Magnetic refrigeration alloy materials, their preparation methods and applications

Abstract

This application relates to a magnetic refrigeration alloy material, its preparation method and application. The magnetic refrigeration alloy material of this application includes a material with the following chemical general formula: Eu 1‑a X a Co 2‑b M b Al 9‑c Z c , where X is selected from at least one of Mg, Ca, Sr, Ba, Ce, Gd and Sm, M is selected from at least one of Cr, Mn, Fe, Ni and Cu, Z is selected from at least one of Zn, Cd, Ga, Si and Ge, 0 ≤ a ≤ 1, 0 ≤ b ≤ 2, 0 ≤ c ≤ 9. The magnetic refrigeration alloy material of this application has excellent magnetocaloric effect, and at the same time can also have a high thermal conductivity under extremely low temperature conditions below 1K, and thus can have a high cooling power density.

Description

Technical Field

[0001] This application relates to the technical field of magnetic refrigeration materials, and particularly to a magnetic refrigeration alloy material, its preparation method and application. Background Art

[0002] Ultra-low temperature refrigeration is an advanced technology for obtaining temperatures below 1K, which can provide key condition support for important fields such as quantum technology, space exploration, and material science. Magnetic refrigeration materials have the magnetocaloric effect, that is, when a magnetic refrigeration material is under the action of a magnetic field, the magnetic moments will align neatly along the magnetic field direction, the magnetic entropy decreases, and heat is released; after removing the magnetic field, the magnetic moments are randomly arranged again, the magnetic entropy increases, and the thermal energy of the surrounding environment is absorbed, causing the environmental temperature to drop. Among them, frustrated quantum magnets have both high magnetic entropy density and low ordering temperature, and the low-energy fluctuations emerging near the quantum critical point can produce a huge magnetocaloric effect, making them powerful materials capable of refrigeration in the sub-Kelvin temperature range. In addition to the characteristics of large entropy change and low ordering temperature, thermal conductivity is also another key parameter of frustrated quantum magnet materials. However, although traditional magnetic refrigeration materials can have excellent magnetocaloric effects, their thermal conductivities strongly decay at temperatures below 1K and they are poor conductors of heat. This severely restricts the cooling power density of magnetic refrigeration materials. Summary of the Invention

[0003] Based on this, it is necessary to provide a magnetic refrigeration alloy material, its preparation method and application. The magnetic refrigeration alloy material of this application has excellent magnetocaloric effects, and at the same time can also have a relatively high thermal conductivity under extremely low temperature conditions below 1K, and thus has a relatively high cooling power density.

[0004] In a first aspect, this application provides a magnetic refrigeration alloy material, including a material having the following chemical general formula: Eu 1- a X a Co 2-b M b Al 9-c Z c , where X is selected from at least one of Mg, Ca, Sr, Ba, Ce, Gd, and Sm, M is selected from at least one of Cr, Mn, Fe, Ni, and Cu, Z is selected from at least one of Zn, Cd, Ga, Si, and Ge, 0 ≤ a ≤ 1, 0 ≤ b ≤ 2, 0 ≤ c ≤ 9.

[0005] In some embodiments, the thermal conductivity of the magnetic refrigeration alloy material at 100 mK temperature is 10 mW / Km to 500 mW / Km.

[0006] In some embodiments, the lowest refrigeration temperature of the magnetic refrigeration alloy material is below 4K.

[0007] In some of these embodiments, the magnetic phase transition temperature of the magnetic refrigeration alloy material is 0K to 20K.

[0008] In some of these embodiments, the magnetic refrigeration alloy material is a single crystal material having a triangular lattice.

[0009] In some of these embodiments, a = 0, b = 0, c = 0.

[0010] In some of these embodiments, a = 0.13, b = 0, c = 0.

[0011] In some of these embodiments, a = 0, b = 0.6, c = 0.

[0012] In some of these embodiments, a = 0, b = 2, c = 0.

[0013] In some of these embodiments, a = 0, b = 0, c = 0.54.

