Preparation method and application of rare earth high-frequency soft magnetic material

Abstract

The application relates to a preparation method and application of a rare earth high-frequency soft magnetic material and belongs to the field of soft magnetic materials. The chemical formula of the rare earth high-frequency soft magnetic material is RE2Co 17 , and the RE is at least one of Nd, Ce, Y and Pr. The preparation method of the rare earth high-frequency soft magnetic material comprises the following steps: taking a metal precursor mixture and a reducing agent, uniformly mixing the metal precursor mixture and the reducing agent under an argon atmosphere through high-energy ball milling, annealing, washing, and drying to obtain the rare earth high-frequency soft magnetic material. The preparation method of the rare earth high-frequency soft magnetic material is favorable for the reduction diffusion reaction through high-energy ball milling, and the rare earth high-frequency soft magnetic material prepared by using the method has unique advantages in morphology control and size adjustment. The preparation method of the rare earth high-frequency soft magnetic material has simple preparation process, low cost and low cost of starting raw materials.

Description

Technical Field

[0001] This invention relates to the field of soft magnetic materials, specifically to a method for preparing and applying a rare-earth high-frequency soft magnetic material. Background Technology

[0002] Soft magnetic materials are materials that can rapidly respond to changes in external magnetic fields and achieve high magnetic induction intensity with low loss. They are mainly used in devices such as inductors, transformers, and relays. In recent years, with the increase in smart devices such as mobile phones and autonomous vehicles, the operating frequencies of various electronic devices have gradually increased, and the high integration of electronic components has placed demands on them to have characteristics such as light weight, thinness, wide absorption bandwidth, and strong absorption peaks. High-frequency soft magnetic materials, due to their advantages such as high saturation magnetization, good DC superposition characteristics, and relatively high operating frequencies, can meet the design and application requirements for manufacturing high-power transformers, inductors, electronic transformers, and other devices. Among them, rare earth alloy materials, due to their saturation magnetization and Curie temperature being much higher than those of ferrites, have become the focus of research and development in high-frequency soft magnetic materials.

[0003] Studies have shown that the Curie temperatures of rare earth alloys and compounds, from lowest to highest, are RE2Fe ... 17 RE2Fe 14 B, RECo5 and RE2Co 17 Among them, the Curie temperature of rare earth-cobalt metal alloys gradually increases with the increase of Co content, which can improve the service temperature of the alloy and make it a promising candidate for military and civilian absorbing materials in high-temperature and high-frequency band communications and radar detection. Furthermore, the rare earth-cobalt metal alloy RE2Co... 17 The presence of an easily magnetized crystal plane gives the alloy high-frequency magnetism, using a rare-earth-cobalt metal alloy RE2Co. 17 The prepared composite material has a low real part of dielectric constant, which ensures good impedance matching and makes it still have excellent wave absorption performance even at a very thin thickness. It is a rare earth high-frequency soft magnetic material with excellent performance at high frequencies.

[0004] Currently, rare earth alloy material RE2Co 17 The manufacturing methods are mainly physical methods, specifically divided into sintering and bonding methods. The sintering method, also known as powder metallurgy, is used for high-performance rare earth alloy materials like RE2Co. 17 The main preparation method is as follows: rare earth metal raw materials are mixed and smelted with Co according to an atomic ratio. The resulting powder is ground, magnetically oriented, pressed, sintered, and finally tempered or aged at high temperature to obtain the rare earth alloy material RE2Co. 17The bonding method uses rare earth cobalt permanent magnet powder as raw material, mixes it with a binder, and then processes it through pressing, extrusion, or injection molding, followed by curing treatment. This method can directly produce RE2Co magnets of various complex shapes. 17 Permanent magnet components.

[0005] However, the above-mentioned preparation of rare earth alloy material RE2Co 17 The physical method for preparing rare earth alloys uses rare earth metals as initial raw materials, resulting in high losses during processing and increased production costs. Furthermore, the physical method for preparing rare earth alloys can cause problems such as uncontrollable grain growth rate and material density, leading to issues with the production of RE2Co rare earth alloys. 17 The non-uniform size and large grain size of rare earth materials degrade their high-frequency electromagnetic properties. Therefore, there is an urgent need to develop a method for preparing rare earth high-frequency soft magnetic materials that is simple to manufacture, has low production costs, and possesses high-frequency electromagnetic properties. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing rare earth high-frequency soft magnetic materials with simple preparation process, inexpensive and readily available reaction starting materials, and low production cost. The rare earth high-frequency soft magnetic materials prepared by this method have the advantages of uniform size and small particle size.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] On one hand, the present invention provides a method for preparing a rare-earth high-frequency soft magnetic material, wherein the chemical formula of the rare-earth high-frequency soft magnetic material is RE2Co. 17 The RE is at least one of Nd, Ce, Y, and Pr; the preparation method of the rare earth high-frequency soft magnetic material is as follows: weigh the metal precursor mixture and the reducing agent, mix them evenly by high-energy ball milling under an argon atmosphere, thermally reduce, wash, and dry to obtain the rare earth high-frequency soft magnetic material; the metal precursor mixture includes Co(OH)2 and RE(OH)3.

