Magnetic refrigeration material, manufacturing method thereof, AMR bed using the same, and magnetic refrigeration device

Abstract

To provide a magnetic refrigeration material having a large magnetic entropy change in the temperature range of 17K to 77K, a manufacturing method thereof, an AMR bed using the same, and a magnetic refrigeration device.SOLUTION: A magnetic refrigeration material contains at least an R element (the R element is at least one element selected from the group consisting of dysprosium (Dy), holmium (Ho), and erbium (Er)), a T element (the T element is at least one element selected from the group consisting of platinum (Pt), cobalt (Co), and nickel (Ni)), and an X element (the X element includes at least aluminum (Al)), and contains an inorganic compound having a cubic Gd4RhIn type crystal structure.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a magnetic refrigeration material, a manufacturing method thereof, an AMR bed using the same, and a magnetic refrigeration device. [Background technology]

[0002] Hydrogen, which is a promising energy carrier, should be used in a "liquid" state that can be stored and transported at high density in order to be widely used. Since hydrogen's liquefaction temperature is about 20 Kelvin (minus 253 degrees), the second lowest after helium, it is essential to develop and improve the efficiency of liquefaction technology. Conventional liquefaction methods that use gas compression and expansion have a theoretical upper limit on liquefaction efficiency (about 40%), which keeps the cost of liquefying hydrogen high. On the other hand, magnetic refrigeration technology based on the magnetocaloric effect, which uses the entropy change that occurs when a magnetic material is magnetized (heat generation) and demagnetized (heat absorption) using a magnetic field, can theoretically achieve a liquefaction efficiency of up to 90%, and is expected to contribute to the widespread use of hydrogen.

[0003] Magnetic refrigeration materials, which are directly linked to hydrogen efficiency, need to have a large entropy change when the magnetic field is turned on and off at around 20 Kelvin, where hydrogen liquefies. Materials such as R4PdMg (R = Er, Ho, Tm), R4CoCd (R = Er, Ho, Tm), and Er4NiCd, which have a cubic Gd4RhIn type crystal structure, have been reported as such magnetic refrigeration materials (see, for example, Non-Patent Document 1). According to Table 5 in Non-Patent Document 1, the magnitude of magnetic entropy change (ΔS M ) is 13.4J / kgK~20.4J / kgK(123.1mJ / cm 3 K~191.8mJ / cm 3 However, these materials use magnesium (Mg) or cadmium (Cd), which have very high vapor pressures, and therefore require sealing in a tantalum tube during production, which results in high costs and the ability to produce only small quantities.

[0004] There have been reports of other materials having a cubic Gd4RhIn type crystal structure (see, for example, Non-Patent Documents 2 to 4). Non-Patent Documents 2 to 4 disclose Gd4RhAl, Tb4RhAl, Ho4RhAl, and Er4RhAl. Unlike Non-Patent Document 1, these use aluminum (Al), making them easier to manufacture. However, according to Non-Patent Documents 2 to 4, the magnitude of magnetic entropy change (ΔS M ) is at most 8J / kgK (80mJ / cm 3 K) and cannot be used for hydrogen liquefaction.

[0005] Thus, even if an inorganic compound has a cubic Gd4RhIn type crystal structure, the magnetic entropy change varies depending on the selected elements, and it is not necessarily possible to use it as a magnetic refrigeration material, especially for hydrogen liquefaction. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] L. Li et al., Journal of Alloys and Compounds, 823, 2020, 153810 [Non-Patent Document 2] R. Kumar et al., PHYSICAL REVIEW MATERIALS 5, 054407, 2021 [Non-Patent Document 3] R. Kumar et al., Journal of Magnetism and Magnetic Materials, 490, 2019, 165515 [Non-Patent Document 4] R. Kumar et al., Journal of Magnetism and Magnetic Materials, 538, 2021, 168285 Summary of the Invention [Problem to be solved by the invention]

[0007] In view of the above, an object of the present invention is to provide a magnetic refrigeration material having a large magnetic entropy change in the temperature range of 17 K or more and 77 K or less, a manufacturing method thereof, an AMR bed using the same, and a magnetic refrigeration device. [Means for solving the problem]

[0008] The magnetic refrigeration material according to the present invention contains at least an R element (the R element is at least one element selected from the group consisting of dysprosium (Dy), holmium (Ho), and erbium (Er)), a T element (the T element is at least one element selected from the group consisting of platinum (Pt), cobalt (Co), and nickel (Ni)), and an X element (the X element includes at least aluminum (Al)), and contains an inorganic compound having a cubic Gd4RhIn type crystal structure, thereby solving the above-mentioned problems. The inorganic compound is R: 60 atomic% or more and 75 atomic% or less, T: 12.5 atom% or more and 21 atom% or less, X: 12.5 atomic % or more and 21 atomic % or less, and Impurity elements less than 1 atomic % (wherein the total of the R element, the T element, the X element and the unavoidable impurity element satisfies 100 atomic %). The inorganic compound is R: 65 atomic% or more and 70 atomic% or less, T: 15 atomic% or more and 20 atomic% or less, X: 15 atomic % or more and 20 atomic % or less, and Impurity elements less than 1 atomic % The composition may consist of: The inorganic compound is R: 65 atomic% or more and 68 atomic% or less, T: 15 atomic% or more and 18 atomic% or less, X: 15 atomic % or more and 18 atomic % or less, and Impurity elements less than 1 atomic % The composition may consist of: The inorganic compound may be a phase represented by the general formula R4TX. The T element may include at least platinum. The inorganic compound is R: 60 atomic% or more and 70 atomic% or less, Pt: more than 0 atomic % and not more than 21 atomic % Co and / or Ni: 0 atomic % or more and less than 21 atomic %; X: 12.5 atomic% or more and 21 atomic% or less, 1 atomic % or less of inevitable impurity elements, and Total of Pt and Co and / or Ni: 12.5 atomic % or more and 21 atomic % or less (wherein the sum of the R element, the Pt, the Co and / or Ni, the X element, and the unavoidable impurity element satisfies 100 atomic %). The inorganic compound is R: 65 atomic% or more and 70 atomic% or less, Pt: 4 atomic% or more and 20 atomic% or less, Co and / or Ni: 0 atomic % or more and less than 16 atomic %; X: 15 atomic% or more and 20 atomic% or less, 1 atomic % or less of inevitable impurity elements, and Total of Pt and Co and / or Ni: 15 atomic % or more and 20 atomic % or less The composition may consist of: The inorganic compound is R: 65 atomic% or more and 68 atomic% or less, Pt: 4 atomic% or more and 18 atomic% or less, Co and / or Ni: 0 atomic % or more and less than 16 atomic %; X: 15 atomic % or more and 18 atomic % or less, 1 atomic % or less of inevitable impurity elements, and Total of Pt and Co and / or Ni: 15 atomic % or more and 18 atomic % or less The composition may consist of: The inorganic compound has the general formula R4Pt 1-α (Co,Ni) αX (α satisfies 0<α≦0.75). The X element may further include at least one element selected from the group consisting of silicon (Si), magnesium (Mg), and cadmium (Cd). General formula R 14 It may further contain a second phase represented by T3X3. The content of the second phase may be in the range of more than 0% by volume to 45% by volume. The content of the second phase may be in the range of more than 0% by volume to 40% by volume. The method for producing the magnetic refrigeration material according to the present invention includes melting a raw material mixture that contains at least an R element (the R element is at least one element selected from the group consisting of dysprosium (Dy), holmium (Ho), and erbium (Er)), a T element (the T element is at least one element selected from the group consisting of platinum (Pt), cobalt (Co), and nickel (Ni)), and an X element (the X element includes at least aluminum (Al)), and the molar ratio of the R element, the T element, and the X element satisfies 3.8-4.2:0.8-1.2:0.8-1.2, thereby solving the above-mentioned problem. The AMR bed according to the present invention includes the above-mentioned magnetic refrigeration material, thereby solving the above-mentioned problems. The magnetic refrigeration device according to the present invention includes the above-mentioned AMR bed, thereby solving the above-mentioned problems. Effect of the Invention

