Magnetic refrigeration material and preparation method thereof
By preparing YCa2SbFe4-xGaxO12 magnetic refrigeration material, using Ga element to regulate phase change temperature and gradient sintering technology, the existing magnetic refrigeration materials have been solved, and efficient and stable magnetic refrigeration effect is achieved, which is suitable for industrial applications.
Patent Information
- Application Number
- CN202410102660.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-25
- Publication Date
- 2025-07-25
AI Technical Summary
The existing magnetic refrigeration materials have high raw material costs, narrow temperature zones, complex preparation processes and unstable chemical properties, which limit their application in magnetic refrigeration technology.
The chemical composition of YCa2SbFe4-xGaxO12 is adopted to prepare magnetic refrigeration materials by ball milling, drying, crushing, sieving and gradient sintering. Ga elements are used to change the superexchange between ions, regulate the phase change temperature and increase the magnetic entropy change. Combined with simple solid-phase reaction and gradient sintering technology, the chemical stability and magnetic refrigeration effect of the material are improved.
It realizes the regulation of the phase change temperature within a large range, significantly reduces the magnetic order temperature, widens the magnetic refrigeration temperature zone, improves the purity and refrigeration efficiency of magnetic refrigeration materials, is simple to operate and environmentally friendly, and is suitable for industrial production.
Smart Images
Figure CN120376267A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of magnetic materials, and particularly relates to a magnetic refrigeration material and a preparation method thereof. Background Art
[0002] Magnetic refrigeration technology is a new type of refrigeration technology developed based on the magnetocaloric effect of magnetic materials. Its core is magnetic materials, and the magnetization intensity and magnetization direction can be adjusted by an external magnetic field. When a magnetic material is magnetized, the magnetic moments tend to be ordered, the magnetic material releases the absorbed heat and cools down, and when the magnetic material is demagnetized, it will return to the high magnetic entropy state, and at the same time, the system absorbs heat. By repeating this process and combining with a special heat transfer medium, the purpose of refrigeration is achieved.
[0003] Compared with the traditional gas compression refrigeration technology, magnetic refrigeration technology has higher refrigeration efficiency, can directly absorb heat from a low-temperature environment and transfer it to a high-temperature environment without the need to compress gas to complete. At the same time, the magnetic working medium of magnetic refrigeration technology is a solid, with a compact structure, and does not require the use of traditional refrigeration equipment such as compressors, condensers, and expansion valves, which can save more space and energy. In addition, magnetic refrigeration technology also has great advantages in environmental protection and does not emit gases harmful to the environment. Traditional gas compression refrigeration technology requires the use of refrigerants, and these refrigerants often escape into the atmosphere, causing environmental pollution.
[0004] As the core of magnetic refrigeration technology, magnetic materials are the key to magnetic refrigeration technology. An ideal magnetic refrigeration material should have a large magnetic entropy change in a wide temperature range and at a low magnetic field, which is beneficial to realizing efficient magnetic refrigeration. The traditional room-temperature magnetic refrigeration material is gadolinium (Gd), but its raw material cost is high, the temperature range is narrow, and the preparation process is complex, which limits its application. New room-temperature magnetic refrigeration materials, such as La(Fe,Si) 13 , Gd-Ge-Si-based, Ni-Mn-In-based, LaCaMnO3, and MnAs-based series compounds, although have some advantages in magnetic refrigeration, also have the above problems. Therefore, finding a magnetic refrigeration material with a high magnetic entropy change and stable chemical properties is crucial for promoting the development of magnetic refrigeration technology and meeting the needs of different application scenarios. Summary of the Invention
[0005] The purpose of the present invention is to provide a magnetic refrigeration material for the above technical problems, whose phase transition temperature can be regulated within a large range, showing a large magnetic entropy change and good chemical stability, and having broad application prospects in the field of magnetic refrigeration.
[0006] In the technical solution of the present invention, the chemical formula of the magnetic refrigeration material is YCa2SbFe 4-x Ga x O 12 , where 0 < x ≤ 3.
