE) ≥ 0.6. In other words, the molar ratio of MA in the rare earth element contained in the oxide superconducting layer 30 is 0.6 or more.

The quantitative ratio of the number of atoms or the number of moles of the rare earth element in the oxide superconducting layer 30 can be calculated based on, for example, the result of measuring the concentration of the element by SIMS.

FIG. 3 is a transmission electron microscope (TEM) image of the oxide superconducting layer 30 of the present embodiment. More specifically, it is a HAADF-STEM (High-Angle Anal Dark Field Scanning TEM) image.

It is an observation image of 4 million times. FIG. 3 is a cross section of the oxide superconducting layer 30 in the layer thickness direction, that is, in the direction parallel to the c-axis. Cross section of a sample having 4%, 4%, and 8% atomic numbers of praseodymium (Pr), samarium (Sm), and lutetium (Lu) when the number of atoms of rare earth elements in the oxide superconducting layer 30 is 100%. It is a figure.

From the observation image of FIG. 3, the perovskite structure oriented at the atomic level can be confirmed. It can be seen that there is no different phase in the oxide superconducting layer 30 and unit cells having the same lattice constant are lined up. In other words, the oxide superconducting layer 30 in FIG. 3 is a single crystal having a perovskite structure.

In FIG. 3, all are single crystals having a perovskite structure in the layer thickness direction. The single crystal has a size of 500 nm × 100 nm or more.

In FIG. 3, the area shown by the white solid line frame is a cluster. Of the three rows of atoms arranged horizontally in the solid white frame, the upper and lower two rows are barium (Ba) site atoms. The row sandwiched between them is the atom of the rare earth site.

Similarly, in the area shown by the white dashed frame, of the three rows of atoms arranged in the horizontal direction, the upper and lower two rows are the atoms of the barium (Ba) site, and the one row sandwiched between them is the atom of the rare earth site. Is. The atoms of the rare earth site in the area shown by the white solid line frame are brighter than the atoms of the rare earth site in the area shown by the white dashed line frame.

In the HAADF-STEM image, elements with a large atomic weight glow brighter. The area shown by the white solid line frame contains praseodymium (Pr), samarium (Sm), and lutetium (Lu), which have a larger atomic weight than yttrium (Y), so it is considered to be brighter than the area shown by the white dashed line frame. Be done.

For example, in the HAADF-STEM image of the oxide superconducting layer 30, when the brightness of barium is I (Ba) and the brightness of rare earth elements sandwiched between barium is I (RE), I (I (RE) in the first region There are a first region and a second region in which RE) / I (Ba) is 1.3 times or more the I (RE) / I (Ba) of the second region. The first area is a cluster.

The first region and the second region are, for example, 10 atoms of one row of rare earth sites arranged horizontally and 10 atoms of each of the upper and lower two rows of barium sites sandwiching the rare earth site, as shown in FIG. And is an area having. In FIG. 3, the white solid line frame is the first region, and the white broken line frame is the second region.

As can be seen from the TEM image of FIG. 3, the barium site is distorted by the lattice, and the angle of the distortion seems to exceed 1 degree. However, as can be seen from FIG. 3, the interatomic distances that are clearly adjacent to each other are almost equal, and it can be considered that a bond as a crystal exists. Therefore, the structure of FIG. 3 is defined as a single crystal.

4 and 5 are diagrams showing the results of X-ray diffraction (XRD) measurement of the oxide superconducting layer 30 of the present embodiment. The oxide superconducting layer was measured by the 2θ / ω method of XRD measurement.

FIG. 4 shows the results of measuring YBCO samples containing no rare earth elements other than yttrium and samples in which the proportions of placeodium, samarium, yttrium, and lutetium in the rare earth elements were 4%, 4%, 84%, and 8%. is there. In addition, FIG. 5 shows a sample in which the ratio of praseodymium, samarium, yttrium, and lutetium in the rare earth elements is 1%, 1%, 96%, and 2%, and the ratio of praseodymium, samarium, yttrium, and lutetium in the rare earth elements is 2. This is the result of measuring%, 2%, 92%, and 4% of the samples.

In FIG. 4, even in the sample containing praseodymium, samarium, and lutetium, the peak coincides with the peak of YBCO, and no other clear peak is confirmed. In addition, no peak separation was observed even in samples containing praseodymium, samarium, and lutetium. Therefore, it can be seen that the sample containing praseodymium, samarium, and lutetium is also a single crystal having a continuous perovskite structure.

In FIG. 5, no peak separation is observed. Therefore, it can be seen that the sample containing praseodymium, samarium, and lutetium is a single crystal having a continuous perovskite structure.

The peak of LAO used on the substrate also appears in FIGS. 4 and 5.

Next, a method of manufacturing the superconducting coil 100 of the present embodiment will be described. First, the superconducting wire 20 is manufactured. The intermediate layer 24 is formed on the tape-shaped base material 22, the oxide superconducting layer 30 is formed on the intermediate layer 24, and the metal layer 40 is formed on the oxide superconducting layer 30. The oxide superconducting layer 30 is formed by the TFA-MOD method.

The formation of the oxide superconducting layer 30 is first of all at least one of the group of acetate of the first element, placeodium (Pr), neodium (Nd), samarium (Sm), uropium (Eu) and gadrinium (Gd). Acetate of the second element, yrbium (Y), terbium (Tb), dysprosium (Dy) and formium (Ho), the acetate of at least one of the third elements, erbium (Er), turium ( Prepare an aqueous solution containing an acetate of at least one fourth element in the group Tm), itterbium (Yb) and lutetium (Lu), an acetate of barium (Ba), and an acetate of copper (Cu). .. Next, the aqueous solution is mixed with a perfluorocarboxylic acid mainly containing trifluoroacetic acid to prepare a mixed solution, and the mixed solution is reacted and purified to prepare a first gel. Next, an alcohol containing methanol is added to the first gel and dissolved to prepare an alcohol solution, and the alcohol solution is reacted and purified to prepare a second gel. Next, alcohol containing methanol is added to the second gel and dissolved to prepare a coating solution having a total weight of residual water and residual acetic acid of 2% by weight or less, and the coating solution is applied onto the substrate to form a gel film. To form. Next, the gel film is calcined at 400 ° C. or lower to form a calcined film. Next, the calcined film is subjected to main firing at 725 ° C. or higher and 850 ° C. or lower and oxygen annealing in a humidified atmosphere to form an oxide superconductor film, that is, an oxide superconducting layer 30.

The perfluorocarboxylic acid preferably contains 98 mol% or more of trifluoroacetic acid from the viewpoint of not deteriorating the superconducting properties.

FIG. 6 is a flowchart showing an example of preparing the coating solution of the present embodiment. Hereinafter, PA, which is the first element, is praseodymium (Pr), SA, which is the second element, is samarium (Sm), MA, which is the third element, is yttrium (Y), and CA, which is the fourth element, is lutetium. The case of (Lu) will be described as an example.

As shown in FIG. 6, metal acetates of yttrium, praseodymium, samarium, lutetium, barium, and copper are prepared (a1). In addition, trifluoroacetic acid is prepared (a2). Next, the prepared metal acetate is dissolved in water (b) and mixed with the prepared trifluoroacetic acid (c). The obtained solution is reacted and purified (d) to obtain a first gel containing impurities (e). Then, the obtained first gel is dissolved in methanol (f) to prepare a solution containing impurities (g). The obtained solution is reacted and purified to remove impurities (h) to obtain a second gel containing a solvent (i). Further, the obtained second gel is dissolved in methanol (j) to prepare a coating solution (k).

As the metal acetate, the metal salt is mixed at RE site (Y, Pr, Sm, Lu): Ba: Cu = 1: 2: 3. Mix so that the amount of Pr in the RE site is 0.00000001 or more and 0.20 or less. After the mixing and reaction, the amount of residual water and acetic acid in the coating solution is reduced to 2 wt% or less by a high-purity solution purification process by the SIG (Stabilized Sevent-Into-Gel) method. The SIG method of the present embodiment is a method for purifying a solution for partial stabilization in order to prevent decomposition of PrBCO, and is a PS-SIG (Partially Stabilized Sevent-Into-Gel) method. The amount of Pr / (Y + Pr + Sm + Lu) is mixed so as to be, for example, 0.0025.

FIG. 7 is a flowchart showing an example of a method of forming a superconductor from the coating solution of the present embodiment.

As shown in FIG. 7, first, the previously prepared coating solution is prepared (a). A coating solution is applied onto a substrate by, for example, a die coating method to form a film (b) to obtain a gel film (c). Then, the obtained gel film is subjected to calcining, which is a primary heat treatment, to decompose organic substances (d), and a calcined film is obtained (e). Further, the calcined film is subjected to main firing, which is a secondary heat treatment (f), and then, for example, pure oxygen annealing is performed (h) to obtain an oxide superconductor film (h).

FIG. 8 is a diagram showing a typical calcining profile of the present embodiment. Trifluoroacetic acid is mainly decomposed at 200 ° C. or higher and 250 ° C. or lower in the calcining under normal pressure. The rate of temperature rise is lowered near 200 ° C. to prevent entry into the temperature range. When the temperature is gradually raised to 250 ° C., the substance decomposed from the trifluoroacetic acid salt contains fluorine and oxygen, and the fluorine and oxygen tend to remain in the membrane due to hydrogen bonds. The temperature is raised to 400 ° C. to remove the substance. The final temperature is generally 350 to 450 ° C. In this way, a translucent brown calcined film composed of oxides and fluorides is obtained.

FIG. 9 is a diagram showing a typical firing profile of the present embodiment. It is a dry mixed gas up to tb1 at 100 ° C., and humidification is performed from there. The humidification start temperature may be 100 ° C. or higher and 400 ° C. or lower. It is considered that the formation of the pseudo-liquid layer starts from around 550 ° C., and the humidification is performed at a temperature lower than that so that the humidifying gas is distributed inside the film so that the pseudo-liquid layer is uniformly formed.

FIG. 9 shows a typical temperature profile of 800 ° C. main firing, but the temperature rise profile is gradual at 775 ° C. or higher and 800 ° C. or lower so that there is no temperature overshoot at tb3. Even with this, the overshoot at 800 ° C. can remain at 2 to 3 ° C., but this is not a particular problem. The partial pressure of oxygen at the maximum temperature depends on the matrix phase. In the case of firing the YBCO superconductor, the optimum oxygen partial pressure is halved at 800 ° C. for 1000 ppm, and then every time the temperature drops at 25 ° C. That is, it is 500 ppm at 775 ° C. and 250 ppm at 750 ° C. In the case of the YBCO system, YBa ₂ Cu ₃ O ₆ is formed in this main firing. At this point it is not a superconductor.

In the highest temperature main firing, dry gas is flowed at tb4 before the main firing is completed and the temperature starts to be lowered. Since the humidifying gas decomposes the superconductor to become an oxide at 700 ° C. or lower, oxygen annealing is performed at tb6 to set the oxygen number of the superconductor from 6.00 to 6.93. It becomes a superconductor with this oxygen number. However, although PrBCO has a perovskite structure, it is not a superconductor. Moreover, since the valence of Pr is unknown, the oxygen number of the unit cell is also unknown, but it seems that the oxygen number is high. This is because the valence of Pr takes a value between 3 and 4, and the number of oxygen increases accordingly in the unit cell. The starting temperature of oxygen annealing is 375 ° C or higher and 525 ° C or lower. After the temperature is maintained, the furnace is cooled from tb8.

The superconducting wire 20 including the oxide superconducting layer 30 is manufactured by the above manufacturing method.

FIG. 10 is a flowchart showing an example of a method of manufacturing the superconducting coil 100 from the superconducting wire 20 of the present embodiment.

As shown in FIG. 10, first, the superconducting wire 20 manufactured earlier is prepared (a). Next, the superconducting wire 20 is wound around the shaft of the bobbin 12 to form the pancake coils 14a, 14b, 14c, 14d (b). The pancake coils 14a, 14b, 14c, and 14d in this state are non-impregnated coils (c). Then, the pancake coils 14a, 14b, 14c, 14d are impregnated with a resin such as an epoxy resin (d). An impregnated resin layer 15 is formed around the pancake coils 14a, 14b, 14c, and 14d to form an impregnated coil (e).

The impregnated coil has higher mechanical strength than the non-impregnated coil.

The superconducting coil 100 of the present embodiment is manufactured by the above manufacturing method.

Next, the operation and effect of the superconducting coil 100 of the present embodiment will be described.

The superconducting coil 100 of the present embodiment uses a superconducting wire 20 having clustered PrBCO as an artificial pin. Since the superconducting wire 20 has excellent magnetic field characteristics, the characteristics of the superconducting coil 100 used in a magnetic field are improved. Further, by using the superconducting wire material 20, it is possible to suppress a quench burnout accident of the superconducting coil 100. Further, by using the superconducting wire material 20, a superconducting coil 100 that generates a stable magnetic field is realized.

First, the improvement of the magnetic field characteristics by the superconducting wire 20 of the present embodiment will be described.

The superconducting wire 20 of the present embodiment contains a matrix phase YBCO in the oxide superconducting layer 30. PrBCO, which is a non-superconductor, is clustered in the matrix phase together with SmBCO and LuBCO, which are superconductors. This cluster functions as an artificial pin at the atomic level, improving the magnetic field characteristics.

The oxide superconducting layer 30 of the present embodiment is composed of PA, SA, MA, and CA. Causes a clustering phenomenon in SA and CA. PA is incorporated into the cluster as part of the SA to form a clustered atom-replaced pin (CARP). This clustered atom-replacement artificial pin improves the magnetic field characteristics.

FIG. 11 is an explanatory diagram of the operation and effect of the present embodiment. FIG. 11 is a diagram showing the relationship between the magnetic field and the critical current density of the superconducting wire 20 of the present embodiment. The measurement result at a temperature of 77K is shown.

