Cold storage material particles, cold storage material particle group, regenerator, refrigerator, cryopump, superconducting magnet, nuclear magnetic resonance imaging device, nuclear magnetic resonance device, magnetic field application type single crystal pulling device, and helium recondensation device

Abstract

A cold storage material particle according to one embodiment comprises: at least one first element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu); nickel (Ni); at least one second element selected from the group consisting of silicon (Si) and germanium (Ge); a crystal phase of a SmNiGe3 type; and at least one of a CeNiSi2 type crystal phase and a CaF2 type crystal phase.

Description

Technical Field

[0001] The embodiments of the present invention relate to cold storage material particles, cold storage material particle groups, cold storage devices, refrigerators, cryogenic pumps, superconducting magnets, nuclear magnetic resonance imaging devices, nuclear magnetic resonance devices, magnetic field applied single crystal pulling devices, and helium recondensation devices. Background Technology

[0002] In recent years, superconducting technology has made significant progress. With the expansion of its applications, the need for small, high-performance cryogenic refrigerators has become indispensable. Cryogenic refrigerators require lightweight, compact design and high thermal efficiency. They have already been put into practical use in various application fields.

[0003] Cryogenic refrigerators contain a cryogenic accumulator filled with multiple cryogenic material particles. For example, cooling is performed through heat exchange between the cryogenic material particles and helium gas passing through the cryogenic accumulator.

[0004] Examples of cryogenic material particles include magnetic cryogenic material particles containing rare earth elements and metals. One example of magnetic cryogenic material particles containing rare earth elements and metals is HoCu2. To improve the performance of cryogenic refrigerators, it is desirable to develop cryogenic material particles with good specific heat characteristics.

[0005] Existing technical documents Patent documents Patent Document 1: WO 2022 / 224783 Non-patent literature Non-patent literature 1: Fabiana R. Arantes et al., "Structure, magnetism, and transport of single-crystalline RNiSi3(R=Y,Gd-Tm,Lu)", Physical Review Materials 2, 044402 (2018) Summary of the Invention

[0006] The problem that the invention aims to solve The purpose of this invention is to provide a cold storage material particle with good specific heat properties.

[0007] means for solving problems One embodiment provides a cold storage material particle comprising: nickel (Ni); at least one first element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu); at least one second element selected from the group consisting of silicon (Si) and germanium (Ge); an SmNiGe3 type crystal phase; and at least one CeNiSi2 type crystal phase or CaF2 type crystal phase. Attached Figure Description

[0008] Figure 1 This is a schematic cross-sectional view of the cold storage material particles in the first embodiment.

[0009] Figure 2 This is a schematic cross-sectional view of the cold storage material particles in the second embodiment.

[0010] Figure 3 This is a schematic cross-sectional view of the cold storage material particles in a modified example of the second embodiment.

[0011] Figure 4 This is a schematic cross-sectional view showing the main components of the refrigerator according to the fourth embodiment.

[0012] Figure 5 This is a cross-sectional view showing the schematic configuration of the cryogenic pump according to the fifth embodiment.

[0013] Figure 6 This is a perspective view showing the schematic configuration of the superconducting magnet according to the sixth embodiment.

[0014] Figure 7 This is a cross-sectional view showing the schematic configuration of the magnetic resonance imaging apparatus according to the seventh embodiment.

[0015] Figure 8 This is a cross-sectional view showing the schematic configuration of the nuclear magnetic resonance apparatus according to the eighth embodiment.

[0016] Figure 9 This is a perspective view showing the schematic configuration of the magnetic field applied single crystal pulling device according to the ninth embodiment.

[0017] Figure 10 This is a schematic diagram showing the general configuration of the helium recondensation apparatus according to the tenth embodiment. Detailed Implementation

[0018] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same or similar components are indicated by the same reference numerals, and descriptions of components that have already been described may be omitted as appropriate.

[0019] In this specification, "ultra-low temperature" refers to a temperature range in which superconductivity can be usefully utilized industrially, for example. Ultra-low temperature is, for example, a temperature range below 25 K.

[0020] (First Implementation) The cold storage material particles of the first embodiment comprise: at least one first element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu); nickel (Ni); at least one second element selected from the group consisting of silicon (Si) and germanium (Ge); an SmNiGe3 type crystal phase; and at least one of a CeNiSi2 type crystal phase or a CaF2 type crystal phase.

[0021] Figure 1 This is a schematic cross-sectional view of the cold storage material particles of the first embodiment. The cold storage material particles 100 of the first embodiment are magnetic cold storage material particles containing rare earth elements and metals.

[0022] like Figure 1 As shown, the cold storage material particles 100 are polycrystalline. The cold storage material particles 100 comprise multiple grains. The multiple grains include a first grain 10a, a second grain 10b, and a third grain 10c. Grain boundary phases may exist between the multiple grains.

[0023] The cold storage material particles 100 contain an SmNiGe3 type crystalline phase. The cold storage material particles 100 contain at least one of a CeNiSi2 type crystalline phase or a CaF2 type crystalline phase. The cold storage material particles 100 may contain only one of a CeNiSi2 type crystalline phase and a CaF2 type crystalline phase. The cold storage material particles 100 may contain both a CeNiSi2 type crystalline phase and a CaF2 type crystalline phase.

[0024] For example, the first grain 10a has an SmNiGe3 type crystal phase. For example, the second grain 10b has a CeNiSi2 type crystal phase. For example, the third grain 10c has a CaF2 type crystal phase.

[0025] For example, among the crystalline phases contained in the cold storage material particles 100, the SmNiGe3 type crystalline phase is the dominant crystalline phase. The fact that the SmNiGe3 type crystalline phase is the dominant crystalline phase means that the proportion of the SmNiGe3 type crystalline phase in the cold storage material particles 100 is higher than the proportion of other crystalline phases. Preferably, the proportion of the SmNiGe3 type crystalline phase in the cold storage material particles 100 is 30% or more, more preferably 50% or more.

[0026] Whether the cold storage material particles 100 contain SmNiGe3, CeNiSi2, or CaF2 crystalline phases can be identified by powder X-ray diffraction (PXRD). Furthermore, whether the SmNiGe3 crystalline phase is the dominant crystalline phase in the cold storage material particles 100 can be determined, for example, by comparing the peak intensities of the crystalline phase obtained by PXRD. Additionally, the weight proportion of crystalline phases present in the sample can be analyzed by performing Rietveld analysis on the diffraction pattern obtained from XRD, and the determination of whether the SmNiGe3 crystalline phase is the dominant crystalline phase can be made by comparing the values ​​obtained from the analysis.

[0027] Furthermore, whether the SmNiGe3 type crystalline phase is the main crystalline phase contained in the cold storage material particles 100 can be determined, for example, by observing the backscattered electron image of the cross-section of the cold storage material particles 100 using a scanning electron microscope (SEM). For example, it can be determined by comparing the area occupied by grains identified as having the SmNiGe3 type crystalline phase in the backscattered electron image with the area occupied by other grains using image processing software. Whether a grain is of the SmNiGe3 type crystalline phase can be determined, for example, by energy-dispersive X-ray spectroscopy (EDX).

[0028] The cold storage material particles 100 contain at least one first element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). The first element is a rare earth element.

[0029] The cold storage material particles 100 contain at least one second element selected from the group consisting of silicon (Si) and germanium (Ge).