[0007] The diamagnetic Ga element in the magnetic refrigeration material can change the super-exchange interaction between ions, thereby significantly reducing the magnetic order temperature, realizing the regulation of the phase transition temperature, and cooperating with other components to enhance the magnetic refrigeration effect of the magnetic refrigeration material.
[0008] Further, the maximum magnetic entropy change value of the above magnetic refrigeration material under an external magnetic field of 5 T is 0.1-0.7 J K -1 mol -1 。
[0009] The present invention also provides a preparation method of the above magnetic refrigeration material, including ball-milling and uniformly mixing a mixed material of Y oxide, Ca-containing Ca compound, Sb oxide, Ga oxide and Fe oxide, drying, crushing, sieving, and then performing gradient sintering.
[0010] Further, the Y oxide is Y2O3, the Ca-containing Ca compound is CaCO3, the Sb oxide is Sb2O3, the Ga oxide is Ga2O3, and the Fe oxide is Fe2O3.
[0011] Further, the ball-milling speed is 200-500 rpm / min, and the ball-milling time is 6-15 h.
[0012] Further, deionized water with a mass 0.5-3.0 times that of the mixed material is added as a ball-milling medium during ball-milling.
[0013] Further, the material-to-ball ratio during ball-milling is 1:2-8, preferably 1:3-6.
[0014] Further, the drying temperature is 80-150 °C, and the time is 6-20 h.
[0015] Preferably, the crushing is to grind for 0.5-1.0 h after being broken by a wall breaker.
[0016] Further, the mesh number of the sieve during sieving is 50-200 meshes.
[0017] Further, the gradient sintering is to keep warm at T1 and T2 temperatures for 1-5 h in sequence, and then keep warm at T3 temperature for 15-25 h.
[0018] Further, T2-T1≥100 °C, T3-T2≥200 °C.
[0019] Further, T1 is 350-600 °C, T2 is 700-800 °C, and T3 is 1000-1350 °C.
[0020] Adopting gradient sintering and gradually increasing the reaction temperature can effectively improve the reaction activity and the purity of the magnetic refrigeration material, thereby improving the magnetic refrigeration effect.
[0021] Furthermore, the heating rate during gradient sintering is 1-10 °C / min.
[0022] Furthermore, the gradient sintering is carried out in an air atmosphere.
[0023] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:
[0024] (1) Through Y-containing compounds, Ca-containing compounds, Sb-containing compounds, Ga-containing compounds and Fe-containing compounds, a magnetic refrigeration material with a large magnetic entropy change and good chemical stability is obtained by a simple solid-phase reaction;
[0025] (2) The diamagnetic Ga element in the magnetic refrigeration material can change the super-exchange interaction between ions, thereby significantly reducing the magnetic order temperature and realizing the regulation of the phase transition temperature;
[0026] (3) By using gradient sintering and gradually increasing the reaction temperature, the reaction activity and the purity of the magnetic refrigeration material can be effectively improved, thereby improving the magnetic refrigeration effect;
[0027] (4) The preparation method of the magnetic refrigeration material is simple in operation, has few by-products, high product yield, and is environmentally friendly, providing the possibility for large-scale industrial production. Description of the Drawings
[0028] Figure 1 It is the X-ray diffraction pattern of the magnetic refrigeration materials obtained in Examples 1-3;
[0029] Figure 2 It is the FC and ZFC M-T curves of the magnetic refrigeration materials obtained in Examples 1-3 and Comparative Example 1 under a 200 Oe magnetic field;
[0030] Figure 3 It is the isothermal magnetization curves of the magnetic refrigeration materials obtained in Examples 1-3 and Comparative Example 1 at different temperatures;
[0031] Figure 4 It is the relationship curve between the magnetic entropy change and the temperature of the magnetic refrigeration materials obtained in Examples 1-3 and Comparative Example 1 under different magnetic field changes. Detailed Embodiments
[0032] The technical solution of the present invention will be further described and illustrated below through specific examples and drawings. It should be understood that the specific examples described herein are only used to help understand the present invention and are not used for specific limitations of the present invention. And the drawings used herein are only for better illustrating the content disclosed by the present invention and do not have a limiting effect on the protection scope. If there is no special description, the raw materials used in the embodiments of the present invention are all commonly used raw materials in the art, and the methods used in the embodiments are all conventional methods in the art.