A sample of YBCO containing no rare earth element other than yttrium (in FIG. 11, marked with a cross), which is a comparative form, and the proportions of placeodium, sumalium, yttrium, and lutetium in the rare earth elements of this embodiment are 1%, 1%, and 96%. , 2% sample (square mark in FIG. 11), 2%, 2%, 92%, 4% of rare earth elements of placeodium, samarium, yttrium, lutetium (triangle mark in FIG. 11), This is the result of measuring samples (circles in FIG. 11) in which the ratios of placeodium, samarium, yttrium, and lutetium in the rare earth elements are 4%, 4%, 84%, and 8%. The horizontal axis is the magnetic field (T) and the vertical axis is the Jc value (MA / cm ² ).

As is clear from FIG. 11, in the present embodiment, a higher critical current density can be obtained as compared with the comparative embodiment, especially in the region exceeding 3T.

The ratio (Pr ratio) of praseodymium to the rare earth elements is preferably 10 ppb (= 0.00000001) or more. When it is 10 ppb or more, the effect of improving the magnetic field characteristics can be obtained.

When the number of atoms of the rare earth element is N (RE) and the number of atoms of the first element which is PA, that is, praseodymium is N (PA), the Pr ratio can be described as N (PA) / N (RE). .. Therefore, it is desirable that 0.00000001 ≦ N (PA) / N (RE).

When the ratio of praseodymium to the total sum of praseodymium and samarium is larger than 50%, the Jc value decreases. Further, if the proportion of praseodymium is less than 5%, the effect of improving the magnetic field characteristics may not be obtained.

Therefore, when the number of atoms of the first element which is PA is N (PA) and the number of atoms of the second element which is SA is N (SA), 0.05 ≦ N (PA) / (N). It is desirable that (PA) + N (SA)) ≦ 0.5.

When the number of atoms of the rare earth element is N (RE) and the number of atoms of the third element which is MA is N (MA), it is desirable that N (MA) / N (RE) ≥ 0.6. .. If it falls below the above range, the proportion of superconducting unit cells decreases, and sufficient superconducting characteristics may not be obtained.

When the number of atoms of the third element, which is MA, is N (MA) and the number of atoms of yttrium contained in the third element is N (Y), N (Y) / N (MA) ≥ 0. It is desirable that it is 5. Since the material of yttrium (Y) is relatively inexpensive, the cost of the superconducting wire 20 can be reduced.

When the number of atoms of the rare earth element is N (RE), the number of atoms of the first element which is PA is N (PA), and the number of atoms of the second element which is SA is N (SA), It is desirable that N (PA) + N (SA)) / N (RE) ≦ 0.2. Further, it is more desirable that (N (PA) + N (SA)) / N (RE) ≦ 0.1. If it exceeds the above range, the proportion of superconducting unit cells decreases, and there is a risk that sufficient superconducting characteristics cannot be obtained.

The number of atoms of the first element, which is PA, is N (PA), the number of atoms of the second element, which is SA, is N (SA), and the number of atoms of the fourth element, which is CA, is N (CA). In some cases, it is desirable that 0.8 × N (CA) ≦ N (PA) + N (SA) ≦ 1.2 × N (CA). If the above conditions are not satisfied, the number of PAs, SAs, or CAs that do not form a cluster may increase, and the superconducting characteristics may decrease.

The oxide superconducting layer 30 contains fluorine of 2.0 × 10 ¹⁵ atoms / cc or more and 5.0 × 10 ¹⁹ atoms / cc or less, and 1.0 × 10 ¹⁷ atoms / cc or more and 5.0 × 10 ²⁰ atoms / cc. It is desirable to include the following carbons.

Residual fluorine and residual carbon are considered to have the effect of maintaining magnetic field characteristics in a very high magnetic field exceeding, for example, 15 T.

From the above viewpoint, it is more desirable that the amount of fluorine contained in the oxide superconducting layer 30 is 2.0 × 10 ¹⁶ atoms / cc or more. Further, it is more desirable that the carbon contained in the oxide superconducting layer 30 is, for example, 1.0 × 10 ¹⁸ atoms / cc or more.

It is assumed that clusters containing PrBCO are not formed in the oxide superconducting layer, and PrBCO is ultimately dispersed in the matrix phase of YBCO. The ultimate dispersion is a state in which PrBCO is dispersed in the matrix phase of YBCO as a single unit cell.

It is considered that Pr forms a perovskite structure with trivalent and then becomes tetravalent to make the unit cell non-superconducting. At that time, it is considered that 1/3 of the perovskite unit cell containing Pr contracts by about 14% and becomes non-superconducting. It is considered that the deformation propagates to the first adjacent unit cell in the a / b plane, and the four unit cells are also non-superconducting. In this way, when the clusters are not formed and Pr is ultimately dispersed, a "5-fold deterioration phenomenon" (5 times degradation phenomenon) in which Jc deterioration of 5 times the amount of Pr is observed is confirmed.

Next, the effect of suppressing the quench burnout accident of the superconducting coil of the present embodiment and the effect of stabilizing the generated magnetic field will be described.

As described above, the superconducting wire material formed by the physical vapor deposition method is prone to quench burnout accidents. The cause is considered to be the internal bypass current (IBC). In IBC, it is considered that the current meanders in the superconducting wire, and the energy that does not contribute to the formation of the magnetic field becomes thermal energy, causing a quench burnout accident. Further, it is considered that the magnetic field generated by the superconducting coil becomes unstable due to IBC.

IBC is considered to be caused by the difference in the local Critical Temperature (Tc) inside the superconducting wire. When the superconducting wire has different Tc points, the local Critical Density (Jc) value, that is, the local Critical Current (Ic) value of each place is different. IBC is always formed in a superconductor with a reduced Tc. For example, in a good Jc YBa ₂ Cu ₃ O _7-x (YBCO), Tc = 90.7K, but IBC is also formed in Tc = 89.7K. To.

If there is a difference in local current flowability at 77K, the tendency seems to be unchanged even when cooling at 30K, for example. For superconductors with similar configurations, the Jc-BT curve shows a similar tendency. Therefore, it is easy for the current to flow where it is easy to flow at 77K or 30K. The number of points of reversal is not zero, but it seems that this tendency will be maintained as a whole. Therefore, IBC is considered to occur even at low temperatures.

The BZO artificial pin itself acts as an obstacle and also reduces ambient oxygen to make it non-superconducting and form an IBC. Even in the superconducting wire material of the TFA-MOD method, Tc is lowered by irradiation. That is, it seems that IBC is formed by irradiation even in the superconducting wire material produced by the TFA-MOD method.

Steady state measurement of IBC is quite difficult. For example, in the case of a superconducting wire that requires 0.01% of magnetic field accuracy, the instantaneous fluctuation of the current value is also at the 0.01% level. Of course, since the quench of superconductors is measured at μV, it is difficult to observe displacements that are several orders of magnitude smaller than this, and it is necessary to magnify the influence of IBC. For that purpose, it seems effective to increase the current value in a short time for measurement.

When the current value is significantly increased in a short time, the electromotive force of noise due to the IBC becomes large if the IBC is present, and the measurement becomes easy. From this, it is considered that the presence of IBC can be indirectly measured and the magnitude of the possibility of quench burnout accident when the coil is formed can be known.

This is the IBC indirect measurement method. The current value up to Ic is measured by increasing the current in about 4 seconds (measured in 5 seconds to a current value of 1.25 times the Ic value), and the voltage fluctuation up to 90% of the Ic value is defined as V (IBC). You can compare by defining.

In the IBC indirect measurement method, V (IBC), which is the fluctuation of the voltage, is obtained. By comparing V (IBC) between the materials, it is considered that the possibility of quench burning accident can be compared.

The definition of V (IBC) calculation is as follows. The current is increased to the Ic value in a certain time (4 seconds in this case), and the maximum voltage Vmax and the minimum voltage Vmin observed in the data up to 90% of the Ic value are used, and the background noise of the measurement system is 0.20 μV. Calculated by subtracting. That is, V (IBC) is represented by the following equation.
V (IBC) = Vmax-Vmin-0.20

Indirect IBC measurement of superconducting wire with BZO artificial pins manufactured by physical vapor deposition confirms an extremely large V (IBC). At 50K / 5T, V (IBC) = 36.05μV. Since it is a value in which the current is increased in a short time, it cannot be directly compared with 1 μV / cm, which is a superconducting transition, but it is no wonder that IBC is the cause of quench burnout.

There are also superconducting wires that generate almost no IBC. It is a superconducting wire made by the TFA-MOD method and having a Dy ₂ O ₃ artificial pin with a diameter of 20 nm to 30 nm inside. In this superconducting wire, the perovskite structure of YBCO is maintained, and the Tc is 90.7K. At 50K / 5T, V (IBC) = 0.14μV, which is V (IBC) which is only 1/250 of the wire rod of the physical vapor deposition method.

The reason why the V (IBC) of the superconducting wire having the Dy ₂ O ₃ artificial pin manufactured by the TFA-MOD method is small is that the current travels straight through most of the internal perovskite structure, and the current flows to Dy ₂ O ₃ . It seems that it is to detour only when it hits. In the BZO artificial pin, Tc is locally different, and local Ic and Jc are also different, so it is considered that the current does not always travel straight. The presence or absence of IBC can be rephrased as the presence or absence of this linear current.

However, the effect of the artificial pin can hardly be expected in the superconducting wire material having the Dy ₂ O ₃ artificial pin. This is because Dy ₂ O ₃ grows freely under the simulated liquid phase at the time of main firing and grows to a size of 20 nm to 30 nm. It is too large to function as an artificial pin.

As described above, in the Y-based superconducting wire, when a coil is formed of a wire having a large V (IBC), excess energy is lost and heat is generated, which is considered to lead to a quench burnout accident. It is also considered that the generated magnetic field is not stable. On the other hand, in the TFA-MOD method wire rod having a small V (IBC), the artificial pin force cannot be expected, so that the magnetic field characteristics are not improved.

Therefore, if a superconducting wire having a small V (IBC) and an effective artificial pin is produced, it can be expected to suppress quench burning accidents. In addition, the stability of the forming magnetic field can be expected.

FIG. 12 is an explanatory diagram of the operation and effect of the present embodiment. FIG. 12 is a schematic view showing the internal structure of a superconducting wire having a Dy ₂ O ₃ artificial pin manufactured by the TFA-MOD method. Dy ₂ O ₃ is formed in the matrix phase of YBCO. Dy ₂ O ₃ has, for example, a diameter of 20 nm to 30 nm.

In the superconducting wire of FIG. 12, the matrix phase of YBCO maintains a perovskite structure and the Tc is 90.7K. It shows a high value in Jc measurement in liquid nitrogen. This indicates that there are few parts where Tc is lowered and that the superconducting current flows sufficiently even at the liquid nitrogen temperature.

In the TFA-MOD method, a pseudo liquid phase is formed at the time of firing and the unit cell grows. Therefore, particles such as Dy ₂ O ₃ that do not form a perovskite structure tend to gather independently and grow large.

When a superconducting current is energized, most of the current flows linearly. However, it bypasses where it hits the Dy ₂ O ₃ particles. A current bypass index Ib is defined to represent the degree of current bypass. The current bypass index Ib is an index showing how much the current is reduced from the amount that should flow due to the occurrence of IBC. The current bypass index Ib can be calculated geometrically.

FIG. 13 is an explanatory diagram of the operation and effect of the present embodiment. FIG. 13 is an explanatory diagram of how to obtain the current bypass index Ib in a superconducting wire having an artificial pin.

As shown in FIG. 13A, the artificial pin is assumed to be a sphere having a radius R, the artificial pin spacing is Dp, and the artificial pin introduction volume ratio is Rvp.

The artificial pin introduction volume ratio Rvp can be expressed as follows.
^{Rvp = (4πR 3/3)} / (πR 2 Dp)
= 4R / (3Dp)

Therefore, the artificial pin spacing Dp can be expressed as follows.
Dp = 4R / (3Rvp)

In order for the current at the position r from the center of the artificial pin shown in FIG. 13 (b) to bypass the artificial pin, it is necessary to move (R-r). Integral is performed to obtain the average value (average moving distance Dm) of the moving distance of the entire superconducting wire.

The average moving distance Dm can be expressed as follows.
^{Dm = (πR 3/3)} / πR 2 = R / 3

The average moving distance Dm is the distance that the current moves laterally on average while the current travels between the distances Dp. The average current bypass ratio (Rib) can be calculated as follows.
Rib = Dm / Dp
= (R / 3) / (4R / 3Rvp)
= Rbp / 4

The average current detour ratio (Rib) is an index showing how much the current moves in the direction perpendicular to the stretching direction when the current advances by a unit length in the stretching direction of the wire rod. It can be seen that Rib does not depend on the radius R of the artificial pin, but only on the artificial pin introduction volume ratio Rvp.

The current bypass index Ib can be calculated as follows.
Ib = 1-cosθ
tan θ = Rib = Rbp / 4
θ = arctan (Rbp / 4)
Ib = 1-cos {arctan (Rbp / 4)}

The current bypass index Ib also does not depend on the radius R of the artificial pin, but only on the artificial pin introduction volume ratio Rvp. The current bypass index Ib indicates how much the current is less than the amount that should flow when the actual current travels at an angle θ.

Taking an extreme case as an example, if the current advances at an angle of 45 degrees, the current in the current direction becomes smaller by about 29%, so the amount of loss is expressed as Ib. That is, Ib = 29%.

Table 1 shows the calculated values of the current bypass index Ib with respect to the artificial pin introduction volume ratio Rbp.