[0014] In a second aspect, the present application provides a method for preparing the magnetic refrigeration alloy material described in any one of the above, comprising the following steps:

[0015] Mix and melt metal raw materials to obtain a metal liquid; the metal raw materials include at least one of Eu and X, where X is selected from at least one of Mg, Ca, Sr, Ba, Ce, Gd, and Sm; the metal raw materials also include at least one of Co and M, where M is selected from at least one of Cr, Mn, Fe, Ni, and Cu; the metal raw materials also include at least one of Al and Z, where Z is selected from at least one of Zn, Cd, Ga, Si, and Ge;

[0016] Perform a temperature reduction treatment on the metal liquid to precipitate the magnetic refrigeration alloy material;

[0017] Separate the magnetic refrigeration alloy material and the metal liquid.

[0018] In some of these embodiments, the mixing and melting are carried out in an inert gas atmosphere or under vacuum.

[0019] In some of these embodiments, the cooling rate of the temperature reduction treatment is less than or equal to 20°C / h.

[0020] In some of these embodiments, the target temperature of the temperature reduction treatment is 650°C to 950°C.

[0021] In a third aspect, the present application provides an application of the magnetic refrigeration alloy material described in any one of the above or the magnetic refrigeration alloy material prepared by the method for preparing the magnetic refrigeration alloy material described in any one of the above as a refrigeration material in a refrigeration device.

[0022] The above-mentioned magnetic refrigeration alloy material is a metallic high-spin frustrated quantum magnet. Its strong spin fluctuations delay the entropy release to the ultra-low temperature region and maintain a high entropy density, possessing excellent magnetocaloric effect. At the same time, the above-mentioned magnetic refrigeration alloy material overcomes the inherent low-temperature adiabatic problem of traditional magnetic refrigeration materials, and can still have a relatively high thermal conductivity under extremely low temperature conditions below 1K, and thus can have a relatively high cooling power density.

[0023] Furthermore, by changing the composition of different alloying elements, the magnetic phase transition temperature of the above-mentioned magnetic refrigeration alloy material can also be regulated within a relatively large range, thereby changing the optimal refrigeration working temperature range and endowing it with a broad application scope. Description of the Drawings

[0024] Figure 1 It is the X-ray energy spectrum (EDX) diagram of the magnetic refrigeration alloy material in Example 1 of this application;

[0025] Figure 2 It is the X-ray energy spectrum (EDX) diagram of the magnetic refrigeration alloy material in Example 2 of this application;

[0026] Figure 3 It is the X-ray energy spectrum (EDX) diagram of the magnetic refrigeration alloy material in Example 3 of this application;

[0027] Figure 4 It is the X-ray energy spectrum (EDX) diagram of the magnetic refrigeration alloy material in Example 4 of this application;

[0028] Figure 5 It is the X-ray energy spectrum (EDX) diagram of the magnetic refrigeration alloy material in Example 5 of this application;

[0029] Figure 6 It is the susceptibility curve diagram of the magnetic refrigeration alloy material in Examples 1 to 5 of this application;

[0030] Figure 7 It is the thermal conductivity curve diagram of the magnetic refrigeration alloy material in Example 1 of this application and the magnetic refrigeration material in Comparative Example 1;

[0031] Figure 8 It is the adiabatic demagnetization curve of the magnetic refrigeration alloy material in Example 1 of this application. Detailed Embodiments

[0032] To make the above objects, features, and advantages of this application more obvious and understandable, the following provides a detailed description of the specific embodiments of this application. Many specific details are set forth in the following description to fully understand this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of this application. Therefore, this application is not limited by the specific embodiments disclosed below.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terms used in the description of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0034] In the description of this application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0035] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of these features. In the description of this application, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0036] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0037] One embodiment of this application provides a magnetic refrigeration alloy material, including a material having the following chemical general formula: Eu 1-a X a Co 2-b M b Al 9-c Z c, wherein X is selected from at least one of Mg, Ca, Sr, Ba, Ce, Gd and Sm, M is selected from at least one of Cr, Mn, Fe, Ni and Cu, Z is selected from at least one of Zn, Cd, Ga, Si and Ge, 0≤a≤1, 0≤b≤2, 0≤c≤9.

