Y-type hexaferrite material with dual magnetic heat effect and preparation method and application thereof

Abstract

The application discloses Y-type hexagonal ferrite material with dual magnetic heat effect and a preparation method and application thereof, belongs to the technical field of ferrite ceramic materials, and is denoted as Sr2Zn 2‑x Ni x Fe 12 O 22 (x=0.0, 0.8 or 2.0), and can be used as a heat sink composite material in the temperature range in which the inverse magnetic heat effect exists. For the Sr2Zn2Fe 12 O 22 material, a platform-shaped conventional magnetic heat effect exists near room temperature, is suitable for Ericsson magnetic refrigeration cycle, the magnetic entropy change and the relative refrigeration power gradually increase with the increase of the Ni ion doping amount, and reach the maximum when the doping amount is 0.8; under the condition that the magnetic field changes by 0-90kOe, the magnetic entropy change reaches 3.16J / kg K at 4K, -1.02J / kg K at 16K and 1.33J / kg K at 354K, and the corresponding relative refrigeration power is 358.68J / kg.

Description

Technical Field

[0001] This invention belongs to the field of ferrite ceramic materials technology, and particularly relates to a Y-type hexagonal ferrite material with dual magnetocaloric effect, its preparation method and application. Background Technology

[0002] Refrigeration and cryogenic technology are relevant to many important fields, such as cryogenic engineering, petrochemicals, high-energy physics, the power industry, precision instruments, superconducting technology, aerospace, and medical devices. Refrigeration technology is also ubiquitous, from small household air conditioners, food refrigerators, and car air conditioners used in daily life, to large-scale technologies such as gas liquefaction, central air conditioning, and aerospace technology, all of which are closely related to people's lives.

[0003] Research on refrigeration technology relies heavily on two key factors: refrigerants and refrigeration machines, with refrigerant research being the most fundamental and crucial element. Currently, refrigeration technologies predominantly employ traditional gas compression and expansion techniques. The refrigerants used in this technology (Freon) severely damage the Earth's ozone layer, contributing significantly to the greenhouse effect. Furthermore, traditional refrigeration technologies have low efficiency, with energy utilization rates of only 15-25%. Therefore, in addition to further improving gas compression and expansion refrigeration technologies, scientists and engineers are exploring new refrigeration technologies. Magnetic refrigeration technology, developed based on the magnetocaloric effect of magnetic materials, offers three significant advantages over conventional gas compression refrigeration: it is environmentally friendly, highly efficient and energy-saving, and stable and reliable. Magnetic refrigeration technology is currently one of the most competitive and promising refrigeration technologies, attracting widespread attention both domestically and internationally. Exploring and optimizing magnetocaloric materials, researching the magnetocaloric effect, and developing magnetic refrigeration technology have become focal points for governments and scientists worldwide, and are also a vital mission for researchers. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a Y-type hexagonal ferrite material with a dual magnetocaloric effect, its preparation method, and its application. The Y-type hexagonal ferrite material exhibits both inverse magnetocaloric and conventional magnetocaloric effects and can be used to prepare refrigeration materials.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A Y-type hexagonal ferrite material with a dual magnetocaloric effect, chemically formulated as: Sr₂Zn 2-x Ni x Fe 12 O 22 x = 0.0 to 2.0.

[0007] Preferably, the chemical formula of the Y-type hexagonal ferrite material with dual magnetocaloric effect is: Sr₂Zn 2-x Ni x Fe 12 O 22 x = 0.0, 0.8, or 2.0, that is, the chemical formula of the Y-type hexagonal ferrite material is Sr2Zn2Fe 12 O 22 Sr2Zn 1.2 Ni 0.8 Fe 12 O 22 or Sr2Ni2Fe 12 O 22 .

[0008] More preferably, the chemical formula of the Y-type hexagonal ferrite material with dual magnetocaloric effect is: Sr₂Zn 2-x Ni x Fe 12 O 22 x = 0.8 or 2.0, with the optimal value being x = 0.8 (i.e., the chemical formula for the Y-type hexagonal ferrite material is: Sr2Zn). 1.2 Ni 0.8 Fe 12 O 22 ).