[0033] Example 1
[0034] The preparation method of the magnetic refrigeration material in this example includes the following steps:
[0035] (1) Weigh Y2O3, CaCO3, Sb2O3, Fe2O3, Ga2O3 according to the molar ratio of the chemical formula YCa2SbFe3GaO 12 (x = 1), and add 1.5 times the total mass of the above components of deionized water as the ball milling medium. Ball mill at a speed of 300 rpm / min and a ball-to-material ratio of 1:4 for 8 h. Keep the obtained slurry at 100 °C for 10 h for drying, break it with a blender and then grind for 0.5 h. Sieve it through a 100-mesh sieve to obtain a mixed material;
[0036] (2) Heat-treat the mixed material in an air atmosphere. First, heat it to 400 °C at a heating rate of 5 °C / min and keep it for 3 h, then heat it to 750 °C and keep it for 2 h, and finally heat it to 1250 °C and keep it for 20 h. Cool it with the furnace to obtain YCa2SbFe3GaO 12 .
[0037] Example 2
[0038] The preparation method of the magnetic refrigeration material in this example includes the following steps:
[0039] (1) Weigh Y2O3, CaCO3, Sb2O3, Fe2O3, Ga2O3 according to the molar ratio of the chemical formula YCa2SbFe2Ga2O 12 (x = 2), and add 1.8 times the total mass of the above components of deionized water as the ball milling medium. Ball mill at a speed of 300 rpm / min and a ball-to-material ratio of 1:5 for 8 h. Keep the obtained slurry at 90 °C for 12 h for drying, break it with a blender and then grind for 0.5 h. Sieve it through a 100-mesh sieve to obtain a mixed material;
[0040] (2) Heat-treat the mixed material in an air atmosphere. First, heat it to 450 °C at a heating rate of 5 °C / min and keep it for 3 h, then heat it to 780 °C and keep it for 2 h, and finally heat it to 1250 °C and keep it for 20 h. Cool it with the furnace to obtain YCa2SbFe2Ga2O 12 .
[0041] Example 3
[0042] The preparation method of the magnetic refrigeration material in this example includes the following steps:
[0043] (1) Weigh Y2O3, CaCO3, Sb2O3, Fe2O3, Ga2O3 according to the molar ratio of the chemical formula YCa2SbFeGa3O 12Weigh the molar ratio of (x = 3), and add 1.5 times the mass of the above components. Using deionized water as the ball-milling medium, ball-mill at a speed of 280 rpm / min and a ball-to-material ratio of 1:4 for 10 h. Keep the obtained slurry at 110 °C for 8 h to dry it, break it up with a blender and then grind it for 0.5 h. After sieving with a 100-mesh sieve, a mixed material is obtained;
[0044] (2) Heat-treat the mixed material in an air atmosphere. First, heat it to 500 °C at a heating rate of 5 °C / min and keep it for 3 h, then heat it to 750 °C and keep it for 2 h, and finally heat it to 1300 °C and keep it for 20 h. Cool it in the furnace to obtain YCa2SbFeGa3O 12 .
[0045] Example 4
[0046] The difference between this example and Example 1 is only that in step (2), the mixed material is heat-treated in an air atmosphere. First, heat it to 400 °C at a heating rate of 5 °C / min and keep it for 5 h, then heat it to 1250 °C and keep it for 20 h. Cool it in the furnace to obtain YCa2SbFe3GaO 12 .
[0047] Example 5
[0048] The difference between this example and Example 1 is only that in step (2), the mixed material is heat-treated in an air atmosphere. First, heat it to 750 °C at a heating rate of 5 °C / min and keep it for 5 h, and finally heat it to 1250 °C and keep it for 20 h. Cool it in the furnace to obtain YCa2SbFe3GaO 12 .
