Magnetic refrigeration material as well as preparation method and application thereof

Abstract

The invention discloses a magnetic refrigeration material as well as a preparation method and application thereof. The chemical composition of the magnetic refrigeration material disclosed by the invention is GdxTbyErzCuaFeb, wherein x, y, z, a and b are atomic percentages; x is equal to 10-60, y is equal to 10-60, z is equal to 10-60, a is equal to 10-60, b is equal to 10-60, and x + y + z + a + b is equal to 100. The magnetic refrigeration material is high in Curie temperature, wide in phase change temperature span, good in relative refrigeration capacity and excellent in refrigeration capacity.

Description

Technical Field

[0001] The invention relates to a magnetic refrigeration material and a preparation method and application thereof. Background Art

[0002] With the advancement of society, refrigeration technology is playing an increasingly important role. Refrigeration technology plays a crucial role in various fields, including household refrigeration, commercial refrigeration, industrial refrigeration, and medical refrigeration. Currently, gas compression refrigeration is the most common refrigeration technology. Gas compression refrigeration often uses hydrofluorocarbons (HFCs) as refrigerants. HFCs are greenhouse gases with a global warming potential thousands of times greater than carbon dioxide. Gas compression refrigeration has low energy efficiency, only 5-10% of the Carnot cycle. The widespread use of gas compression refrigeration causes environmental damage. For example, emissions of the commonly used hydrofluorocarbon refrigerant Freon (CFC) can deplete the atmospheric ozone layer and contribute to the greenhouse effect. Many countries and organizations have enacted relevant laws and regulations to control HFC refrigerant emissions. Therefore, the development of new refrigeration technologies is urgent.

[0003] Magnetic refrigeration technology, a new, environmentally friendly, energy-efficient, and reliable refrigeration technology, has garnered increasing attention. Magnetic refrigeration technology is based on the magnetocaloric effect of magnetic materials, utilizing thermodynamic cycles to achieve refrigeration. The magnetocaloric effect refers to the heat absorption and release exhibited by magnetic refrigeration materials in a changing magnetic field. The magnitude of the magnetocaloric effect largely determines the cooling capacity and efficiency of the magnetic refrigeration material. The development of magnetic refrigeration materials with a large magnetocaloric effect is crucial for the application of magnetic refrigeration technology.

[0004] High-entropy alloys, a novel alloy design concept, exhibit high entropy effects, lattice distortion effects, slow diffusion effects, and a "cocktail" effect. Their emergence has driven the development of magnetic refrigeration technology. Compared to crystalline structures, amorphous alloys, due to their disordered structure, are secondary magnetic phase transition materials, offering advantages such as low magnetic and thermal hysteresis and a wide phase transition temperature range. Therefore, developing high-entropy amorphous alloys with a wide refrigeration temperature range has become a new research direction in magnetic refrigeration.

[0005] CN105296893A discloses a high entropy amorphous alloy. The chemical formula of the high entropy amorphous alloy is A 20 B 20 C 20 T 20 Al 20 , where A, B, and C are different and are each selected from a rare earth element selected from Gd, Tb, Dy, Ho, Er, and Tm; and T is selected from a rare earth element selected from Co, Ni, and Fe. This high-entropy amorphous alloy exhibits a large magnetocaloric effect over a wide temperature range and good stability. However, its Curie temperature and phase transition temperature span are low, limiting its operating temperature range and resulting in unsatisfactory cooling capacity.

[0006] CN105734311A discloses a magnetic refrigeration Ho x Tb y M z It is a high entropy alloy. The chemical formula of high entropy alloy is Gd 20 Dy 20 Er 20 Ho 20 Tb 20 The high entropy alloy has a close-packed hexagonal structure from 20K to room temperature, showing strong structural stability. The phase transition critical point of the high entropy alloy is 186K, and the maximum isothermal magnetic entropy change at 0-5T is 8.6J·kg -1 ·K -1 , cooling capacity is 627J·kg -1 , showing good magnetocaloric effect. However, the Curie temperature and phase transition temperature span of this high-entropy alloy are narrow and low, the operating temperature range is limited, and the cooling capacity is not ideal.