[0030] The chemical composition of the SmNiGe3 type crystalline phase contained in the cold storage material particles 100 can be expressed as, for example, R 1±x Ni 1±x (SiyGe 1-y ) 3±x (R represents at least one rare earth element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu), 0 ≤ x ≤ 0.5, and 0 ≤ y ≤ 1). The chemical composition of the SmNiGe3 type crystal phase contained in the cold storage material particles 100 is, for example, HoNiSi3 or HoNiGe3.

[0031] The chemical composition of the CeNiSi2 type crystalline phase contained in the cold storage material particles 100 can be expressed as, for example, R 1±x Ni 1±x (SiyGe 1-y ) 2±x (R represents at least one rare earth element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu), 0 ≤ x ≤ 0.5, and 0 ≤ y ≤ 1). The chemical composition of the CeNiSi2 type crystalline phase contained in the cold storage material particles 100 is, for example, HoNiSi2 or HoNiGe2.

[0032] The chemical composition of the CaF2-type crystalline phase contained in the cold storage material particles 100 is, for example, Ni. 1±x Si 2±x (0≤x≤0.5).

[0033] The detection of elements contained in the cold storage material particles 100 and the measurement of elemental atomic concentrations can be performed using, for example, inductively coupled plasma atomic emission spectrometry (ICP-AES). For example, the cold storage material particles 100 are dissolved in a liquid, and the dissolved cold storage material particles 100 are measured by inductively coupled plasma atomic emission spectrometry.

[0034] The detection of elements and the measurement of elemental atomic concentrations contained in the cold storage material particles 100, the first grain 10a, the second grain 10b, or the third grain 10c can be performed using, for example, energy-dispersive X-ray spectroscopy (EDX) or wavelength-dispersive spectroscopy (WDX).

[0035] The peak intensity of the peak corresponding to the (131) plane of the SmNiGe3 type crystal phase obtained from the cold storage material particles 100 by powder X-ray diffraction is defined as the first peak intensity (Ia), the peak intensity of the peak corresponding to the (131) plane of the CeNiSi2 type crystal phase is defined as the second peak intensity (Ib), and the peak intensity of the peak corresponding to the (111) plane of the CaF2 type crystal phase obtained by powder X-ray diffraction is defined as the third peak intensity (Ic). The ratio of the sum of the second peak intensity (Ib) and the third peak intensity (Ic) to the first peak intensity (Ia) ((Ib+Ic) / Ia) is 0.01 or more and 0.3 or less.

[0036] When measuring the cold storage material particles 100 by powder X-ray diffraction, for example, the cold storage material particles 100 are crushed in an agate mortar. Then, the powder that has passed through a 500-mesh sieve is used as the measurement sample.

[0037] The particle size of the cold storage material particles 100 is, for example, 50 μm or more and 3 mm or less. The shape of the cold storage material particles 100 is, for example, spherical.

[0038] In this specification, the particle size of the cold storage material particles is the equivalent circle diameter (circle equivalent diameter). The equivalent circle diameter is the diameter of a true circle that corresponds to the area of ​​the pattern observed in an image (such as an optical microscope image or a scanning electron microscope image). The particle size of the cold storage material particles can be obtained, for example, by image analysis of an optical microscope image or a scanning electron microscope image.

[0039] When the perimeter of the projected image of the cold storage material particle 100 is denoted as L, and the actual area of ​​the projected image is denoted as A, then 4πA / L 2 The indicated roundness R is greater than 0.5. The roundness R of the cold storage material particles 100 can be obtained, for example, by image analysis of optical microscope images or scanning electron microscope images.

[0040] The aspect ratio of the cold storage material particles 100 is, for example, 1 or more and 5 or less. The aspect ratio of the cold storage material particles 100 is the ratio of the major axis to the minor axis of the cold storage material particles 100. The aspect ratio of the cold storage material particles 100 can be obtained, for example, by image analysis of optical microscope images or scanning electron microscope images.

[0041] The maximum volumetric specific heat of the cold storage material particles 100 in the temperature range below 25K is 0.38 J / (cm³). 3 ·K) and above.

[0042] Next, an example of a method for manufacturing the cold storage material particles according to the first embodiment will be described. In the following description, the case in which the first element is holmium (Ho) and the second element is silicon (Si) will be used as an example.

[0043] First, a HoNiSi3 master alloy was prepared by high-frequency induction melting. Next, the HoNiSi3 master alloy was melted and dropped onto a rotating disk in an argon atmosphere for rapid solidification. Cold storage material particles were then fabricated through the rapid solidification of the molten alloy.

[0044] The cooling rate of the molten alloy can be controlled by adjusting the rotational speed of the rotating disk. For example, increasing the rotational speed of the rotating disk increases the cooling rate of the molten alloy. Conversely, decreasing the rotational speed of the rotating disk decreases the cooling rate of the molten alloy.

[0045] By controlling the cooling rate of the molten alloy, the ratio ((Ib+Ic) / Ia) of the sum of the second and third peak intensities of the manufactured refrigerant particles to the first peak intensity can be controlled to a desired value. For example, this ratio ((Ib+Ic) / Ia) can be decreased by increasing the cooling rate of the molten alloy. Conversely, this ratio ((Ib+Ic) / Ia) can be increased by decreasing the cooling rate of the molten alloy.

[0046] The cold storage material particles 100 of the first embodiment can be manufactured by the above manufacturing method.

[0047] The cold storage material particles 100 of the first embodiment contain a SmNiGe3 type crystalline phase and contain a first element, nickel (Ni), and a second element. The chemical composition of the SmNiGe3 type crystalline phase contained in the cold storage material particles 100 can be represented, for example, as RNi(Si). x Ge 1-x )3(R represents at least one rare earth element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu), and 0≤x≤1).

[0048] The cold storage material particles 100 of the first embodiment can achieve a higher volumetric specific heat than HoCu2.

[0049] Furthermore, in the cold storage material particles 100 of the first embodiment, for example, the atomic proportion of rare earth elements is smaller than their proportion in HoCu2. Since the atomic proportion of expensive rare earth elements is smaller, the manufacturing cost of the cold storage material particles 100 can be reduced.

[0050] Cold storage material particles with a roundness R of 0.5 or less may have uneven surfaces. For example, when a cold storage material particle with uneven surfaces is filled in the cold storage accumulator of a refrigeration machine, the porosity in the cold storage accumulator becomes uneven, or the filling stability of the cold storage accumulator becomes unstable. Therefore, for example, when the working medium flows into the cold storage accumulator, the cold storage performance of the cold storage accumulator will deteriorate.

[0051] Furthermore, for example, due to stress applied to the refrigerant particles during filling or operation of the refrigeration unit, the refrigerant particles may move or break, forming microparticles that can clog the gaps in the refrigerant. Clogged gaps can reduce the refrigeration performance or long-term reliability of the refrigeration unit.

[0052] Therefore, the cold storage material particles filled in the cold accumulator are preferably spherical. In other words, the roundness R of the cold storage material particles 100 is preferably high, and the roundness R is preferably close to 1. The roundness R of the cold storage material particles 100 is preferably higher than 0.5, more preferably 0.7 or higher, and even more preferably 0.9 or higher.

[0053] In the cold storage material particles 100 of the first embodiment, the peak intensity of the peak corresponding to the (131) plane of the SmNiGe3 type crystal phase obtained by powder X-ray diffraction is defined as the first peak intensity (Ia), the peak intensity of the peak corresponding to the (131) plane of the CeNiSi2 type crystal phase is defined as the second peak intensity (Ib), and the peak intensity of the peak corresponding to the (111) plane of the CaF2 type crystal phase obtained by powder X-ray diffraction is defined as the third peak intensity (Ic). The ratio of the sum of the second and third peak intensities to the first peak intensity ((Ib+Ic) / Ia) is preferably 0.01 or more and 0.3 or less.