[0009] The magnetic refrigeration material of the present invention has the above-mentioned specific composition, and therefore has a magnetic flux density of 10 J / kgK or more at 5 T (tesla) or 100 mJ / cm in the temperature range of 17 K or more and 77 K or less. 3 Since the magnetic entropy change is large at 100 K or more, it shows excellent magnetic refrigeration properties. Since the magnetic refrigeration material of the present invention contains Al, it is easy to manufacture. Furthermore, if the magnetic refrigeration material of the present invention is applied to an AMR bed and a magnetic refrigeration device, it will function effectively in liquefying hydrogen, etc. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing the crystal structure of an inorganic compound constituting the magnetic refrigeration material of the present invention. [Diagram 2] Schematic diagram showing the crystal structure of the second phase represented by the general formula R14T3X3 [Diagram 3] FIG. 1 is a flowchart showing the production of a magnetic refrigeration material according to the present invention. [Figure 4] Schematic diagram showing a magnetic refrigeration device of the present invention. [Diagram 5] Schematic diagram showing an AMR bed with multiple magnetic refrigeration materials [Figure 6] FIG. 1 shows XRD patterns of samples of Examples 1 to 5. [Figure 7] FIG. 1 shows XRD patterns of samples of Examples 6 to 8. [Figure 8] FIG. 1 shows an XRD pattern of the sample of Example 9. [Figure 9] FIG. 1 shows the results of magnetization measurement of the sample in Example 1. [Figure 10] FIG. 1 shows the results of magnetization measurement of the sample in Example 2. [Figure 11] FIG. 1 shows the results of magnetization measurement of the sample in Example 3. [Figure 12] FIG. 1 shows the results of magnetization measurement of the sample in Example 4. [Figure 13] FIG. 1 shows the results of magnetization measurement of the sample in Example 5. [Figure 14] Magnetic entropy change diagram of samples of Examples 1 to 5 [Figure 15] FIG. 1 shows the results of magnetization measurement of the sample in Example 6. [Figure 16] FIG. 1 shows the results of magnetization measurement of the sample in Example 7. [Figure 17] FIG. 1 shows the results of magnetization measurement of the sample in Example 8. [Figure 18] FIG. 1 shows the results of magnetization measurement of the sample of Example 9. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that like elements are given like reference numerals and their description will be omitted. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. (Embodiment 1) In the first embodiment, a magnetic refrigeration material and a method for producing the same of the present invention will be described in detail.

[0012] The magnetic refrigeration material of the present invention contains at least an R element (wherein the R element is at least one element selected from the group consisting of dysprosium (Dy), holmium (Ho), and erbium (Er)), a T element (wherein the T element is at least one element selected from the group consisting of platinum (Pt), cobalt (Co), and nickel (Ni)), and an X element (wherein the X element includes at least aluminum (Al)), and contains an inorganic compound having a cubic Gd4RhIn type crystal structure. The present inventors have found that an inorganic compound composed of the above-mentioned specific elements and having a cubic Gd4RhIn type crystal structure has a large magnetic entropy change in the temperature range of 17 K to 77 K, and functions as a magnetic refrigeration material. In the present specification, a large magnetic entropy change ΔS m At 5T (tesla), the absolute value is 10J / kgK or more, or 100mJ / cm 3 This refers to those that meet K or higher.

[0013] FIG. 1 is a schematic diagram showing the crystal structure of an inorganic compound constituting the magnetic refrigeration material of the present invention.

[0014] FIG. 1 shows the crystal structure of Ho4PtAl crystal when R element is Ho, T element is Pt, and X element is Al. Ho4PtAl crystal has a cubic Gd4RhIn type crystal structure, belongs to the F43m space group (space group number 216 in the International Tables for Crystallography), and has the crystal parameters and atomic coordinate positions shown in Table 1. In this specification, "4" represents an overbar over 4.

[0015] In Table 1, the lattice constants a, b, and c indicate the lengths of the axes of the unit cell, and α, β, and γ indicate the angles between the axes of the unit cell. The atomic coordinates indicate the position of each atom in the unit cell, with values ​​between 0 and 1 in units of the unit cell.

[0016] [Table 1]

[0017] According to the data in Table 1, the structure of the Ho4PtAl crystal is as shown in Figure 1, and there is a crystal phase represented by the general formula R4TX as an inorganic compound containing R, T and X elements and having a cubic Gd4RhIn crystal structure, where R is at least one element selected from the group consisting of Dy, Ho and Er, T is at least one element selected from the group consisting of Pt, Co and Ni, and X is at least Al.

[0018] In the crystal phases represented by R4TX other than the Ho4PtAl crystal, the lattice constant changes due to the replacement of the components of the Ho4PtAl crystal with other elements, but the atomic positions given by the crystal structure, the sites occupied by the atoms, and their coordinates do not change so much that the chemical bonds between the skeletal atoms are broken. In the present invention, if the lattice constants and the distance between adjacent atoms calculated from the atomic coordinates obtained by crystal structure analysis of the results of X-ray diffraction or neutron diffraction in the F43m space group are within ±5% of the chemical bond lengths calculated from the lattice constants and atomic coordinates shown in Table 1, the compound may be defined as an inorganic compound having a cubic Gd4RhIn type crystal structure. If the chemical bond length changes by more than ±5%, it may become a different crystal.

[0019] For simplicity, an inorganic compound having a cubic Gd4RhIn type crystal structure may be determined to have been obtained when the X-ray diffraction results measured for the synthesized inorganic compound coincide with the diffraction peak positions (2θ) calculated from Table 1 for the main peaks. In this case, it is advisable to determine the main peaks based on about 10 peaks with the strongest diffraction intensities.

