An Alkali Metal Alkali Earth Metal Gadolinium Borate Magnetic Refrigeration Material, Its Preparation Method and Application

Abstract

This invention relates to alkali metal and alkaline earth metal gadolinium borate magnetic refrigeration materials, their preparation methods, and applications. The chemical formula of the magnetic refrigeration material is: LiXGd m (BO3) n X is Sr or Ca; when X is Sr, m takes the value of 2 and n takes the value of 3; when X is Ca, m takes the value of 5 and n takes the value of 6. This invention successfully obtained two alkali metal and alkaline earth metal gadolinium-based borate magnetic refrigeration materials with different crystal structures. When the alkaline earth metal is Sr, a trigonal LiSrGd2(BO3)3 crystal system is formed; when the alkaline earth metal is Ca, a hexagonal LiCaGd5(BO3)6 crystal system is formed. This series of materials all exhibit excellent magnetocaloric effects at low temperatures. Under magnetic field changes of 0 to 7T, the maximum magnetic entropy changes of LiSrGd2(BO3)3 and LiCaGd5(BO3)6 are 54.2 J / kg·K and 60.6 J / kg·K, respectively. Moreover, the raw materials of this invention are inexpensive and the preparation process is simple. The obtained materials have broad application prospects in cutting-edge scientific fields such as space exploration, superconductivity and quantum technology.

Description

Technical Field

[0001] This invention belongs to the field of magnetic refrigeration materials technology, specifically relating to an alkali metal alkaline earth metal gadolinium-based borate magnetic refrigeration material, its preparation method, and its application. Background Technology

[0002] Cryogenic refrigeration technology has irreplaceable application value in cutting-edge scientific fields such as space exploration, high-energy physics, superconductivity, and quantum technology. Currently, the mainstream method for obtaining and maintaining temperatures below 4.2K still relies on the compression-expansion cycle of liquid helium. Especially for the cryogenic region of 2K and below, helium-3 is usually required as the refrigerant. However, helium-3 resources are scarce and expensive, which seriously restricts the further development of cryogenic science and technology. Therefore, developing a new refrigeration technology that is efficient, stable, environmentally friendly, and does not require a scarce refrigerant has become a research hotspot in the global cryogenic engineering field.

[0003] Magnetic refrigeration technology is based on the magnetocaloric effect (also known as the magnetocaloric effect), which means that when a magnetic material is subjected to a changing external magnetic field, the order of its magnetic moments changes, accompanied by reversible heat absorption or release. Compared with traditional gas compression refrigeration, magnetic refrigeration technology has significant advantages such as compact structure, stable and reliable operation, high theoretical refrigeration efficiency, and no greenhouse gas emissions, and is considered one of the most promising solid-state "green" refrigeration technologies. The magnetocaloric effect is one of the intrinsic properties of magnetic materials, and its strength is determined by the degree of coupling between the magnetic field and the magnetic sublattice. It is a key indicator for measuring the cooling capacity and energy conversion efficiency of materials. Therefore, designing and fabricating novel magnetic refrigeration materials with large / giant magnetocaloric effects has always been a core scientific problem in this field.

[0004] Trivalent gadolinium ions (Gd) 3+ With a ground-state spin quantum number S=7 / 2, and its orbital angular momentum quenched, gadolinium exhibits extremely weak magnetic exchange coupling and negligible magnetocrystalline anisotropy, making it an ideal magnetic center for constructing high-performance magnetic refrigeration materials. Among numerous gadolinium-based compounds, gadolinium-borate systems possess advantages such as simple preparation processes, stable physicochemical properties, and high magnetic center density. Furthermore, their lattice thermal vibrations are negligible at low temperatures, thus making them a key candidate system for low-temperature magnetic refrigeration materials.