[0054] When the ratio ((Ib+Ic) / Ia) is 0.01 or higher and 0.3 or lower, it is easy to form the cold storage material particles 100 into spherical particles. When the ratio ((Ib+Ic) / Ia) is 0.01 or higher and 0.3 or lower, it is easy to increase the sphericity R of the cold storage material particles 100. When the ratio ((Ib+Ic) / Ia) is 0.01 or higher and 0.3 or lower, it is easy to make the sphericity R of the cold storage material particles 100 approach 1.

[0055] The maximum volumetric specific heat of the cold storage material particles 100 in the temperature range below 25K is preferably 0.38 J / (cm³). 3 ·K) or higher, more preferably 0.4J / (cm) 3 ·K) or higher, more preferably 0.45J / (cm) 3 ·K) and above.

[0056] The cold storage material particle group may contain cold storage material particles 100 of the first embodiment, with a particle number ratio of 90% or more.

[0057] As described above, according to the first embodiment, cold storage material particles with good specific heat properties can be provided. Furthermore, according to the first embodiment, cold storage material particles that are easily formed into spherical particles can be provided.

[0058] (Second Implementation) The cold storage material particles of the second embodiment comprise: nickel (Ni); at least one first element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu); at least one second element selected from the group consisting of silicon (Si) and germanium (Ge); an SmNiGe3 type crystal phase; and a first phase with an atomic concentration of the second element greater than 70 atomic percent. The cold storage material particles of the second embodiment differ from those of the cold storage material particles of the first embodiment in that they include a phase with an atomic concentration of the second element greater than 70 atomic percent. In the following description, some of the details described in the first embodiment may be omitted.

[0059] Figure 2 This is a schematic cross-sectional view of the cold storage material particles according to the second embodiment. The cold storage material particles 200 of the second embodiment are magnetic cold storage materials containing rare earth elements and metals.

[0060] like Figure 2 As shown, the cold storage material particles 200 are polycrystalline. The cold storage material particles 200 comprise multiple grains. The multiple grains include a first grain 10a. Furthermore, the cold storage material particles 200 comprise particles 10x.

[0061] The cold storage material particles 200 contain an SmNiGe3 type crystalline phase. For example, the first grain 10a has an SmNiGe3 type crystalline phase.

[0062] For example, among the crystalline phases contained in the cold storage material particles 200, the SmNiGe3 type crystalline phase is the dominant crystalline phase. The fact that the SmNiGe3 type crystalline phase is the dominant crystalline phase means that the proportion of the SmNiGe3 type crystalline phase in the cold storage material particles 200 is higher than the proportion of other crystalline phases. The proportion of the SmNiGe3 type crystalline phase in the cold storage material particles 100 is preferably 30% or more, more preferably 50% or more.

[0063] Whether the cold storage material particles 200 contain the SmNiGe3 type crystalline phase can be identified by powder X-ray diffraction. Furthermore, whether the SmNiGe3 type crystalline phase is the main crystalline phase contained in the cold storage material particles 200 can be determined, for example, by comparing the peak intensities of the crystalline phases obtained by powder X-ray diffraction.

[0064] Furthermore, whether the SmNiGe3 type crystalline phase is the main crystalline phase contained in the cold storage material particles 200 can be determined, for example, by observing the backscattered electron image of the cross-section of the cold storage material particles 200 using a scanning electron microscope. For instance, it can be determined by comparing the area occupied by grains identified as having the SmNiGe3 type crystalline phase in the backscattered electron image with the area occupied by other grains using image processing software. Whether a grain possesses the SmNiGe3 type crystalline phase can be determined, for example, by energy-dispersive X-ray spectroscopy.

[0065] The cold storage material particles 200 contain a first phase with a second element having an atomic concentration greater than 70 atomic percent. The second element is at least one element selected from the group consisting of silicon (Si) and germanium (Ge). The second element can be only one of silicon (Si) or germanium (Ge). The second element can be both silicon (Si) and germanium (Ge). For example, particles 10x have a first phase.

[0066] The first phase is, for example, crystalline or amorphous. Particles 10x are, for example, crystalline or amorphous. The atomic concentration of the second element contained in the first phase is, for example, less than 100 atomic percent. Furthermore, the second and third phases are, for example, crystalline or amorphous.

[0067] In the cross-section of the cold storage material particles 200, the area ratio of the first phase is, for example, more than 0.01% and less than 45%.

[0068] Whether the cold storage material particles 200 contain a first phase can be determined using, for example, energy dispersive X-ray spectroscopy or wavelength dispersive spectroscopy.

[0069] Furthermore, the area ratio of the first phase contained in the cold storage material particles 200 can be determined, for example, by observing the backscattered electron image of the cross-section of the cold storage material particles 200 using a scanning electron microscope. For example, image processing software can be used to measure the area occupied by particles identified as the first phase in the backscattered electron image. Whether a particle possesses a first phase can be determined, for example, by energy-dispersive X-ray spectroscopy.

[0070] The cold storage material particles 200 contain at least one first element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). The first element is a rare earth element.

[0071] The cold storage material particles 200 contain at least one second element selected from the group consisting of silicon (Si) and germanium (Ge).

[0072] The chemical composition of the SmNiGe3 type crystalline phase contained in the cold storage material particles 200 can be represented, for example, as RNi(Six Ge 1-x )3(R represents at least one rare earth element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu), and 0≤x≤1). The chemical composition of the SmNiGe3 type crystal phase contained in the cold storage material particles 200 is, for example, HoNiSi3 or HoNiGe3.

[0073] The detection of elements contained in the cold storage material particles 200 and the measurement of elemental atomic concentrations can be performed using, for example, inductively coupled plasma atomic emission spectrometry (ICP-AES). For instance, the cold storage material particles 200 are dissolved in a liquid, and the dissolved cold storage material particles 200 are measured using ICP-AES.

[0074] The detection of elements and the measurement of elemental atomic concentrations contained in the cold storage material particles 200, the first grain 10a, or the particles 10x can be performed using, for example, energy-dispersive X-ray spectroscopy or wavelength-dispersive spectroscopy.

[0075] The particle size of the cold storage material particles 200 is, for example, 50 μm or more and 3 mm or less. The shape of the cold storage material particles 200 is, for example, spherical.

[0076] When the perimeter of the projected image of the cold storage material particles 200 is denoted as L, and the actual area of ​​the projected image is denoted as A, then 4πA / L 2 The indicated roundness R is, for example, greater than 0.5.

[0077] The aspect ratio of the cold storage material particles 200 is, for example, 1 or more and 5 or less.

[0078] The maximum volumetric specific heat of the cold storage material particles 200 in the temperature range below 25K is, for example, 0.38 J / (cm³). 3 ·K) and above.

[0079] Next, an example of a method for manufacturing the cold storage material particles according to the second embodiment will be described. In the following description, the case in which the first element is holmium (Ho) and the second element is silicon (Si) will be used as an example.

[0080] First, a HoNiSi3 master alloy was prepared by high-frequency induction melting. Next, the HoNiSi3 master alloy was melted and dropped onto a rotating disk in an argon atmosphere for rapid solidification. Cold storage material particles were then fabricated through the rapid solidification of the molten alloy.