[0009] The method for preparing rare-earth high-frequency soft magnetic materials according to the present invention involves high-energy ball milling of a metal precursor mixture and a reducing agent under an argon atmosphere. This process ensures uniform mixing of the metal precursor mixture and the reducing agent, facilitating reduction and diffusion and resulting in better morphological control and size adjustment of the rare-earth high-frequency soft magnetic materials. Furthermore, the high-energy ball milling process generates significant energy through internal collisions. Although the overall temperature within the milling apparatus is not high, the temperatures at local collision points can exceed 70°C. These extremely high temperatures at some collision points help atoms recombine and reorganize bonds. Through prolonged operation of the high-energy ball mill, some Co(OH)₂ in the metal precursor mixture can be decomposed into CoO, and some RE(OH)₃ into RE₂O₃, which is beneficial for subsequent thermal reduction reactions. Using the uniformly mixed metal precursor mixture obtained through high-energy ball milling according to the present invention, followed by thermal reduction, yields materials with uniform size and well-controlled grain size of 4–6 μm. The resulting rare-earth high-frequency soft magnetic materials also exhibit good high-frequency electromagnetic and wave-absorbing properties.

[0010] Through experimental research, the inventors discovered that even after uniformly mixing the metal precursors Co(OH)₂ and RE(OH)₃ obtained in this invention using traditional mechanical stirring methods, followed by a thermal reduction reaction, they were unable to prepare the rare-earth high-frequency soft magnetic material RE₂Co with uniform size, small grain size, and good high-frequency absorption performance. 17 .

[0011] As a preferred embodiment of the preparation method of the rare earth high-frequency soft magnetic material of the present invention, the method for preparing RE(OH)3 of the metal precursor mixture is as follows: dissolve RECl3 in deionized water, add sodium hydroxide solution with a concentration of 3-5 mol / L, heat under reflux, wash and dry to obtain RE(OH)3 of the metal precursor mixture; the RECl3 includes at least one of NdCl3, CeCl3, YCl3 and PrCl3.

[0012] RE(OH)3 is prepared using the method of this invention. RECl3 and NaOH are reacted under reflux conditions to obtain RE(OH)3 precipitate, and the reaction is complete. The metal precursor RE(OH)3 prepared by this method can be used to prepare rare-earth high-frequency soft magnetic material RE2Co through subsequent heat treatment. 17 The alloying process is fully utilized, which is beneficial to improving the utilization rate of rare earth element RE. Furthermore, by using RECl3 as the reaction starting material, this invention has the advantages of reducing costs and making the raw materials readily available, thus solving the problem of using high-cost rare earth metal RE as the reaction raw material when preparing rare earth high-frequency soft magnetic materials by physical sintering.

[0013] Rare earth elements (RE) have strong reducing properties, and cannot be stored completely isolated from air. Prolonged storage can lead to the formation of an oxide layer on the surface of rare earth metal blocks. Therefore, a physical method is used to prepare RE₂Co. 17 When alloying, the surface oxide layer needs to be polished before it can be used. Furthermore, because rare earth metals have low melting points and are highly volatile at high temperatures, excessive amounts of rare earth metals need to be added during physical sintering, which further increases the reaction cost.

[0014] This invention uses RECl3 as the initial raw material for preparing rare-earth high-frequency soft magnetic materials, which has the advantages of being inexpensive and readily available, thus greatly reducing production costs. Furthermore, this invention uses RECl3 and NaOH under reflux heating to obtain RE(OH)3 precipitate, simplifying the preparation process, improving the utilization rate of raw materials, and avoiding waste.

[0015] In a preferred embodiment of the preparation method of the rare earth high-frequency soft magnetic material of the present invention, the high-energy ball milling time is 1 to 3 hours.

[0016] In a preferred embodiment of the preparation method of the rare earth high-frequency soft magnetic material of the present invention, the heating temperature is 30℃~100℃.

[0017] In a preferred embodiment of the preparation method of the rare earth high-frequency soft magnetic material of the present invention, the reducing agent is CaH2.

[0018] In a preferred embodiment of the preparation method of the rare earth high-frequency soft magnetic material of the present invention, the thermal reduction reaction temperature is 750-900℃ and the reaction time is 10-60 min.