[0009] This invention relates to a Y-type hexagonal ferrite material (Sr2Zn) exhibiting a dual magnetocaloric effect. 2-x Ni x Fe 12 O 22 The three products (x = 0.0, 0.8, or 2.0) all exhibit both contramagnetic-cryogenic and conventional magnetocryogenic effects within the temperature range of 2–400 K. Within the temperature range where the contramagnetic-cryogenic effect exists, they can be used as heat sink composite materials. With the doping of Ni ions, the saturation magnetization of the material initially increases and then decreases within the temperature range of 2–400 K. This increase and decrease in saturation magnetization is because Ni is a magnetic ion, while Zn is a non-magnetic ion. Replacing Zn with Ni increases the total magnetic moment, leading to an increase in saturation magnetization. Furthermore, the superexchange interaction between Fe ions changes with the ratio of Ni to Zn; initially, the superexchange interaction strengthens, but weakens as the amount of Ni increases. Ion occupancy also affects the saturation magnetization; the different occupancy tendencies of Zn and Ni ions in tetrahedra and octahedra result in the initial increase followed by a decrease in saturation magnetization.

[0010] For the expression Sr2Zn2Fe 12 O 22The material exhibits inverse magnetocaloric effect in the temperature range of 4K–24K. Under magnetic field variations of 0–90 kOe, the maximum magnetic entropy change is -0.45 J / kg K at 16K. The conventional magnetocaloric effect occurs in the temperature regions <4K and >24K. Interestingly, the magnetic entropy change <4K ​​generally decreases with increasing magnetic field, reaching 0.0232 J / kg K in the 0–10 kOe range and 0.0053 J / kg K in the 0–90 kOe range. Near room temperature, the magnetic entropy change increases with increasing magnetic field and exhibits a plateau-like curve with temperature. This effectively eliminates the influence of lattice entropy on the total entropy change, thus allowing the material to be used in Eriksen magnetocooling cycles near room temperature. The maximum magnetic entropy change is 0.68 J / kg K at 286K, corresponding to a relative cooling power of 223.23 J / kg.

[0011] With increasing Ni doping concentration, both the diamagnetic and conventional magnetocaloric effects of the material are significantly enhanced, with the conventional magnetocaloric effect showing a more pronounced increase at low temperatures. Furthermore, the shape of the magnetic entropy change curve as a function of temperature near room temperature changes from a plateau to a sharp peak. For the expression Sr₂Zn… 1.2 Ni 0.8 Fe 12 O 22 The material exhibits the strongest magnetocaloric effect, manifested in the increase in magnetic entropy change. The maximum magnetic entropy change is 3.16 J / kg K at 4 K, -1.02 J / kg K at 16 K, and 1.33 J / kg K at 354 K. The corresponding relative cooling power is 358.68 J / kg, and the magnetic field change ranges from 0 to 90 kOe.

[0012] For the expression Sr2Ni2Fe 12 O 22 The material, whose magnetocaloric effect is expressed as Sr₂Zn, has a similar expression. 1.2 Ni 0.8 Fe 12 O 22 The material strength is somewhat reduced, but still stronger than the parent material, and the temperature range of the diamagnetic thermal effect is significantly increased (12K~65K). The maximum magnetic entropy change is 1.54J / kg K (4K), -0.50J / kg K (16K), 0.81J / kg K (366K), the relative cooling power is 106.19J / kg, and the magnetic field change is 0~90kOe.

[0013] The present invention also provides a method for preparing the Y-type hexagonal ferrite material with dual magnetocaloric effect, comprising the following steps:

[0014] SrCO3, ZnO, NiO, and Fe2O3 were weighed according to the material composition, mixed, ground, and calcined three times to obtain the Y-type hexagonal ferrite material (Sr2ZnO) with binary magnetocaloric effect.2-x Ni x Fe 12 O 22 (x = 0.0 to 2.0).

[0015] Preferably, when x = 0.0, the molar ratio of SrCO3, ZnO and Fe2O3 is 1:1:6;

[0016] When x = 0.8, the molar ratio of SrCO3, ZnO, NiO and Fe2O3 is 5:3:2:30;

[0017] When x = 2.0, the molar ratio of SrCO3, NiO and Fe2O3 is 1:1:6.