If the artificial pin maintains Tc, even if Rbp = 20%, Ib = 0.12%. Even if the artificial pin introduction volume ratio is 20%, only this amount of bypass current is generated. Therefore, the influence of IBC will be suppressed to a small extent.

In the superconducting wire material in which Tc is maintained, the amount of bypass current is small. However, as described above, if the artificial pin size is large as in the Dy ₂ O ₃ artificial pin, the effect of improving the magnetic field characteristics cannot be expected.

FIG. 14 is an explanatory diagram of the operation and effect of the present embodiment. FIG. 14 is a schematic view showing the internal structure of a superconducting wire having a BaZrO ₃ (BZO) artificial pin manufactured by a physical vapor deposition method.

The BZO artificial pin has a perovskite structure, and the size of the artificial pin can be made smaller than that of Dy ₂ O ₃ . However, since there is a lattice mismatch of about 9% between BZO and YBCO, there is a gap between BZO and YBCO. The non-superconductivity of the void portion is increased.

Further, it is known that when YBCO and BZO are adjacent to each other, Jc and Tc of YBCO decrease because BZO extracts oxygen of YBCO. Therefore, it is considered that a structure having an internal distribution of Tc as shown in FIG. 14 is formed. In FIG. 14, the dark hatched region in the YBCO matrix phase is the low Tc region, and the light hatched region is the high Tc region.

In many cases, the region where Tc is low is the region where the Jc value is small in the comparison of the same temperature. With superconducting wires having the same configuration, the magnitude of the Jc value inside the wire maintains the same tendency as high temperature even at low temperatures. The existence of a difference in Jc value inside the wire leads to the formation of IBC.

The influence of IBC is particularly large when a current with a magnitude close to the Jc value is passed. When the current is small compared to the Jc value, the current flows straight because the current capacity in each region has a relatively large margin. However, when a current is passed in the vicinity of the Jc value, there is almost no region where the current capacity has a surplus in the entire wire rod, and the influence of the current bypass inside the wire rod becomes large.

It is presumed that the stronger the magnetic field, the greater the effect of IBC. FIG. 14 shows a state in which the current flows from right to left, but the individual currents deviate from the vector direction. It is considered that the component flowing in the current direction becomes smaller than 100%, and the surplus becomes heat energy, which further increases the possibility of quench burning accident.

In order to achieve both improvement of the magnetic field characteristics and suppression of quench burnout accident, for example, it is conceivable to make the Dy ₂ O ₃ artificial pin of FIG. 12 small or reduce the influence of the BZO artificial pin of FIG.

However, if a different phase other than the perovskite structure is formed during the main firing of the TFA-MOD method, the growth occurs in the liquid phase at 800 ° C. Therefore, it is difficult to make the Dy ₂ O ₃ artificial pin smaller than ₂₀ nm to 30 nm because the grain growth is fast. Also, even in the physical vapor deposition method, the pins that do not form a perovskite structure become large as well.

On the other hand, artificial pins that form a perovskite structure, such as BZO artificial pins, have non-uniform superconducting characteristics due to the formation of gaps in the lattice or the extraction of oxygen. Therefore, it is also difficult to reduce the influence of the BZO artificial pin on the superconducting characteristics.

FIG. 15 is an explanatory diagram of the operation and effect of the present embodiment. FIG. 15 is a schematic view showing the internal structure of the superconducting wire 20 of the present embodiment.

FIG. 15 is an enlarged schematic cross-sectional view of the oxide superconducting layer 30 observed so that the lower side is the base material 22 and the upper side is the metal layer 40. Each rectangle represents a unit cell in a single crystal. The c-axis length of the unit unit cell is about three times the a-axis length and the b-axis length. Therefore, when the unit cell is observed, it is observed as shown in FIG.

In FIG. 15, a blank square indicates a unit cell having matrix phase atoms (MA: Matrix Atoms) at a rare earth site. For example, the element that enters the rare earth site is Y. Those shown by horizontal lines are atoms (PA: Pinning Atom) that become artificial pins. Pr is the only rare earth element that forms PA. The unit cell shown by the vertical line is an atom (SA: Supporting Atoms) of the supporting phase, and for example, Sm or the like is used. It may be established without SA alone. The unit cell indicated by the check pattern is a counter phase atom (CA: Counter Atoms). For example, Yb is used for rare earth sites.

MA accounts for 60% of the number of elements. The type of element of MA is not limited to one, and Gd, Ho, Dy, etc. may be used in addition to Y. The upper limits of PA + SA and CA are 20% each. PA and SA are large unit cells when the perovskite structure is formed, and CA is a small unit cell. These large and small unit cells are integrated by a clustering phenomenon that aggregates due to shape anisotropy. FIG. 15 illustrates a state in which they are assembled in two places.

In FIG. 15, unit cells adjacent to the PA in the a / b axis direction become non-superconducting, and in a cluster in which a certain amount of unit cells are integrated, the superconducting state is reduced by 75% on average to become an artificial pin. The blank portion is a YBCO superconductor, and Tc is considered to be 90.7K except for the portion adjacent to Pr. Therefore, the superconducting current flows straight in the stretching direction of the wire rod as shown in FIG. 15, except for the clustered artificial pin (CARP). Therefore, it is possible to improve the magnetic field characteristics and suppress quench burnout accidents.

The superconducting coil 100 of the present embodiment includes an artificial pin having a small size, so that the magnetic field characteristics are improved. Moreover, since the decrease in Tc of the matrix phase can be suppressed, the influence of IBC can be reduced.

It is thought that IBC generates an unnecessary voltage when a superconducting current flows, and at the same time, energy loss leads to the generation of thermal energy, which causes a quench burnout accident.

CARP of this embodiment is a system in which YBCO is MA, and even if 4% Pr (PA), 4% Sm (SA), and 8% Lu (CA) are added, almost no IBC is generated. As described above, since it is difficult to directly observe IBC, the current value can be increased to near Jc in a short time and examined by the IBC indirect measurement method for detecting V (IBC).

For example, in the above configuration, V (IBC) = 0.11 μV at 50 K / 5T, which is a considerably small value.

It should be noted that V (IBC) is disadvantageous when the calculated Ic value is large. With the involvement of the inductance component, V (IBC) is proportional to the current. Since the current increases to the Ic value in about 4 seconds, the current flows in a direction other than the original current component. Even when V (IBC) is generated by the Lorentz force in the magnetic field applied to the current, it is still proportional to the current value. Therefore, the degree of influence of the internal bypass current If (IBC) (Influence of IBC) is considered to be represented by the quotient of the Ic value as follows.
If (IBC) = V (IBC) / Ic

At present, it is not always possible to specify the value of If (IBC) that allows the coil to operate without causing a quench burnout accident. However, in the superconducting wire material of Dy ₂ O ₃ artificial pin, there is a track record of switch operation 30 times with a current limiter. Further, in the superconducting wire material of the BZO artificial pin, a quench burnout accident is observed when applied to the coil. Therefore, it is considered to be between the If (IBC) of each superconducting wire. If (IBC) at 50K / 5T was 0.004 and 0.361, respectively.

The IBC indirect measurement method is a measurement that attempts to detect by increasing the current to the Ic value in 4 seconds and increasing V (IBC). If the quench burnout accident can be avoided when the voltage can be suppressed to 2 μV at 100 A by this measurement method, If (IBC) = 0.020 is the boundary value. In the discussion herein, this value is used as a provisional guide. If the relationship between the quench burnout accident and If (IBC) becomes clear in the future, the boundary value will be clear.

As described above, according to the present embodiment, a superconducting coil capable of suppressing quench burnout accidents can be realized. In addition, a superconducting coil with improved magnetic field characteristics and capable of generating a stable magnetic field can be realized.

(Second Embodiment)
In the superconducting coil of the present embodiment, the second element is at least one of the groups of neodymium (Nd) and samarium (Sm), and the third element is ittrium (Y), dysprosium (Dy) and holmium (Ho). It is the same as the first embodiment except that the fourth element is limited to at least one kind of the group of erbium (Er) and thulium (Tm). Therefore, the description of the contents overlapping with the first embodiment will be omitted.

In the present embodiment, the difference between the ionic radius of MA, which is the third element, and the ionic radius of CA, which is the fourth element, is relatively small, so that the nucleation frequency is high. Therefore, the size of the artificial pin is reduced, and a superconducting coil having excellent magnetic field characteristics in a low temperature range can be realized.

From the viewpoint of realizing a superconducting coil having excellent magnetic field characteristics in a low temperature region, in particular, the second element is samarium (Sm), and the third element is at least one of the yttrium (Y) and holmium (Ho) groups. It is desirable that the fourth element is thulium (Tm).

Hereinafter, the action / effect of the present embodiment will be described, and the CARP formation model will also be described.

FIG. 16 is an explanatory diagram of the operation and effect of the present embodiment. FIG. 16 is a diagram showing the relationship between the magnetic field and the critical current density of the superconducting wire 20 of the present embodiment. The measurement result at a temperature of 30K is shown.

A sample of YBCO containing no rare earth element other than yttrium, which is a comparative form (crossed in FIG. 16), and the proportions of placeodium, samarium, yttrium, and thulium in the rare earth elements of this embodiment are 1%, 1%, and 96%. Samples with 2, 2% (black circles in Fig. 16), 2%, 2%, 92%, and 4% of rare earth elements of placeodium, samarium, yttrium, and thulium (white circles in Fig. 16). This is the result of the measurement. The horizontal axis is the magnetic field (T) and the vertical axis is the Jc value (MA / cm ² ).

As is clear from FIG. 16, in this embodiment, a higher critical current density can be obtained as compared with the comparative embodiment.

For example, in the case of application to a power transmission cable or a current limiter, it is required that the magnetic field characteristics are improved in the temperature range of 77K to 50K. On the other hand, for example, in the case of application to a superconducting coil used in a heavy ion beam cancer treatment machine, a magnetic levitation train, etc., it is required that the magnetic field characteristics be improved at around 30K. Therefore, it is also necessary to improve the magnetic field characteristics in the low temperature range.

In order to exert the effect as an artificial pin in a low temperature range, it is necessary to reduce the size of the artificial pin. This is because even if the same artificial pin volume is introduced, the smaller the size, the larger the area adjacent to the superconductor, and the potential difference on that surface becomes the microscopic pin force of the artificial pin. Therefore, when CARP is used as an artificial pin, it is necessary to reduce the size of CARP. In order to reduce the CARP size, it is necessary to grasp the currently realized CARP size and control the size to be small. However, it is difficult to know the size of CARP.

BaZrO ₃ Artificial pins have been developed in the past, the structure for YBCO lattice constant of the matrix phase is different and separate, clear interface is present. Therefore, it was easy to identify the position of BZO. Therefore, it was easy to grasp the size.

However. CARP has a completely different structure from the conventional BZO, and a part of the continuous perovskite structure forms an artificial pin. Therefore, it is difficult to distinguish between CARP and YBCO superconductor even by TEM observation, and it is extremely difficult to directly observe the size of CARP.

Although it is difficult to directly observe the size of CARP, there are some samples in which a small magnetic field characteristic improving effect is obtained under the conditions of a temperature of 30 K and a magnetic field of 1 T to 3 T by using a pin size control technique. Based on the conventional reported examples, the size of the artificial pin of this sample is estimated to be about 15 nm to 20 nm. Therefore, it is estimated that the size of CARP is about 15 nm to 20 nm.

The existence position of CARP is inferred from fluctuations in the position of Cu atoms that can be observed by TEM, and it is highly possible that CARP is distributed in a lump over the entire film. The massive CARP is distributed substantially uniformly in the membrane, and its diameter is assumed to be 15 nm to 20 nm. Therefore, if the CARP formation model (CARP glow model) can be understood, the size of the CARP can be controlled by applying the model.

The above-mentioned CARP is formed by accumulating PA, SA, and CA by a clustering phenomenon, and PA non-superconducting adjacent 4-unit cells in the a / b plane. Then, it is presumed that the entire CARP functions as an artificial pin. In order to control the size of CARP, it is necessary to know which unit cell is the starting point of CARP formation.

The starting point for CARP formation seems to be likely to be CA. In the YBCO perovskite structure, there is a correlation between the ionic radius of the element entering the Y site and the optimum oxygen partial pressure at the time of film formation. The optimum oxygen partial pressure is a value at which the Jc value of the obtained superconductor is the maximum in liquid nitrogen. The oxygen partial pressure has an inverse correlation with the ionic radius.

For example, LaBCO has an optimum oxygen partial pressure of 0.2 ppm, NdBCO has 5 ppm, and SmBCO has 20 ppm. The ionic radius is La> Nd> Sm> Y> Tm> Yb> Lu. In YBCO, it is 1000 ppm. The exact values of TmBCO, YbBCO, and LuBCO are considered to be around 2000 ppm, 3000 ppm, and 4000 ppm, although the exact values are unknown.

The difference in effective ionic radii between elements seems to be determined by how much logarithmically there is a difference from the optimal oxygen partial pressure of YBCO. The difference from the optimum oxygen partial pressure of YBCO is 1/50 of that of YBCO, that is, 50 times the optimum oxygen partial pressure of SmBCO constituting CARP. TmBCO is 2 times, YbBCO is 3 times, and LuBCO is 4 times. Although there is no data on PrBCO, it is located between La and Nd and is estimated to be 0.2 ppm to 5 ppm, but it is considered to be about 1 ppm. CA has the smallest difference between YBCO and the effective ionic radius. The smaller the difference in ionic radii, the higher the nucleation frequency should be, and it is highly possible that the starting point of CARP growth is CA. The nucleation frequency of PA and SA is lower than that of CA.

An important factor in determining CARP size is the frequency of MA and CA nucleation. When the nucleation frequency of CA is 1/1 million of MA, one CA grows for every 1 million MA, and the surrounding CARP constituent elements are accumulated. They form CARP. It is assumed that one CA grows in one million MAs when the CA is Lu. Further, it is assumed that one CA grows in 10,000 MAs when the CA is Tm.