[0007] CN113929446A discloses a rare earth perovskite high-entropy oxide. The general chemical formula of the rare earth perovskite high-entropy oxide is RETMO3, where RE is two or three of the rare earth elements Gd, Tb, Dy, Ho, and Er, with the molar content of each element ranging from 25% to 55% and the total content being 100%, and TM is three or four of the rare earth elements Mn, Fe, Co, Cu, Ni, Zn, Al, and Cr, with the molar content of each element ranging from 20% to 35% and the total content being 100%. The rare earth perovskite high-entropy oxide has a single-phase orthorhombic perovskite structure and belongs to the Pnma space group. Under an external field variation of 0 to 5T, the isothermal magnetic entropy change is 13.6 to 18.2 J·kg -1 ·K -1 However, the rare earth perovskite high entropy oxide is a high entropy ceramic material with low mechanical strength, high density and high characteristic impedance, which leads to reduced efficiency of magnetic refrigeration and easy fatigue failure.

[0008] CN118668115A discloses a rare earth-based high entropy amorphous alloy. The general chemical formula of the rare earth-based high entropy amorphous alloy is Gd 20 Tb 20 Er 20 Al 20 M 20 , where the M element is one of Fe and Co. This rare earth-based high-entropy amorphous alloy, as a low-temperature magnetic refrigeration material, exhibits a pronounced table-shaped magnetic entropy change and a good magnetocaloric effect. However, this rare earth-based high-entropy amorphous alloy has a low Curie temperature, a limited operating temperature range, and unsatisfactory refrigeration performance. Summary of the Invention

[0009] In view of this, one object of the present invention is to provide a magnetic refrigeration material having a high Curie temperature, a wide phase transition temperature span, and excellent refrigeration capacity. Another object of the present invention is to provide a method for preparing the magnetic refrigeration material. A further object of the present invention is to provide a use of the magnetic refrigeration material in refrigeration.

[0010] The present invention adopts the following technical solutions to achieve the above-mentioned purpose.

[0011] On the one hand, the present invention provides a magnetic refrigeration material, the chemical composition of which is Gd x Tb y Er z Cu a Fe b ;

[0012] Wherein, x, y, z, a, and b are atomic percentages;

[0013] x=10~60, y=10~60, z=10~60, a=10~60, b=10~60, x+y+z+a+b=100.

[0014] According to the magnetic refrigeration material of the present invention, preferably, x=15-40, y=15-40, z=15-40, a=15-40, and b=15-40.

[0015] According to the magnetic refrigeration material of the present invention, preferably, x is an integer between 15 and 40, y is an integer between 15 and 40, z is an integer between 15 and 40, a is an integer between 15 and 40, and b is an integer between 15 and 40.

[0016] According to the magnetic refrigeration material of the present invention, preferably, x:y:z:a:b=1:1:1:1:1.

[0017] On the other hand, the present invention also provides a method for preparing the above-mentioned magnetic refrigeration material, comprising the following steps:

[0018] 1) Providing alloy raw materials according to the atomic ratio of Gd, Tb, Er, Cu and Fe;

[0019] 2) Under protective gas and 0.01-0.1 MPa conditions, the alloy raw materials are smelted at 1500-2500 K until melted, then kept warm and cooled to obtain an alloy ingot;

[0020] 3) crushing the alloy ingot to obtain alloy particles;

[0021] 4) Under protective gas and 0.01-0.1 MPa conditions, the alloy particles are smelted at 1500-2500 K until they are melted to obtain alloy liquid; the alloy liquid is spun to obtain a magnetic refrigeration material.

[0022] According to the preparation method of the present invention, preferably, in step 2), the smelting time is 2 to 10 minutes.