[0005] Although gadolinium-based borate systems have shown promise in low-temperature magnetic refrigeration, current research still faces key bottlenecks. In the synthesis of these materials, boric acid (H3BO3), as the boron source, exhibits significant volatility and reactivity at high temperatures. It readily reacts with alkali metal ions such as Li⁺ in the system to form a low-melting-point borate glass phase. This glass phase not only coats unreacted solid particles, hindering the complete solid-state reaction, but also makes the crystal structure of the final product extremely sensitive to the ratio of raw materials, especially to minute changes in boric acid content. Traditional high-temperature solid-state methods struggle to accurately compensate for boron volatilization losses, easily resulting in products with mixed phases, leading to unstable and difficult-to-optimize magnetocaloric properties. Furthermore, the structural control mechanisms of alkali metal gadolinium-based borates have not yet been fully elucidated by current techniques. Reported compounds, such as GdBO3, Gd(BO2)3, KBaGd(BO3)2, and K3Li3Gd7(BO3)9, mostly have fixed stoichiometric ratios, lacking the ability to systematically control crystal structure and Gd by changing synthetic conditions, especially the amount of boric acid. 3+ The spatial arrangement of ions and the magnetic exchange pathways have not yet been studied. For example, the effects of introducing different alkaline earth metal ions (Ca) on ion spatial arrangement and magnetic exchange pathways have not yet been revealed. 2+ or Sr 2+ At that time, how to selectively construct crystal structures with different dimensional magnetic networks (layered, chain-like, or three-dimensional networks) by precisely controlling the proportion of boric acid is a challenge. The lack of structure-property relationship between this structure and magnetocaloric properties seriously hinders the design and preparation of materials with excellent magnetocaloric properties.

[0006] Therefore, the existing technology has the following defects: (1) It lacks an effective strategy to address the volatilization of boric acid and the formation of the glass phase during the synthesis process, resulting in poor controllability of the product crystal structure; (2) It fails to establish a deterministic regulatory relationship between the boric acid ratio and a specific crystal structure; (3) The magnetic entropy change -ΔS of existing gadolinium borates in the low-temperature region at 2K and below is limited. M The values ​​are generally too low to meet the requirements of practical applications. Summary of the Invention

[0007] Based on the aforementioned shortcomings and deficiencies in the prior art, one of the objectives of this invention is to at least solve one or more of the aforementioned problems in the prior art. In other words, one of the objectives of this invention is to provide an alkali metal alkaline earth metal gadolinium-based borate magnetic refrigeration material that meets one or more of the aforementioned requirements, as well as its preparation method and application.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: An alkali metal alkaline earth metal gadolinium-based borate magnetic refrigeration material, with the chemical formula: LiXGd m (BO3) n X is Sr or Ca; When X is Sr, m takes the value 2 and n takes the value 3; When X is Ca, m takes the value 5 and n takes the value 6.

[0009] As a preferred embodiment, the LiSrGd2(BO3)3 belongs to the trigonal crystal system with space group P. m1; The LiCaGd5(BO3)6 belongs to the hexagonal crystal system and has the space group P6522.

[0010] As a preferred embodiment, the maximum magnetic entropy change of the LiSrGd2(BO3)3 material is 54.2 J / kg·K under a magnetic field variation of 0–7T. The maximum magnetic entropy change of the LiCaGd5(BO3)6 material under a magnetic field variation of 0–7T is 60.6 J / kg·K.

[0011] This invention also provides a method for preparing alkali metal and alkaline earth metal gadolinium-based refrigeration materials as described in any of the preceding embodiments, comprising the following steps: (1) Mix Li-containing compounds, Sr or Ca-containing compounds, Gd-containing compounds and boric acid evenly, heat to 550-850℃ in a normal pressure and oxygen-containing environment, pre-calcine at a constant temperature for 1-3 days, and obtain pre-calcined material after one cooling. (2) After grinding the pre-burned material, press it into tablets under a pressure of 15-30 MPa, and then place it in a normal pressure and oxygen environment to heat it to 800-1000℃ for a second sintering for 1-3 days. After natural cooling, the target product is obtained.

[0012] As a preferred option, when the target product is LiSrGd2(BO3)3, the molar ratio of Li:Sr:Gd:H3BO3 of each raw material is controlled to be 1:1:2:(3~7). When the target product is LiCaGd5(BO3)6, the molar ratio of Li:Ca:Gd:H3BO3 of each raw material is controlled to be 1:1:2:(6~10).

[0013] As a preferred embodiment, the Li-containing compound is lithium carbonate.

[0014] As a preferred embodiment, the Sr or Ca-containing compound is strontium carbonate or calcium carbonate.

[0015] As a preferred embodiment, the Gd-containing compound is gadolinium oxide.