[0081] The cooling rate of the molten alloy can be controlled by adjusting the rotational speed of the rotating disk. For example, increasing the rotational speed of the rotating disk increases the cooling rate of the molten alloy. Conversely, decreasing the rotational speed of the rotating disk decreases the cooling rate of the molten alloy.

[0082] By controlling the cooling rate of the molten alloy, the area ratio of the first phase in the manufactured cold storage material particles can be controlled to a desired value. For example, the area ratio of the first phase can be decreased by increasing the cooling rate of the molten alloy. Conversely, the area ratio of the first phase can be increased by decreasing the cooling rate of the molten alloy.

[0083] The cold storage material particles 200 of the second embodiment can be manufactured by the above manufacturing method.

[0084] The cold storage material particles 200 of the second embodiment contain an SmNiGe3 type crystalline phase and include a first element, nickel (Ni), and a second element. The chemical composition of the SmNiGe3 type crystalline phase contained in the cold storage material particles 200 can be represented, for example, as RNi(Si). x Ge 1-x )3(R represents at least one rare earth element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu), and 0≤x≤1).

[0085] The cold storage material particles 200 of the second embodiment can achieve a higher volumetric specific heat than HoCu2.

[0086] Furthermore, in the cold storage material particles 200 of the second embodiment, for example, the atomic proportion of rare earth elements is lower than that in HoCu2. Since the atomic proportion of expensive rare earth elements is smaller, the manufacturing cost of the cold storage material particles 200 can be reduced.

[0087] Cold storage material particles with a roundness R of 0.5 or less may have uneven surfaces. For example, when multiple cold storage material particles containing more than 5% of the particles with uneven surfaces are filled into the cold storage accumulator of a refrigeration machine, the porosity in the cold storage accumulator becomes uneven, or the filling becomes unstable. Therefore, for example, when the working medium flows into the cold storage accumulator, the cold storage performance of the cold storage accumulator will deteriorate.

[0088] Furthermore, for example, due to stress applied to the refrigerant particles during filling or operation of the refrigeration unit, the refrigerant particles may move or break, forming microparticles that can clog the gaps in the refrigerant. Clogged gaps can reduce the refrigeration performance or long-term reliability of the refrigeration unit.

[0089] Therefore, the cold storage material particles filled in the cold accumulator are preferably spherical. In other words, the roundness R of the cold storage material particles 200 is preferably high, and the roundness R is preferably close to 1. The roundness R of the cold storage material particles 200 is preferably higher than 0.5, more preferably 0.7 or higher, and even more preferably 0.9 or higher.

[0090] In the cold storage material particles 200 of the second embodiment, the area ratio of the first phase with an atomic concentration of the second element of more than 70 atomic% is preferably 0.01% or more and 45% or less.

[0091] When the area ratio of the first phase is 0.01% or more and 45% or less, it is easy to form the cold storage material particles 200 into spherical particles. When the area ratio of the first phase is 0.01% or more and 45% or less, it is easy to increase the sphericity R of the cold storage material particles 200. When the area ratio of the first phase is 0.01% or more and 45% or less, it is easy to make the sphericity R of the cold storage material particles 200 approach 1.

[0092] From the perspective of forming the cold storage material particles 200 into spherical particles, the area ratio of the first phase is more preferably 0.1% or more and 30% or less, and even more preferably 1% or more and 20% or less.

[0093] From the perspective of forming the cold storage material particles 200 into spherical particles, the atomic concentration of the second element contained in the first phase is more preferably 75% or more.

[0094] The maximum volumetric specific heat of the cold storage material particles 200 in the temperature range below 25K is preferably 0.4 J / (cm³). 3 ·K) or higher, more preferably 0.5J / (cm) 3 ·K) and above.

[0095] (Modified Example) The cold storage material particles of the modified embodiment of the second embodiment differ from those of the cold storage material particles of the second embodiment in that they contain at least one of the CeNiSi2 type crystal phase or the CaF2 type crystal phase.

[0096] Figure 3 This is a schematic cross-sectional view of the cold storage material particles in a modified example of the second embodiment. The cold storage material particles 210 in the modified example of the second embodiment are magnetic cold storage materials containing rare earth elements and metals.

[0097] like Figure 3 As shown, the cold storage material particles 210 can be polycrystalline. In the case of polycrystalline cold storage material particles, the cold storage material particles 210 comprise multiple grains. The multiple grains include a first grain 10a, a second grain 10b, and a third grain 10c. Furthermore, the cold storage material particles 210 comprise particles 10x.

[0098] The cold storage material particles 210 contain an SmNiGe3 type crystalline phase. The cold storage material particles 210 contain at least one of a CeNiSi2 type crystalline phase or a CaF2 type crystalline phase. The cold storage material particles 210 may contain only one of a CeNiSi2 type crystalline phase and a CaF2 type crystalline phase. The cold storage material particles 210 may contain both a CeNiSi2 type crystalline phase and a CaF2 type crystalline phase.

[0099] For example, the first grain 10a has an SmNiGe3 type crystal phase. For example, the second grain 10b has a CeNiSi2 type crystal phase. For example, the third grain 10c has a CaF2 type crystal phase.

[0100] The cold storage material particles 210 contain a first phase with a second element having an atomic concentration of more than 70 atomic percent. The second element is at least one element selected from the group consisting of silicon (Si) and germanium (Ge). For example, particles 10x have the first phase.

[0101] The cold storage material particles 210 of the modified embodiment of the second embodiment have the same effect as the cold storage material particles 200 of the second embodiment.

[0102] The cold storage material particle group may contain cold storage material particles 200 of the second embodiment, with a particle number ratio of 90% or more.

[0103] As described above, according to the second embodiment and its modifications, cold storage material particles with good specific heat properties can be provided. Furthermore, according to the second embodiment and its modifications, cold storage material particles that are easily formed into spherical particles can be provided.

[0104] (Third Implementation) The cold storage device of the third embodiment is a cold storage device filled with a plurality of cold storage material particles of the first or second embodiment. In the cold storage device of the third embodiment, for example, when the perimeter of the projected image of the plurality of cold storage material particles of the first or second embodiment is denoted as L, and the actual area of ​​the projected image is denoted as A, 4πA / L 2 The proportion of cold storage material particles with a roundness R of 0.5 or less is 5% or less.

[0105] The roundness R can be obtained by performing image processing on the shape of multiple cold storage material particles in an image obtained using an optical microscope. Cold storage material particles with a roundness R of less than 0.5 have irregularities on their surface, for example.

[0106] For example, when a cold accumulator is filled with multiple cold accumulator particles, including more than 5% of which have uneven surfaces, the porosity in the cold accumulator becomes non-uniform, or the filling stability of the cold accumulator becomes unstable. Therefore, for example, when the working medium flows into the cold accumulator, the cold storage performance of the cold accumulator will deteriorate.

[0107] Furthermore, for example, due to stress applied to the refrigerant particles during filling or operation of the refrigeration unit, the refrigerant particles may move or break, forming microparticles that can clog the gaps in the refrigerant. Clogged gaps can reduce the refrigeration performance or long-term reliability of the refrigeration unit.

[0108] Therefore, the cold storage material particles with a roundness R of 0.5 or less filling the cold storage device are preferably 2% or less, and more preferably 0%.

[0109] As described above, according to the third embodiment, a cold accumulator with good properties can be realized by using cold accumulator particles with good properties.

[0110] (Fourth Implementation) The refrigerator of the fourth embodiment is a refrigerator of the third embodiment that includes a cold storage device filled with a plurality of cold storage material particles of the first or second embodiment. In the following text, some of the details described in the first, second, and third embodiments will be omitted.