[0023] According to the preparation method of the present invention, preferably, in step 2), the insulation time is 1 to 10 minutes.

[0024] According to the preparation method of the present invention, preferably, in step 4), the smelting time is 1 to 5 minutes.

[0025] In another aspect, the present invention further provides use of the magnetic refrigeration in refrigeration equipment.

[0026] According to the use of the present invention, preferably, the Curie temperature of the magnetic refrigeration material is above 110K; the phase transition temperature span of the magnetic refrigeration material under the change of magnetic induction intensity of 0 to 5T is above 120K, and the relative cooling capacity is 615J·kg -1 The magnetic refrigeration material has a phase change temperature span of more than 130K under the change of magnetic induction intensity of 0~7T, and a relative cooling capacity of 880J·kg -1 above.

[0027] The magnetic refrigeration material of the present invention has a high Curie temperature, a wide phase change temperature span, a good relative refrigeration capacity, and an excellent refrigeration capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the XRD pattern of Experimental Example 1 of the present invention.

[0029] Figure 2 This is a TEM image of Experimental Example 1 of the present invention; wherein, 1 and 2 in the right image are filtered images of the areas marked by 1 and 2 in the left image, respectively.

[0030] Figure 3 This is the energy spectrum analysis diagram of Experimental Example 1 of the present invention.

[0031] Figure 4 is the magnetocaloric curve of Experimental Example 2 of the present invention; wherein, Fe ZFC is the zero field cooling curve of iron element, Fe FC is the field cooling curve of iron element, T f Freezing temperature.

[0032] Figure 5 This is the isothermal magnetization curve of Experimental Example 2 of the present invention.

[0033] Figure 6 This is the Arrott curve diagram of Experimental Example 2 of the present invention.

[0034] Figure 7 This is a graph showing the isothermal magnetic entropy change versus temperature in Experimental Example 2 of the present invention.

[0035] Figure 8 This is a graph showing the relationship between the phase change temperature span and the applied magnetic field in Experimental Example 2 of the present invention. DETAILED DESCRIPTION

[0036] The present invention will be further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0037] The "Curie temperature" mentioned in the present invention refers to the temperature at which the spontaneous magnetization intensity of a magnetic material drops to zero, usually denoted as T c , unit is K.

[0038] The "phase transition temperature span" mentioned in the present invention refers to the temperature change range of the magnetic material during the phase transition process, usually recorded as ΔT FWHM , unit is K.

[0039] The "isothermal magnetic entropy change" mentioned in the present invention refers to the change in magnetic entropy of a magnetic material caused by a change in an external magnetic field under isothermal conditions, usually recorded as ΔS M , unit is J·kg -1 ·K -1 .

[0040] The "relative cooling capacity" mentioned in the present invention refers to the integral value of the magnetic entropy change per unit mass and the temperature during the isothermal magnetization process of the material under a specific magnetic field change, usually recorded as RCP, with the unit of J·kg -1 .

[0041] <Magnetic Refrigeration Materials>

[0042] The chemical composition of the magnetic refrigeration material of the present invention is Gd x Tb y Er z Cu a Fe b ; Wherein, x, y, z, a, and b are atomic percentages x+y+z+a+b=100.

[0043] According to one embodiment of the present invention, x may be an integer between 10 and 60, preferably between 15 and 40, and more preferably between 15 and 40.

[0044] According to one embodiment of the present invention, y may be an integer between 10 and 60, preferably between 15 and 40, and more preferably between 15 and 40.

[0045] According to one embodiment of the present invention, z may be an integer between 10 and 60, preferably between 1 and 40, and more preferably between 15 and 40.

[0046] According to one embodiment of the present invention, a may be an integer between 10 and 60, preferably between 15 and 40, and more preferably between 15 and 40.

[0047] According to one embodiment of the present invention, b may be an integer between 10 and 60, preferably between 15 and 40, and more preferably between 15 and 40.