[0016] The present invention also provides the application of alkali metal alkaline earth metal gadolinium-based borate magnetic refrigeration materials as described in any of the preceding embodiments, or alkali metal alkaline earth metal gadolinium-based borate magnetic refrigeration materials prepared by the preparation method described in any of the preceding embodiments, for use in space exploration, superconductivity, or quantum refrigeration.

[0017] Compared with the prior art, the beneficial effects of this invention are: This invention successfully obtained two alkali metal and alkaline earth metal gadolinium-based borate magnetic refrigeration materials with different crystal structures by adjusting the boric acid ratio under the same raw material molar ratio of Li:Ca / Sr:Gd=1:1:2 and the same high-temperature solid-state reaction conditions. When the alkaline earth metal is strontium (Sr), a trigonal LiSrGd2(BO3)3 crystal system is formed; when the alkaline earth metal is Ca, a hexagonal LiCaGd5(BO3)6 crystal system is formed. Both series of materials exhibit excellent magnetocaloric effects at low temperatures. Under magnetic field variations of 0–7T, the maximum magnetic entropy changes of LiSrGd2(BO3)3 and LiCaGd5(BO3)6 are 54.2 J / kg·K and 60.6 J / kg·K, respectively. Moreover, the raw materials of this invention are inexpensive, the preparation process is simple, and the obtained materials have broad application prospects in cutting-edge scientific fields such as space exploration, superconductivity, and quantum technology. Attached Figure Description

[0018] Figure 1 The X-ray diffraction pattern of the LiSrGd2(BO3)3 polycrystalline material in Example 1 of this invention and its refined image compared with the standard CIF. Figure 2 The X-ray diffraction pattern of the LiCaGd5(BO3)6 polycrystalline material in Example 2 of this invention and its refined image compared with the standard CIF. Figure 3 The isothermal magnetization curves of the LiSrGd2(BO3)3 polycrystalline material of Example 1 of the present invention at different temperatures are shown. Figure 4 The isothermal magnetization curves of the LiCaGd5(BO3)6 polycrystalline material in Example 2 of this invention at different temperatures are shown. Figure 5 The graph shows the change in magnetic entropy of the LiSrGd2(BO3)3 polycrystalline material in Example 1 of this invention as a function of temperature under varying magnetic fields from 0 to 7T. Figure 6 This is a graph showing the change in magnetic entropy of the LiCaGd5(BO3)6 polycrystalline material in Example 2 of the present invention as a function of temperature under a magnetic field ranging from 0 to 7 T. Detailed Implementation

[0019] The following provides a detailed description of the alkali metal and alkaline earth metal gadolinium-based borate magnetic refrigeration materials of the present invention, their preparation methods, and their applications.

[0020] The alkali metal and alkaline earth metal gadolinium-based borate magnetic refrigeration material of the present invention has the chemical formula: LiXGd m (BO3) n X is Sr or Ca; When X is Sr, m takes the value of 2, n takes the value of 3, that is, the chemical formula is LiSrGd2(BO3)3, which belongs to the trigonal crystal system and the space group is P. m1; When X is Ca, m takes the value of 5, and n takes the value of 6, the chemical formula is LiCaGd5(BO3)6, which is a hexagonal crystal system with space group P6522.

[0021] The maximum magnetic entropy change of the above-mentioned LiSrGd2(BO3)3 material is 54.2 J / kg·K under magnetic field variations of 0–7T. The maximum magnetic entropy change of the above-mentioned LiCaGd5(BO3)6 material is 60.6 J / kg·K under a magnetic field variation of 0 to 7T.

[0022] The preparation method of the above-mentioned alkali metal and alkaline earth metal gadolinium-based borate magnetic refrigeration materials includes the following steps: (1) Mix the Li-containing compound, the Sr or Ca-containing compound, the Gd-containing compound and the boric acid evenly, and heat them to 550-850℃ at a rate of 1-5℃ / min in an atmospheric pressure and oxygen-containing environment. Pre-calcine at a constant temperature for 1-3 days, and obtain the pre-calcined material after one cooling. Specifically, the Li-containing compound is preferably a commonly used Li-containing compound such as lithium carbonate, the Sr or Ca-containing compound is preferably a commonly used Sr or Ca-containing compound such as strontium carbonate or calcium carbonate, and the Gd-containing compound is preferably a commonly used Gd-containing compound such as gadolinium oxide. The preheating temperature and time mentioned above can be determined according to actual application requirements; (2) After grinding the pre-burned material, press it into tablets under a pressure of 15-30 MPa, and then place it in an atmospheric pressure and oxygen environment and heat it to 800-1000℃ at a rate of 1-5℃ / min for a second sintering for 1-3 days. After natural cooling, the target product is obtained. The pressure for pressing the tablets and the temperature and time for secondary sintering can be determined according to the actual application requirements.