[0111] Figure 4 This is a schematic cross-sectional view showing the main components of the refrigerator according to the fourth embodiment. Figure 4 This is a schematic cross-sectional view showing the main components of a GM refrigerator, an example of a refrigerator according to the fourth embodiment. The GM refrigerator, an example of a refrigerator according to the fourth embodiment, includes a cold accumulator of the third embodiment filled with a plurality of cold storage material particles of the first or second embodiment.

[0112] The refrigerator in the fourth embodiment is a two-stage cryogenic refrigerator 300 used for cooling superconducting devices and the like. The refrigerator can be, for example, a Stirling refrigerator or a pulse tube refrigerator.

[0113] The cryogenic storage type cryogenic refrigerator 300 (refrigeration unit) includes a first cylinder 111, a second cylinder 112, a vacuum container 113, a first accumulator 114, a second accumulator 115 (accumulator), a first sealing ring 116, a second sealing ring 117, a first cryogenic storage material 118, a second cryogenic storage material 119 (cryogenic storage material particles), a first expansion chamber 120, a second expansion chamber 121, a first cooling stage 122, a second cooling stage 123, and a compressor 124.

[0114] The cryogenic storage type cryogenic refrigerator 300 includes a vacuum container 113, in which a large-diameter first cylinder 111 and a small-diameter second cylinder 112 coaxially connected to the first cylinder 111 are disposed. A first accumulator 114 is disposed in the first cylinder 111 and can reciprocate freely. In the second cylinder 112, a second accumulator 115, as an example of the accumulator in the fourth embodiment, is disposed and can reciprocate freely.

[0115] The first sealing ring 116 is disposed between the first cylinder 111 and the first accumulator 114. The second sealing ring 117 is disposed between the second cylinder 112 and the second accumulator 115.

[0116] The first cold storage unit 114 is filled with a first cold storage material 118, such as a Cu mesh. The second cold storage unit 115 is filled with a plurality of cold storage material particles, which are the second cold storage material 119 in the first or second embodiment.

[0117] The second cold storage unit 115 can be separated by a metal mesh material and can contain multiple cold storage material filling layers. When the second cold storage unit 115 is divided into multiple filling layers, at least one filling layer is filled with a group of cold storage material particles containing multiple cold storage material particles of the first or second embodiment. Then, for example, it can be used in combination with at least one cold storage material particle group selected from rare earth oxide cold storage material particle groups, rare earth oxide sulfide cold storage material particle groups, lead cold storage material particle groups, bismuth cold storage material particle groups, tin cold storage material particle groups, holmium copper cold storage material particle groups, erbium nickel cold storage material particle groups, erbium cobalt cold storage material particle groups, and gadolinium aluminum oxide cold storage material particle groups.

[0118] In the combination of cold storage materials, the side with the higher peak temperature of specific heat is defined as the first cold storage material particle group, and the side with the lower peak temperature of specific heat is defined as the second cold storage material particle group, and they are combined in such a way that the peak temperature of specific heat decreases sequentially.

[0119] The first cold storage unit 114 and the second cold storage unit 115 each have a working medium channel disposed in the gap between the first cold storage material 118 and the second cold storage material 119. The working medium is helium.

[0120] A first expansion chamber 120 is disposed between a first accumulator 114 and a second accumulator 115. Furthermore, a second expansion chamber 121 is disposed between the distal walls of the second accumulator 115 and the second cylinder 112. A first cooling stage 122 is disposed at the bottom of the first expansion chamber 120. Furthermore, a second cooling stage 123, with a temperature lower than the first cooling stage 122, is formed at the bottom of the second expansion chamber 121.

[0121] High-pressure working medium is supplied from compressor 124 to the aforementioned two-stage cryogenic storage refrigerator 300. The supplied working medium passes through the first cryogenic storage material 118 filled in the first cryogenic storage tank 114 and reaches the first expansion chamber 120. Then, the working medium passes through the second cryogenic storage material 119 filled in the second cryogenic storage tank 115 and reaches the second expansion chamber 121.

[0122] At this time, the working medium is cooled by providing heat energy to the first cold storage material 118 and the second cold storage material 119. The working medium, after passing through the first cold storage material 118 and the second cold storage material 119, expands in the first expansion chamber 120 and the second expansion chamber 121, thereby generating cooling. Then, the first cooling stage 122 and the second cooling stage 123 are cooled.

[0123] The expanding working medium flows in opposite directions through the first cold storage material 118 and the second cold storage material 119. The working medium receives heat energy from the first cold storage material 118 and the second cold storage material 119 and is then discharged. The cold storage type cryogenic refrigerator 300 is configured such that, in such a process, as the regeneration effect is improved, the thermal efficiency of the working medium circulation is increased, thereby achieving a lower temperature.

[0124] In the cryogenic refrigeration unit included in the cryogenic storage type cryogenic refrigerator 300 of the fourth embodiment, the second cryogenic storage unit 115 is filled with a plurality of cryogenic storage material particles of the first or second embodiment, which serve as the second cryogenic storage material 119. At least a portion of the second cryogenic storage material 119 consists of cryogenic storage material particles of the first or second embodiment.

[0125] For multiple cold storage material particles in the first or second embodiments, when the perimeter of each projected image of the cold storage material particle is denoted as L and the actual area of ​​the projected image is denoted as A, 4πA / L 2 The proportion of cold storage material particles with a roundness R of 0.5 or less is preferably 5% or less.

[0126] To improve the cooling capacity of a cryogenic refrigerator, it is desirable to increase the specific heat per unit volume of the cryogenic storage material, as well as its thermal conductivity and heat transfer coefficient. The cryogenic storage type cryogenic refrigerator 300 of the fourth embodiment includes a cryogenic storage material or cryogenic storage material particles that maintain specific heat per unit volume and improve thermal conductivity and heat transfer coefficient. The cryogenic storage type cryogenic refrigerator 300 of the fourth embodiment also includes a cryogenic storage material or cryogenic storage material particles that can reduce manufacturing costs.

[0127] For example, by using the cryogenic storage type cryogenic refrigerator 300 of the fourth embodiment in a maglev train, the long-term reliability of the maglev train can be improved.

[0128] As described above, according to the fourth embodiment, a refrigerator with good properties can be realized by using cold storage material particles with good properties.

[0129] (Fifth Implementation) The cryogenic pump of the fifth embodiment includes the refrigerator of the fourth embodiment. In the following text, some details described in the fourth embodiment will be omitted.

[0130] Figure 5This is a cross-sectional view showing the schematic configuration of the cryogenic pump according to the fifth embodiment. The cryogenic pump of the fifth embodiment is a cryogenic pump 500 that includes the cold storage type cryogenic refrigerator 300 of the fourth embodiment.

[0131] The cryogenic pump 500 includes a cryogenic plate 501 for condensing or adsorbing gas molecules, a cryogenic storage type cryogenic refrigerator 300 for cooling the cryogenic plate 501 to a predetermined low temperature, a shield 503 disposed between the cryogenic plate 501 and the cryogenic storage type cryogenic refrigerator 300, a baffle 504 disposed at the inlet, and a ring 505 for changing the exhaust speed of argon, nitrogen, hydrogen, etc.

[0132] According to the fifth embodiment, a cryogenic pump with good characteristics can be realized by using a refrigeration unit with good characteristics.

[0133] (Sixth Implementation Method) The superconducting magnet of the sixth embodiment includes the refrigerator of the fourth embodiment. In the following text, some details described in the fourth embodiment will be omitted.