[0048] According to a preferred embodiment of the present invention, x:y:z:a:b=1:1:1:1:1

[0049] By controlling the element ratio within the above range, it can be ensured that the magnetic refrigeration material is a high-entropy amorphous alloy and a secondary magnetic phase change material, so that it has the characteristics of low thermal hysteresis and low magnetic hysteresis, which is conducive to the magnetic refrigeration material obtaining a higher Curie temperature, a faster phase change temperature span and better relative refrigeration capacity.

[0050] In the magnetic refrigeration material of the present invention, the elements Gd (gadolinium), Tb (terbium), and Er (erbium) have a special 4f electron layer structure and a large atomic magnetic moment. Under the action of an external magnetic field, the atomic magnetic moment will be deflected, thereby producing a change in order, so that the magnetic refrigeration material has a large magnetic entropy change, resulting in an endothermic phenomenon. The elements Cu (copper) and Fe (iron) have a large atomic radius difference from the elements Gd, Tb, and Er. The introduction of Cu and Fe elements improves the amorphous forming ability. The introduction of these five elements can overcome the shortcomings of single elements such as easy oxidation and poor stability. At the same time, the high entropy alloying of the magnetic refrigeration material of the present invention can expand the refrigeration temperature range of the magnetic refrigeration material and improve the refrigeration capacity of the magnetic refrigeration material.

[0051] <Preparation method>

[0052] The method for preparing the magnetic refrigeration material includes a step of providing raw materials, a step of smelting, a step of crushing, and a step of stripping, which will be described in detail below.

[0053] Raw material supply steps

[0054] Alloy raw materials are provided according to the atomic ratio of Gd, Tb, Er, Cu and Fe.

[0055] According to one embodiment of the present invention, the alloy raw materials can be pure elements of Gd, Tb, Er, Cu and Fe, or intermediate alloys of Gd, Tb, Er, Cu and Fe, or a combination of pure elements and intermediate alloys of each element, as long as the elemental composition of the magnetic refrigeration material is met.

[0056] The pure elements or master alloys used in the present invention can be commercially available or prepared by existing methods, and are not particularly limited. The purity of the pure elements or master alloys of the present invention is at least industrial purity (99.9 wt%).

[0057] Melting steps

[0058] Under protective gas and 0.01-0.1Mpa conditions, the alloy raw materials are smelted until melted, then kept warm and cooled to obtain alloy ingots.

[0059] According to one embodiment of the present invention, the melting temperature may be 1500-2500 K (Kelvin), preferably 1750-2150 K, more preferably 1800-2000 K. The melting time may be 2-10 min, preferably 2.5-8.5 min, more preferably 3-7 min.

[0060] According to one embodiment of the present invention, the alloy ingot is re-smelted 1 to 4 times, preferably 2 to 4 times, more preferably 2 to 3 times. Reasonable number of smelting times is beneficial to the uniformity of the chemical composition of the alloy ingot.

[0061] According to one embodiment of the present invention, stirring may also be performed during the smelting process.

[0062] According to one embodiment of the present invention, the pressure during smelting may be 0.01 to 0.1 MPa, preferably 0.02 to 0.09 MPa, and more preferably 0.03 to 0.08 MPa.

[0063] The protective gas involved in the present invention can be selected from at least one of nitrogen and inert gases, and the inert gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe); preferably, the protective gas is selected from at least one of nitrogen, helium, neon, and argon; more preferably, the protective gas is selected from at least one of nitrogen, helium, and argon.

[0064] In the present invention, smelting can be carried out in any type of smelting equipment known in the art, without particular limitation herein, for example, a vacuum arc furnace.

[0065] According to a preferred embodiment of the present invention, the process may further include evacuating the smelting equipment and cleaning the smelting equipment with a protective gas before smelting.