[0049] Example 6
[0050] The difference between this example and Example 1 is only that in step (2), the mixed material is heat-treated in an air atmosphere. First, heat it to 400 °C at a heating rate of 5 °C / min and keep it for 13 h, then heat it to 750 °C and keep it for 12 h. Cool it in the furnace to obtain YCa2SbFe3GaO 12 .
[0051] Example 7
[0052] The difference between this example and Example 1 is only that in step (2), the mixed material is heat-treated in an air atmosphere. Heat it to 1250 °C at a rate of 5 °C / min and keep it for 25 h. Cool it in the furnace to obtain YCa2SbFe3GaO 12 .
[0053] Comparative Example 1
[0054] The preparation method of the magnetic refrigeration material in this comparative example includes the following steps:
[0055] (1) Weigh Y2O3, CaCO3, Sb2O3, and Fe2O3 according to the molar ratio of the chemical formula YCa2SbFe4O 12 and add 1.5 times the sum of the masses of the above components with deionized water as the ball-milling medium. Ball-mill at a rotation speed of 300 rpm / min and a ball-to-material ratio of 1:4 for 8 h. Keep the obtained slurry at 100 °C for 10 h for drying, break it up with a blender and then grind for 0.5 h, and sieve it through a 100-mesh sieve to obtain a mixed material;
[0056] (2) Heat-treat the mixed material in an air atmosphere. First, heat it to 400 °C at a heating rate of 5 °C / min and keep it for 3 h, then heat it to 750 °C and keep it for 2 h, and finally heat it to 1250 °C and keep it for 20 h, and cool it with the furnace to obtain YCa2SbFe4O 12 .
[0057] Comparative Example 2
[0058] The preparation method of the magnetocaloric material in this comparative example includes the following steps:
[0059] (1) Weigh Y2O3, CaCO3, Sb2O3, and Ga2O3 according to the molar ratio of the chemical formula YCa2SbGa4O 12 and add 1.5 times the sum of the masses of the above components with deionized water as the ball-milling medium. Ball-mill at a rotation speed of 300 rpm / min and a ball-to-material ratio of 1:4 for 8 h. Keep the obtained slurry at 100 °C for 10 h for drying, break it up with a blender and then grind for 0.5 h, and sieve it through a 100-mesh sieve to obtain a mixed material;
[0060] (2) Heat-treat the mixed material in an air atmosphere. First, heat it to 400 °C at a heating rate of 5 °C / min and keep it for 3 h, then heat it to 750 °C and keep it for 2 h, and finally heat it to 1250 °C and keep it for 20 h, and cool it with the furnace to obtain YCa2Sb Ga4O 12 .