CARP containing Lu will nucleate with a probability of 1/1 million, and after nucleation, the construction of CARP will proceed until the concentration of surrounding CARP constituent elements is diluted. Then, it can be easily guessed that a considerably large CARP will be created. If the CARP constituent element is 8%, CARP consisting of 125,000 unit cells can be formed in one in 1 million MA unit cells.

On the other hand, in the case of Tm, the nucleation frequency is 1 / 10,000. In this case, it means that 100 Tm nucleations are produced in the region where Lu-CARP is formed. That is, 12,500 unit cells are divided into about 100 equal parts, and 100 CARPs composed of 125 unit cells are formed.

FIG. 17 is a diagram showing the operation and effect of the second embodiment. FIG. 17 is a diagram schematically showing the difference in growth of CARP when CAs having different ionic radii are applied.

FIG. 17A shows a case where CA is Tm, and FIG. 17B shows a case where CA is Lu. Tm has a smaller ionic radius difference from Y than Lu. Therefore, the difference between the TmBCO unit cell size and the YBCO unit cell size is smaller than the difference between the YbBCO unit cell size and the YBCO unit cell size, and the nucleation frequency becomes high.

When CA is Lu, nucleation does not easily occur, and if it does occur, the surrounding CARP constituent elements gather to form CARP. Therefore, it becomes a large CARP as shown in FIG. 17 (b). On the other hand, when CA is Tm, a large number of nuclei are formed due to the high nucleation rate. CARP constituent elements migrate to each of the many nuclei to form CARP. Since the amount of CARP constituent elements that move to each nucleus is small, the size of CARP is smaller than that when CA is Lu, as shown in FIG. 17 (a).

It is presumed that CARP formed at Pr: Sm: Yb = 1: 1: 2 will form CARP of the same size even if the amount of CARP constituent elements is doubled. It is assumed that a film having Pr: Sm: Yb = 1: 1: 2 (%) as sample 1 and a sample 2 having the same ratio of 2: 2: 4 (%) was formed.

Since the amount of Yb nucleation produced in the latter is twice that in the former, the number of CARPs in the same volume is doubled. The area where CARP constituent elements can be taken in is halved. However, since the concentrations of the CARP constituent elements are doubled in that region, the CARP size will be the same in the end. Further generalizing, the same result can be obtained by n times 1: 1: 2. When the PA: SA: CA ratio is the same but the total amount is different, only the number of CARPs of the same size increases.

In the above case, for example, in the case of PA: SA: CA = 1: 1: 2, if only CA is increased and PA: SA: CA = 1: 1: 8, the volumes of the CARP constituent elements are the same (CA). 6% of the surplus does not form CARP), and the number of nucleations is four times that before the increase in CA. That is, four times as many CARPs as the conventional CA are formed. As a result, it has been confirmed that the characteristics of Yb-based CARP are increasing at 30K / 1-3T. The above is the CARP formation model that is known at this time.

When reducing the CARP size, a particularly effective means is to (1) increase only the CA and (2) use a CA with a higher nucleation frequency. Further, when the number of nucleations is increased, the final CARP size is determined by the amount of CARP constituent elements. The CARP size in the current CARP growth model can be written as follows.

D (CP) = k x M (CP) x V (MA) / V (CA),
In the above formula, the definition of each symbol is as follows.
D (CP): Average diameter of CARP (Diameter of CARP)
M (CP): Number of moles per unit volume of CARP constituent elements (Mass of CARP)
V (MA): MA nucleation rate (frequency) (Velocity of MA nucleation)
V (CA): CA nucleation rate (frequency) (Velocity of CA nucleation)
k: Constant in the CARP growth model.

In order to reduce D (CP) and exert an effect at 30K, V (MA) should be reduced or V (CA) should be increased when M (CP) is the same amount. The elements that can be used for MA are limited, and if Gd is used for 100% MA, precipitation is likely to occur in the solution. Therefore, selecting an element of CA or using a mixture of CA is the key to reducing D (CP) and improving the characteristics at 30K.

When the above (1) is used as a means for reducing the CARP size, the effect is confirmed by using Yb for CA. However, increasing the amount of CA also means that a region having a small Tc is formed inside, which may lead to an increase in the internal bypass current. However. At this time, no significant adverse effects have been confirmed.

In coil applications where it is desired to avoid voltage formation due to internal bypass current, it is considered more effective to exert the effect at 30K by using only the technique (2) above as a means for reducing the CARP size. That is, a technique for increasing V (CA) while maintaining the amount of PA + SA = CA is desired.

It is known that in order to realize a large V (CA), the lattice mismatch with MA should be reduced. The frequency of CA nucleation is determined by the lattice mismatch with MA. Naturally, the velocity is maximized when there is no lattice mismatch, that is, when the MA itself nucleates on the MA.

However, it is said that as the lattice mismatch increases, the nucleation frequency or nucleation rate decreases, and if the lattice mismatch exceeds 7%, cube on cube does not grow. That is, the speed is zero.

There is no report on the specific experimental results of how much the nucleation rate increases when the lattice mismatch is 4%, 3%, or 2%, but according to computational scientists, the 1% lattice mismatch can be reduced. For example, the nucleation rate may increase by about 10 times.

It seems difficult to directly measure the exact lattice constant at the time when the perovskite structure is formed by the TFA-MOD method in which HF gas is generated. It is speculated that the lattice mismatch when Lu, Yb, and Tm come to the Y site is 4%, 3%, and 2%. It seems that the nucleation rate from Lu to Yb is about 10 times, and that from Tm is about 100 times.

The nucleation rate is adjusted mainly by adding Er and Yb based on Tm. If the nucleation rate is high at Tm, Yb is partially mixed, and if the nucleation rate is insufficient, Er is mixed. As a result, a superconductor having high characteristics at 30K can be obtained. Moreover, since the area other than the CARP region is composed of MA, the voltage disturbance due to the internal bypass current is small. Further, even if the CARP is formed small, the noise of the internal bypass current is small.

Although it is a voltage disturbance due to an internal bypass current, a huge voltage disturbance has been confirmed in the BZO artificial pin. The voltage noise of CARP made of Yb, that is, Yb-CARP, is only about 1/300. This small voltage noise seems to be due to how much the superconducting current is moved to a position deviated from the traveling direction after moving a certain distance. It seems to be related to the ratio of how much the current was moved in the direction perpendicular to the traveling direction.

As the calculation results are shown in Table 1, Ib = 0.020% at Rbp = 8%. Moreover, this value is a value that does not depend on the radius R when the artificial pin is assumed to be a sphere. In other words, theoretically, CARP is considered to be an artificial pin that does not increase the internal bypass current and does not increase noise even if the pin size is reduced.

From the above calculation, a CA containing at least Tm and Er is prepared, and if MA is Y, the characteristics can be expected to be improved at 30K by clustering. Then, the superconducting wire material containing the CARP theoretically does not generate a large voltage noise. If a coil is made using a superconducting wire containing CARP with this new structure, a superconducting coil that is difficult to quench can be made.

(Third Embodiment)
The superconducting coil of the present embodiment includes a superconducting wire material. The superconducting wire has an oxide superconducting layer. The oxide superconducting layer has a continuous perovskite structure containing rare earth elements, barium (Ba), and copper (Cu). The rare earth element is a second element of at least one of the first element, gadolinium (Gd), ytterbium (Y), terbium (Tb), dysprosium (Dy) and holmium (Ho), which is placeodium (Pr). It contains an element and at least one third element in the group dysprosium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu).

The superconducting coil of the present embodiment is different from the first embodiment in that the oxide superconducting layer 30 does not include the SA (Supporting Atom) of the first embodiment. Hereinafter, the description of the content overlapping with the first embodiment will be omitted.

The oxide superconducting layer 30 of the present embodiment includes a third generation clustered atomic substitution type artificial pin (3rd-CARP).

The oxide superconducting layer 30 of the present embodiment is composed of PA, MA, and CA. The first element is PA (Pinning Atom), the second element is MA (Matrix Atom), and the third element is CA (Counter Atom).

By adjusting the average size of MA and directly bringing the average ionic radius of PA and CA closer to MA, clusters are formed and become artificial pins.

Since the oxide superconducting layer 30 of the present embodiment does not have SA, which is a superconducting unit cell, the potential of the artificial pinsite is equivalent to that of a perfect non-superconductor. Therefore, the pin force is theoretically the maximum.

When the number of atoms of the rare earth element is N (RE) and the number of atoms of the second element, which is MA, is N (MA), N (MA) / N (RE) ≥ 0.6. Is desirable. If it falls below the above range, the proportion of superconducting unit cells decreases, and sufficient superconducting characteristics may not be obtained.

Further, when the number of atoms of the second element is N (MA) and the number of atoms of yttrium contained in the second element which is MA is N (Y), N (Y) / N (MA) ≧ It is preferably 0.5. Since the material of yttrium (Y) is relatively inexpensive, it is possible to reduce the cost of the oxide superconductor.

Further, when the number of atoms of the rare earth element is N (RE) and the number of atoms of the first element which is PA is N (PA), 0.00000001 ≦ N (PA) / N (RE). Is desirable. If it falls below the above range, a sufficient effect of improving the magnetic field characteristics may not be obtained.

Further, when the number of atoms of the rare earth element is N (RE) and the number of atoms of the first element which is PA is N (PA), N (PA) / N (RE) ≤ 0.2. Is desirable. Further, it is more desirable that N (PA) / N (RE) ≦ 0.1. If it exceeds the above range, the proportion of superconducting unit cells decreases, and there is a risk that sufficient superconducting characteristics cannot be obtained.

As described above, according to the present embodiment, as in the first embodiment, a superconducting coil capable of suppressing quench burnout accidents can be realized. In addition, a superconducting coil with improved magnetic field characteristics and capable of generating a stable magnetic field can be realized.

(Fourth Embodiment)
The superconducting device of the present embodiment is a superconducting device including the superconducting coil of the first embodiment or the second embodiment. Hereinafter, the description of the contents overlapping with the first embodiment, the second embodiment, or the second embodiment will be omitted.

FIG. 18 is a block diagram of the superconducting device of the present embodiment. The superconducting device of this embodiment is a heavy ion beam therapy device 200.

The heavy ion beam therapy device 200 includes an incident system 50, a synchrotron accelerator 52, a beam transport system 54, an irradiation system 56, and a control system 58.

The incident system 50 has, for example, a function of generating carbon ions used for treatment and performing preliminary acceleration for incident on the synchrotron accelerator 52. The incident system 50 has, for example, an ion source and a linear accelerator.

The synchrotron accelerator 52 has a function of accelerating the carbon ion beam incident from the incident system 50 to energy suitable for treatment. The superconducting coil 100 of the first embodiment or the second embodiment is used for the synchrotron accelerator 52.

The beam transport system 54 has a function of transporting the carbon ion beam incident from the synchrotron accelerator 52 to the irradiation system 56. The beam transport system 54 has, for example, a deflection electromagnet.

The irradiation system 56 has a function of irradiating a patient to be irradiated with a carbon ion beam incident from the beam transport system 54. The irradiation system 56 has, for example, a rotating gantry that enables irradiation of a carbon ion beam from an arbitrary direction. The superconducting coil 100 of the first embodiment or the second embodiment is used for the rotating gantry.

The control system 58 controls the incident system 50, the synchrotron accelerator 52, the beam transport system 54, and the irradiation system 56. The control system 58 is, for example, a computer.

In the heavy ion beam therapy device 200 of the present embodiment, the superconducting coil 100 of the first embodiment or the second embodiment is used for the synchrotron accelerator 52 and the rotating gantry. Therefore, quench burnout accidents are suppressed and high reliability is realized. Further, since the superconducting coil 100 can generate a stable magnetic field, it is possible to irradiate the affected portion with a highly accurate ion beam.

Hereinafter, examples will be described.

In the following examples, a large number of metal acetates are mixed to prepare a solution or a superconductor having a perovskite structure. The Y-based superconductor having a perovskite structure contains Y or lanthanoid elements in the Y site (rare earth site), and the others are Ba and Cu. The ratio is 1: 2: 3. Therefore, focusing on the metal elements used in the Y site, the description is as follows.

Four kinds of elements (some of which are three kinds of elements) are used as the elements of the Y site in the following examples. PA that creates artificial pins, SA that assists it. MA that becomes the matrix phase. Finally, the CA has a small ionic radius and is required to form a cluster. PA has only Pr. As SA, Nd, Sm, Eu, and Gd can be used. MA can use Tb, Dy, Ho, Y. Er, Tm, Yb, and Lu can be used for CA. Gd can also be used as a part of MA as 3rd-CARP.

In most of the examples, PA = SA and PA + SA = CA in terms of the number of moles (atomic number). The amount excluding PA + SA + CA from the whole is equal to MA. PA + SA + MA + CA = 100%. For example, suppose that there is a mixing ratio of 4% Pr (PA), 4% Sm (SA), 84% Y (MA), and 8% Lu (CA). It is described herein as 4% Pr4% Sm-Y-8% Lu. However, in the case of PA + SA = CA in which the number of large elements and small elements in the cluster portion is the same, the amount of CA shall be omitted and described as 4% Pr4% Sm-Y-Lu. Further, when PA = SA and there is only one type of SA, the amount thereof shall be omitted. That is, in the above case, it is described as 4% PrSm-Y-Lu. This description shows 4% Pr4% Sm-84% Y-8% Lu.