[0020] As described above, the magnetic refrigeration material of the present invention contains an inorganic compound that contains an R element, a T element, and an X element and has a cubic Gd4RhIn type crystal structure. The inorganic compound is preferably R: 60 atomic% or more and 75 atomic% or less, T: 12.5 atom% or more and 21 atom% or less, X: 12.5 atomic % or more and 21 atomic % or less, and Impurity elements less than 1 atomic % However, the total of the R element, T element, X element and unavoidable impurity element must be 100 atomic %. Within this range, the cubic Gd4RhIn type crystal structure is stable and a large magnetic entropy change is exhibited in the above temperature range. When multiple elements are selected as the R element, T element and X element, the total atomic percentage of the multiple elements must be within the above range.

[0021] Of course, the inevitable impurity elements may be at the detection limit, and may even be 0 atomic %, but from the viewpoint of magnetic refrigeration characteristics, it is preferable to suppress the content to 1 atomic % or less. The inevitable impurity elements include impurity elements in raw materials and impurity elements mixed in during the manufacturing stage, and examples thereof include calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), silicon (Si), vanadium (V), carbon (C), lead (Pb), sodium (Na), zinc (Zn), arsenic (As), antimony (Sb), bismuth (Bi), sulfur (S), and tin (Sn).

[0022] In the magnetic refrigeration material of the present invention, the inorganic compound is more preferably R: 65 atomic% or more and 70 atomic% or less, T: 15 atomic% or more and 20 atomic% or less, X: 15 atomic % or more and 20 atomic % or less, and Impurity elements less than 1 atomic % In this range, the cubic Gd4RhIn type crystal structure becomes more stable, and a large magnetic entropy change is exhibited in the above temperature range.

[0023] In the magnetic refrigeration material of the present invention, the inorganic compound is more preferably R: 65 atomic% or more and 68 atomic% or less, T: 15 atomic% or more and 18 atomic% or less, X: 15 atomic % or more and 18 atomic % or less, and Impurity elements less than 1 atomic % In this range, the cubic Gd4RhIn type crystal structure is particularly stable, and a large magnetic entropy change is exhibited in the above temperature range.

[0024] In particular, when Ho and / or Er is selected as the R element, the peak of the magnetic entropy change is located in the range of 14 K or more and 25 K or less, which is advantageous for hydrogen liquefaction.

[0025] In the magnetic refrigeration material of the present invention, the T element preferably contains at least platinum (Pt). By containing Pt, a larger magnetic entropy change is exhibited in the above temperature range. The T element may be Pt alone, or may contain Co and / or Ni in addition to platinum. If the T element is Pt alone, the second phase described below can be reduced as much as possible.

[0026] In the magnetic refrigeration material of the present invention, when the T element contains Pt, the inorganic compound is preferably R: 60 atomic% or more and 70 atomic% or less, Pt: more than 0 atomic % and not more than 21 atomic % Co and / or Ni: 0 atomic % or more and less than 21 atomic %; X: 12.5 atomic% or more and 21 atomic% or less, 1 atomic % or less of inevitable impurity elements, and Total of Pt, Co and / or Ni: 12.5 atomic % or more and 21 atomic % or less However, the total of the R element, Pt, Co and / or Ni, the X element, and the unavoidable impurity elements is 100 atomic %. Within this range, the cubic Gd4RhIn type crystal structure is stable, and a larger magnetic entropy change is shown in the above temperature range.

[0027] In the magnetic refrigeration material of the present invention, when the T element contains Pt, the inorganic compound is more preferably R: 65 atomic% or more and 70 atomic% or less, Pt: 4 atomic% or more and 20 atomic% or less, Co and / or Ni: 0 atomic % or more and less than 16 atomic %; X: 15 atomic% or more and 20 atomic% or less, 1 atomic % or less of inevitable impurity elements, and Total of Pt, Co and / or Ni: 15 atomic % or more and 20 atomic % or less In this range, due to the effect of Pt, the cubic Gd4RhIn type crystal structure and the second phase described below become stable, and a large magnetic entropy change is exhibited in the above temperature range.

[0028] In the magnetic refrigeration material of the present invention, when the T element contains Pt, the inorganic compound is more preferably R: 65 atomic% or more and 68 atomic% or less, Pt: 4 atomic% or more and 18 atomic% or less, Co and / or Ni: 0 atomic % or more and less than 16 atomic %; X: 15 atomic % or more and 18 atomic % or less, 1 atomic % or less of inevitable impurity elements, and Total of Pt, Co and / or Ni: 15 atomic % to 18 atomic % In this range, the effect of Pt stabilizes the cubic Gd4RhIn type crystal structure and the second phase described later, and a particularly large magnetic entropy change is shown in the above temperature range. In particular, the content of Pt can be reduced, which is advantageous for cost reduction.

[0029] In the magnetic refrigeration material of the present invention, when the T element contains Pt, the inorganic compound is represented by the general formula R4Pt 1-α (Co,Ni) αX (where α satisfies 0<α≦0.75). Within this range, the cubic Gd4RhIn crystal structure is stable and exhibits a large magnetic entropy change in the above temperature range. α is preferably 0.3≦α≦0.75. By setting α within this range, the cubic Gd4RhIn crystal structure is stable and exhibits a particularly large magnetic entropy change in the above temperature range. For example, if α is set to 0.3≦α≦0.5, the Pt content is reduced, which is advantageous for reducing costs. In the above general formula, "(Co,Ni)" means Co and / or Ni, and there is no limit to the ratio of Co to Ni as long as α is satisfied.

[0030] The magnetic refrigeration material of the present invention must contain Al as the X element, but may contain silicon (Si), magnesium (Mg), cadmium (Cd), etc. in addition to Al. In this case, the content of Al in the X element is preferably 50 atomic % or more. This stabilizes the cubic Gd4RhIn type crystal structure and allows for good production yield. It is particularly preferable that the X element is simple Al. This not only makes the cubic Gd4RhIn type crystal structure particularly stable, but also reduces the production cost of the magnetic refrigeration material.

[0031] The magnetic refrigeration material of the present invention is preferably made of an inorganic compound having the above-mentioned cubic Gd4RhIn type crystal structure, but it is also preferable that the magnetic refrigeration material of the present invention is made of an inorganic compound having the general formula R 14 The magnetic refrigeration material of the present invention may further contain a second phase represented by T3X3. Here again, the R element is at least one element selected from the group consisting of dysprosium (Dy), holmium (Ho), and erbium (Er), the T element is at least one element selected from the group consisting of platinum (Pt), cobalt (Co), and nickel (Ni), and the X element includes at least aluminum (Al). Even if the magnetic refrigeration material of the present invention contains a second phase, it has a large magnetic entropy change in the above temperature range, and therefore can be manufactured without setting strict manufacturing conditions, which is advantageous.

[0032] FIG. 2 shows the general formula R 14FIG. 2 is a schematic diagram showing the crystal structure of a second phase represented by T3X3.