[0023] When the target product is LiSrGd2(BO3)3, the molar ratio of Li:Sr:Gd:H3BO3 of each raw material is controlled at 1:1:2:(3~7). The specific molar ratio can be determined according to the actual application requirements. When the target product is LiCaGd5(BO3)6, the molar ratio of Li:Ca:Gd:H3BO3 of each raw material is controlled at 1:1:2:(6~10). The specific molar ratio can be determined according to the actual application requirements. This invention, under the condition of a fixed molar ratio of alkali metal Li, alkaline earth metal Ca or Sr to rare earth element Gd of 1:1:2, can overcome the technical problem of uncontrollable products caused by the reaction of boric acid with alkali metal ions to form a low-melting-point borate glass phase during high-temperature synthesis by precisely controlling the amount of boric acid added. Thus, two low-temperature magnetic refrigeration materials with different crystal structures and magnetocaloric properties can be obtained in a directional manner. When the alkaline earth metal is Sr with a large ionic radius, the molar ratio of B to Sr can be controlled within the range of 3:1 to 7:1 to obtain trigonal LiSrGd2(BO3)3 material. When the alkaline earth metal is Ca with a small ionic radius, the hexagonal LiCaGd5(BO3)6 material can be obtained by controlling the molar ratio of B to Ca to be in the range of 6:1 to 10:1.

[0024] The preparation method of the present invention effectively suppresses the adverse effects of generating a low-melting-point glass phase by using a specific raw material ratio range and combining a two-step high-temperature solid-state reaction process, thus ensuring the controllable synthesis of the target crystal structure.

[0025] The alkali metal and alkaline earth metal gadolinium-based borate magnetic refrigeration materials of the present invention exhibit magnetocaloric properties in the low-temperature region of 2K and below. Specifically, for the LiSrGd2(BO3)3 material, its low boric acid ratio induces the formation of a three-dimensional network structure that is conducive to magnetic exchange, with a maximum magnetic entropy change of 54.2 J / kg·K under magnetic field variations of 0–7T; for the LiCaGd5(BO3)6 material, its high boric acid ratio promotes the formation of Gd 3 The ⁺ denser layered structure of ions and significantly shortened spacing between Gd-Gd particles resulted in a maximum magnetic entropy change of 60.6 J / kg·K under magnetic field variations of 0–7 T, which is significantly superior to existing gadolinium-based oxide low-temperature magnetic refrigeration materials, such as the commercially available gadolinium gallium garnet (Gd₃Ga₅O₃). 12 The maximum magnetic entropy change of gadolinium fluoride (GdLiF4) is approximately 38 J / kg·K, that of gadolinium fluoride (GdLiF4) is approximately 50 J / kg·K, that of alkali metal fluoroborate (Ba5Gd3(BO3)6F) is approximately 30 J / kg·K, and that of alkali metal fluoroborate (Li3K9Gd3(BO3)7) is approximately 40 J / kg·K.

[0026] This invention innovatively proposes a synthesis strategy that regulates the crystal structure through the boric acid ratio. By precisely controlling the boric acid feed ratio, a controllable transformation of the crystal structure between the trigonal LiSrGd2(BO3)3 and the hexagonal LiCaGd5(BO3)6 is achieved; furthermore, a correlation between crystal structure and low-temperature magnetocaloric properties is established. Specifically, the boric acid ratio corresponding to the synthesis of LiCaGd5(BO3)6, i.e., the molar ratio of B to Ca, is in the range of 6:1 to 10:1, which is conducive to the formation of layered or chain-like substructures with higher gadolinium ion density and reduces the spacing between magnetic ions, thereby leading to enhanced low-temperature magnetocaloric properties. In addition, both materials prepared by this invention exhibit excellent magnetocaloric properties in the temperature range below 2K. The preparation method provided by this invention effectively solves the technical difficulty of easily forming a low-melting-point borate glass phase by precisely limiting the raw material molar ratio range and using a two-step sintering process. It has the advantages of a wide process window, simple operation, no need for special atmosphere, and suitability for large-scale production.