[0038] The above-mentioned magnetic refrigeration alloy material is a metallic high-spin frustrated quantum magnet. Its strong spin fluctuations delay the entropy release to the ultra-low temperature region and maintain a high entropy density, having excellent magnetocaloric effect. At the same time, the above-mentioned magnetic refrigeration alloy material overcomes the inherent low-temperature adiabatic problem of traditional magnetic refrigeration materials. The thermal conductivity of traditional magnetic refrigeration materials at 100 mK temperature is only less than or equal to 1 mW / Km. The above-mentioned magnetic refrigeration alloy material can still have a relatively high thermal conductivity under extremely low temperature conditions below 1 K, and thus can have a relatively high cooling power density. Further, by changing the composition of different alloying elements, the magnetic phase transition temperature of the above-mentioned magnetic refrigeration alloy material can be regulated within a relatively large range, thereby changing the optimal refrigeration working temperature range and enabling it to have a wide application range.

[0039] It can be understood that when a is 0, the above-mentioned magnetic refrigeration alloy material does not contain element X. When a is greater than 0 and less than 1, element X partially replaces Eu element. When a is 1, Eu element is completely replaced by element X. Optionally, the value of a is 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1. Or, a can also be within the range between any two of the above values.

[0040] When b is 0, the above-mentioned magnetic refrigeration alloy material does not contain element M. When b is greater than 0 and less than 2, element M partially replaces Co element. When b = 2, Co element is completely replaced by element M. Optionally, the value of b is 0, 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8 or 2. Or, b can also be within the range between any two of the above values.

[0041] When c is 0, the above-mentioned magnetic refrigeration alloy material does not contain element Z. When c is greater than 0 and less than 9, Al element is partially replaced by element Z. When c is 9, Al element is completely replaced by element Z. Optionally, the value of c is 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5 or 9. Or, c can also be within the range between any two of the above values.

[0042] In some embodiments, the thermal conductivity of the magnetic refrigeration alloy material at 100 mK temperature is 10 mW / Km to 500 mW / Km.

[0043] Exemplarily, among traditional magnetic refrigeration materials, the spin solid-state magnetic refrigeration materials represented by Na2BaCo(PO4)2 ([Nature 625, 270 (2024)]) have excellent magnetocaloric effects and achieve an extremely low temperature of 94 mK near the spin supersolid quantum critical point. However, their heat transport depends on thermally coupled phonons and magnons, and their thermal conductivity shows a cubic decay with temperature in the temperature range below 1 K, being only less than or equal to 1 mW / Km at 100 mK. The thermal conductivity of the magnetic refrigeration alloy material of the present application is 10 mW / Km to 500 mW / Km at 100 mK, far higher than that of traditional magnetocaloric materials. Optionally, the thermal conductivity of the magnetic refrigeration alloy material at 100 mK is 10 mW / Km, 20 mW / Km, 50 mW / Km, 100 mW / Km, 150 mW / Km, 200 mW / Km, 250 mW / Km, 300 mW / Km, 350 mW / Km, 400 mW / Km, 450 mW / Km or 500 mW / Km, or the thermal conductivity of the magnetic refrigeration alloy material at 100 mK can also be within the range between any two of the above thermal conductivities.

[0044] In some embodiments, the minimum refrigeration temperature of the magnetic refrigeration alloy material is below 4 K.

[0045] It can be understood that the above magnetic refrigeration alloy material has excellent magnetocaloric effects and the minimum refrigeration temperature is below 4 K. Optionally, the minimum refrigeration temperature of the magnetic refrigeration alloy material is below 3 K, or the minimum refrigeration temperature of the magnetic refrigeration alloy material is below 2 K, or the minimum refrigeration temperature of the magnetic refrigeration alloy material is below 1 K, or the minimum refrigeration temperature of the magnetic refrigeration alloy material is below 0.8 K, or the minimum refrigeration temperature of the magnetic refrigeration alloy material is below 0.6 K, or the minimum refrigeration temperature of the magnetic refrigeration alloy material is below 0.5 K, or the minimum refrigeration temperature of the magnetic refrigeration alloy material is below 0.3 K, or the minimum refrigeration temperature of the magnetic refrigeration alloy material is below 0.2 K, or the minimum refrigeration temperature of the magnetic refrigeration alloy material is below 0.1 K.