[0033] In FIG. 2, the R element is Ho, the T element is Ni, and the X element is Al. 14 The crystal structure of Ni3Al3 crystal is shown. 14 The Ni3Al3 crystal is a tetragonal Gd 14 Co3In 2.7 It has a type crystal structure, belongs to the P42 / nmc space group (space group No. 137 in the International Tables for Crystallography), and has the crystal parameters and atomic coordinate positions shown in Table 2.

[0034] In Table 2, the lattice constants a, b, and c indicate the lengths of the axes of the unit cell, and α, β, and γ indicate the angles between the axes of the unit cell. The atomic coordinates indicate the position of each atom in the unit cell, with values ​​between 0 and 1 in units of the unit cell.

[0035] [Table 2]

[0036] Tetragonal Gd 14 Co3In 2.7 The general formula R 14 Whether or not the second phase represented by T3X3 is contained may be determined in the same manner as in the determination of inorganic compounds having a cubic Gd4RhIn type crystal structure described with reference to Table 1.

[0037] The content of the second phase in the inorganic compound may be, for example, in the range of more than 0 volume % to 45 volume % or less. If the upper limit of the second phase is set to 45 volume % or less, the desired magnetic entropy change can be achieved in the above temperature range. From this viewpoint, in the magnetic refrigeration material of the present invention, the inorganic compound having a cubic Gd4RhIn type crystal structure is contained in an amount of more than 55 volume %. The content of the second phase is preferably in the range of 40 volume % or less. In particular, when the T element contains Co and / or Ni in addition to Pt, the magnetic refrigeration material of the present invention can be produced without restrictions on the production conditions within this range, and the yield is excellent. In the present specification, the content of the second phase refers to a value calculated by fitting the diffraction patterns from each phase calculated by the Rietveld method or the like based on data of powder X-ray diffraction or neutron diffraction.

[0038] The form of the magnetic refrigeration material of the present invention is not particularly limited, but may be, for example, a bulk body or particles. For example, if the magnetic refrigeration material has a particulate shape, when it is applied to an AMR bed and a magnetic refrigeration device described later, it can increase heat exchange with gas or liquid. When the magnetic refrigeration material of the present invention has a particulate shape, the particle size satisfies a particle size (average particle size) in the range of 10 μm to 3000 μm in the case of spherical approximation. This makes it applicable to a magnetic refrigeration device. For example, the magnetic refrigeration material may be in the form of particles having a diameter of 50 μm or more, 100 μm or more, or 200 μm or more, 2000 μm or less, 1000 μm or less, or 500 μm or less in the case of spherical approximation. Among them, the magnetic refrigeration material of the present invention is preferably in the form of particles having a diameter in the range of 200 μm to 400 μm, since it can maximize heat exchange.

[0039] The average particle size is determined by measuring the particle sizes of 100 randomly selected particles in an image observed with a scanning electron microscope (SEM) using image analysis software, and using this as the average particle size.

[0040] Next, a method for producing the magnetic refrigeration material of the present invention will be described. FIG. 3 is a flowchart showing a method for producing the magnetic refrigeration material of the present invention.

[0041] Step S310: A raw material mixture containing at least an R element (the R element is at least one element selected from the group consisting of dysprosium (Dy), holmium (Ho), and erbium (Er)), a T element (the T element is at least one element selected from the group consisting of platinum (Pt), cobalt (Co), and nickel (Ni)), and an X element (the X element includes at least aluminum (Al)), in which the molar ratio of the R element, the T element, and the X element satisfies 3.8-4.2:0.8-1.2:0.8-1.2, is uniformly melted.

[0042] In this way, the magnetic refrigeration material of the present invention can be produced by melting raw materials that satisfy the molar ratio of R element, T element, and X element, eliminating the need for special techniques and the like, which is advantageous for practical use.

[0043] The raw material mixture containing the R element, the T element, and the X element may be composed of a raw material containing the R element, a raw material containing the T element, and a raw material containing the T element, respectively, and may be an R metal element, a T metal element, and an X metal element, but may also be, for example, an alloy or intermetallic compound of two or more elements selected from the group consisting of the R element, the T element, and the X element, or, when the X element contains silicon in addition to Al, a silicide of R, a silicide of T, a silicide of X, etc. In this case, too, it is sufficient to mix so that the molar ratio of each element in the compound satisfies the above-mentioned range.

[0044] In step S310, the firing of the raw material mixture is not particularly limited as long as the mixture can be melted and reacted, but for example, it may be heated to a temperature range of 1000° C. to 2200° C. The melting and reaction may be preferably carried out under atmospheric pressure, below atmospheric pressure, or above atmospheric pressure, in a high vacuum atmosphere, or in a rare gas atmosphere such as argon or helium. For example, arc melting or high frequency melting may be used for such melting and reaction.

[0045] Following step S310, the reactants may be cast and quenched to obtain a magnetic refrigeration material of a desired shape.

[0046] Following step S310, the reactants may be heat-treated to homogenize the reactants. Such homogenization may be performed in a vacuum or in a rare gas atmosphere at a temperature in the range of 600° C. to 850° C. for a period of 10 hours to 100 hours.

[0047] The reaction product (solidified product) thus obtained is the magnetic refrigeration material of the present invention. If the solidified product is pulverized into particles, the magnetic refrigeration material of the present invention can be provided in the form of particles.

[0048] (Embodiment 2) In the second embodiment, a magnetic refrigeration device using the magnetic refrigeration material of the present invention described in the first embodiment will be described.

[0049] FIG. 4 is a schematic diagram showing a magnetic refrigeration device of the present invention.

[0050] The magnetic refrigeration device 400 of the present invention, which includes the magnetic refrigeration material of the present invention described in the first embodiment, can be used to generate ultra-low temperatures, for example, liquefy hydrogen. The magnetic refrigeration device 400 of the present invention further includes an AMR bed 420 filled with the magnetic refrigeration material, a magnetic field application means 430 for applying a magnetic field thereto, a cooling stage 490 for cooling an object to be cooled by cold and hot, and a heat exchanger 440 for discharging heat generated by the magnetic refrigeration material in the AMR bed 420. Here, the magnetic refrigeration material 401 is the magnetic refrigeration material described in the first embodiment.

[0051] The magnetic field application means 430 can be any means for applying a magnetic field to the AMR bed 420, and it is practical to use a magnetic field with a strength of about 1 to 10 T (tesla), for example. A superconducting magnet, a permanent magnet, or the like can be adopted as the magnetic field application means 430. In addition, the relative positions of the magnetic field application means 430 and the AMR bed 420 can be changed by a driving mechanism (not shown) to change the magnitude of the magnetic field applied to the AMR bed 420.