[0018] Preferably, the three calcinations are:

[0019] The first calcination involves heating the product from room temperature to 900–1000°C, maintaining the temperature for 600 minutes, and then allowing it to cool naturally to room temperature before grinding the product. The second calcination involves heating the product from the first calcination to 1000–1100°C, maintaining the temperature for 1200 minutes, and then allowing it to cool naturally to room temperature before grinding the product. The third calcination involves heating the product from the second calcination to 1150°C, maintaining the temperature for 1200 minutes, and then allowing it to cool naturally to room temperature before grinding the product, thus obtaining the Y-type hexagonal ferrite material with dual magnetocaloric effect.

[0020] Preferably, the time for the first calcination to raise the temperature from room temperature to 900-1000℃ is 300 min, the time for the second calcination to raise the temperature from room temperature to 1000-1100℃ is 600 min, and the time for the third calcination to raise the temperature from room temperature to 1150℃ is 600 min.

[0021] More preferably, the temperature during the first calcination is 950°C, and the time to raise the temperature from room temperature to 950°C is 300 min; the temperature during the second calcination is 1050°C, and the time to raise the temperature from room temperature to 1050°C is 600 min; the temperature during the third calcination is 1150°C, and the time to raise the temperature from room temperature to 1150°C is 600 min.

[0022] Multiple calcinations are performed to ensure a more complete reaction and more uniform particle size distribution in the synthesis process. The first calcination temperature is between 900 and 1000°C, at which point the main products are M-type and Y-type hexagonal ferrites, with a small amount of spinel. The second calcination temperature is between 1000 and 1100°C, again producing Y-type and M-type hexagonal ferrites with a small amount of spinel. Theoretically, the third calcination temperature can reach 1200°C, but experiments have shown that reaching 1200°C will generate W-type ferrites. Therefore, this invention limits the third calcination temperature to 1150°C to produce Y-type hexagonal ferrites.

[0023] The present invention also provides the application of the Y-type hexagonal ferrite material with dual magnetocaloric effect in the preparation of refrigeration materials.

[0024] Preferably, the refrigeration material is a refrigerant.

[0025] The present invention also provides the application of the Y-type hexagonal ferrite material with dual magnetocaloric effect in the preparation of heat sink composite materials.

[0026] Compared with the prior art, the present invention has the following advantages and technical effects:

[0027] (1) Different synthesis methods have a significant impact on the microstructure and properties of Y-type hexagonal ferrites. The Y-type hexagonal ferrite material (Sr2Zn) synthesized by solid-state reaction method in this invention has a better microstructure and properties. 2-x Ni x Fe 12 O 22 (x = 0.0, 0.8 or 2.0) It possesses both inverse magnetocaloric effect and conventional magnetocaloric effect in different temperature ranges. The doping of Ni ions enhances both of the above magnetocaloric effects.

[0028] (2)Sr2Zn2Fe 12 O 22 The wide plateau-shaped temperature range (200K~398K) near room temperature is beneficial for the application of the Eriksen magnetocooling cycle. Attached Figure Description

[0029] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0030] Figure 1 The Y-type hexagonal ferrite material Sr2Zn prepared in Examples 1 to 3 2-x Ni x Fe 12 O 22 XRD plots for x = 0.0, 0.8, or 2.0.

[0031] Figure 2 The Y-type hexagonal ferrite Sr2Zn prepared in Examples 1 to 3 2-x Ni x Fe 12 O 22 FE-SEM plots for x = 0.0, 0.8, or 2.0, where (a) is x = 0.0, (b) is x = 0.8, and (c) is x = 2.0.

[0032] Figure 3The Y-type hexagonal ferrite material Sr2Zn prepared in Examples 1 to 3 2-x Ni x Fe 12 O 22 Magnetization curves (x = 0.0, 0.8 or 2.0) in the range of 2 to 400 K and saturation magnetization curves at 2 K, 100 K, 300 K and 400 K as a function of Ni doping amount, where (a), (b) and (c) are Examples 1 to 3 respectively, and (d) is the saturation magnetization curve at 2 K, 100 K, 300 K and 400 K as a function of Ni doping amount.

[0033] Figure 4 It is the Y-type hexagonal ferrite material Sr2Zn2Fe in Example 1 12 O 22 The curve of magnetic entropy change with temperature and its low-temperature magnified diagram.

[0034] Figure 5 It is the Y-type hexagonal ferrite material Sr2Zn in Example 2 1.2 Fe 0.8 O 22 The curve of magnetic entropy change with temperature and its low-temperature magnified diagram.