[0046] In some embodiments, the magnetic phase transition temperature of the magnetic refrigeration alloy material is 0 K to 20 K.

[0047] It can be understood that by changing the composition of different alloying elements, the magnetic phase transition temperature of the above-mentioned magnetic refrigeration alloy materials can also be regulated within a large range, thereby changing the optimal refrigeration working temperature range. Among them, the magnetic phase transition temperature of the magnetic refrigeration alloy material being 0K means that the magnetic refrigeration alloy material does not have a magnetic phase transition temperature. Optionally, the magnetic phase transition temperature of the magnetic refrigeration alloy material is 0K, 0.2K, 0.5K, 0.8K, 1K, 1.5K, 2K, 3K, 4K, 5K, 6K, 7K, 8K, 9K, 10K, 12K, 15K, 18K or 20K, or the magnetic phase transition temperature of the magnetic refrigeration alloy material can also be within the range between any two of the above magnetic phase transition temperatures.

[0048] In some of these embodiments, the magnetic refrigeration alloy material is a single crystal material with a triangular lattice.

[0049] It can be understood that the above-mentioned polycrystalline magnetic refrigeration alloy materials can also have a good magnetocaloric effect, and the single crystal magnetic refrigeration alloy materials with a triangular lattice can have better thermal conductivity within the temperature range below 1K.

[0050] In some of these embodiments, a = 0, b = 0, c = 0.

[0051] In some of these embodiments, the chemical formula of the magnetic refrigeration alloy material is EuCo2Al9.

[0052] Taking EuCo2Al9 as an example, EuCo2Al9 is a metallic high-spin frustrated quantum magnet with spin 7 / 2, showing great potential for quantum refrigeration: the total magnetic entropy is 18.3 J / molK; the single crystal undergoes two magnetic phase transitions at T N1 = 3.6K and T N2 = 1.1K respectively. Below 1.1K, the material enters the spin supersolid state, with strong spin fluctuations. The strong spin fluctuations delay the entropy release to the ultra-low temperature region and maintain a high entropy density, possessing a huge magnetocaloric effect. Its thermal conductivity is dominated by high-mobility electrons and holes. The thermal conductivity is about 1 W / Km at 1K temperature and about 100 mW / Km at 100 mK temperature, approximately decreasing linearly with temperature, overcoming the low-temperature adiabatic problem of traditional magnetic refrigeration materials.

[0053] In some of these embodiments, a = 0.13, b = 0, c = 0.

[0054] In some of these embodiments, the chemical formula of the magnetic refrigeration alloy material is Eu 0.87 Sr 0.13 Co2Al9.

[0055] In some of these embodiments, a = 0, b = 0.6, c = 0.

[0056] In some of these embodiments, the chemical formula of the magnetic refrigeration alloy material is Eu(Co 0.7 Ni 0.3 )2Al9.

[0057] The magnetic phase transition temperature T of the Eu(Co 0.7 Ni 0.3 )2Al9 single crystal is increased from 1.1 K to 2.6 K. N2

[0058] In some of these embodiments, a = 0, b = 2, c = 0.

[0059] In some of these embodiments, the chemical formula of the magnetic refrigeration alloy material is Eu1Ni2Al9.

[0060] The magnetic phase transition temperature T of the Eu1Ni2Al9 single crystal is further increased to 8.3 K. N2

[0061] In some of these embodiments, a = 0, b = 0, c = 0.54.

[0062] In some of these embodiments, the chemical formula of the magnetic refrigeration alloy material is EuCo2(Al 0.94 Si 0.06 )9.

[0063] Another embodiment of the present application provides a method for preparing the magnetic refrigeration alloy material of any one of the above, including the following steps:

[0064] Mix and melt the metal raw materials to obtain a metal liquid; the metal raw materials include at least one of Eu and X, where X is selected from at least one of Mg, Ca, Sr, Ba, Ce, Gd, and Sm; the metal raw materials further include at least one of Co and M, where M is selected from at least one of Cr, Mn, Fe, Ni, and Cu; the metal raw materials further include at least one of Al and Z, where Z is selected from at least one of Zn, Cd, Ga, Si, and Ge;

[0065] Perform a cooling treatment on the metal liquid to precipitate the magnetic refrigeration alloy material;

[0066] Separate the magnetic refrigeration alloy material from the metal liquid.