[0052] A pre-cooling stage 460 is provided on the high temperature side of the AMR bed 420, an 80K shield 470 is connected to the low temperature side of the pre-cooling stage 460, and a 300K shield 480 is connected to the high temperature side of the pre-cooling stage 460. Furthermore, a cooling stage 490 is provided on the low temperature side of the AMR bed 420, and a liquefaction vessel 450 is provided and thermally connected to the cooling stage 490. In other words, the liquefaction vessel 450 is the object to be cooled. In addition, an inlet and outlet for the heat transport refrigerant are provided in the AMR bed 420, and the heat transport refrigerant can flow back and forth inside the AMR bed 420 through the gaps in the magnetic refrigeration material 401.

[0053] A gas 410 to be liquefied (eg, hydrogen, helium (He), etc.) is supplied to the liquefaction vessel 450 from a tank (not shown).

[0054] The magnetic refrigeration device 400 of the present invention operates as follows, and can produce liquid hydrogen or gas-cool it.

[0055] First, a magnetic field is applied by a magnetic field application means 430 to the AMR bed 420 filled with the magnetic refrigeration material 401, thereby increasing the temperature of the magnetic refrigeration material 401.

[0056] Next, the heat transport refrigerant is caused to flow in a direction 400A from the low temperature end side to the high temperature end side of the AMR bed 420. The heat transport refrigerant exchanges heat with the magnetic refrigeration material 401 filled inside the AMR bed 420 and receives hot heat, while flowing through the gaps in the magnetic refrigeration material 401, and flows out from the high temperature end of the AMR bed 420. The heat transport refrigerant flowing out from the high temperature end of the AMR bed 420 flows through the pre-cooling stage 460 into the heat exchanger 440 that dissipates the hot heat, and excess heat is dissipated to the outside.

[0057] Next, the magnetic field of the AMR bed 420 filled with the magnetic refrigeration material 401 is removed (reduced), causing the temperature of the magnetic refrigeration material 401 to drop.

[0058] Next, the heat transport refrigerant is caused to flow in a direction 400B from the high temperature end side to the low temperature end side of the AMR bed 420. The heat transport refrigerant flows into the high temperature end of the AMR bed 420 via the pre-cooling stage 460, and while being cooled by heat exchange with the magnetic refrigeration material 401 filled inside, it flows through the gaps in the magnetic refrigeration material 401 and reaches the low temperature end of the AMR bed 420. The flow of the heat transport refrigerant is driven by a refrigerant driving means (not shown). The refrigerant driving means is not particularly limited as long as it can drive an oscillating flow that causes the heat transport refrigerant to flow back and forth in synchronization with the AMR cycle, and examples of the refrigerant driving means include a system that combines a piston, a blower and a valve.

[0059] When the temperature of the low-temperature end of the AMR bed 420 drops below the boiling point of liquid hydrogen (20 K at atmospheric pressure), the hydrogen gas supplied to the liquefaction vessel 450 is cooled by heat exchange with a cooling stage 490 provided on the low-temperature end side of the AMR bed 420, and is concentrated and liquefied.

[0060] This process is repeated to periodically liquefy and / or cool the gas within liquefying vessel 450 .

[0061] In FIG. 4, the magnetic refrigeration material 401 filled in the AMR bed 420 has been described as being a single magnetic refrigeration material of the present invention, but it may be provided with other magnetic refrigeration materials in addition to the magnetic refrigeration material of the present invention.

[0062] FIG. 5 is a schematic diagram showing an AMR bed including multiple magnetic refrigeration materials.

[0063] As shown in Fig. 5, a plurality of different magnetic refrigeration materials 510-550 including the magnetic refrigeration material of the present invention can be filled in an AMR bed 420. The magnetic refrigeration materials 510-550 are arranged in a space separated by a partition 560. The partition 560 may have any shape as long as it does not allow different materials to mix and does not impede the flow of the heat transport refrigerants 400A and 400B (Fig. 4), but specific examples of the partition include a mesh or a partition plate having fine holes.

[0064] By selecting the magnetic refrigeration materials 510-550 having different peak temperatures of magnetic entropy change, it is possible to achieve a high magnetic refrigeration function in a wider temperature range than when a single magnetic refrigeration material is used. When the AMR bed 420 is incorporated into the magnetic refrigeration device 400 and operated, it is effective to increase the refrigeration performance by sequentially arranging and filling the magnetic refrigeration materials 510-550 on the side corresponding to the high temperature side of the AMR bed 420 so that the peak temperature of the magnetic entropy change is high. The number of types of magnetic refrigeration materials having different peak temperatures to be combined is not particularly limited to the number shown in the schematic diagram of FIG. 4, and multiple appropriate materials can be combined in consideration of the characteristics of the temperature dependence of each magnetic entropy change. By sequentially arranging multiple magnetic refrigeration materials having different peak temperatures, that is, multiple magnetic refrigeration materials having different optimal operating temperature ranges, in the order of the operating temperature ranges, multiple highly efficient heat cycles are combined, making it possible to efficiently cool from high temperatures to extremely low temperatures of 20K or less.

[0065] Other magnetic refrigeration materials to be combined with the magnetic refrigeration material of the present invention are not particularly limited, and can be appropriately combined with the magnetic refrigeration material of the present invention by referring to the magnetic entropy change and Curie temperature of other magnetic refrigeration materials. For example, in the magnetic refrigeration material of the present invention, when R is Er or Ho, this material has a large magnetic entropy change at 14K to 25K, so that it is particularly effective for the purpose of hydrogen liquefaction to place this material in a position in the AMR bed that operates at about 20K and combine it with other materials.

[0066] The present invention will now be described in detail with reference to specific examples, but it should be noted that the present invention is not limited to these examples. EXAMPLES

[0067] [Raw materials used in synthesis] The raw materials for R elements are dysprosium (Dy) raw materials (manufactured by Furuuchi Chemical Co., Ltd., grain, shape: 5-10mm irregular chunk, purity: 99.9%, packaging: oil-immersed), holmium (Ho) raw materials (manufactured by Furuuchi Chemical Co., Ltd., grain, shape: 5-10mm irregular chunk, purity: 99.9%, packaging: oil-immersed), erbium (Er) raw materials (manufactured by Furuuchi Chemical Co., Ltd., grain, shape: 5-10mm irregular chunk, purity: 99.9%, packaging: oil-immersed). The following raw materials were used: Gadolinium (Gd) raw material (Furuuchi Chemical Co., Ltd., grain, shape: 5-10mm irregular lump, purity: 99.9%, packaging: oil-immersed), Gadolinium (Gd) raw material (Furuuchi Chemical Co., Ltd., grain, shape: 5-10mm irregular lump, purity: 99.9%, packaging: oil-immersed), and Terbium (Tb) raw material (Furuuchi Chemical Co., Ltd., grain, shape: 5-10mm irregular lump, purity: 99.9%, packaging: oil-immersed). In order to remove the oil, acetone (Kishida Chemical Co., Ltd.) was placed in a beaker (HARIO Co., Ltd., B-200 SCI) together with the above raw materials, and the materials were washed for 15 minutes using an ultrasonic cleaner (AS ONE Co., Ltd., AS22GTU).