[0066] In the present invention, the smelting equipment can be evacuated to a vacuum degree of 10 before smelting. -3 Pa or less, preferably 10 -5 ~10 -3 Pa, more preferably 10 -4 ~10 -3Then, the smelting equipment is cleaned with protective gas for more than 3 times, preferably 3 to 6 times, more preferably 3 to 5 times. Then, the protective gas is filled to the pressure required for smelting.

[0067] According to one embodiment of the present invention, the insulation time may be 1 to 10 minutes, preferably 2 to 8 minutes, and more preferably 3 to 7 minutes.

[0068] In the present invention, cooling can be achieved by any type of cooling method or cooling equipment known in the art, and is not particularly limited herein. For example, it can be natural cooling or air cooling.

[0069] Reasonable melting conditions can ensure the uniformity of the alloy composition, which is conducive to the preparation of magnetic refrigeration materials that are high-entropy amorphous alloys and secondary magnetic phase change materials. It is also more conducive to the preparation of magnetic refrigeration materials that have higher Curie temperature, faster phase change temperature span and better relative refrigeration capacity.

[0070] Crushing steps

[0071] The alloy ingot is crushed to obtain alloy particles.

[0072] According to one embodiment of the present invention, the particle size of the alloy particles may be 2 to 12 mm, preferably 3 to 11 mm, and more preferably 5 to 10 mm.

[0073] The crushing of the present invention can be achieved using any crushing equipment known in the art, which will not be described in detail here.

[0074] The present invention may further include the steps of grinding and cleaning the alloy ingot before crushing. The grinding and cleaning of the alloy ingot can be achieved using any grinding and cleaning methods and equipment known in the art, which will not be described in detail here.

[0075] Belt swinging steps

[0076] Under the conditions of protective gas and 0.01-0.1Mpa, the alloy particles are smelted until they are melted to obtain alloy liquid; the alloy liquid is spun to obtain a magnetic refrigeration material.

[0077] According to one embodiment of the present invention, the melting temperature may be 1500-2500 K, preferably 1600-2300 K, more preferably 1800-2000 K. The melting time may be 1-5 min, preferably 2-5 min, more preferably 2-3 min.

[0078] According to one embodiment of the present invention, the pressure during smelting may be 0.01 to 0.1 MPa, preferably 0.02 to 0.09 MPa, and more preferably 0.03 to 0.08 MPa.

[0079] The protective gas involved in the present invention can be selected from at least one of nitrogen and inert gases, and the inert gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe); preferably, the protective gas is selected from at least one of nitrogen, helium, neon, and argon; more preferably, the protective gas is selected from at least one of nitrogen, helium, and argon.

[0080] In the present invention, the smelting can be carried out in any type of belt-spinning equipment known in the art, without particular limitation. For example, it can be a vacuum belt-spinning furnace. The belt-spinning equipment all has its own copper rollers.

[0081] According to a preferred embodiment of the present invention, the method may further include the steps of evacuating the belt-spinning device and cleaning the belt-spinning device with a protective gas before smelting.

[0082] In the present invention, the belt-spinning equipment can be evacuated to a vacuum degree of 10 before smelting. -3 Pa or less, preferably 10 -5 ~10 -3 Pa, more preferably 10 -4 ~10 -3 Then, the stripping equipment is cleaned with protective gas for more than 3 times, preferably 3 to 6 times, more preferably 3 to 5 times. Then, the protective gas is filled to the pressure required for smelting.

[0083] According to one embodiment of the present invention, the distance between the ejection port of the belt-spinning device and the copper roller may be 0.5 to 2 m, preferably 0.8 to 2 m, and more preferably 0.8 to 1.5 m.

[0084] According to one embodiment of the present invention, the spray pressure of the belt-swinging device may be 0.2 to 1 MPa, preferably 0.25 to 0.85 MPa, and more preferably 0.3 to 0.6 MPa.

[0085] According to one embodiment of the present invention, during the belt spinning, the rotation speed of the copper roller may be 2000-5000 rpm, preferably 2500-4500 rpm, more preferably 2800-4000 rpm. The surface temperature of the copper roller may be 200-500K, preferably 200-400K, more preferably 250-350K.