[0027] The alkali metal alkaline earth metal gadolinium borate magnetic refrigeration material of the present invention, based on its excellent magnetocaloric properties, can be used for refrigeration applications in space exploration, superconductivity, or quantum mechanics.

[0028] The following specific embodiments and comparative examples further explain and illustrate the alkali metal and alkaline earth metal gadolinium-based borate magnetic refrigeration materials of the present invention, their preparation methods, and applications.

[0029] Example 1: The preparation process of the LiSrGd2(BO3)3 polycrystalline material in this embodiment includes: Step 1: Using Li2CO3 (99.9%), SrCO3 (99.9%), Gd2O3 (99.99%), and H3BO3 (analytical grade) as raw materials, weigh them according to the molar ratio of Li:Sr:Gd:B = 1:1:2:5, calculate and weigh the corresponding mass of raw materials; Step 2: Place the weighed raw material in an agate mortar, add an appropriate amount of anhydrous ethanol, grind and mix thoroughly for 2 hours, transfer the uniformly mixed powder to a corundum crucible, place it in a muffle furnace, heat it to 550°C at a rate of 3°C / min, keep it at that temperature for 24 hours, and cool it to room temperature with the furnace to obtain the pre-calcined material. Step 3: Take out the pre-fired material, grind it thoroughly again, and press it into a cylindrical blank with a diameter of about 10 mm and a thickness of about 3 mm under a pressure of 18 MPa. Place the blank in a corundum boat, put it into a muffle furnace, heat it to 800°C at a rate of 3°C / min, hold it at that temperature for 24 hours, and then let it cool naturally to room temperature to obtain a white and dense polycrystalline bulk, which is LiSrGd2(BO3)3.

[0030] The LiSrGd2(BO3)3 compound of this embodiment was tested as follows: 1) Structural characterization: The prepared samples were subjected to X-ray powder diffraction analysis, such as... Figure 1 As shown, its diffraction peaks are highly consistent with the standard CIF of trigonal LiSrGd2(BO3)3, confirming that the product is a pure phase; 2) Magnetic testing: Using a superconducting quantum interference device (SQUID), measurements were taken every 0.5K or 1K within the temperature range of 1.8–20K. The magnetic field range was 0–7T, and the magnetic entropy change was obtained using Maxwell's equations. Figure 3 and Figure 5 As shown, the maximum magnetic entropy change of the LiSrGd2(BO3)3 material prepared in this embodiment is 54.2 J / kg·K under a magnetic field variation of 0 to 7T.

[0031] Example 2: The preparation process of the LiCaGd5(BO3)6 polycrystalline material in this embodiment includes: Step 1: Using Li₂CO₃ (99.9%), CaCO₃ (99.9%), Gd₂O₃ (99.99%), and H₃BO₃ (analytical grade) as raw materials, weigh them according to the molar ratio of Li:Ca:Gd:B = 1:1:2:8, calculate and weigh the corresponding mass of raw materials; Step 2: Place the weighed raw material in an agate mortar, add an appropriate amount of anhydrous ethanol, grind and mix thoroughly for 2 hours, transfer the uniformly mixed powder to a corundum crucible, place it in a muffle furnace, heat it to 550°C at a rate of 3°C / min, keep it at that temperature for 24 hours, and cool it to room temperature with the furnace to obtain the pre-calcined material. Step 3: Take out the pre-fired material, grind it thoroughly again, and press it into a cylindrical blank with a diameter of about 10 mm and a thickness of about 3 mm under a pressure of 18 MPa. Place the blank in a corundum boat, put it into a muffle furnace, heat it to 800°C at a rate of 3°C / min, hold it at that temperature for 24 hours, and then let it cool naturally to room temperature to obtain a white and dense polycrystalline bulk, which is LiCaGd5(BO3)6.