[0068] The raw materials for the T elements used were platinum (Pt) raw material (purity: 99.99%), cobalt (Co) raw material (manufactured by Rare Metallic Co., Ltd., purity: 99.97%), and nickel (Ni) raw material (manufactured by Rare Metallic Co., Ltd., purity: 99.99%).

[0069] The raw material of the X element was aluminum (Al) raw material (manufactured by Furuuchi Chemical Co., Ltd., shape: Grains 2-5 mm, purity: 99.999%).

[0070] It was confirmed by ICP emission spectrometry that the raw materials contained unavoidable impurities such as calcium, copper, iron, magnesium, and silicon at a ratio of 0.00005% by weight or less each.

[0071] The raw material was cut into pieces of 1 to 3 mm x 1 to 3 mm x 1 to 3 mm using nippers as necessary, and used as the raw material for synthesis.

[0072] [Example 1] In Example 1, an inorganic compound having the general formula R4TX, where R is holmium (Ho), T is platinum (Pt), and X is aluminum (Al), was synthesized by arc melting, and its magnetic properties and magnetic entropy change were investigated.

[0073] In detail, the raw materials were mixed to a total of about 1 g so as to satisfy the mixture composition shown in Tables 3 to 5, and a raw material mixture was obtained. Next, the raw material mixture was placed on the water-cooled copper hearth of a small vacuum arc melting device (TMA-3N, manufactured by Techno Search Co., Ltd.), and a vacuum was drawn with a rotary pump for about 30 minutes. After the pressure reached less than 1 Pa, argon gas was introduced into the chamber at about 0.05 MPa. Thereafter, the titanium mass was arc-melted, and the oxygen remaining in the chamber was absorbed by the titanium.

[0074] The raw material mixture thus obtained was arc-melted at a current value of 50A to 100A in an argon atmosphere. The temperature at this time reached about 2000°C. After the raw material mixture was irradiated with an arc, it was inverted using an inversion rod and irradiated with an arc again. This procedure was repeated three times. As a result, a button-shaped homogeneous synthetic sample (as-cast) with a diameter of 5mm to 10mm was obtained. When the mass of the obtained synthetic sample was measured, no substantial change was observed from that of the raw material mixture. This showed that the composition of the synthetic sample maintained the designed composition.

[0075] A part of the obtained synthetic sample was powdered, packed into a glass sample plate, and identified by a powder X-ray diffractometer (Rigaku Corporation, MiniFlex600, radiation source: CuKα). The results are shown in Figure 6.

[0076] Tantalum foil (manufactured by Sunric Co., Ltd., dimensions: 0.05 mm x 100 mm x 300 mm, purity: 99%) was prepared and cut into tantalum foil pieces measuring 30 mm x 20 mm with metal scissors, and the above synthetic sample was wrapped in the tantalum foil pieces.

[0077] The alloy sample wrapped in tantalum foil was placed in a quartz tube (manufactured by Daiken Quartz Glass Co., Ltd., inner diameter: 12 mm, outer diameter: 14 mm), and the inside of the quartz tube was evacuated for about 1 hour using a high vacuum exhaust device (Daia Vacuum Co., Ltd., DS-A212Z). The pressure was 3×10 -3 After the pressure reached 10 Pa, Ar was filled inside at about 0.05 MPa, and the quartz tube was sealed using an oxyhydrogen burner (Kinoshita Rika Kogyo Co., Ltd., KBSS-500) to obtain a quartz tube containing an alloy sample with a length of 80 mm. The obtained quartz tube containing the alloy sample was placed in an electric furnace (Tokyo Glass Equipment Co., Ltd., F-120-SP) and annealed at 800°C for 50 hours for homogenization. After cooling, the annealed synthesis sample (annealed) was taken out at room temperature, opened, and cut with a low-speed cutting machine Isomet (Beuhler).

[0078] The temperature dependence of magnetization was measured by the DC method using a magnetization measurement device (Quantum Design, MPMS3). After synthesis, powdered synthetic samples (approximately 3-5 mg) that had been evaluated by powder X-ray diffraction were placed in gelatin capsules (Kobayashi Capsule Co., Ltd., No. 5, capacity 0.16 cc.) to serve as samples for measurement. The synthetic samples were fixed with a small amount (5-10 mg) of Apiezon Grease M to avoid orientation of powder crystals due to the magnetic field. This capsule was fixed in a straw, and after attaching a measurement probe, it was set in the temperature variable part and magnetic field center of the device. The sample measurement range was between temperature: 5-300 K and magnetic field: 0.1-5 T (tesla). The measurement data was analyzed, and the magnetic entropy change ΔS was calculated using Maxwell's relational equation ∂M / ∂T=∂S / ∂H. The results are shown in Figures 9 and 14.

[0079] [Examples 2-9] In Examples 2 to 9, the general formula R4TX or R4Pt 1-α (Co,Ni) α In X, the raw material mixtures (1 g to 2 g) shown in Tables 3 to 5 were prepared, and synthetic samples were obtained in the same manner as in Example 1. They were identified by X-ray diffraction, and their magnetic properties and magnetic entropy changes were examined. The results are shown in Figures 7 to 18.

[0080] [Table 3]

[0081] [Table 4]

[0082] [Table 5]

[0083] The above results will be summarized. FIG. 6 is a diagram showing XRD patterns of the samples of Examples 1 to 5. FIG. 7 is a diagram showing XRD patterns of the samples of Examples 6 to 8. As shown in FIG. FIG. 8 shows the XRD pattern of the sample of Example 9.

[0084] Figures 6 and 8 show XRD patterns of samples of Examples 1 to 5 and 9 before homogenization. Figure 7(A) shows XRD patterns of samples of Examples 6 to 8 before homogenization, and Figure 7(B) shows XRD patterns of samples of Examples 6 to 8 after homogenization. For reference, Figure 7(A) also shows the XRD pattern of sample of Example 1.

[0085] According to FIG. 6, the XRD patterns of the samples of Examples 1 to 5 all match the XRD pattern of Ho4PtAl calculated from the crystal structure parameters in Table 1, and it was shown that the samples of Examples 1 to 5 are inorganic compounds having a cubic Gd4RhIn type crystal structure.

[0086] According to FIG. 7(B), the XRD patterns of the samples of Example 6 and Example 7 match the XRD pattern of Ho4PtAl calculated from the crystal structure parameters in Table 1, indicating that the samples of Example 6 and Example 7 are inorganic compounds having a cubic Gd4RhIn type crystal structure.