The elements are listed in the order of PA, SA, MA, CA, starting from the one with the smallest atomic number of the lanthanoid group. When Y is used in MA, Y is described at the end. PA + SA, MA, CA are connected by a bar. That is, it is described as 4% Pr4% Sm-Y-Lu. There are some without SA, but in that case, the amount of CA can be omitted even when PA + SA = CA. For example, in the case of 4% Pr-Y-4% Lu, it is described as 4% Pr-Y-Lu.

(Comparative Example 1)
As Comparative Example 1, a superconducting wire having a Dy ₂ O ₃ artificial pin manufactured by the TFA-MOD method was evaluated. The width of the superconducting wire portion is 4 mm, and the film thickness is estimated to be about 2 μm. The superconducting wire was cut to 3 cm and current terminals were attached to both ends. In addition, two voltage terminals were attached to the inside of the superconducting wire at 1 cm intervals. The sample was placed in a refrigerator cooling device, a magnetic field was applied to perform current-voltage measurement (IV measurement), and V (IBC) and If (IBC) were determined by the IBC indirect measurement method.

The measurement was carried out under the conditions of a magnetic field of 1T to 15T at a temperature of 50K and 5T to 15T at a temperature of 30K.

Table 2 shows the measurement results of V (IBC) and If (IBC). The background noise (delta VBG) was set to 0.20 μV from the observation results.

19, FIG. 20, FIG. 21, FIG. 22, FIG. 23, and FIG. 24 are graphs showing the current-voltage characteristics of Comparative Example 1. 19, FIGS. 20, 21, and 22 are measurements at a temperature of 50 K, and FIGS. 23 and 24 are measurements at a temperature of 30 K. The black circles are the data points considered to have reached the Ic value.

As can be seen from the graphs of FIGS. 19, 20, 21, and 22, V (IBC) was a low and stable result. However, from Table 2, it can be seen that the value of If (IBC) increases, that is, deteriorates as the magnetic field increases.

At 50K / 5T, If (IBC) = 0.004, which is a stable result that is extremely close to zero. However, the value increases with the magnetic field strength, and at 12.5T, it becomes 0.031, which exceeds the provisional boundary value of 0.020. Conversely, it can be seen that up to 10T is 0.019 or less, which is below the boundary value.

The measurement result of If (IBC) at 30K was almost the same as that at 50K. Although it seemed to improve a little at 15T, the other results were almost the same. It was also found that there was no significant improvement at 30K.

The measurement results of the current-voltage characteristics in FIGS. 23 and 24 seem to have changed because they were not corrected by the Ic value, but it was found that there was not much change when the If (IBC) value was taken. .. The effect of IBC was also thought to be more pronounced at high temperatures, but no difference was observed between 50K and 30K.

(Comparative Example 2)
As Comparative Example 2, a superconducting wire having a BZO artificial pin manufactured by a physical vapor deposition method was evaluated instead of the superconducting wire having a Dy ₂ O ₃ artificial pin of Comparative Example 1. The width of the superconducting wire portion is 4 mm, and the film thickness is estimated to be about 1 μm. The superconducting wire was cut to 3 cm and current terminals were attached to both ends. In addition, two voltage terminals were attached to the inside of the superconducting wire at 1 cm intervals. The sample was placed in a refrigerator cooling device, a magnetic field was applied to perform IV measurement, and V (IBC) and If (IBC) were determined as in Comparative Example 1.

The measurement was performed under the conditions of a temperature of 50 K and a magnetic field of 1 T to 15 T.

Table 2 shows the measurement results of V (IBC) and If (IBC). 25, 26, 27, and 28 are graphs showing the current-voltage characteristics of Comparative Example 2. The black circles are the data points considered to have reached the Ic value.

As is clear from the graphs of FIGS. 25, 26, 27, and 28, V (IBC), which is a clear voltage disturbance, is observed from 2T at 50K. The If (IBC) seen in Table 2 also fell below the provisional boundary value of 0.020 only at 0.013 of 1T, and the value deteriorated significantly at 2T and above. At 50K / 5T, it was 0.361, which was almost 100 times larger than that of Comparative Example 1, which was close to the background noise.

In the superconducting wire of Comparative Example 2, If (IBC) continues to increase as the magnetic field strength increases, reaching 3.08 at 12.5T. The possibility that the coil has a quench burnout accident due to the influence of IBC can be indirectly known from this measurement result.

Even with the superconducting wire of Comparative Example 2, if (IBC) is not expected to improve dramatically at at least 30K, and it is highly possible that If (IBC) remains well above 0.020 even at 30K. It is speculated that this may have led to the quench burning accident.

Considering that the superconducting wire of Comparative Example 1 is successful in the current limiter, if the superconducting wire of If (IBC) ≤ 0.020 is made, the influence of IBC can be suppressed and the product may be successful. There is. In other words, this has the same meaning as making a superconductor with Tc = 90.7K and forming an artificial pin inside while maintaining the Tc.

Even if a material that suppresses the influence of IBC is developed, it will take 4 to 5 years to make it into a long wire, actually coil it, and actually measure it so that a current can flow to near the Ic value. However, if the value of If (IBC) is the same as that of the superconducting wire material of Comparative Example 1 and the material functions as an artificial pin, it is considered that a stable system can be formed while preventing the quench burnout accident of the coil. ..

(Example 1)
First, two types of coating solutions for superconductors are synthesized and purified according to the flowchart shown in FIG. Hydrate of metal acetates Pr (OCOCH ₃ ) ₃ , Sm (OCOCH ₃ ) ₃ , Y (OCOCH ₃ ) ₃ , Lu (OCOCH ₃ ) ₃ , Ba (OCOCH ₃ ) ₂ , Cu (OCOCH ₃ ) ₂ Dissolve in ion-exchanged water at a metal ion molar ratio of 0.01: 0.01: 0.96: 0.02: 2: 3, mix and stir with CF ₃ COOH in an equimolar amount of reaction. The obtained mixed solution was placed in a eggplant-shaped flask, and the reaction and purification were carried out under reduced pressure in a rotary evaporator for 12 hours. A translucent blue substance 1Mi-1% PrSm-Y-Lu (substance described in Example 1, Y-based Material with impurity) was obtained.

Similarly, each of the metal acetates Pr (OCOCH ₃ ) ₃ , Sm (OCOCH ₃ ) ₃ , Y (OCOCH ₃ ) ₃ , Lu (OCOCH ₃ ) ₃ , Ba (OCOCH ₃ ) ₂ , and Cu (OCOCH ₃ ) ₂ . Using hydrate powder, metal ion molar ratio 0.02: 0.02: 0.92: 0.04: 2: 3 and 0.04: 0.04: 0.84: 0.08: 2: Prepare the solution dissolved in ion-exchanged water in step ₃ , mix and stir with CF ₃ COOH in an equimolar amount of reaction, put the obtained mixed solution in a eggplant-shaped flask, and react and purify under reduced pressure in a rotary evaporator. Was carried out for 12 hours. A translucent blue substance, 1Mi-2% PrSm-Y-Lu, and 1Mi-4% PrSm-Y-Lu were obtained.

The obtained translucent blue substance 1Mi-1% PrSm-Y-Lu, 1Mi-2% PrSm-Y-Lu, 1Mi-4% PrSm-Y-Lu was a reaction by-product during solution synthesis. It contains about 7 wt% of certain water and acetic acid.

The obtained translucent blue substance 1Mi-1% PrSm-Y-Lu, 1Mi-2% PrSm-Y-Lu, and 1Mi-4% PrSm-Y-Lu each contain about 100 times the weight of methanol. (F in FIG. 6) was added to completely dissolve the solution, and the solution was reacted and purified again under reduced pressure in a rotary evaporator for 12 hours. The translucent blue substance 1M-1% PrSm-Y-Lu (Example). The substance described in 1 (Y-based Material without impurity), 1M-2% PrSm-Y-Lu, and 1M-4% PrSm-Y-Lu were obtained, respectively.

A translucent blue substance 1M-1% PrSm-Y-Lu, 1M-2% PrSm-Y-Lu, 1M-4% PrSm-Y-Lu was dissolved in methanol (j in FIG. 6) to prepare a volumetric flask. 1Cs-1% PrSm-Y-Lu coating solution 1Cs-1% PrSm-Y-Lu (Example 1, Coating Solution for Y-based superconducor), 1Cs-4% PrSm-Y-Lu, respectively. Was obtained respectively. Using the coating solution 1Cs-1% PrSm-Y-Lu, 1Cs-2% PrSm-Y-Lu, and 1Cs-4% PrSm-Y-Lu, a film was formed at a maximum rotation speed of 2000 rpm using a spin coating method.

Next, calcining was performed with the profile shown in FIG. 8 in a pure oxygen atmosphere of 400 ° C. or lower. Next, the profile shown in FIG. 9 was used for main firing in 1000 ppm oxygen-mixed argon gas at 800 ° C., and annealing was performed in pure oxygen at 525 ° C. or lower. Superconducting membranes 1FS-1% PrSm-Y-Lu (Example 1, Y-based Film of Superconductor), 1FS-2% PrSm-Y-Lu, 1FS-4% PrSm-Y-Lu were obtained, respectively.

The superconducting film 1FS-1% PrSm-Y-Lu and 1FS-4% PrSm-Y-Lu were measured by the 2θ / ω method of XRD measurement, respectively, and the results are shown in FIGS. 4 and 5. From FIGS. 4 and 5, it was confirmed that only one peak was obtained at almost the same position as the YBCO (00n) peak. Good peak intensity has also been confirmed, which is one of the evidences that the added rare earth elements form a continuous perovskite structure without separation.

Next, the high-magnification TEM observation result of the superconducting film 1FS-2% PrSm-Y-Lu is shown in FIG. As can be seen from FIG. 3, a structure in which a continuous perovskite structure is maintained as a whole is shown. Since the lattice constant is almost the same as that of YBCO, it can be confirmed that Pr, Sm, and Lu are incorporated into the rare earth site to form a continuous perovskite structure.

FIG. 3 is a HAADF-STEM image, which glows brightly when the atomic weight is large. The regular horizontal pattern of the three rows is that the bright two rows are Ba and the rest are rare earths. The inside of the solid line frame is brighter in the center than the bright Ba at both ends, and the inside of the broken line frame is darker. This indicates that a cluster in which Pr, Sm, and Lu are aggregated is formed inside the solid line frame.

When the superconducting membrane 1FS-1% PrSm-Y-Lu and 1FS-4% PrSm-Y-Lu were placed in liquid nitrogen and the superconducting characteristics under the self-magnetic field were measured by the induction method, the Jc values were 6. It was 3, 6.2 MA / cm ² (77K, 0T). This Jc value is relatively good. The 5-fold deterioration phenomenon due to the ultimate dispersion of PrBCO should be confirmed in the above sample, especially if the Jc value is reduced by 20% in the latter 1FS-4% PrSm-Y-Lu, but it is not confirmed. It was. It is considered that the result shows that the atomic substitution type artificial pins are clustered and aggregated and accumulated in some places.

The results of measuring the Jc value of the superconducting film 1FS-1% PrSm-Y-Lu, 1FS-2% PrSm-Y-Lu, 1FS-4% PrSm-Y-Lu at 77K in a magnetic field of 1 to 5T, respectively. It is shown in FIG. The horizontal axis of the figure is the magnetic field, the unit is T, and the vertical axis is the Jc value, which is the logarithmic axis.

In all the samples, the Jc value was YBCO or less at 1T, but it became almost the same value at 3T, and it can be seen that it improved at 5T. It is shown that the magnetic field characteristics were improved by CARP.

For FS-4% PrSm-Y-Lu, Jc-BT measurements were performed at 1 to 15T at 50K and 5 to 15T at 30K to investigate the effect of IBC. The results are shown in Table 2, FIG. 29, FIG. 20, FIG. 31, FIG. 32, FIG. 33, and FIG. 34. In FIGS. 29, 30, 31, 31, 32, 33, and 34, the black circles are data points considered to have reached the Ic value.

29, 30, 31, and 32 are the results of examining V (IBC) at 50K. Voltage fluctuation is hardly confirmed up to 15T. Since the sample is only 220 nm thick, Table 2 shows the results of examining If (IBC) in order to correct the effect. As can be seen from Table 2, If (IBC) ≤ 0.020 is up to 10T at 50K. This is almost the same result as the superconducting wire material of Comparative Example 1.

It is considered that the reason why the result was almost the same as that of the superconducting wire of Comparative Example 1 was that the YBCO superconductor, which is MA, maintained Tc = 90.7K and the influence of IBC was small. Moreover, in the Jc-B measurement showing the effect of the artificial pin in the superconductor of Example 1, the result that the magnetic field characteristic is improved is also shown. The results of this experiment show that the magnetic field characteristics could be improved while avoiding the influence of IBC.

33 and 34 are the results of examining V (IBC) at 30K. The results shown in FIGS. 33 and 34 show stable results with little voltage fluctuation. Comparing If (IBC) corrected for the influence of the current value, it was found from Table 2 that If (IBC) ≤ 0.020 up to 10T at 30K. It is considered that the reason why the superconducting wire material of Comparative Example 1 is stable is that it has the same structure as that of Comparative Example 1 and a Tc value of 90.7K is obtained.

CARP has a structure in which the influence of IBC is equal to or less influential than that of the Dy ₂ O ₃ artificial pin. Moreover, the Dy ₂ O ₃ artificial pin does not have the effect of improving the magnetic field characteristics, but the CARP has the effect of improving the magnetic field characteristics. Then, if the superconducting wire having CARP is coiled and mounted on the superconducting device, stable operation can be expected and the possibility of quench burnout accident can be significantly reduced.

Until now, CARP has not been realized with Y-based superconducting wires. This is because the firing conditions of PrBCO and YBCO are too different. The optimum oxygen partial pressures are 1 ppm and 1000 ppm, respectively, which is a condition in which one of them is surely decomposed by the physical vapor deposition method. Moreover, it is difficult to realize the structure of CARP by sharing the same perovskite structure even in the production of a bulk superconductor. This is because the condition for forming a film on one side is the condition for decomposing the film on the other side.