[0067] It can be understood that the metal raw materials of the above elements are all selected as the simple substances of the respective metal elements.

[0068] In some of these embodiments, the mixing and melting are carried out in an inert gas atmosphere or under vacuum.

[0069] In some of these embodiments, the cooling rate of the cooling treatment is less than or equal to 20 °C / h. ​​

[0070] It can be understood that cooling treatment at a relatively large cooling rate can also cause the precipitation of the magnetic refrigeration alloy material. By controlling the cooling rate of the cooling treatment to be less than or equal to 20 °C / h, and performing the cooling treatment at a relatively low cooling rate, it is convenient to obtain a single-crystal magnetic refrigeration alloy material. Optionally, the cooling rate of the cooling treatment is less than or equal to 18 °C / h, or the cooling rate of the cooling treatment is less than or equal to 15 °C / h, or the cooling rate of the cooling treatment is less than or equal to 12 °C / h, or the cooling rate of the cooling treatment is less than or equal to 10 °C / h, or the cooling rate of the cooling treatment is less than or equal to 5 °C / h, or the cooling rate of the cooling treatment is less than or equal to 2 °C / h, or the cooling rate of the cooling treatment is less than or equal to 1 °C / h, or the cooling rate of the cooling treatment is less than or equal to 0.5 °C / h, or the cooling rate of the cooling treatment is less than or equal to 0.1 °C / h.

[0071] In some embodiments, the target temperature of the cooling treatment is 650 °C to 950 °C.

[0072] It can be understood that the target temperature of the cooling treatment being 650 °C to 950 °C means cooling the molten metal to 650 °C to 950 °C. Optionally, the target temperature of the cooling treatment is 650 °C, 680 °C, 700 °C, 720 °C, 750 °C, 780 °C, 800 °C, 820 °C, 850 °C, 880 °C, 900 °C, 920 °C or 950 °C, or the target temperature of the cooling treatment can also be within the range between any two of the above temperatures.

[0073] In some embodiments, mixing and melting the metal raw materials to obtain the molten metal includes the following steps:

[0074] Mixing and heating the metal raw materials to above 1000 °C to obtain the molten raw materials;

[0075] Insulating the molten raw materials for more than 0.1 h.

[0076] It can be understood that mixing and heating the metal raw materials to above 1000 °C can achieve a better melting effect of the metal raw materials. At the same time, insulating the molten raw materials for more than 0.1 h can achieve a more uniform mixing effect among the molten metal raw materials.

[0077] In some embodiments, the heating temperature of the metal raw materials is 1000 °C to 1200 °C.

[0078] Optionally, the heating temperature of the metal raw materials is 1000 °C, 1020 °C, 1040 °C, 1060 °C, 1080 °C, 1100 °C, 1120 °C, 1140 °C, 1160 °C, 1180 °C or 1200 °C, or the heating temperature of the metal raw materials can also be within the range between any two of the above temperatures.

[0079] In some of these embodiments, the heat preservation time of the molten raw material is 0.1 h to 48 h.

[0080] Optionally, the heat preservation time of the molten raw material is 0.1 h, 0.5 h, 1 h, 2 h, 5 h, 10 h, 20 h, 24 h, 28 h, 32 h, 36 h, 40 h, 44 h or 48 h. Alternatively, the heat preservation time of the molten raw material can also be within the range between any two of the above times.

[0081] Another embodiment of the present application provides an application of a magnetic refrigeration alloy material of any one of the above or a magnetic refrigeration alloy material prepared by the preparation method of any one of the above magnetic refrigeration alloy materials as a refrigeration material in a refrigeration device.

[0082] In some of these embodiments, the refrigeration device is used to achieve a refrigeration temperature below 1 K.

[0083] The following are specific examples

[0084] Example 1

[0085] The magnetic refrigeration alloy material in Example 1 is: EuCo2Al9.