[0087] On the other hand, according to FIG. 7(B) and FIG. 8, the XRD patterns of the samples of Example 8 and Example 9 mainly matched the XRD pattern of Ho4PtAl calculated from the crystal structure parameters in Table 1, but some diffraction peaks were different from the XRD pattern of Ho4PtAl calculated from the crystal structure parameters in Table 2. 14 The XRD pattern of the samples in Examples 8 and 9 was consistent with that of Ni3Al3. This indicates that the main phase of the samples in Examples 8 and 9 was an inorganic compound having a cubic Gd4RhIn type crystal structure, and the main phase was a tetragonal Gd 14 Co3In 2.7 The general formula R 14 It was shown to contain a second phase represented by T3X3. The content of the second phase was calculated by Rietveld analysis based on the XRD pattern.

[0088] Furthermore, as shown in Table 6, when the lattice length (lattice constant) was calculated from the XRD patterns in Figures 6 and 7, it was found that the lattice length a decreased in the order of increasing atomic number of the R element (Gd, Tb, Dy, Ho, Er), which coincided with the decrease in the ionic radius of the rare earth elements. Focusing on the change in density, it was confirmed that by selecting Co or Ni as the T element, the density decreased, which is advantageous for weight reduction.

[0089] [Table 6]

[0090] FIG. 9 shows the results of magnetization measurement of the sample of Example 1. FIG. 10 shows the results of magnetization measurement of the sample of Example 2. FIG. 11 is a diagram showing the results of magnetization measurement of the sample of Example 3. FIG. 12 is a diagram showing the results of magnetization measurement of the sample of Example 4. FIG. 13 is a diagram showing the results of magnetization measurement of the sample of Example 5. FIG. 14 is a graph showing the magnetic entropy changes of the samples of Examples 1 to 5. In FIG. FIG. 15 is a diagram showing the results of magnetization measurement of the sample of Example 6. FIG. 16 is a diagram showing the results of magnetization measurement of the sample of Example 7. FIG. 17 is a diagram showing the results of magnetization measurement of the sample of Example 8. FIG. 18 is a diagram showing the results of magnetization measurement of the sample of Example 9.

[0091] 9 to 13 and 15 to 18 show the temperature (T) dependence of magnetic susceptibility (χ) (χ-T), the magnetic field (H) dependence of magnetic moment (M) (MH), the temperature (T) dependence of magnetic moment (M), and the magnetic entropy change (ΔS m ) temperature (T) dependence (ΔS m -T). The temperature dependence of the magnetic entropy change was calculated from the MT graphs at various magnetic fields, as described above.

[0092] According to the χ-T graph in Fig. 9, it was found that the sample (Ho4PtAl) of Example 1 became ferromagnetic at about 20 K. According to the MH graph in Fig. 9, the saturation magnetic moment of the sample of Example 1 at 2 K was about 7 μB per Ho atom.

[0093] According to the χ-T graph in Fig. 10, it was found that the sample (Dy4PtAl) of Example 2 became ferromagnetic at about 30 K. According to the MH graph in Fig. 10, the saturation magnetic moment of the sample of Example 2 at 2 K was about 6 μB per Dy atom.

[0094] According to the χ-T graph in Fig. 11, it was found that the sample of Example 3 (Er4PtAl) became ferromagnetic at about 15 K. According to the MH graph in Fig. 11, the saturation magnetic moment of the sample of Example 3 at 2 K was about 6 μB per Er atom.

[0095] According to the χ-T graph in Fig. 12, it was found that the sample of Example 4 (Gd4PtAl) exhibited a magnetic phase transition at about 20 K and about 70 K, and that the ferromagnetic correlation was dominant. According to the MH graph in Fig. 12, the magnetic moment of the sample of Example 4 at 2 K and a magnetic field of 5 T was about 5 μB per Gd atom.

[0096] According to the χ-T graph in Fig. 13, it was found that the sample of Example 5 (Tb4PtAl) exhibited a magnetic phase transition at about 45 K, and that the ferromagnetic correlation was dominant. According to the MH graph in Fig. 13, the magnetic moment of the sample of Example 5 at 2 K and a magnetic field of 5 T was about 5 μB per Tb atom.

[0097] It was confirmed that the samples of Examples 1 to 3 have similar magnetic properties. On the other hand, in the samples of Examples 4 and 5, the same ferromagnetic properties as the samples of Examples 1 to 3 were observed in terms of the temperature dependence of the magnetic susceptibility, but it was found that the samples differed from the samples of Examples 1 to 3 in terms of their behavior when a strong magnetic field of 1 T or more was applied. In particular, as shown in Table 7, when focusing on the magnetization M (5 K and 5 T), the magnetization M of the samples of Examples 4 and 5 was 125 to 130 emu / g, while the magnetization M of the samples of Examples 1 to 3 exceeded 150 emu / g, which was significantly increased. This shows that even inorganic compounds having the same cubic Gd4RhIn type crystal structure have different properties depending on the selected element, suggesting that the properties cannot necessarily be predicted even when selecting within the rare earth element group.

[0098] According to the results of magnetic entropy change shown in FIG. 9 to FIG. 14 and Table 7, the samples of Examples 1 to 3 have a magnetic entropy of 10 J / kgK or more at 5 T or 100 mJ / cm in the temperature range of 17 K or more and 77 K or less. 3 It was found that the material had a magnetic entropy change of more than 100 K and functioned as a magnetic refrigeration material that could be used for hydrogen liquefaction. The magnitude of this magnetic entropy change was two to three times that of the samples in Examples 4 and 5, indicating that Ho, Dy, and Er are unique as R elements.

[0099] From the above, it has been demonstrated that an inorganic compound containing an R element (wherein the R element is at least one element selected from the group consisting of dysprosium (Dy), holmium (Ho), and erbium (Er)), a T element (wherein the T element is at least one element selected from the group consisting of platinum (Pt), cobalt (Co), and nickel (Ni)), and an X element (wherein the X element includes at least aluminum (Al)), and having a cubic Gd4RhIn-type crystal structure, functions as a magnetic refrigeration material that enables hydrogen liquefaction.

[0100] In particular, an inorganic compound having the following composition and containing a phase represented by the general formula R4TX has been shown to have excellent magnetic properties. R: 65 atomic% or more and 68 atomic% or less, T: 15 atomic% or more and 18 atomic% or less, X: 15 atomic % or more and 18 atomic % or less, and Impurity elements less than 1 atomic %

[0101] 15 to 18 show that the magnetic properties of the sample (Ho4PtAl) of Example 1 are well maintained even if a part of the T element is replaced with Co or Ni. According to the magnetic entropy change results in Table 7, the samples of Examples 6 to 9 have a magnetic entropy of 10 J / kgK or more at 5 T or 100 mJ / cm in the temperature range of 17 K or more and 77 K or less. 3 It was found that the material has a magnetic entropy change of more than 100 K and can function as a magnetic refrigeration material that can be used for hydrogen liquefaction.