[0032] The LiCaGd5(BO3)6 compound prepared in this example was tested as follows: 1) Structural characterization: The prepared samples were subjected to X-ray powder diffraction analysis, such as... Figure 2 As shown, its diffraction peaks are highly consistent with the standard CIF of the hexagonal LiCaGd5(BO3)6 crystal system, confirming that the product is a pure phase; 2) Magnetic testing: Using a superconducting quantum interference device (SQUID), measurements were taken every 0.5K or 1K within the temperature range of 1.8–20K. The magnetic field range was 0–7T, and the magnetic entropy change was obtained using Maxwell's equations. Figure 4 and Figure 6 As shown, the maximum magnetic entropy change of the LiCaGd5(BO3)6 material prepared in this embodiment is 60.6 J / kg·K under a magnetic field change of 0 to 7T.

[0033] The composition and maximum magnetic entropy change under different boric acid ratios were compared and tested, and the results are shown in Tables 1 and 2: Table 1. Comparison of the composition and maximum magnetic entropy change of the target product under different boric acid ratios. ; Table 2 Comparison of the composition and maximum magnetic entropy change of the target product under different boric acid ratios ; As shown in Tables 1 and 2, when the boric acid ratio is not within the above molar ratio control range, the product is monoclinic GdBO3, and the corresponding maximum magnetic entropy change at 2T is significantly lower.

[0034] Given that there are numerous embodiments of the present invention, and the raw materials and quantities involved can be selected within a limited range according to actual needs, and that the experimental data for each embodiment are extensive and numerous, it is not suitable to list and describe them one by one here. However, the content to be verified and the final conclusions obtained in each embodiment are similar. Therefore, the verification content of each embodiment will not be described one by one here.

[0035] The above description is merely a detailed explanation of preferred embodiments and principles of the present invention. For those skilled in the art, there may be changes in specific implementation methods based on the ideas provided by the present invention, and these changes should also be considered within the scope of protection of the present invention.

Claims

1. An alkali metal alkaline earth metal gadolinium-based borate magnetic refrigeration material, characterized in that, Its chemical formula is: LiXGd m (BO3) n X is Sr or Ca; When X is Sr, m takes the value 2 and n takes the value 3; When X is Ca, m takes the value 5 and n takes the value 6.

2. The alkali metal alkaline earth metal gadolinium-based borate magnetic refrigeration material according to claim 1, characterized in that, The LiSrGd2(BO3)3 belongs to the trigonal crystal system and has space group P. m1; The LiCaGd5(BO3)6 belongs to the hexagonal crystal system and has the space group P6522.

3. The alkali metal alkaline earth metal gadolinium-based borate magnetic refrigeration material according to claim 1 or 2, characterized in that, The maximum magnetic entropy change of the LiSrGd2(BO3)3 material under a magnetic field variation of 0–7T is 54.2 J / kg·K; The maximum magnetic entropy change of the LiCaGd5(BO3)6 material under a magnetic field variation of 0–7T is 60.6 J / kg·K.

4. The method for preparing the alkali metal alkaline earth metal gadolinium-based borate magnetic refrigeration material according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Mix Li-containing compounds, Sr or Ca-containing compounds, Gd-containing compounds and boric acid evenly, heat to 550-850℃ in a normal pressure and oxygen-containing environment, pre-calcine at a constant temperature for 1-3 days, and obtain pre-calcined material after one cooling. (2) After grinding the pre-burned material, press it into tablets under a pressure of 15-30 MPa, and then place it in a normal pressure and oxygen environment to heat it to 800-1000℃ for a second sintering for 1-3 days. After natural cooling, the target product is obtained.

5. The preparation method according to claim 4, characterized in that, When the target product is LiSrGd2(BO3)3, the molar ratio of Li:Sr:Gd:H3BO3 of each raw material is controlled as 1:1:2:(3~7). When the target product is LiCaGd5(BO3)6, the molar ratio of Li:Ca:Gd:H3BO3 of each raw material is controlled to be 1:1:2:(6~10).

6. The preparation method according to claim 4, characterized in that, The Li-containing compound is lithium carbonate.

7. The preparation method according to claim 4, characterized in that, The Sr or Ca-containing compound is strontium carbonate or calcium carbonate.

8. The preparation method according to claim 4, characterized in that, The Gd-containing compound is gadolinium oxide.

9. The application of the alkali metal alkaline earth metal gadolinium-based borate magnetic refrigeration material according to any one of claims 1-3 or the alkali metal alkaline earth metal gadolinium-based borate magnetic refrigeration material prepared by the preparation method according to any one of claims 4-8, characterized in that, Cooling for space exploration, superconductivity, or quantum applications.

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