Even with the TFA-MOD method, it is not easy to create a CARP structure. This is because if any impurities are present in the solution, the other substance will be decomposed when the film is formed under the film forming conditions of one substance at the time of main firing. In addition, it is desirable to use the clustering phenomenon to adjust the size of artificial pins. There is no example of intentionally mixing PrBCO and LuBCO with YBCO, or mixing SmBCO as a support element. It is considered that CARP having magnetic field characteristics was introduced for the first time by the TFA-MOD method, which has a proven record of mass productivity, and a superconductor having a low If (IBC) and a low possibility of quench burning accident was formed.

(Example 2)

First, two types of coating solutions for superconductors are synthesized and purified according to the flowchart shown in FIG. Hydrate of metal acetates Pr (OCOCH ₃ ) ₃ , Sm (OCOCH ₃ ) ₃ , Y (OCOCH ₃ ) ₃ , Tm (OCOCH ₃ ) ₃ , Ba (OCOCH ₃ ) ₂ , Cu (OCOCH ₃ ) ₂ Dissolve in ion-exchanged water at a metal ion molar ratio of 0.01: 0.01: 0.96: 0.02: 2: 3, mix and stir with CF ₃ COOH in an equimolar amount of reaction. The obtained mixed solution was placed in a eggplant-shaped flask, and the reaction and purification were carried out under reduced pressure in a rotary evaporator for 12 hours. A translucent blue substance 2Mi-1% PrSm-Y-Tm (substance described in Example 2, Y-based Material with impurity) was obtained.

Similarly, water of Pr (OCOCH ₃ ) ₃ , Sm (OCOCH ₃ ) ₃ , Y (OCOCH ₃ ) ₃ , Yb (OCOCH ₃ ) ₃ , Ba (OCOCH ₃ ) ₂ , Cu (OCOCH ₃ ) ₂ , which are metal acetates. Using Japanese powder, prepare a solution dissolved in ion-exchanged water at a metal ion molar ratio of 0.01: 0.01: 0.84: 0.02: 2: 3, and add CF ₃ COOH in an equimolar amount of reaction. After mixing and stirring, the obtained mixed solution was placed in a eggplant-shaped flask, and the reaction and purification were carried out under reduced pressure in a rotary evaporator for 12 hours. A translucent blue substance 2Mi-1% PrSm-Y-Yb was obtained.

The obtained translucent blue substance 2Mi-1% PrSm-Y-Tm and 2Mi-1% PrSm-Y-Yb contain about 7 wt% of water and acetic acid, which are reaction by-products during solution synthesis. ..

Completely, the obtained translucent blue substance 2Mi-1% PrSm-Y-Tm and 2Mi-1% PrSm-Y-Yb were added with methanol (f in FIG. 6) corresponding to about 100 times the weight of each. When the solution is reacted and purified again in a rotary evaporator under reduced pressure for 12 hours, the translucent blue substance 2M-1% PrSm-Y-Tm (the substance described in Example 2, Y-based Material) Without impurity), 2M-1% PrSm-Y-Yb were obtained, respectively.

A translucent blue substance 2M-1% PrSm-Y-Tm, 2M-1% PrSm-Y-Yb was dissolved in methanol (j in FIG. 6), diluted using a volumetric flask, and converted into metal ions. A coating solution of 1.50 mol / l, 2Cs-1% PrSm-Y-Tm (Example 2, Coating Solution for Y-based superconductor), and 2Cs-1% PrSm-Y-Yb were obtained, respectively. Using a coating solution of 2Cs-1% PrSm-Y-Tm and 2Cs-1% PrSm-Y-Yb, a film was formed at a maximum rotation speed of 2000 rpm using a spin coating method.

Next, calcining was performed with the profile shown in FIG. 8 in a pure oxygen atmosphere of 400 ° C. or lower. The profile shown in FIG. 9 was burnt in 1000 ppm oxygen-mixed argon gas at 800 ° C. and annealed in pure oxygen at 525 ° C. or lower. Superconducting membranes 2FS-1% PrSm-Y-Tm (Example 2, Y-based Film of Superconductor) and 2FS-1% PrSm-Y-Yb were obtained, respectively.

The superconducting film 2FS-1% PrSm-Y-Tm and 2FS-1% PrSm-Y-Yb were measured by the 2θ / ω method of XRD measurement, and only one peak was obtained at almost the same position as the YBCO (00n) peak. It was confirmed that Good peak intensity was also confirmed, and it is considered that the added rare earth elements form a continuous perovskite structure without separation.

When the superconducting membrane 2FS-1% PrSm-Y-Tm and 2FS-1% PrSm-Y-Yb were placed in liquid nitrogen and the superconducting characteristics under the self-magnetic field were measured by the induction method, the Jc values were 6. It was 1, 6.0 MA / cm ² (77K, 0T). This Jc value is considered to be a relatively good Jc value. It is difficult to confirm the 5-fold deterioration phenomenon due to the ultimate dispersion of PrBCO because it corresponds to a 5% decrease in the above sample. However, looking at the magnetic field characteristics described later, it is considered that clustering has occurred.

The Jc value of the superconducting membrane 2FS-1% PrSm-Y-Tm and 2FS-1% PrSm-Y-Yb was measured in a magnetic field of 1 to 5T at 60K, respectively, and improvement of the Jc value was confirmed at 60K. ..

For the superconducting membrane 2FS-1% PrSm-Y-Tm, Jc-BT measurements were performed at 1 to 15T at 50K and 5 to 15T at 30K in order to investigate the effect of IBC. As for the superconducting film 2FS-1% PrSm-Y-Tm, the result was obtained that If (IBC) ≤ 0.20 was satisfied at 7T or less for both 50K and 30K. The result was obtained that the superconducting film 2FS-1% PrSm-Y-Yb was 8T or less and If (IBC) ≦ 0.20 was satisfied.

Although the magnetic field strength range in which the effect is produced is slightly different from that when CA is Lu, the effect of improving the magnetic field characteristics as an artificial pin was confirmed while avoiding the influence of IBC. In particular, it is known from the experimental results that when Tm or Yb is used for Lu, the nucleation frequency increases and the magnetic field characteristics are improved at a lower temperature.

In addition, since the influence of IBC is small, it is considered that by incorporating these superconducting wires as coils into the system, it is possible to create a stable superconducting application system in which quench burnout accidents are unlikely to occur. A coil that is less affected by IBC is considered to have excellent magnetic field stability, and is also advantageous for application to systems that require high magnetic field accuracy.

It was found that even if the CA site is changed from Lu to Tm or Yb, the effect of CARP will be maintained and a coil that is less likely to cause quench burnout will be formed.

(Example 3)
First, a coating solution for superconductors is synthesized and purified according to the flowchart shown in FIG. Hydrate of metal acetates Pr (OCOCH ₃ ) ₃ , Gd (OCOCH ₃ ) ₃ , Y (OCOCH ₃ ) ₃ , Tm (OCOCH ₃ ) ₃ , Ba (OCOCH ₃ ) ₂ , Cu (OCOCH ₃ ) ₂ Dissolve in ion-exchanged water at a metal ion molar ratio of 0.02: 0.48: 0.48: 0.02: 2: 3, mix and stir with CF ₃ COOH in an equimolar amount of reaction. The obtained mixed solution was placed in a eggplant-shaped flask, and the reaction and purification were carried out under reduced pressure in a rotary evaporator for 12 hours. A translucent blue substance 3Mi-2% Pr-GdY-Tm (substance described in Example 3, Y-based Material with impurity) was obtained.

The obtained translucent blue substance 3Mi-2% Pr-GdY-Tm contains about 7 wt% of water and acetic acid, which are reaction by-products during solution synthesis.

The obtained translucent blue substance 3Mi-2% Pr-GdY-Tm was completely dissolved by adding methanol (f in FIG. 6) corresponding to about 100 times the weight of each, and the solution was dissolved in a rotary evaporator. When the reaction and purification were carried out again under reduced pressure for 12 hours, a translucent blue substance 3M-2% Pr-GdY-Tm (substance described in Example 3, Y-based Material without impurity) was obtained.

A translucent blue substance 3M-2% Pr-GdY-Tm was dissolved in methanol (j in FIG. 6), diluted using a volumetric flask, and each was a coating solution 3Cs- of 1.50 mol / l in terms of metal ions. 2% Pr-GdY-Tm (Example 3, Coating Solution for Y-based superconducor) was obtained, respectively. A film was formed using a coating solution of 3Cs-2% Pr-GdY-Tm at a maximum rotation speed of 2000 rpm using a spin coating method.

Next, calcining was performed with the profile shown in FIG. 8 in a pure oxygen atmosphere of 400 ° C. or lower. Next, the profile shown in FIG. 9 was used for main firing in 1000 ppm oxygen-mixed argon gas at 800 ° C., and annealing was performed in pure oxygen at 525 ° C. or lower. Superconducting membranes 3FS-2% Pr-GdY-Tm (Example 3, Y-based Film of Superconductor) were obtained, respectively.

The superconducting film 3FS-2% Pr-GdY-Tm was measured by the 2θ / ω method of XRD measurement, and it was confirmed that only one peak was obtained on the slightly lower angle side from the YBCO (00n) peak. Good peak intensity was also confirmed, and it is considered that the added rare earth elements form a continuous perovskite structure without separation.

When the superconducting film 3FS-2% Pr-GdY-Tm was placed in liquid nitrogen and the superconducting characteristics under the self-magnetic field were measured by the induction method, the Jc values were 5.7 MA / cm ² (77K, 0T), respectively. there were. This Jc value is a relatively good Jc value. The 5-fold deterioration phenomenon due to the ultimate dispersion of PrBCO corresponds to a 10% decrease in the above sample, but no Jc decrease to that extent is observed. It seems that CARP is formed.

The Jc value of the superconducting film 3FS-2% Pr-GdY-Tm was measured in a magnetic field of 1, 5T at 77K, respectively, and the improvement effect of increasing the Jc value by 1.3 times at 77K was confirmed.

For the superconducting film 3FS-2% Pr-GdY-Tm, Jc-BT measurements were performed at 1 to 15T at 50K and 5 to 15T at 30K to investigate the effect of IBC. The superconducting film 3FS-2% Pr-GdY-Tm was 6T or less at 50K, and 7T or less at 30K, and If (IBC) ≤ 0.020 was satisfied.

The third embodiment has a form in which MA is composed of Gd and Y, and is an artificial pin called 3rd-CARP described in the second embodiment. Since the artificial pin force was not obtained as expected, it is possible that the conditions were insufficient, but it seems that a superconductor that is less likely to cause quench burnout accidents could be formed. By incorporating this into a coil and incorporating the coil into a superconducting device, it is considered that a superconducting application device system that is less likely to cause quench burnout accidents and has less magnetic field disturbance can be constructed.

(Example 4)
First, a coating solution for superconductors is synthesized and purified according to the flowchart shown in FIG. Hydrate of metal acetates Pr (OCOCH ₃ ) ₃ , Sm (OCOCH ₃ ) ₃ , Y (OCOCH ₃ ) ₃ , Yb (OCOCH ₃ ) ₃ , Ba (OCOCH ₃ ) ₂ , Cu (OCOCH ₃ ) ₂ Dissolve in ion-exchanged water at a metal ion molar ratio of 0.10: 0.10: 0.60: 0.20: 2: 3, mix and stir with CF ₃ COOH in an equimolar amount of reaction. The obtained mixed solution was placed in a eggplant-shaped flask, and the reaction and purification were carried out under reduced pressure in a rotary evaporator for 12 hours. A translucent blue substance 4Mi-10% PrSm-Y-Yb (the substance described in Example 4, Y-based Material with impurity) was obtained.

The obtained translucent blue substance 4Mi-10% PrSm-Y-Yb contains about 7 wt% of water and acetic acid, which are reaction by-products during solution synthesis.

The obtained translucent blue substance 4Mi-10% PrSm-Y-Yb was completely dissolved by adding methanol (f in FIG. 6) corresponding to about 100 times the weight of each, and the solution was dissolved in a rotary evaporator. When the reaction and purification were carried out again under reduced pressure for 12 hours, a translucent blue substance 4M-10% PrSm-Y-Yb (the substance described in Example 4, Y-based Material without impurity) was obtained.

A translucent blue substance 4M-10% PrSm-Y-Yb was dissolved in methanol (j in FIG. 6), diluted using a volumetric flask, and each was a coating solution 4Cs- of 1.50 mol / l in terms of metal ions. 10% PrSm-Y-Yb (Example 4, Coating Solution for Y-based superconducor) was obtained, respectively.

Similarly, a coating solution for YBCO, 4Cs-Y, was prepared, and the following solution was prepared by dilution and mixing with 4Cs-10% PrSm-Y-Yb. 4Cs-1% PrSm-Y-Yb, 4Cs-1000ppmPrSm-Y-Yb, 4Cs-100ppmPrSm-Y-Yb, 4Cs-10ppmPrSm-Y-Yb, 4Cs-1ppmPrSm-Y-Yb, 4Cs-100ppbPrSm-Y-Yb, 4Cs-10ppbPrSm-Y-Yb and 4Cs-1ppbPrSm-Y-Yb were obtained.

Coating solution 4Cs-10% PrSm-Y-Yb, 4Cs-1% PrSm-Y-Yb, 4Cs-1000ppm PrSm-Y-Yb, 4Cs-100ppm PrSm-Y-Yb, 4Cs-10ppm PrSm-Y-Yb, 4Cs-1ppm PrSm- Using Y-Yb, 4Cs-100ppbPrSm-Y-Yb, 4Cs-10ppbPrSm-Y-Yb, 4Cs-1ppbPrSm-Y-Yb, a film was formed at a maximum rotation speed of 2000 rpm using a spin coating method.