[0035] Figure 6 It is the Y-type hexagonal ferrite material Sr2Ni2Fe in Example 3 12 O 22 The curve of magnetic entropy change with temperature and its low-temperature magnified diagram.

[0036] Figure 7 The Y-type hexagonal ferrite material Sr2Zn prepared in Examples 1 to 3 2-x Ni x Fe 12 O 22 The curve of relative cooling power versus external magnetic field for (x = 0.0, 0.8 or 2.0). Detailed Implementation

[0037] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0038] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0039] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0040] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0041] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0042] Unless otherwise specified, the room temperature in the embodiments of the present invention is 25±2℃.

[0043] All raw materials used in the embodiments of this invention were purchased commercially. Specifically, SrCO3, ZnO, NiO, and Fe2O3 were all analytically pure, with purities of 99%, 99.99%, 99.99%, and 99.9%, respectively.

[0044] In this embodiment of the invention, a Y-type hexagonal ferrite material (Sr2Zn) exhibiting a dual magnetocaloric effect is used. 2-x Ni x Fe 12 O 22 The performance testing method (x = 0.0, 0.8, or 2.0) is as follows:

[0045] The phase characterization of the prepared material was performed using an X-ray diffraction analyzer (XRD, model Philips PW1050, Cu Kα rays), with a scanning angle 2θ ranging from 20 to 70° and a scanning speed of 4.8° / min.

[0046] The morphology of the samples was measured at room temperature using a field emission electron microscope (FE-SEM, FEI Sirion 200).

[0047] The magnetic properties of the material were tested using a physical property testing system (PPMS, model PPMSDynaCool). Isothermal magnetization curves of the material were measured within a varying magnetic field range of 0–90 kOe and a temperature range of 2–400 K. The magnetic entropy change and relative cooling power of the sample were calculated using relevant formulas (magnetic entropy change calculation formula and relative cooling power formula).

[0048] Formula for calculating magnetic entropy change:

[0049]

[0050] In formula (1), and The magnetization is measured at temperatures T1 and T2, in emu / g; ΔH is the change in magnetic field, in kOe; magnetic entropy change is -ΔS. M The unit is J / Kg K.

[0051] Relative cooling power formula:

[0052]

[0053] In formula (2), The maximum magnetic entropy change is expressed in J / kg K; δT FWHM -ΔS M The half-peak width of the -T curve, in K; the relative cooling power of RCP, in J / Kg.

[0054] The technical solution of the present invention will be further illustrated by the following embodiments.

[0055] Example 1: Y-type hexagonal ferrite material Sr2Zn 2-x Ni x Fe 12 O 22 Preparation of (x=0.0)

[0056] SrCO3, ZnO, and Fe2O3 were weighed according to a molar ratio of 1:1:6, mixed, and ground for 2 hours. The mixed powder was then subjected to high-temperature calcination: For the first calcination, the temperature was raised from room temperature to 950℃ within 300 minutes, maintained for 600 minutes, and then naturally cooled to room temperature; the product was then ground for 2 hours. For the second calcination, the product from the first calcination was raised from room temperature to 1050℃ within 600 minutes, maintained for 1200 minutes, and then naturally cooled to room temperature; the product was then ground for 2 hours. For the third calcination, the product from the second calcination was raised from room temperature to 1150℃ within 600 minutes, maintained for 1200 minutes, and then naturally cooled to room temperature; the product was then ground for 0.5 hours to obtain Sr2Zn. 2- x Ni x Fe 12 O 22 (x=0.0), i.e., Sr2Zn2Fe 12 O 22 .

[0057] Example 2: Y-type hexagonal ferrite material Sr2Zn 2-x Ni x Fe 12 O 22 Preparation of (x=0.8)

[0058] SrCO3, ZnO, NiO, and Fe2O3 were weighed according to a molar ratio of 5:3:2:30, mixed, and ground for 2 hours. The mixed powder was then subjected to high-temperature calcination: For the first calcination, the temperature was raised from room temperature to 950℃ within 300 minutes, maintained for 600 minutes, and then naturally cooled to room temperature; the product was then ground for 2 hours. For the second calcination, the product from the first calcination was raised from room temperature to 1050℃ within 600 minutes, maintained for 1200 minutes, and then naturally cooled to room temperature; the product was then ground for 2 hours. For the third calcination, the product from the second calcination was raised from room temperature to 1150℃ within 600 minutes, maintained for 1200 minutes, and then naturally cooled to room temperature; the product was then ground for 0.5 hours to obtain Sr2Zn. 2- x Ni x Fe 12 O 22 (x=0.8), i.e., Sr2Zn 1.2 Ni 0.8 Fe 12 O 22 .