[0134] Figure 6 This is a perspective view showing the schematic configuration of the superconducting magnet according to the sixth embodiment. The superconducting magnet of the sixth embodiment is a superconducting magnet 600 for use in a magnetic levitation train, which includes the cryogenic storage type cryogenic refrigerator 300 of the fourth embodiment.

[0135] The superconducting magnet 600 for maglev trains includes a superconducting coil 601, a liquid helium tank 602 for cooling the superconducting coil 601, a liquid nitrogen tank 603 for preventing liquid helium from evaporating, a multilayer insulating material 605, power leads 606, a permanent current switch 607, and a cryogenic refrigerator 300 for cold storage.

[0136] According to the sixth embodiment, a superconducting magnet with good properties can be realized by using a refrigerator with good properties.

[0137] (Seventh Implementation) The magnetic resonance imaging apparatus of the seventh embodiment includes the refrigerator of the fourth embodiment. In the following text, some details described in the fourth embodiment will be omitted.

[0138] Figure 7 This is a cross-sectional view showing the schematic configuration of the magnetic resonance imaging (MRI) apparatus according to the seventh embodiment. The magnetic resonance imaging (MRI) apparatus of the seventh embodiment is an MRI apparatus 700 that includes the cryogenic cryostat 300 of the fourth embodiment.

[0139] The magnetic resonance imaging (MRI) device 700 includes a superconducting static magnetic field coil 701 that applies a spatially uniform and time-stable static magnetic field to the human body, a correction coil (not shown) that corrects for inhomogeneities in the generated magnetic field, a gradient magnetic field coil 702 that provides a magnetic field gradient to the measurement area, a radio frequency transmit / receive probe 703, a cryostat 705, and a radiation-insulating shield 706. A cryogenic cryostat 300 is used to cool the superconducting static magnetic field coil 701.

[0140] According to the seventh embodiment, a magnetic resonance imaging device with good characteristics can be realized by using a refrigerator with good characteristics.

[0141] (Eighth Implementation Method) The nuclear magnetic resonance apparatus of the eighth embodiment includes the refrigerator of the fourth embodiment. In the following text, some details described in the fourth embodiment will be omitted.

[0142] Figure 8 This is a cross-sectional view showing the schematic configuration of the nuclear magnetic resonance (NMR) apparatus according to the eighth embodiment. The nuclear magnetic resonance (NMR) apparatus of the eighth embodiment is an NMR apparatus 800 that includes the cryogenic cryogenic refrigerator 300 of the fourth embodiment.

[0143] The nuclear magnetic resonance (NMR) apparatus 800 includes: a superconducting static magnetic field coil 802 that applies a magnetic field to a sample, such as an organic substance, placed in a sample tube 801; a high-frequency oscillator 803 that applies radio frequency to the sample tube 801 in the magnetic field; and an amplifier 804 that amplifies the induced current generated in a coil (not shown) around the sample tube 801. Furthermore, the NMR apparatus 800 includes a cryogenic cryostat 300 for cooling the superconducting static magnetic field coil 802.

[0144] According to the eighth embodiment, a nuclear magnetic resonance device with good characteristics can be realized by using a refrigerator with good characteristics.

[0145] (Ninth Implementation) The magnetic field-applied single crystal pulling apparatus of the ninth embodiment includes the refrigerator of the fourth embodiment. In the following text, some details described in the fourth embodiment will be omitted.

[0146] Figure 9 This is a perspective view showing the schematic configuration of the magnetic field-applied single crystal pulling apparatus of the ninth embodiment. The magnetic field-applied single crystal pulling apparatus of the ninth embodiment is a magnetic field-applied single crystal pulling apparatus 900 that includes the cryogenic storage type cryogenic refrigerator 300 of the fourth embodiment.

[0147] The magnetic field-applied single crystal pulling device 900 includes a single crystal pulling section 901 with a raw material melting crucible, a heater, a single crystal pulling mechanism, etc., a superconducting coil 902 that applies a static magnetic field to the molten raw material, a lifting mechanism 903 for the single crystal pulling section 901, a current lead 905, a heat shield 906, and a helium container 907. A cryogenic refrigerator 300 is used to cool the superconducting coil 902.

[0148] According to the ninth embodiment, a magnetic field-applied single crystal pulling device with good characteristics can be realized by using a refrigerator with good characteristics.

[0149] (Tenth Implementation) The helium recondensation apparatus of the tenth embodiment includes the refrigerator of the fourth embodiment. In the following text, some details described in the fourth embodiment will be omitted.

[0150] Figure 10 This is a schematic diagram showing the general configuration of the helium recondensation apparatus according to the tenth embodiment. The helium recondensation apparatus of the tenth embodiment is a helium recondensation apparatus 1000 that includes the cryogenic storage type cryogenic refrigerator 300 of the fourth embodiment.

[0151] The helium recondensation device 1000 includes a cryogenic storage type cryogenic refrigerator 300, an evaporation tube 1001, and a liquefaction tube 1002.

[0152] The helium recondenser 1000 can recondense helium gas evaporated from a liquid helium device back into liquid helium. Liquid helium devices are, for example, superconducting magnets, nuclear magnetic resonance (NMR) devices, nuclear magnetic resonance imaging (MRI) devices, physical property measurement systems (PPMS), or magnetic property measurement systems.

[0153] Helium gas is introduced from a liquid helium unit (not shown) through an evaporator 1001 into a helium recondenser 1000. The helium gas is cooled to 4K below the liquefaction temperature of helium by a cryogenic cryogenic refrigerator 300. The condensed and liquefied liquid helium is returned to the liquid helium unit through a liquefaction pipe 1002.

[0154] According to the tenth embodiment, a helium recondensation device with good characteristics can be realized by using a refrigerator with good characteristics.

[0155] Example The following describes embodiments, comparative examples, and evaluation results of the implementation methods.

[0156] (Example 1) HoNiSi3 master alloy was prepared by high-frequency induction melting. Next, the HoNiSi3 master alloy was melted at approximately 1500°C. Then, the molten alloy was dropped onto a rotating disk under an argon atmosphere at approximately 101 kPa pressure and rapidly solidified. The rotation speed of the rotating disk was controlled to achieve a rapid cooling rate of approximately 1000°C / s for the molten alloy, thus producing the cold storage material particles of Example 1.

[0157] In the cold storage material particles of Example 1, the first element is holmium (Ho) and the second element is silicon (Si). Furthermore, in the cold storage material particles of Example 1, the first phase is a phase in which the atomic concentration of silicon (Si) is higher than 70 atomic%.

[0158] The manufactured cold storage material particles were measured by powder X-ray diffraction. The diffraction patterns obtained by the measurements were subjected to Rietveld analysis. Through Rietveld analysis, the ratio of the sum of the second and third peak intensities to the first peak intensity ((Ib+Ic) / Ia) was calculated when the first peak intensity (Ia) corresponds to the (131) plane of the SmNiGe3 type crystal phase, the second peak intensity (Ib) corresponds to the (131) plane of the CeNiSi2 type crystal phase, and the third peak intensity (Ic) corresponds to the (111) plane of the CaF2 type crystal phase.

[0159] The cold storage material particles were crushed in an agate mortar, and the powder that passed through a 500-mesh sieve was used as a sample for powder X-ray diffraction.

[0160] For the manufactured cold storage material particles, the area ratio of the first phase was measured. Scanning electron microscopy backscattered electron images of the particle cross-sections were observed. The area occupied by particles identified as the first phase in the cross-section was measured using ImageJ image processing software. Whether a particle is the first phase was determined by energy-dispersive X-ray spectroscopy.