[0086] In the present invention, the width of the strip of magnetic refrigeration material prepared can be 1-5 mm, preferably 1.5-4.5 mm, more preferably 2-4 mm. The thickness of the strip can be 5-50 μm, preferably 10-45 μm, more preferably 15-40 μm.

[0087] Reasonable stripping conditions are conducive to the preparation of magnetic refrigeration materials that are high-entropy amorphous alloys and secondary magnetic phase change materials, and are more conducive to the magnetic refrigeration materials obtaining higher Curie temperature, faster phase change temperature span and better relative refrigeration capacity.

[0088] <Purpose>

[0089] The present invention also provides use of the magnetic refrigeration material in refrigeration equipment.

[0090] In the present invention, the refrigeration equipment can be any refrigeration equipment known in the art, and is not particularly limited here. For example, it can be an air conditioner, a refrigerator, an ice maker, an industrial chiller, a freeze dryer, etc.

[0091] In the present invention, the Curie temperature of the magnetic refrigeration material may be above 110K, preferably above 112K, and more preferably above 113K.

[0092] The phase transition temperature span of the magnetic refrigeration material under a magnetic field change of 0 to 5 T can be above 120 K, preferably above 121 K, and more preferably above 122 K. The relative cooling capacity of the magnetic refrigeration material under a magnetic field change of 0 to 5 T can be 615 J·kg -1 Above, preferably 618 J·kg -1 More than 620 J·kg -1 above.

[0093] The phase transition temperature span of the magnetic refrigeration material under a magnetic field change of 0 to 7 T is above 130 K, preferably above 132 K, and more preferably above 133 K. The relative cooling capacity of the magnetic refrigeration material under a magnetic field change of 0 to 7 T can be 880 J·kg -1 Above, preferably 890 J·kg -1 More than 900 J·kg -1 above.

[0094] The magnetic refrigeration material of the present invention has a high Curie temperature, a wide phase change temperature span, and a good relative refrigeration capacity, and is particularly suitable as a refrigeration material in low-temperature refrigeration equipment.

[0095] <Test method>

[0096] XRD measurement: A Bruker D8 Focus X-ray diffractometer produced by Bruker, Germany, was used for detection; Cu Kα rays were used as the diffraction source, and the scanning rate was 2° / min.

[0097] TEM measurement: A JEM-2010 transmission electron microscope produced by JEOL Ltd. (JEOL) was used for detection.

[0098] Magnetization intensity: The material is tested using a comprehensive physical property measuring instrument (PPMS) produced by Quantum Design, USA.

[0099] <Ingredients>

[0100] Unless otherwise specified, the raw materials in the following examples are all commercially available products.

[0101] Example 1

[0102] Preparation of magnetic refrigeration material Gd 20 Tb 20 Er 20 Cu 20 Fe 20 , the specific method is as follows:

[0103] Using pure metals of Gd (gadolinium), Tb (terbium), Er (erbium), Cu (copper), and Fe (iron) as raw materials, according to Gd 20 Tb 20 Er 20 Cu 20 Fe 20 The atomic number provides alloy raw materials.

[0104] Place the alloy raw materials in a vacuum arc furnace and evacuate the vacuum arc furnace to a vacuum degree of 10 -3 Pa. Next, the furnace chamber was purged three times with argon and then filled with argon to a pressure of 0.05 MPa. The alloy raw materials were melted at 1900K for 5 minutes to completely melt them. Next, the mixture was held at 1900K for 5 minutes and then naturally cooled to obtain an alloy ingot. The alloy ingot was remelted two more times (i.e., three times of co-melting) to ensure uniformity of the alloy composition.

[0105] The alloy ingot after smelting three times was polished and cleaned with alcohol, and then the alloy ingot was crushed into alloy particles with a particle size of 10 mm using a crusher.