[0059] Example 3: Y-type hexagonal ferrite material Sr2Zn 2-x Ni x Fe 12 O 22 Preparation of (x=2.0)

[0060] SrCO3, NiO, and Fe2O3 were weighed according to a molar ratio of 1:1:6, mixed, and ground for 2 hours. The mixed powder was then subjected to high-temperature calcination: For the first calcination, the temperature was raised from room temperature to 950℃ within 300 minutes, maintained for 600 minutes, and then naturally cooled to room temperature; the product was then ground for 2 hours. For the second calcination, the product from the first calcination was raised from room temperature to 1050℃ within 600 minutes, maintained for 1200 minutes, and then naturally cooled to room temperature; the product was then ground for 2 hours. For the third calcination, the product from the second calcination was raised from room temperature to 1150℃ within 600 minutes, maintained for 1200 minutes, and then naturally cooled to room temperature; the product was then ground for 0.5 hours to obtain Sr2Zn. 2- x Ni x Fe 12 O 22 (x=2.0), i.e., Sr2Ni2Fe 12 O 22 .

[0061] Y-type hexagonal ferrite material Sr2Zn prepared in Examples 1 to 3 2-x Ni x Fe 12 O 22 XRD plots for (x = 0.0, 0.8, or 2.0) are shown below. Figure 1 As can be seen, the intensity of each diffraction peak is significant, and comparison with the standard PDF card confirms that the prepared material conforms to the Y-type ferrite Sr2Zn standard. 2-x Ni x Fe 12 O 22 (ICDD No. 73-2035).

[0062] Y-type hexagonal ferrite Sr2Zn prepared in Examples 1 to 3 2-x Ni x Fe 12 O 22 FE-SEM plots for (x = 0.0, 0.8, or 2.0) are shown below. Figure 2 As can be seen, the generated samples are a mixture of hexagonal flakes and elongated shapes. The growth of hexagonal ferrite grains is related to grain boundary movement and Ostwald ripening. The appearance of elongated shapes is an extreme growth process that occurs during discontinuous grain growth and is closely related to the latter. Figure 3 The Y-type hexagonal ferrite material Sr2Zn prepared in Examples 1 to 3 2- x Ni x Fe 12 O 22Magnetization curves (x = 0.0, 0.8, or 2.0) in the range of 2–400 K and saturation magnetization curves at 2 K, 100 K, 300 K, and 400 K as a function of Ni doping concentration show that for the expression Sr₂Zn₂Fe 12 O 22 The material exhibits inverse magnetocaloric effect in the temperature range of 4K–24K. Under magnetic field variations of 0–90 kOe, the maximum magnetic entropy change is -0.45 J / kg K at 16K. The conventional magnetocaloric effect occurs in the temperature regions <4K and >24K. Interestingly, the magnetic entropy change <4K ​​generally decreases with increasing magnetic field, reaching 0.0232 J / kg K in the 0–10 kOe range and 0.0053 J / kg K in the 0–90 kOe range. Near room temperature, the magnetic entropy change increases with increasing magnetic field and exhibits a plateau-like curve with temperature. This effectively eliminates the influence of lattice entropy on the total entropy change, thus allowing the material to be used in Eriksen magnetocooling cycles near room temperature. The maximum magnetic entropy change is 0.68 J / kg K at 286K, corresponding to a relative cooling power of 223.23 J / kg. With increasing Ni doping concentration, both the diamagnetic and conventional magnetocaloric effects of the material are significantly enhanced, with the conventional magnetocaloric effect showing a more pronounced increase at low temperatures. Furthermore, the shape of the magnetic entropy change curve as a function of temperature near room temperature changes from a plateau to a sharp peak. For the expression Sr₂Zn… 1.2 Ni 0.8 Fe 12 O 22 The material exhibits the strongest magnetocaloric effect, manifested in the increased magnetic entropy change. The maximum magnetic entropy change is 3.16 J / kg K at 4 K, -1.02 J / kg K at 16 K, and 1.33 J / kg K at 354 K, corresponding to a relative cooling power of 358.68 J / kg, with a magnetic field variation ranging from 0 to 90 kOe. For the material expressed as Sr₂Ni₂Fe… 12 O 22 The material, whose magnetocaloric effect is expressed as Sr₂Zn, has a similar expression. 1.2 Ni 0.8 Fe 12 O 22 The material strength is somewhat reduced, but it is still stronger than the parent material, and the temperature range of the diamagnetic thermal effect is significantly increased (12K~65K). The maximum magnetic entropy change is 1.54J / kg K (4K), -0.50J / kg K (16K), 0.81J / kg K (366K), the relative cooling power is 106.19J / kg, and the magnetic field change is 0~90kOe.