[0019] The method for preparing rare-earth high-frequency soft magnetic materials of the present invention controls the thermal reduction reaction temperature at 750–900°C and the reaction time at a preferred time of 10–60 min, thereby obtaining the rare-earth high-frequency soft magnetic material RE2Co. 17 The alloy is characterized by uniform size and small grain size.

[0020] In a preferred embodiment of the preparation method of the rare earth high-frequency soft magnetic material of the present invention, the reducing agent is CaH2.

[0021] The inventors of this invention discovered in a large number of comparative studies of reducing agents that by adding CaH2 as a reducing agent, the byproducts generated by Ca in the process of reducing the precursor will not affect the performance of the rare earth high-frequency soft magnetic material of this invention. On the other hand, they can be removed by adding water, ethanol or methanol solution containing ammonium chloride. However, other types of reducing agents, such as those containing Al or Mg metals, will generate Al2O3 or MgO after the reaction, which are insoluble in water or ethanol and will also have a negative impact on the dictionary parameters.

[0022] In a preferred embodiment of the preparation method of the rare earth high-frequency soft magnetic material of the present invention, the molar ratio of the metal precursor mixture to the reducing agent is metal precursor mixture: reducing agent = 1:(1~2).

[0023] Studies have found that when the molar ratio of the metal precursor mixture to the reducing agent used in this invention is as described above, an excess of reducing agent can allow the metal precursor to react fully, thus preparing the rare earth high-frequency soft magnetic material described in this invention. However, when the precursor mixture and the reducing agent react in a 1:1 ratio, the reaction will be insufficient, and some residual metal oxides will not be reduced.

[0024] In a preferred embodiment of the preparation method of the rare earth high-frequency soft magnetic material of the present invention, the molar ratio of Co(OH)2 and RE(OH)3 in the metal precursor mixture is RE(OH)3:Co(OH)2 = 2:17.

[0025] In a preferred embodiment of the preparation method of the rare earth high-frequency soft magnetic material of the present invention, the washing solution includes a mixed solution of ammonium chloride and methanol.

[0026] The present invention first uses deionized water and ethanol solution to wash the precipitate, but it was found that washing with deionized water and ethanol could not completely remove the impurities in the precipitate, resulting in poor high-frequency electromagnetic performance of the prepared rare earth high-frequency soft magnetic material.

[0027] Through extensive research in various washing solutions, the inventors discovered that washing the precipitate with a solution of ammonium chloride and methanol can effectively remove a large amount of CaO byproducts generated by the reducing agent CaH2, thereby preparing rare earth high-frequency soft magnetic materials with excellent high-frequency electromagnetic properties.

[0028] On the other hand, the present invention also provides an application of rare earth high-frequency soft magnetic materials in high-frequency magnetic devices and communications.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: the preparation method of the rare earth high-frequency soft magnetic material of the present invention has a simple preparation process, the reaction starting materials are cheap and readily available, and the cost is low. Furthermore, the rare earth high-frequency soft magnetic material prepared by the present invention has uniform size, small grains, and good wave absorption performance at high frequencies, making it a high-performance high-frequency soft magnetic material. Attached Figure Description

[0030] Figure 1 The X-ray diffraction patterns of Co(OH)2 and Nd(OH)3 prepared in Example 1 of this invention are shown.

[0031] Figure 2 This is the X-ray diffraction pattern of the metal precursor mixture obtained by high-energy ball milling in Example 1 of the present invention.

[0032] Figure 3 The X-ray diffraction patterns of the heat-treated product of Example 1 of the present invention before and after washing are shown.

[0033] Figure 4 This is a SEM image of the rare-earth high-frequency soft magnetic material of Embodiment 1 of the present invention.

[0034] Figure 5 The diagram shows the relationship between complex permeability and frequency of a ring-shaped sample prepared using the rare-earth high-frequency soft magnetic material of Example 1 of this invention.

[0035] Figure 6 The diagram shows the complex dielectric constant and frequency relationship of a ring-shaped sample prepared using the rare-earth high-frequency soft magnetic material of Example 1 of this invention.

[0036] Figure 7 The graph shows the relationship between reflection loss and frequency of a ring-shaped sample prepared using the rare-earth high-frequency soft magnetic material of Example 1 of this invention. Detailed Implementation

[0037] The technical solution of the present invention will be further described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the methods or operations used in the embodiments are conventional methods or operations in the art.

[0038] Example 1

[0039] This invention provides a high-frequency soft magnetic material, wherein the chemical formula of the high-frequency soft magnetic material described in this embodiment is Nd₂Co. 17 .