[0106] The alloy particles were placed in the quartz tube of the vacuum belt furnace, and the distance between the injection port of the quartz tube and the copper roller was set to 1 mm, and the injection pressure was set to 0.5 MPa. The furnace chamber of the vacuum belt furnace was evacuated to a vacuum degree of 10 -3 The furnace chamber was then purged three times with argon and then filled with argon to a pressure of 0.05 MPa. The alloy particles were melted at 1900 K for 2 minutes, completely dissolving into a molten alloy. Next, with the copper roller surface temperature at 300 K and the roller rotating at 3000 rpm, the molten alloy was sprayed onto the surface of the copper roller, forming a 2 mm wide and 20 μm thick strip, thus producing the magnetic refrigeration material.

[0107] Comparative Example 1

[0108] According to the example of CN118668115A, Er was prepared 20 Dy 20 Co 20 Al 20 Tb 20 Experiments were conducted and the test results are shown in Table 1.

[0109] Comparative Example 2

[0110] Gd was prepared according to Example 2 of CN105296893A 20 Tb 20 Dy 20 Ni 20 Al 20 Experiments were conducted and the test results are shown in Table 1.

[0111] Experimental Example 1

[0112] A 4 cm long piece of the magnetic refrigeration material prepared in Example 1 was taken as a sample, and the structure of the sample was tested by XRD. The test results are as follows: Figure 1 As shown. Figure 1 It can be seen that the sample has an amorphous structure.

[0113] The microstructure of the sample was examined by TEM and the distribution of the constituent elements was measured using an energy spectrum analyzer mounted on a transmission electron microscope. The results are as follows: Figure 2 and Figure 3 As shown. Figure 2 It can be seen that the atoms of the sample are arranged in a long-range disordered manner, which indicates that the sample has an amorphous structure. Figure 3 It can be seen that the constituent elements of the sample are evenly distributed, indicating that there is no element segregation problem in the sample.

[0114] Experimental Example 2

[0115] The magnetic refrigeration material prepared in Example 1 with a length of 4 cm was cut as a sample, and the magnetization intensity of the sample at different temperatures was measured and a magnetocaloric curve was prepared. The results are shown in FIG. Figure 4 By taking the derivative of the magnetocaloric curve, the temperature corresponding to the minimum value of the derivative curve is 113K, which indicates that the Curie temperature (T c ) is 113K, which represents the optimal working temperature of the sample.

[0116] The magnetization intensity of the sample near the Curie temperature was measured and a series of isothermal magnetization curves and Arrott curves were prepared. The results are shown in the figure. Figure 5 and Figure 6 As shown. Figure 5It can be seen that when the sample is below the Curie temperature, the magnetization intensity is sensitive to the change of the magnetic induction intensity of the applied magnetic field and quickly reaches saturation, showing a ferromagnetic state. When the sample is above the Curie temperature, the magnetization intensity changes linearly with the change of the magnetic induction intensity of the applied magnetic field, showing a paramagnetic state. The sample undergoes a transition from ferromagnetic state to paramagnetic state at the Curie temperature. Figure 6 It can be seen that there is no point with a slope less than or equal to 0 on all Arrott curves of the sample, indicating that the sample is a secondary magnetic phase change material.

[0117] The isothermal magnetic entropy change of the alloy can be calculated by combining the isothermal magnetization curve with the Maxwell relationship below.

[0118] During the isothermal magnetization process, the isothermal magnetic entropy change ΔS of the alloy M It can be calculated using Maxwell's formula:

[0119]

[0120] Wherein, T represents temperature, M represents magnetization intensity, H represents magnetic field intensity, and H1 and H2 represent the minimum and maximum magnetic field intensity of the applied magnetic field, respectively.