[0161] The maximum volumetric specific heat of the manufactured cold storage material particles was measured. The measurement was performed using a Physical Property Measurement System (PPMS).

[0162] The ratio of cold storage material particles with a roundness R of less than 0.5 was measured from optical microscopic images of multiple manufactured cold storage material particles. ImageJ image processing software was used for the measurements.

[0163] The results of the above measurements are provided in Table 1. In Table 1, when the proportion of cold storage material particles with a roundness R of 0.5 or less is 5% or less, the sphericity assessment of the particles is "good". Furthermore, when the proportion of cold storage material particles with a roundness R of 0.5 or less is greater than 5%, the sphericity assessment of the particles is "poor".

[0164] (Examples 2 to 5) Except for changing the rotational speed of the rotating disk to alter the rapid cooling rate of the molten alloy, the regenerative material particles were manufactured using the same method as in Example 1. The rotational speed was increased when the rapid cooling rate of the molten alloy was increased, and decreased when the rapid cooling rate of the molten alloy was decreased.

[0165] Perform the same measurements as in Example 1. The results are provided in Table 1.

[0166] (Examples 6 to 9) In addition to changing the rotational speed of the rotating disk to alter the rapid cooling rate of the molten alloy, the melting temperature was also changed. Otherwise, the regenerative material particles were manufactured using the same method as in Example 1. The rotational speed was increased when the rapid cooling rate of the molten alloy was increased, and decreased when the rapid cooling rate of the molten alloy was decreased.

[0167] Perform the same measurements as in Example 1. The results are provided in Table 1.

[0168] (Example 10) Except for using the HoNiGe3 master alloy, the cold storage material particles were manufactured in the same manner as in Example 1.

[0169] In the cold storage material particles of Example 10, the first element is holmium (Ho), and the second element is germanium (Ge). Furthermore, in the cold storage material particles of Example 10, the first phase is a phase in which the atomic concentration of germanium (Ge) is higher than 70 atomic%.

[0170] Perform the same measurements as in Example 1. The results are provided in Table 1.

[0171] (Example 11) Except for using the GdNiSi3 master alloy, the cold storage material particles were manufactured in the same manner as in Example 1.

[0172] In the cold storage material particles of Example 11, the first element is gadolinium (Gd) and the second element is silicon (Si). Furthermore, in the cold storage material particles of Example 11, the first phase is a phase in which the atomic concentration of silicon (Si) is higher than 70 atomic%.

[0173] Perform the same measurements as in Example 1. The results are provided in Table 1.

[0174] (Example 12) Except for using the DyNiSi3 master alloy, the cold storage material particles were manufactured in the same manner as in Example 1.

[0175] In the cold storage material particles of Example 12, the first element is dysprosium (Dy), and the second element is silicon (Si). Furthermore, in the cold storage material particles of Example 12, the first phase is a phase in which the atomic concentration of silicon (Si) is higher than 70 atomic%.

[0176] (Comparative Example 1) Except for reducing the rotational speed of the rotating disk to reduce the rapid cooling rate of the molten alloy, the cold storage material particles were manufactured in the same manner as in Example 1.

[0177] Perform the same measurements as in Example 1. The results are provided in Table 1.

[0178] (Comparative Example 2) In addition to increasing the rotational speed of the rotating disk to improve the rapid cooling rate of the molten alloy, the cold storage material particles were manufactured in the same manner as in Example 1.

[0179] Perform the same measurements as in Example 1. The results are provided in Table 1.

[0180] Table 1

[0181] In all of Examples 1 to 12, the particle size of the cold storage material particles with a roundness R of 0.5 or higher is in the range of 50 μm or more to 3 mm or less. Furthermore, in all of Examples 1 to 12, the aspect ratio of the cold storage material particles with a roundness R greater than 0.5 is in the range of 1 or more to 5 or less.

[0182] As can be clearly seen from Table 1, the maximum volumetric specific heat is 0.4 or higher within the range where the ratio of the sum of the second and third peak intensities to the first peak intensity ((Ib+Ic) / Ia) is 0.01 or higher and 0.3 or lower. For example, the maximum volumetric specific heat of HoCu2 is approximately 0.4, and a value greater than the maximum volumetric specific heat of HoCu2 is obtained within the range where the ratio ((Ib+Ic) / Ia) is 0.01 or higher and 0.3 or lower.

[0183] As can be clearly seen from Table 1, within the range where the ratio of the sum of the second and third peak intensities to the first peak intensity ((Ib+Ic) / Ia) is 0.01 or higher and 0.3 or lower, the proportion of cold storage material particles with a roundness R of 0.5 or lower is 5% or lower. Therefore, within the range where the ratio ((Ib+Ic) / Ia) is 0.01 or higher and 0.3 or lower, sphericity of the cold storage material particles becomes easier.

[0184] As can be clearly seen from Table 1, when the area ratio of the first phase is between 0.01% and 45%, the maximum volumetric specific heat is greater than 0.4. Within the range of the first phase area ratio between 0.01% and 45%, a maximum volumetric specific heat greater than that of HoCu2 is obtained.

[0185] As can be clearly seen from Table 1, within the range of 0.01% to 45% of the area ratio of the first phase, the proportion of cold storage material particles with a roundness R of 0.5 or less is 5% or less. Therefore, within the range of 0.01% to 45% of the area ratio of the first phase, sphericalization of the cold storage material particles becomes easier.

[0186] While some embodiments of the invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments may be implemented in various other forms and various omissions, substitutions, and changes may be made without departing from the spirit of the invention. For example, a component of one embodiment may be replaced or changed to a component of another embodiment. These embodiments and modifications thereof are included within the scope or spirit of the invention and within the scope of the invention and its equivalents as described in the claims.

[0187] The technical solutions of the present invention will be described below. These technical solutions are included within the scope of the present invention.

[0188] (Technical Solution 1) A type of cold storage material particle, comprising: The first element is selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu); Nickel (Ni); At least one second element selected from the group consisting of silicon (Si) and germanium (Ge); SmNiGe3 type crystal phase; and At least one of CeNiSi2 type crystal phase and CaF2 type crystal phase.

[0189] (Technical Solution 2) According to the cold storage material particles described in technical solution 1, wherein, In the case where the peak intensity of the peak corresponding to the (131) plane of the SmNiGe3 type crystal phase obtained by powder X-ray diffraction is defined as the first peak intensity, the peak intensity of the peak corresponding to the (131) plane of the CeNiSi2 type crystal phase obtained by powder X-ray diffraction is defined as the second peak intensity, and the peak intensity of the peak corresponding to the (111) plane of the CaF2 type crystal phase obtained by powder X-ray diffraction is defined as the third peak intensity, then... The ratio of the sum of the second peak intensity and the third peak intensity to the first peak intensity is greater than 0.01 and less than 0.3.

[0190] (Technical Solution 3) A type of cold storage material particle, comprising: The first element is selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu); Nickel (Ni); At least one second element selected from the group consisting of silicon (Si) and germanium (Ge); SmNiGe3 type crystal phase; and The atomic concentration of at least one second element in the first phase is higher than 70 atomic percent.

[0191] (Technical Solution 4) According to the cold storage material particles described in technical solution 3, the area ratio of the first phase in its cross-section is more than 0.01% and less than 45%.