[0086] Preparation method of the magnetic refrigeration alloy material:

[0087] Put Eu particles, Co particles and Al blocks with a molar ratio of 6:8:86 into an alumina crucible, and seal them in a quartz tube filled with argon. After heating the mixture to 1150 °C and holding for 24 h, slowly cool it to 950 °C at a rate of 2 °C / h to precipitate the magnetic refrigeration alloy material. After centrifugal separation, a high-quality single-crystal EuCo2Al9 magnetic refrigeration alloy material is obtained.

[0088] Example 2

[0089] The magnetic refrigeration alloy material in Example 2 is: Eu 0.87 Sr 0.13 Co2Al9.

[0090] Preparation method of the magnetic refrigeration alloy material:

[0091] Put Eu particles, Sr particles, Co particles and Al blocks with a molar ratio of 4.8:1.2:8:86 into an alumina crucible, and seal them in a quartz tube filled with argon. After heating the mixture to 1150 °C and holding for 24 h, slowly cool it to 950 °C at a rate of 2 °C / h to precipitate the magnetic refrigeration alloy material. After centrifugal separation, a high-quality single-crystal Eu 0.87 Sr 0.13 Co2Al9 magnetic refrigeration alloy material is obtained.

[0092] Example 3

[0093] The magnetocaloric alloy material in Example 3 is: EuCo2(Al 0.94 Si 0.06 )9.

[0094] Preparation method of the magnetocaloric alloy material:

[0095] Put Eu particles, Co particles, Al blocks and Si particles with a molar ratio of 6:8:86:8 into an alumina crucible, and seal it in a quartz tube filled with argon. After heating the mixture to 1150 °C and holding for 24 h, it is slowly cooled to 950 °C at a rate of 2 °C / h to precipitate the magnetocaloric alloy material. After centrifugal separation, high-quality single-crystal EuCo2(Al 0.94 Si 0.06 )9 magnetocaloric alloy material is obtained.

[0096] Example 4

[0097] The magnetocaloric alloy material in Example 4 is: Eu(Co 0.7 Ni 0.3 )2Al9.

[0098] Preparation method of the magnetocaloric alloy material:

[0099] Put Eu particles, Co particles, Ni sheets and Al blocks with a molar ratio of 1:1:1:20 into an alumina crucible, and seal it in a quartz tube filled with argon. After heating the mixture to 1095 °C and holding for 24 h, it is slowly cooled to 870 °C at a rate of 2 °C / h to precipitate the magnetocaloric alloy material. After centrifugal separation, high-quality single-crystal Eu(Co 0.7 Ni 0.3 )2Al9 magnetocaloric alloy material is obtained.

[0100] Example 5

[0101] The magnetocaloric alloy material in Example 5 is: EuNi2Al9.

[0102] Preparation method of the magnetocaloric alloy material:

[0103] Put Eu particles, Ni sheets and Al blocks with a molar ratio of 1:1:20 into an alumina crucible, and seal it in a quartz tube filled with argon. After heating the mixture to 1000 °C and holding for 24 h, it is slowly cooled to 780 °C at a rate of 2 °C / h to precipitate the magnetocaloric alloy material. After centrifugal separation, high-quality single-crystal EuNi2Al9 magnetocaloric alloy material is obtained.

[0104] Comparative Example 1

[0105] The magnetocaloric material in Comparative Example 1 is Na2BaCo(PO4)2.