[0121] When magnetic fields of different magnetic induction intensities are applied, the absolute value of the isothermal magnetic entropy change of the sample (|ΔS M |)The curve of change with temperature is as follows Figure 7 The results show that the maximum isothermal magnetic entropy change ΔS of the sample under the change of magnetic induction intensity from 0 to 5T is M max The absolute value (|ΔS M max |) is 5.1 J·kg -1 ·K -1 , the sample has a large magnetic entropy change in a large temperature range. The phase transition temperature span of the sample (ΔT FWHM ) and the applied magnetic field. Figure 8 As shown. Figure 8 It can be seen that the phase transition temperature span of the sample under the change of magnetic induction intensity (μ0H) from 0 to 5T is 122K, and the phase transition temperature span of the sample under the change of magnetic induction intensity (μ0H) from 0 to 7T is 134K, indicating that the sample has a wide phase transition temperature span.

[0122] Experimental Example 3

[0123] According to the phase change temperature span (ΔT FWHM ) and the maximum isothermal magnetic entropy change ΔS M max The absolute value of the relative cooling capacity (RCP) is calculated using the following formula:

[0124] RCP=ΔTFWHM ×|ΔS M max |.

[0125] Determine the Curie temperature (T c ), phase change temperature span (ΔT FWHM ) and relative cooling capacity (RCP), the results are shown in Table 1 below.

[0126] Table 1

[0127]

[0128] As can be seen from Table 1, the magnetic refrigeration material of the present invention has a high Curie temperature, a wide phase transition temperature span, and a good relative refrigeration capacity, and is very suitable as a low-temperature refrigeration material.

[0129] The present invention is not limited to the above-mentioned embodiments. Any modification, improvement, or substitution that can be conceived by those skilled in the art without departing from the essential content of the present invention shall fall within the scope of the present invention.

Claims

1. A magnetic refrigeration material, characterized in that: Its chemical composition is Gd x Tb y Er z Cu a Fe b ; Wherein, x, y, z, a, and b are atomic percentages; x=10~60, y=10~60, z=10~60, a=10~60, b=10~60, x+y+z+a+b=100.

2. The magnetic refrigeration material according to claim 1, characterized in that x=15~40, y=15~40, z=15~40, a=15~40, b=15~40.

3. The magnetic refrigeration material according to claim 2, characterized in that x is an integer between 15 and 40, y is an integer between 15 and 40, z is an integer between 15 and 40, a is an integer between 15 and 40, and b is an integer between 15 and 40.

4. The magnetic refrigeration material according to claim 3, characterized in that x:y:z:a:b=1:1:1:1:

1.

5. A method for preparing the magnetic refrigeration material according to any one of claims 1 to 4, comprising the following steps: 1) Providing alloy raw materials according to the atomic percentage of Gd, Tb, Er, Cu and Fe; 2) Under protective gas and 0.01-0.1 MPa conditions, the alloy raw materials are smelted at 1500-2500 K until melted, then kept warm and cooled to obtain an alloy ingot; 3) crushing the alloy ingot to obtain alloy particles; 4) Under protective gas and 0.01-0.1 MPa conditions, the alloy particles are smelted at 1500-2500 K until they are melted to obtain alloy liquid; the alloy liquid is spun to obtain a magnetic refrigeration material.

6. The preparation method according to claim 5, characterized in that In step 2), the smelting time is 2 to 10 minutes.

7. The preparation method according to claim 5, characterized in that In step 2), the insulation time is 1 to 10 minutes.

8. The preparation method according to claim 5, characterized in that In step 4), the smelting time is 1 to 5 minutes.

9. Use of the magnetic refrigeration material according to any one of claims 1 to 4 in refrigeration equipment.

10. The use according to claim 9, characterized in that The Curie temperature of the magnetic refrigeration material is above 110K; the phase transition temperature span of the magnetic refrigeration material under the change of magnetic induction intensity from 0 to 5T is above 120K, and the relative cooling capacity is 615J·kg -1 The magnetic refrigeration material has a phase change temperature span of more than 130K under the change of magnetic induction intensity of 0~7T, and a relative cooling capacity of 880J·kg -1 above.

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