Next, calcining was performed with the profile shown in FIG. 8 in a pure oxygen atmosphere of 400 ° C. or lower. Next, the profile shown in FIG. 9 was used for main firing in 1000 ppm oxygen-mixed argon gas at 800 ° C., and annealing was performed in pure oxygen at 525 ° C. or lower. Superconducting film 4FS-10% PrSm-Y-Yb (Example 4, Y-based Film of Superconductor), 4FS-1% PrSm-Y-Yb, 4FS-1000ppm PrSm-Y-Yb, 4FS-100ppm PrSm-Yb, 4FS-10ppmPrSm-Y-Yb, 4FS-1ppmPrSm-Y-Yb, 4FS-100ppbPrSm-Y-Yb, 4FS-10ppbPrSm-Y-Yb, 4FS-1ppbPrSm-Y-Yb were obtained, respectively.

Superconducting film 4FS-10% PrSm-Y-Yb, 4FS-1% PrSm-Y-Yb, 4FS-1000ppm PrSm-Y-Yb, 4FS-100ppm PrSm-Y-Yb, 4FS-10ppm PrSm-Y-Yb, 4FS-1ppm PrSm- Y-Yb, 4FS-100ppbPrSm-Y-Yb, 4FS-10ppbPrSm-Y-Yb, 4FS-1ppbPrSm-Y-Yb were measured by the 2θ / ω method of XRD measurement. It was confirmed that one peak was obtained at almost the same position as the YBCO (00n) peak in all the samples. In addition, good peak intensity was also confirmed, and it is considered that the added rare earth elements form a continuous perovskite structure without separation.

Superconducting film 4FS-10% PrSm-Y-Yb, 4FS-1% PrSm-Y-Yb, 4FS-1000ppm PrSm-Y-Yb, 4FS-100ppm PrSm-Y-Yb, 4FS-10ppm PrSm-Y-Yb, 4FS-1ppm PrSm- Y-Yb, 4FS-100ppbPrSm-Y-Yb, 4FS-10ppbPrSm-Y-Yb, 4FS-1ppbPrSm-Y-Yb were placed in liquid nitrogen, respectively, and the superconducting characteristics under a self-magnetic field were measured by an induction method. The Jc values were 5.5, 5.8, 6.0, 6.1, 6.0, 6.2, 6.0, 6.2, 6.1 MA / cm ² (77K, 0T), respectively. .. All Jc values are considered to be relatively good values. The 5-fold deterioration phenomenon due to the ultimate dispersion of PrBCO was not observed, and it is considered that CARP was formed.

Superconducting film 4FS-10% PrSm-Y-Yb, 4FS-1% PrSm-Y-Yb, 4FS-1000ppm PrSm-Y-Yb, 4FS-100ppm PrSm-Y-Yb, 4FS-10ppm PrSm-Y-Yb, 4FS-1ppm PrSm- The Jc values of Y-Yb, 4FS-100ppbPrSm-Y-Yb, 4FS-10ppbPrSm-Y-Yb, and 4FS-1ppbPrSm-Y-Yb were measured at 77K in a magnetic field of 1,5T, respectively. The Jc value improved up to 1.3 times at 77K when the Pr amount was 10 ppb or more. When the amount of Pr was 1 ppb, it was almost 1 times and no effect was observed.

Superconducting film 4FS-10% PrSm-Y-Yb, 4FS-1% PrSm-Y-Yb, 4FS-1000ppm PrSm-Y-Yb, 4FS-100ppm PrSm-Y-Yb, 4FS-10ppm PrSm-Y-Yb, 4FS-1ppm PrSm- For Y-Yb, 4FS-100ppbPrSm-Y-Yb, 4FS-10ppbPrSm-Y-Yb, Jc-BT measurements were performed at 1 to 15T at 50K and 5 to 15T at 30K to investigate the effect of IBC. In all samples, If (IBC) ≤ 0.020 was confirmed at 10 T or less at 50 K and 30 K. When the amount of clusters is small, it seems to be a result showing that the influence of IBC does not occur.

The artificial pin of Example 4 is 2nd-CARP, but the influence of IBC can be reduced by clustering. The coil formed by using the superconductor of Example 4 is less likely to cause quench burnout and is excellent in magnetic field stability. Therefore, it is considered that a superconducting device can be made with excellent magnetic field stability without causing a quench burnout accident.

(Example 5)
The coating solution for superconductors is synthesized and purified according to the flowchart shown in FIG. Hydrate of metal acetates Pr (OCOCH ₃ ) ₃ , Sm (OCOCH ₃ ) ₃ , Y (OCOCH ₃ ) ₃ , Tm (OCOCH ₃ ) ₃ , Ba (OCOCH ₃ ) ₂ , Cu (OCOCH ₃ ) ₂ Dissolve in ion-exchanged water at a metal ion molar ratio of 0.02: 0.02: 0.92: 0.04: 2: 3, mix and stir with CF ₃ COOH in an equimolar amount of reaction. The obtained mixed solution was placed in a eggplant-shaped flask, and the reaction and purification were carried out under reduced pressure in a rotary evaporator for 12 hours. A translucent blue substance 5Mi-2% PrSm-Y-Tm (substance described in Example 5, Y-based Material with impedance) was obtained.

Similarly, waters of Pr (OCOCH ₃ ) ₃ , Sm (OCOCH ₃ ) ₃ , Y (OCOCH ₃ ) ₃ , Tm (OCOCH ₃ ) ₃ , Ba (OCOCH ₃ ) ₂ , and Cu (OCOCH ₃ ) ₂ are added to the metal acetate. Using Japanese powder, prepare a solution dissolved in ion-exchanged water at a metal ion molar ratio of 0.01: 0.01: 0.96: 0.02: 2: 3, and add CF ₃ COOH in an equimolar amount of reaction. Mixing and stirring were performed, and the obtained mixed solution was placed in a eggplant-shaped flask, and the reaction and purification were carried out under reduced pressure in a rotary evaporator for 12 hours. A translucent blue substance 5Mi-1% PrSm-Y-Tm was obtained.

The obtained translucent blue substance 5Mi-2% PrSm-Y-Tm, 5Mi-1% PrSm-Y-Tm contains about 7 wt% of water and acetic acid, which are reaction by-products during solution synthesis. ..

The obtained translucent blue substance 5Mi-2% PrSm-Y-Tm and 5Mi-1% PrSm-Y-Tm are completely added with methanol (f in FIG. 6) corresponding to about 100 times the weight of each. When the solution is reacted and purified again in a rotary evaporator under reduced pressure for 12 hours, the translucent blue substance 5M-2% PrSm-Y-Tm (the substance described in Example 5, Y-based Material) Without impurity), 5M-1% PrSm-Y-Tm were obtained, respectively.

A translucent blue substance 5M-2% PrSm-Y-Tm, 5M-1% PrSm-Y-Tm was dissolved in methanol (j in FIG. 6), diluted using a volumetric flask, and converted into metal ions. A coating solution of 1.50 mol / l, 5Cs-2% PrSm-Y-Tm (Example 5, Coating Solution for Y-based superconductor), and 5Cs-1% PrSm-Y-Tm were obtained, respectively.

Using a coating solution of 5Cs-2% PrSm-Y-Tm and 5Cs-1% PrSm-Y-Tm, a film was formed at a maximum rotation speed of 2000 rpm using a spin coating method, and the profile shown in FIG. 8 was pure at 400 ° C. or lower. Temporary firing was performed in an oxygen atmosphere, main firing was performed in 1000 ppm oxygen-mixed argon gas at 800 ° C. with the profile shown in FIG. 9, annealing was performed in pure oxygen at 525 ° C. or lower, and the superconducting film 5FS-2% PrSm-Y was performed. -Tm (Example 5, Y-based Film of Superconductor), 5FS-1% PrSm-Y-Tm were obtained, respectively.

The superconducting film 5FS-2% PrSm-Y-Tm and 5FS-1% PrSm-Y-Tm are measured by the 2θ / ω method of XRD measurement, and a peak can be obtained at almost the same position as the YBCO (00n) peak. confirmed.

The superconducting film 5FS-2% PrSm-Y-Tm and 5FS-1% PrSm-Y-Tm were measured by the 2θ / ω method of XRD measurement, respectively. Although a small heterogeneous phase of the BaCu-based composite oxide was observed, almost the same peak as the single peak of YBCO (00n) was obtained. Each peak was one without separation. Even from the YBCO (006) peak at 2θ = 46.68 degrees, the peak was not separated and was clear with one line.

The intensity of the peak is strong enough, and it is estimated that all materials form a perovskite structure. That is, it is shown that PrBCO, SmbCO, and TmBCO are incorporated into the perovskite structure of YBCO in this system.

FIG. 16 shows the results of Jc measurement of the superconducting membranes 5FS-2% PrSm-Y-Tm and 5FS-1% PrSm-Y-Tm at 30K and 1 to 5T. The data (circles) on the upper side of FIG. 16 is the sample. In FIG. 16, the measurement results of YBCO not containing CARP are also shown by crosses and broken lines.

The CARP of the superconducting membrane 5FS-2% PrSm-Y-Tm is 8%. It is expected that the characteristics will decrease in the vicinity of 30K / 5T by that amount, but as can be seen from the results in FIG. 16, a Jc value far higher than that of YBCO has been obtained. The detailed data of the lattice mismatch of Yb and Tm with respect to Y at 800 ° C. at the time of main firing is unknown, but it seems to be about 3% and about 2%, respectively. With this lattice mismatch difference, Tm may have a nucleation frequency about 10 times higher than Yb, or the nucleation rate may be faster.

The CARP formation model shows that if the nucleation rate is about 10 times faster, the number of CARPs in a unit volume will also be about 10 times faster. Since the CARP size is proportional to the reciprocal of its cube root, the CARP radius seems to be 0.46 times. It is probable that the effect was apparent in the Yb excess type CARP, because the CARP became smaller at once using Tm, and the quantum magnetic flux was easily captured by the CARP.

In order to confirm the effect, the measurement results in a magnetic field of the superconducting film 5FS-1% PrSm-Y-Tm with the amount of CARP halved are also shown in FIG. It is the data of the white circle in the figure. The CARPs in this superconducting membrane are theoretically the same size and halved in number. The result is that the result is about half. Strict discussion suggests that the amount of decrease in CARP as an obstacle is an intermediate value between 5FS-2% PrSm-Y-Tm, but the difference seems to be buried in the experimental error.

As can be seen from this result, it is theoretically found that CARP exerts its effect when an element closer to Tm or MA than that is used for CA. This is because the CARP size can be explained by the CARP formation model. Since the CARP size is determined by the nucleation frequency and the amount of substance present therein, it is effective in combination with MA and CA, which have a high nucleation frequency.

From the experiments so far, the substance that can be used for MA is Y or Gd by itself. However, it is known that when mixed, it becomes a solution. On the other hand, CA has good Er and Tm, and it is conceivable to add some Yb to adjust the size. Of course, it is also possible to adjust by mixing some elements having an atomic number smaller than that of Er. With this combination, the characteristic improvement at 30K, which is considered to be particularly important for practical use, has been observed.

As described above, by applying the CARP formation model, a combination in which artificial pins whose characteristics improve at 30K are particularly easy to form has been found. This is mainly a case where a superconductor using Er or Tm for CA and Y or the like for MA. In addition, it is considered that a combination that matches this model will exert an effect, and the above combination seems to be particularly good for exerting an effect at 30K.

The above CARP has another characteristic, and the Tc of the superconductor does not decrease. In addition, it is known from experimental data that almost no internal bypass current is generated.

34, 35, 36, 37, 38, 39, and 40 are graphs showing the current-voltage characteristics of the fifth embodiment. The results at the time of Jc-BT measurement of the superconducting film 5FS-2% PrSm-Y-Tm are shown. As can be seen from the figure, the noise during IV measurement is extremely low.

The data of Example 5 is shown at the bottom of Table 2. The data of 50K measures only 1 to 5T. All 50K data are zero within the experimental error range. In addition, 30K is also a result close to zero except that the value is slightly larger at 15T. This result is in agreement with the speculation from the model that the voltage due to the internal bypass current of CARP is theoretically not generated. Furthermore, this result is consistent with the theory that the voltage due to the internal bypass current does not depend on the pin size even if the CARP pin size is reduced. The data also support that it is an artificial pin that has never been seen in the past.

(Example 6)
The coating solution for superconductors is synthesized and purified according to the flowchart shown in FIG. Hydrate of metal acetates Pr (OCOCH ₃ ) ₃ , Sm (OCOCH ₃ ) ₃ , Y (OCOCH ₃ ) ₃ , Er (OCOCH ₃ ) ₃ , Ba (OCOCH ₃ ) ₂ , Cu (OCOCH ₃ ) ₂ Dissolve in ion-exchanged water at a metal ion molar ratio of 0.02: 0.02: 0.92: 0.04: 2: 3, mix and stir with CF ₃ COOH in an equimolar amount of reaction. The obtained mixed solution was placed in a eggplant-shaped flask, and the reaction and purification were carried out under reduced pressure in a rotary evaporator for 12 hours. A translucent blue substance 6Mi-2% PrSm-Y-Er (substance described in Example 6, Y-based Material with impurity) was obtained.