[0102] Focusing on the crystal phases in Table 6 and the magnetic entropy change in Table 7, the samples of Example 8 and Example 9 have 15 vol % and 39 vol % of the second phase, respectively, and it was shown that the amount of the inorganic compound having a cubic GdRhIn type crystal structure as the main phase should be more than 55 vol %, and preferably more than 60 vol %.

[0103] From the above, it has been demonstrated that an inorganic compound containing an R element (wherein the R element is at least one element selected from the group consisting of dysprosium (Dy), holmium (Ho), and erbium (Er)), Ni and / or Co in addition to Pt as the T element, and an X element (wherein the X element includes at least aluminum (Al)), and having a cubic Gd4RhIn-type crystal structure, functions as a magnetic refrigeration material that enables hydrogen liquefaction.

[0104] In particular, the compound has the following composition and the general formula R4Pt 1-α (Co,Ni) α It has been shown that inorganic compounds containing a phase represented by X (α satisfies 0<α≦0.75) have excellent magnetic properties. R: 65 atomic% or more and 68 atomic% or less, Pt: 4 atomic% or more and 18 atomic% or less, Co and / or Ni: 0 atomic % or more and less than 16 atomic %; X: 15 atomic % or more and 18 atomic % or less, 1 atomic % or less of inevitable impurity elements, and Total of Pt, Co and / or Ni: 15 atomic % to 18 atomic %

[0105] [Table 7] [Industrial Applicability]

[0106] The magnetic refrigeration material of the present invention is easy to manufacture and has a large magnetic entropy change in the temperature range of 17 K to 77 K, and therefore can be used in magnetic refrigeration devices and is particularly effective in liquefying hydrogen, etc. This can contribute to the widespread use of hydrogen, which is a promising energy carrier. [Explanation of symbols]

[0107] 400 Magnetic Refrigeration Unit 401, 510, 520, 530, 540, 550 Magnetic refrigeration materials 410 Gas 420 AMR Bed 430 Magnetic field application means 440 Heat exchanger 450 Liquefaction vessel 460 Pre-cooling stage 470 80K Shield 480 300K Shield 490 Cooling Stage 560 Partition

Claims

1. It contains at least one element R (where R is selected from the group consisting of dysprosium (Dy), holmium (Ho), and erbium (Er)), at least one element T (where T is selected from the group consisting of platinum (Pt), cobalt (Co), and nickel (Ni)), and at least one element X (where X contains aluminum (Al)), and is in a cubic Gd crystal structure. ４ A magnetic refrigeration material containing an inorganic compound having a RhIn-type crystal structure.

2. The aforementioned inorganic compound R: 60 atomic % or more and 75 atomic % or less, T: 12.5 at% or more and 21 at% or less, X: 12.5 atomic percent or more and 21 atomic percent or less, Unavoidable impurity elements at a concentration of less than 1 atom The magnetic refrigeration material according to claim 1, having a composition consisting of (wherein the sum of the R element, the T element, the X element, and the unavoidable impurity element satisfies 100 atomic percent).

3. The aforementioned inorganic compound R: 65 atomic % or more and 70 atomic % or less, T: 15 atomic % or more and 20 atomic % or less, X: 15 atomic percent or more and 20 atomic percent or less, Unavoidable impurity elements at a concentration of less than 1 atom A magnetic refrigeration material according to claim 2, having a composition comprising the above.

4. The aforementioned inorganic compound R: 65 at% or more and 68 at% or less, T: 15 at% or more and 18 at% or less, X: 15 atomic percent or more and 18 atomic percent or less, Unavoidable impurity elements at a concentration of less than 1 atom A magnetic refrigeration material according to claim 3, having a composition comprising the above.

5. The inorganic compound is, General formula R ４ The magnetic refrigeration material according to claim 1, wherein the phase is represented by TX.

6. The magnetic refrigeration material according to claim 1, wherein the element T comprises at least platinum.

7. The aforementioned inorganic compound R: 60 atomic% or more and 70 atomic% or less, Pt: More than 0 atomic percent and less than or equal to 21 atomic percent. Co and / or Ni: 0 atomic% or more and less than 21 atomic% X: 12.5 atomic% or more and 21 atomic% or less, Unavoidable impurity elements of 1 atomic percent or less, Total of Pt, Co, and / or Ni: 12.5 atomic% to 21 atomic% The magnetic refrigeration material according to claim 6, having a composition consisting of (wherein the sum of the R element, the Pt, the Co and / or Ni, the X element, and the unavoidable impurity element satisfies 100 atomic percent).

8. The aforementioned inorganic compound R: 65 atomic % or more and 70 atomic % or less, Pt: 4 at% or more and 20 at% or less, Co and / or Ni: 0 atomic% or more and less than 16 atomic% X: 15 atomic % or more and 20 atomic % or less, Unavoidable impurity elements of 1 atomic percent or less, Total of Pt, Co, and / or Ni: 15% to 20% The magnetic refrigeration material according to claim 7, having a composition comprising the above.

9. The aforementioned inorganic compound R: 65 at% or more and 68 at% or less, Pt: 4 at% or more and 18 at% or less, Co and / or Ni: 0 atomic% or more and less than 16 atomic% X: 15 atomic % or more and 18 atomic % or less, Unavoidable impurity elements of 1 atomic percent or less, Total of Pt, Co, and / or Ni: 15 atomic percent to 18 atomic percent A magnetic refrigeration material according to claim 8, having a composition comprising the above.

10. The inorganic compound is, General formula R ４ Pt １－α (Co, Ni) α The magnetic refrigeration material according to claim 6, wherein the phase is represented by X (where α satisfies 0 < α ≤ 0.75).

11. The magnetic refrigeration material according to claim 1, wherein the element X further comprises at least one element selected from the group consisting of silicon (Si), magnesium (Mg), and cadmium (Cd).

12. General formula R １４ T ３ X ３ The magnetic refrigeration material according to claim 1, further comprising a second phase represented by .

13. The magnetic refrigeration material according to claim 12, wherein the content of the second phase is in the range of more than 0 volume% and 45 volume% or less.

14. The magnetic refrigeration material according to claim 13, wherein the content of the second phase is in the range of more than 0 volume% and 40 volume% or less.

15. A method for producing a magnetic refrigeration material according to any one of claims 1 to 14, comprising dissolving a raw material mixture containing at least one element R (where R is at least one element selected from the group consisting of dysprosium (Dy), holmium (Ho), and erbium (Er)), one element T (where T is at least one element selected from the group consisting of platinum (Pt), cobalt (Co), and nickel (Ni)), and one element X (where X includes at least aluminum (Al)), wherein the molar ratio of the R element, the T element, and the X element is 3.8 to 4.2:0.8 to 1.2:0.8 to 1.

2.

16. An AMR bed comprising a magnetic refrigeration material according to any one of claims 1 to 14.

17. A magnetic refrigeration system equipped with an AMR bed, The AMR bed is the AMR bed described in claim 16, in a magnetic refrigeration apparatus. A light-emitting device, including a light-emitting device.

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