[0192] (Technical Solution 5) According to any one of technical solutions 1 to 4, when the perimeter of the projected image of the cold storage material particle is denoted as L and the actual area of ​​the projected image is denoted as A, the value is calculated as 4πA / L. 2 The indicated roundness R is greater than 0.5.

[0193] (Technical Solution 6) The cold storage material particles according to any one of technical solutions 1 to 5 have a particle size of 50 μm or more and 3 mm or less.

[0194] (Technical Solution 7) According to any one of technical solutions 1 to 6, the maximum volumetric specific heat of the cold storage material particles in the temperature range below 25K is 0.38 J / (cm³). 3 ·K) and above.

[0195] (Technical Solution 8) A cold storage material particle assembly comprising more than 90% of the cold storage material particles described in any one of technical solutions 1 to 7.

[0196] (Technical Solution 9) A cold storage device filled with cold storage material particles as described in any one of the following technical solutions 1 to 7.

[0197] (Technical Solution 10) A refrigeration machine having the cold storage device described in technical solution 9.

[0198] (Technical Solution 11) A cryogenic pump comprising the refrigeration unit described in technical solution 10.

[0199] (Technical Solution 12) A superconducting magnet having the refrigerator described in technical solution 10.

[0200] (Technical Solution 13) A nuclear magnetic resonance imaging device, comprising the refrigerator described in technical solution 10.

[0201] (Technical Solution 14) A nuclear magnetic resonance device comprising the refrigerator described in technical solution 10.

[0202] (Technical Solution 15) A magnetic field-applied single crystal pulling device, which includes the refrigerator described in technical solution 10.

[0203] (Technical Solution 16) A helium recondensation device comprising the refrigerator described in technical solution 10.

[0204] Explanation of reference numerals in the attached figures 100 cold storage material particles 115 Second Cold Storage Unit (Cold Storage Unit) 200 cold storage material particles 210 cold storage material particles 300℃ Cold Storage Type Ultra-Low Temperature Refrigeration Unit (Refrigeration Unit) 500 Cryogenic Pump 600 superconducting magnet 700 nuclear magnetic resonance imaging device 800 nuclear magnetic resonance device 900 Magnetic Field Applied Single Crystal Pulling Device 1000 helium recondenser Claims (as amended under Article 19 of the Treaty) 1. [Modified] A type of cold storage material particle, comprising: Nickel (Ni); The first element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu); and At least one second element selected from the group consisting of silicon (Si) and germanium (Ge), It includes at least one of the following: SmNiGe3 type crystal phase; and CeNiSi2 type crystal phase or CaF2 type crystal phase. 2. The cold storage material particles according to claim 1, wherein, In the case where the peak intensity of the peak corresponding to the (131) plane of the SmNiGe3 type crystal phase obtained by powder X-ray diffraction is defined as the first peak intensity (Ia), the peak intensity of the peak corresponding to the (131) plane of the CeNiSi2 type crystal phase obtained by powder X-ray diffraction is defined as the second peak intensity (Ib), and the peak intensity of the peak corresponding to the (111) plane of the CaF2 type crystal phase obtained by powder X-ray diffraction is defined as the third peak intensity (Ic), The ratio of the sum of the second peak intensity and the third peak intensity to the first peak intensity ((Ib+Ic) / Ia) is greater than 0.01 and less than 0.3. 3. [Modified] A type of cold storage material particle, comprising: Nickel (Ni); The first element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu); and At least one second element selected from the group consisting of silicon (Si) and germanium (Ge), It includes: a SmNiGe3 type crystal phase; and a first phase in which the atomic concentration of the at least one second element is higher than 70 atomic%. 4. The cold storage material particles according to claim 3, wherein the area ratio of the first phase in its cross-section is 0.01% or more and 45% or less. 5. The cold storage material particles according to claim 1 or 3, when the perimeter of its projected image is denoted as L and the actual area of ​​the projected image is denoted as A, is calculated as 4πA / L. 2 The indicated roundness R is greater than 0.5. 6. The cold storage material particles according to claim 1 or 3 have a particle size of 50 μm or more and 3 mm or less. 7. The cold storage material particles according to claim 1 or 3, wherein the maximum volumetric specific heat in the temperature range below 25K is 0.38 J / (cm³). 3 ·K) and above. 8. A cold storage material particle group comprising more than 90% of the cold storage material particles as described in claim 1 or 3. 9. A cold storage device filled with a plurality of cold storage material particles as described in claim 1 or 3. 10. A refrigeration machine comprising the cold accumulator as described in claim 9. 11. A cryogenic pump comprising the refrigeration unit of claim 10. 12. A superconducting magnet comprising the refrigerator of claim 10. 13. A magnetic resonance imaging device comprising the refrigerator as described in claim 10. 14. A nuclear magnetic resonance device comprising the refrigerator of claim 10. 15. A magnetic field-applied single crystal pulling device comprising the refrigerator as described in claim 10. 16. A helium recondensation apparatus comprising the refrigerator of claim 10.

Claims

1. A cold storage material particle, comprising: Nickel (Ni); The first element is selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu); At least one second element selected from the group consisting of silicon (Si) and germanium (Ge); SmNiGe3 type crystal phase; and At least one of the CeNiSi2 type crystal phase or CaF2 type crystal phase.

2. The cold storage material particles according to claim 1, wherein, In the case where the peak intensity of the peak corresponding to the (131) plane of the SmNiGe3 type crystal phase obtained by powder X-ray diffraction is defined as the first peak intensity (Ia), the peak intensity of the peak corresponding to the (131) plane of the CeNiSi2 type crystal phase obtained by powder X-ray diffraction is defined as the second peak intensity (Ib), and the peak intensity of the peak corresponding to the (111) plane of the CaF2 type crystal phase obtained by powder X-ray diffraction is defined as the third peak intensity (Ic), The ratio of the sum of the second peak intensity and the third peak intensity to the first peak intensity ((Ib+Ic) / Ia) is greater than 0.01 and less than 0.

3.

3. A cold storage material particle, comprising: Nickel (Ni); The first element is selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu); At least one second element selected from the group consisting of silicon (Si) and germanium (Ge); SmNiGe3 type crystal phase; and The atomic concentration of at least one second element in the first phase is higher than 70 atomic percent.

4. The cold storage material particles according to claim 3, wherein the area ratio of the first phase in its cross-section is 0.01% or more and 45% or less.

5. The cold storage material particles according to claim 1 or 3, when the perimeter of its projected image is denoted as L and the actual area of ​​the projected image is denoted as A, is calculated as 4πA / L. 2 The indicated roundness R is greater than 0.

5.

6. The cold storage material particles according to claim 1 or 3 have a particle size of 50 μm or more and 3 mm or less.

7. The cold storage material particles according to claim 1 or 3, wherein the maximum volumetric specific heat in the temperature range below 25K is 0.38 J / (cm³). 3 ·K) and above.

8. A cold storage material particle group comprising more than 90% of the cold storage material particles as described in claim 1 or 3.

9. A cold storage device filled with a plurality of cold storage material particles as described in claim 1 or 3.

10. A refrigeration machine comprising the cold accumulator as described in claim 9.

11. A cryogenic pump comprising the refrigeration unit of claim 10.

12. A superconducting magnet comprising the refrigerator of claim 10.

13. A magnetic resonance imaging device comprising the refrigerator as described in claim 10.

14. A nuclear magnetic resonance device comprising the refrigerator of claim 10.

15. A magnetic field-applied single crystal pulling device comprising the refrigerator as described in claim 10.

16. A helium recondensation apparatus comprising the refrigerator of claim 10.

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