[0106] As shown in Figures 1 to 5 the following figures Figures 1 to 5 are the EDX spectra of the magnetocaloric alloy materials in Examples 1 to 5, respectively. It can be seen that the magnetocaloric alloy materials in Examples 1 to 5 have the following chemical formulas in sequence: EuCo2Al9, Eu 0.87 Sr 0.13 Co2Al9, Eu 0.87 Sr 0.13 Co2Al9, Eu(Co 0.7 Ni 0.3 )2Al9, and EuNi2Al9. As shown in Figure 6 the following figures Figure 6 are the susceptibility curves of the magnetocaloric alloy materials in Examples 1 to 5. When testing, the magnetic field is parallel to the c-axis of each sample. It can be seen that by chemically doping on the basis of the EuCo2Al9 matrix and regulating its alloy composition, the magnetic phase transition temperature of the magnetocaloric alloy material can be greatly changed. As shown in Figure 7 the following figures Figure 7 are the thermal conductivity curves of the magnetocaloric alloy material in Example 1 and the magnetocaloric material in Comparative Example 1. It can be seen that in the temperature range below 1K, the thermal conductivity of EuCo2Al9 is much higher than that of the Na2BaCo(PO4)2 material. Further, at a temperature of 100mK, the thermal conductivity of EuCo2Al9 can reach 100mW / Km, which is more than 100 times that of the Na2BaCo(PO4)2 material. As shown in Figure 8 the following figures Figure 8 is the adiabatic demagnetization curve of the EuCo2Al9 magnetocaloric alloy material in Example 1, whose initial temperature is 1.8K and the magnetic induction intensity of the magnetic field is 12T. It can be seen that the lowest refrigeration temperature of the magnetocaloric alloy material is 116mK.

[0107] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0108] The above-described embodiments only represent several implementation manners of the present application. Their descriptions are relatively specific and detailed, but they should not be construed as limitations on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims, and the description and drawings can be used to explain the content of the claims.

Claims

1. A magnetic refrigeration alloy material, characterized in that, Comprising a material having the following general chemical formula: Eu 1-a X a Co 2- b M b Al 9-c Z c , wherein X is selected from at least one of Mg, Ca, Sr, Ba, Ce, Gd, and Sm, M is selected from at least one of Cr, Mn, Fe, Ni, and Cu, Z is selected from at least one of Zn, Cd, Ga, Si, and Ge, 0 ≤ a ≤ 1, 0 ≤ b ≤ 2, 0 ≤ c ≤ 9.

2. The magnetic refrigeration alloy material according to claim 1, wherein The thermal conductivity of the magnetic refrigeration alloy material at 100 mK is 10 mW / Km to 500 mW / Km.

3. The magnetocaloric alloy material according to claim 1, wherein The lowest refrigeration temperature of the magnetic refrigeration alloy material is below 4 K.

4. The magnetocaloric alloy material according to claim 1, wherein The magnetic phase transition temperature of the magnetic refrigeration alloy material is 0 K to 20 K.

5. The magnetocaloric alloy material according to claim 1, characterized in that, The magnetic refrigeration alloy material is a single crystal material with a triangular lattice.

6. The magnetocaloric alloy material according to any one of claims 1 to 5, characterized in that, a = 0, b = 0, c = 0; or, a = 0.13, b = 0, c = 0; or, a = 0, b = 0.6, c = 0; or, a = 0, b = 2, c = 0; or, a = 0, b = 0, c = 0.

54.

7. A method for preparing the magnetocaloric alloy material according to any one of claims 1 to 6, characterized in that, It includes the following steps: Mix and melt metal raw materials to obtain a metal liquid; the metal raw materials include at least one of Eu and X, where X is selected from at least one of Mg, Ca, Sr, Ba, Ce, Gd, and Sm; the metal raw materials also include at least one of Co and M, where M is selected from at least one of Cr, Mn, Fe, Ni, and Cu; the metal raw materials also include at least one of Al and Z, where Z is selected from at least one of Zn, Cd, Ga, Si, and Ge; Perform a temperature reduction treatment on the metal liquid to precipitate the magnetic refrigeration alloy material; Separate the magnetic refrigeration alloy material and the metal liquid.

8. The preparation method of the magnetocaloric alloy material according to claim 7, characterized in that, The mixing and melting are carried out in an inert gas atmosphere or under vacuum.

9. The method for preparing a magnetic refrigeration alloy material according to claim 7 or 8, characterized in that, The temperature reduction rate of the temperature reduction treatment is less than or equal to 20 °C / h; and / or, The target temperature of the temperature reduction treatment is 650 °C to 950 °C.

10. Application of the magnetic refrigeration alloy material prepared by the preparation method of the magnetic refrigeration alloy material according to any one of claims 1 to 6 or the magnetic refrigeration alloy material according to any one of claims 7 to 9 as a refrigeration material in a refrigeration device.

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