[0061] As Figure 1 shown, the crystallization peaks in the X-ray diffraction pattern of the magnetocaloric material have a high degree of compatibility with the PDF card. It can be seen that Examples 1-3 respectively obtain pure YCa2SbFe3GaO 12 , YCa2SbFe2Ga2O 12 and YCa2SbFeGa3O 12 ; as Figure 2 shown, there is a small bifurcation phenomenon in the FC and ZFC M-T curves of the magnetocaloric materials obtained in Examples 1-3 at low temperatures, which is caused by the domain wall pinning effect. Above the Curie temperature, the ZFC and FC M-T curves of the compound coincide with each other, indicating that the thermal hysteresis phenomenon in their magnetic phase transition can be ignored, which is beneficial to magnetocaloric applications; as Figure 3As shown, the magnetocaloric materials obtained in Examples 1-3 have a fast change rate of magnetization intensity with magnetic field intensity at low temperature and low magnetic field, showing good magnetocaloric performance. And with the increase of magnetic field intensity, the magnetization intensity of the magnetocaloric material gradually increases and approaches the saturation value at a temperature of 11 K and a magnetic field of 5 T, which is very close to the theoretical value. As Figure 4 shown, the -ΔS m -T curve of the magnetocaloric material obtained in Comparative Example 1 shows a peak near 250 K, and with the increase of ΔH, the magneto-entropy change value also gradually increases. When the applied magnetic field is 5 T, the maximum magneto-entropy change -ΔS m max is 0.83 J K -1 mol -1 . The maximum magneto-entropy changes -ΔS m max of the magnetocaloric materials obtained in Examples 1-3 are 0.48 J K - 1 mol -1 , 0.64 J K -1 mol -1 and 0.135 J K -1 mol -1 , respectively. The phase transition temperature is significantly reduced (consistent with the Figure 2 data), broadening the magnetocaloric temperature range, enabling refrigeration in a lower temperature range and enhancing the refrigeration effect. The heat treatment in Example 4 is to first heat up to 400 °C and hold for 5 h, then heat up to 1250 °C and hold for 20 h. The heat treatment in Example 5 is to first heat up to 750 °C and hold for 5 h, and finally heat up to 1250 °C and hold for 20 h. The heat treatment in Example 6 is to first heat up to 400 °C and hold for 13 h, then heat up to 750 °C and hold for 12 h. The heat treatment in Example 7 is to heat up to 1250 °C and hold for 25 h. Examples 4-7 adopt different heat treatment processes, resulting in a decrease in reaction activity, the presence of certain impurities in the magnetocaloric material, and a deterioration of the magnetocaloric effect. The magnetocaloric material obtained in Comparative Example 2 is YCa2SbGa4O 12 . When it does not contain Fe element, the phase transition temperature is between 18 - 42 K, the magnetocaloric temperature range becomes narrower, and the refrigeration effect becomes worse.
[0062] Finally, it should be noted that the specific embodiments described herein are only illustrative of the spirit of the present invention and not a limitation on the implementation manners of the present invention. Those skilled in the art of the present invention can make various modifications or supplements to the described embodiments or use similar ways to replace them. It is not necessary and impossible to list all the implementation manners here. And these obvious changes or variations derived from the essence of the present invention still fall within the protection scope of the present invention. Interpreting them as any additional limitation is contrary to the spirit of the present invention.
Claims
1. A magnetic refrigeration material, characterized in that, The chemical formula of the magnetocaloric material is YCa2SbFe 4-x Ga x O 12 , where 0 < x ≤ 3.
2. The magnetic refrigeration material according to claim 1, wherein The maximum magnetic entropy change value of the magnetic refrigeration material is 0.1 - 0.7 J K -1 mol -1 .
3. A method for preparing a magnetic refrigeration material as described in claim 1, characterized in that, The preparation method includes ball-milling and uniformly mixing a Y-containing oxide, a Ca-containing oxide, an Sb-containing oxide, a Ga-containing oxide, and an Fe-containing oxide, followed by drying, crushing, sieving, and then gradient sintering.
4. The preparation method according to claim 3, characterized in that, The ball-milling speed is 200 - 500 rpm / min, and the ball-milling time is 6 - 15 h.
5. The preparation method according to claim 3, characterized in that, During ball-milling, deionized water with a mass 0.5 - 3.0 times that of the mixed materials is added as the ball-milling medium.
6. The preparation method according to claim 3, characterized in that, The drying temperature is 80 - 150 °C, and the time is 6 - 20 h.
7. The preparation method according to claim 3, characterized in that When sieving, the mesh number of the sieve is 50 - 200 meshes.
8. The preparation method according to claim 3, characterized in that, Gradient sintering is to hold the temperature at T1 and T2 for 1 - 5 h each in sequence, and then hold the temperature at T3 for 15 - 25 h.
9. The preparation method according to claim 8, characterized in that, T2 - T1 ≥ 100 °C, T3 - T2 ≥ 200 °C.
10. The preparation method according to claim 8, characterized in that, T1 is 350 - 600 °C, T2 is 700 - 800 °C, and T3 is 1000 - 1350 °C.