Similarly, water of Pr (OCOCH ₃ ) ₃ , Sm (OCOCH ₃ ) ₃ , Y (OCOCH ₃ ) ₃ , Tm (OCOCH ₃ ) ₃ , Ba (OCOCH ₃ ) ₂ , Cu (OCOCH ₃ ) ₂ , which are metal acetates. Using Japanese powder, prepare a solution dissolved in ion-exchanged water at a metal ion molar ratio of 0.02: 0.02: 0.92: 0.04: 2: 3, and add CF ₃ COOH in an equimolar amount of reaction. Mixing and stirring were performed, and the obtained mixed solution was placed in a eggplant-shaped flask, and the reaction and purification were carried out under reduced pressure in a rotary evaporator for 12 hours. A translucent blue substance 6Mi-2% PrSm-Y-Tm was obtained.

Similarly, of the metal acetates Pr (OCOCH ₃ ) ₃ , Sm (OCOCH ₃ ) ₃ , Y (OCOCH ₃ ) ₃ , Yb (OCOCH ₃ ) ₃ , Ba (OCOCH ₃ ) ₂ , and Cu (OCOCH ₃ ) ₂ . Using hydrate powder, prepare a solution dissolved in ion-exchanged water at a metal ion molar ratio of 0.02: 0.02: 0.92: 0.04: 2: 3, and prepare a reaction equimolar amount of CF ₃ COOH. And the mixture was mixed and stirred, and the obtained mixed solution was placed in a eggplant-shaped flask, and the reaction and purification were carried out under reduced pressure in a rotary evaporator for 12 hours. A translucent blue substance 6Mi-2% PrSm-Y-Yb was obtained.

In the obtained translucent blue substance 6Mi-2% PrSm-Y-Er, 6Mi-2% PrSm-Y-Tm, and 6Mi-2% PrSm-Y-Yb, there are reaction by-products during solution synthesis. It contains about 7 wt% of certain water and acetic acid.

The obtained translucent blue substance 6Mi-2% PrSm-Y-Er, 6Mi-2% PrSm-Y-Tm, and 6Mi-2% PrSm-Y-Yb each contain about 100 times the weight of methanol. (F in FIG. 6) was added to completely dissolve the solution, and the solution was reacted and purified again under reduced pressure in a rotary evaporator for 12 hours. The translucent blue substance 6M-2% PrSm-Y-Er (Example). The substances described in 6, Y-based Material without impurities), 6M-2% PrSm-Y-Tm, and 6M-2% PrSm-Y-Yb were obtained, respectively.

A translucent blue substance 6M-2% PrSm-Y-Er, 6M-2% PrSm-Y-Tm, and 6M-2% PrSm-Y-Yb were dissolved in methanol (j in FIG. 6) to prepare a volumetric flask. Coating solution 6Cs-2% PrSm-Y-Er (Example 6, Coating Solution for Y-based superconducor), 6Cs-2% PrSm-Y-Tm, respectively, diluted using and diluted with 1.50 mol / l in terms of metal ions. , 6Cs-2% PrSm-Y-Yb were obtained, respectively.

The coating solution 6Cs-2% PrSm-Y-Er and 6Cs-2% PrSm-Y-Tm were mixed at a ratio of 1: 9, 2: 8, 3: 7, and the coating solution 6Cs-2% PrSm-Y-0. 4% Er3.6% Tm, 6Cs-2% PrSm-Y-0.8% Er3.2% Tm, and 6Cs-2% PrSm-Y-1.2% Er2.8% Tm were obtained, respectively.

The coating solution 6Cs-2% PrSm-Y-Tm and 6Cs-2% PrSm-Y-Yb were mixed at 8: 2, 6: 4, 4: 6, and the coating solution 6Cs-2% PrSm-Y-3. 2% Tm0.8% Yb, 6Cs-2% PrSm-Y-2.4% Tm1.6% Yb, and 6Cs-2% PrSm-Y-1.6% Tm2.4% Yb were obtained, respectively.

Coating solution 6Cs-2% PrSm-Y-0.4% Er3.6% Tm, 6Cs-2% PrSm-Y-0.8% Er3.2% Tm, 6Cs-2% PrSm-Y-1.2% Er2.8% Tm, 6Cs-2% PrSm-Y-3.2% Tm0.8% Yb, 6Cs-2% PrSm-Y-2.4% Tm1.6% Yb, 6Cs-2% PrSm-Y- Using 1.6% Tm2.4% Yb, a film was formed at a maximum rotation speed of 2000 rpm using a spin coating method, and calcined with the profile shown in FIG. 8 in a pure oxygen atmosphere of 400 ° C. or lower, and shown in FIG. The profile was burnt in 1000 ppm oxygen mixed argon gas at 800 ° C., annealed in pure oxygen at 525 ° C. or lower, and superconducting film 6FS-2% PrSm-Y-0.4% Er3.6% Tm (implemented). Example 6, Y-based Film of Superconductor), 6FS-2% PrSm-Y-0.8% Er3.2% Tm, 6FS-2% PrSm-Y-1.2% Er2.8% Tm, 6FS-2 % PrSm-Y-3.2% Tm0.8% Yb, 6FS-2% PrSm-Y-2.4% Tm1.6% Yb, 6FS-2% PrSm-Y-1.6% Tm2.4% Yb Was obtained respectively.

Superconducting film 6FS-2% PrSm-Y-0.4% Er3.6% Tm, 6FS-2% PrSm-Y-0.8% Er3.2% Tm, 6FS-2% PrSm-Y-1.2% Er2.8% Tm, 6FS-2% PrSm-Y-3.2% Tm0.8% Yb, 6FS-2% PrSm-Y-2.4% Tm1.6% Yb, 6FS-2% PrSm-Y- 1.6% Tm2.4% Yb was measured by the 2θ / ω method of XRD measurement, respectively, and it was confirmed that a peak was obtained at almost the same position as the YBCO (00n) peak.

Superconducting film 6FS-2% PrSm-Y-0.4% Er3.6% Tm, 6FS-2% PrSm-Y-0.8% Er3.2% Tm, 6FS-2% PrSm-Y-1.2% Er2.8% Tm, 6FS-2% PrSm-Y-3.2% Tm0.8% Yb, 6FS-2% PrSm-Y-2.4% Tm1.6% Yb, 6FS-2% PrSm-Y- 1.6% Tm2.4% Yb was measured by the 2θ / ω method of XRD measurement, respectively. Although a small heterogeneous phase of the BaCu-based composite oxide was observed, almost the same peak as the single peak of YBCO (00n) was obtained. Each peak was one without separation. Even from the YBCO (006) peak at 2θ = 46.68 degrees, the peak was not separated and was clear with one line.

The intensity of the peak is strong enough, and it is estimated that all materials form a perovskite structure. That is, it is shown that PrBCO, SmBCO, ErBCO, TmBCO, and YbBCO are incorporated into the perovskite structure of YBCO in this system.

Superconducting film 6FS-2% PrSm-Y-0.4% Er3.6% Tm, 6FS-2% PrSm-Y-0.8% Er3.2% Tm, 6FS-2% PrSm-Y-1.2% Er2.8% Tm, 6FS-2% PrSm-Y-3.2% Tm0.8% Yb, 6FS-2% PrSm-Y-2.4% Tm1.6% Yb, 6FS-2% PrSm-Y- The results (MA / cm ² ) of Jc measurement of 1.6% Tm 2.4% Yb at 30K and 5T, respectively, are 2.13, 2.39, 2.60, 1.65, and 1. It was 44 and 1.21.

The discussion of the lattice mismatch between Tm and Yb was as described above, and there was a strong tendency for the CARP size to increase and the characteristics of 30K / 5T to decline as the Yb ratio increased. This result was also in line with the CARP formation model, in which the nucleation rate determines the CARP size.

On the other hand, the characteristics of the sample in which a small amount of Er was added to Tm were significantly improved. This also indicates that the nucleation rate of Er is considerably faster than that of Tm, suggesting that the CARP size is decreasing. It is believed that this improved the characteristics of 30K / 5T.

Superconducting film 6FS-2% PrSm-Y-0.4% Er3.6% Tm, 6FS-2% PrSm-Y-0.8% Er3.2% Tm, 6FS-2% PrSm-Y-1.2% Er2.8% Tm, 6FS-2% PrSm-Y-3.2% Tm0.8% Yb, 6FS-2% PrSm-Y-2.4% Tm1.6% Yb, 6FS-2% PrSm-Y- The noise at the time of IV measurement at 30K / 5T of 1.6% Tm2.4% Yb was about 1/100 to 1/300 as compared with the superconducting film of the physical vapor deposition method in which the BZO artificial pin was introduced. The result is almost zero.

This time, although the CARP formed inside the superconductor measured in the above embodiment has different sizes, it is theorized that the CARP is detoured independently of the CARP radius R from the calculation of the current detour by the superconducting current and the CARP. I know it. From the results, the voltage due to all internal bypass currents should be around 1/300, but a voltage of around 1/100 was also confirmed. However, this voltage level is probably not a problem in practice.

The superconducting film containing the BZO artificial pin formed by the PLD method has an actual measurement value of 0. The value is 1%, which is more than 10 times higher. This makes it impossible to accurately irradiate the affected area of the patient with a particle beam.

However, when the coil is made of the wire rod containing the CARP pin developed this time, the magnetic field accuracy is expected to be improved by about 100 times, and the accuracy at 5T is likely to be 0.001%. Since it will take several years to make a coil using this technology as a long wire, the accuracy of the magnetic field formed is unknown at this time, but the noise voltage due to the internal bypass current is improved by about 100 times. Is expected to be. A 10-fold improvement in accuracy is easily reached, and there is a high possibility that it will be the first technology to provide a practical level Y-based coil.

In the embodiment, a heavy ion beam therapy device has been described as an example of a superconducting device, but it can also be applied to a superconducting device such as a superconducting magnetic levitation type railway vehicle or a fusion reactor.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. For example, the components of one embodiment may be replaced or modified with the components of another embodiment. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

20 Superconducting wire material 22 Base material 24 Intermediate layer 30 Oxide superconducting layer 40 Metal layer 100 Superconducting coil 200 Heavy particle beam therapy device

Claims (14)

It has a continuous perovskite structure containing a rare earth element, barium (Ba), and copper (Cu), and the rare earth element is a first element, neodium (Nd), samarium (Sm), which is a placeodium (Pr). At least one second element in the group of europium (Eu) and gadrinium (Gd), at least one third element in the group of ittrium (Y), terbium (Tb), dysprosium (Dy) and formium (Ho). A superconducting wire comprising an element and an oxide superconducting layer containing at least one fourth element in the group of dysprosium (Er), turium (Tm), itterbium (Yb) and lutetium (Lu). The second element is at least one kind in the group of neodymium (Nd) and samarium (Sm), and the third element is at least one kind in the group of thulium (Y), dysprosium (Dy) and holmium (Ho). The superconducting wire material according to claim 1, wherein the fourth element is at least one kind in the group of erbium (Er) and thulium (Tm). Claim that the second element is samarium (Sm), the third element is at least one of the groups yttrium (Y) and holmium (Ho), and the fourth element is thulium (Tm). The superconducting wire material according to claim 1 or 2. The oxide superconducting layer contains fluorine (F) of 2.0 × 10 ¹⁵ atoms / cc or more and 5.0 × 10 ¹⁹ atoms / cc or less, and 1.0 × 10 ¹⁷ atoms / cc or more and 5.0 × 10 ^20. The superconducting wire material according to any one of claims 1 to 3, which contains carbon (C) of atoms / cc or less. Claims 1 to 0.6 where N (MA) / N (RE) ≥ 0.6 when the number of atoms of the rare earth element is N (RE) and the number of atoms of the third element is N (MA). 4. The superconducting wire according to any one of claims. Claim 1 to 0.00000001 ≦ N (PA) / N (RE) when the number of atoms of the rare earth element is N (RE) and the number of atoms of the first element is N (PA). 5. The superconducting wire according to any one of claims 5. When the number of atoms of the rare earth element is N (RE), the number of atoms of the first element is N (PA), and the number of atoms of the second element is N (SA), (N (PA) ) + N (SA)) / N (RE) ≤ 0.2. The superconducting wire according to any one of claims 1 to 6. 0.8 when the number of atoms of the first element is N (PA), the number of atoms of the second element is N (SA), and the number of atoms of the fourth element is N (CA). The superconducting wire material according to any one of claims 1 to 7, wherein × N (CA) ≦ N (PA) + N (SA) ≦ 1.2 × N (CA). It has a continuous perovskite structure containing a rare earth element, barium (Ba), and copper (Cu), and the rare earth element is a first element, gadolinium (Gd), ytterbium (Y), which is a placeodium (Pr). At least one second element in the terbium (Tb), dysprosium (Dy) and holmium (Ho) groups, as well as in the terbium (Er), turium (Tm), ytterbium (Yb) and lutetium (Lu) groups. A superconducting wire having an oxide superconducting layer containing at least one third element. The oxide superconducting layer contains fluorine of 2.0 × 10 ¹⁵ atoms / cc or more and 5.0 × 10 ¹⁹ atoms / cc or less, and 1.0 × 10 ¹⁷ atoms / cc or more and 5.0 × 10 ²⁰ atoms / cc. The superconducting wire material according to claim 9, which includes the following carbon. Claim 9 or claim 9 where N (MA) / N (RE) ≥ 0.6 when the number of atoms of the rare earth element is N (RE) and the number of atoms of the second element is N (MA). The superconducting wire material according to claim 10. Claim 9 to 0.00000001 ≦ N (PA) / N (RE) when the number of atoms of the rare earth element is N (RE) and the number of atoms of the first element is N (PA). 11. The superconducting wire according to any one of claims 11. Claims 9 to 0.2, where N (PA) / N (RE) ≤ 0.2 when the number of atoms of the rare earth element is N (RE) and the number of atoms of the first element is N (PA). 12. The superconducting wire according to any one of claims 12. Further provided with a tape-shaped base material and a metal layer,
The superconducting wire material according to any one of claims 1 to 13, wherein the oxide superconducting layer exists between the base material and the metal layer.