[0063] In Example 1, the Y-type hexagonal ferrite material Sr2Zn2Fe 12 O 22 The curve of magnetic entropy change with temperature and its low-temperature magnified figure are shown below. Figure 4As shown, under the condition that the magnetic field changes from 0 to 90 kOe, the magnetic entropy changes to 0.0053 J / kg K (4 K), -0.45 J / kg K (16 K), and 0.68 J / kg K (286 K).

[0064] Y-type hexagonal ferrite material Sr2Zn in Example 2 1.2 Fe 0.8 O 22 The curve of magnetic entropy change with temperature and its low-temperature magnified figure are shown below. Figure 5 As shown, under the condition that the magnetic field changes from 0 to 90 kOe, the magnetic entropy changes are 3.16 J / kg K (4 K), -1.02 J / kg K (16 K), and 1.33 J / kg K (354 K).

[0065] In Example 3, the Y-type hexagonal ferrite material Sr2Ni2Fe 12 O 22 The curve of magnetic entropy change with temperature and its low-temperature magnified figure are shown below. Figure 6 As shown, under the condition that the magnetic field changes from 0 to 90 kOe, the magnetic entropy changes to 1.54 J / kg K (4 K), -0.50 J / kg K (16 K), and 0.81 J / kg K (366 K).

[0066] Y-type hexagonal ferrite material Sr2Zn prepared in Examples 1 to 3 2-x Ni x Fe 12 O 22 The curves showing the relative cooling power versus the applied magnetic field for (x = 0.0, 0.8, or 2.0) are shown below. Figure 7 As shown, the relative cooling powers of the three materials near room temperature are 223.23 J / kg, 358.68 J / kg, and 106.19 J / kg, respectively, under magnetic field variations of 0–90 kOe.

[0067] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for preparing a Y-type hexagonal ferrite material with a dual magnetocaloric effect, characterized in that, Includes the following steps: SrCO3, ZnO, NiO, and Fe2O3 were weighed according to the material composition, mixed, ground, and calcined three times to obtain the Y-type hexagonal ferrite material with binary magnetocaloric effect. The chemical formula is: Sr2Zn 2-x Ni x Fe 12 O 22 , x =0.8; when x When the molar ratio is 0.8, the molar ratio of SrCO3, ZnO, NiO and Fe2O3 is 5:3:2:30; The three calcinations are as follows: the first calcination is carried out by heating from room temperature to 900~1000 ℃, maintaining the temperature for 600 min, and then naturally cooling to room temperature, followed by grinding the product; The second calcination involves heating the product from the first calcination at room temperature to 1000-1100℃ and maintaining it for 1200 minutes, then allowing it to cool naturally to room temperature before grinding the product. The third calcination involves heating the product from the second calcination at room temperature to 1150°C and maintaining it for 1200 min, then naturally cooling it to room temperature, grinding the product, and obtaining the Y-type hexagonal ferrite material with the dual magnetocaloric effect. The time to raise the temperature from room temperature to 900~1000 ℃ during the first calcination is 300 min, the time to raise the temperature from room temperature to 1000~1100 ℃ during the second calcination is 600 min, and the time to raise the temperature from room temperature to 1150 ℃ during the third calcination is 600 min.

2. The application of a Y-type hexagonal ferrite material with a dual magnetocaloric effect prepared by the method of claim 1 in the preparation of refrigeration materials.

3. The application according to claim 2, characterized in that, The refrigeration material is a refrigerant.

4. The application of a Y-type hexagonal ferrite material with a dual magnetocaloric effect prepared by the method of claim 1 in the preparation of heat sink composite materials.

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