[0040] The high-frequency soft magnetic material preparation method described in this embodiment includes the following steps:

[0041] (1) Preparation of Co(OH)2: Weigh 0.2207g of anhydrous cobalt chloride, dissolve it in 50mL of deionized water, stir evenly, add 3.5mol / L sodium hydroxide solution, heat to 100℃, reflux for 5h, use deionized water and ethanol solution to centrifuge and wash three times, centrifuge speed set to 8500rpm, centrifuge time for 10min, dry the washed precipitate in an oven at 60℃ for 12h to obtain the Co(OH)2;

[0042] (2) Preparation of Nd(OH)3: Weigh 0.1435 g of anhydrous cobalt chloride, dissolve it in 50 mL of deionized water, stir well, add 3.5 mol / L sodium hydroxide solution, heat to 100 °C, reflux for 5 h, wash the precipitate three times with deionized water and ethanol solution by centrifugation, set the centrifugation speed to 8500 rpm and the centrifugation time to 10 min, and dry the washed precipitate in an oven at 60 °C for 12 h to obtain the RE(OH)3;

[0043] (3) Under an argon atmosphere, Co(OH)2 and Nd(OH)3 were weighed at a molar ratio of 2:17 to obtain the metal precursor mixture; the metal precursor mixture and CaH2 were weighed at a molar ratio of 1:1.5, mixed evenly, and ball-milled at high energy for 2 hours with a ball-to-material ratio of 20:1 and a speed of 500 rpm.

[0044] (4) The mixture after high-energy ball milling is placed in a crucible made of corundum. Under an argon atmosphere, the crucible is placed in a tube furnace for thermal reduction reaction. The temperature is increased from room temperature to 850℃ at 5℃ / min and held for 30min. 2g of ammonium chloride is dissolved in 100mL of methanol solution to obtain a mixed solution of ammonium chloride and methanol. The thermal reduction product is washed with a mixture of ammonium chloride and methanol solution and dried to obtain the rare earth high-frequency soft magnetic material.

[0045] Example 2

[0046] This invention provides a high-frequency soft magnetic material, wherein the chemical formula of the high-frequency soft magnetic material described in this embodiment is Nd₂Co. 17 .

[0047] The high-frequency soft magnetic material preparation method described in this embodiment includes the following steps:

[0048] (1) Preparation of Co(OH)2: Weigh 0.2207g of anhydrous cobalt chloride, dissolve it in 50mL of deionized water, stir evenly, add 3.5mol / L sodium hydroxide solution, heat to 100℃, reflux for 5h, use deionized water and ethanol solution to centrifuge and wash three times, centrifuge speed set to 8500rpm, centrifuge time for 10min, dry the washed precipitate in an oven at 60℃ for 12h to obtain the Co(OH)2;

[0049] (2) Preparation of Nd(OH)3: Weigh 0.1435 g of anhydrous cobalt chloride, dissolve it in 50 mL of deionized water, stir well, add 3.5 mol / L sodium hydroxide solution, heat to 100 °C, reflux for 5 h, wash the precipitate three times with deionized water and ethanol solution by centrifugation, set the centrifugation speed to 8500 rpm and the centrifugation time to 10 min, and dry the washed precipitate in an oven at 60 °C for 12 h to obtain the RE(OH)3;

[0050] (3) Under an argon atmosphere, Co(OH)2 and Nd(OH)3 were weighed at a molar ratio of 2:17 to obtain the metal precursor mixture; the metal precursor mixture and CaH2 were weighed at a molar ratio of 1:1.5, mixed evenly, and ball-milled at high energy for 1 hour with a ball-to-material ratio of 20:1 and a speed of 500 rpm.

[0051] (4) The mixture after high-energy ball milling is placed in a crucible made of corundum. Under an argon atmosphere, the crucible is placed in a tube furnace for thermal reduction reaction. The temperature is increased from room temperature to 850℃ at 5℃ / min and held for 30min. 2g of ammonium chloride is dissolved in 100mL of methanol solution to obtain a mixed solution of ammonium chloride and methanol. The thermal reduction product is washed with the mixed solution of ammonium chloride and methanol and dried to obtain the rare earth high-frequency soft magnetic material.

[0052] Example 3

[0053] This invention provides a high-frequency soft magnetic material, wherein the chemical formula of the high-frequency soft magnetic material described in this embodiment is Nd₂Co. 17 .

[0054] The high-frequency soft magnetic material preparation method described in this embodiment includes the following steps:

[0055] (1) Preparation of Co(OH)2: Weigh 0.2207g of anhydrous cobalt chloride, dissolve it in 50mL of deionized water, stir evenly, add 3.5mol / L sodium hydroxide solution, heat to 100℃, reflux for 5h, use deionized water and ethanol solution to centrifuge and wash three times, centrifuge speed set to 8500rpm, centrifuge time for 10min, dry the washed precipitate in an oven at 60℃ for 12h to obtain the Co(OH)2;

[0056] (2) Preparation of Nd(OH)3: Weigh 0.1435 g of anhydrous cobalt chloride, dissolve it in 50 mL of deionized water, stir well, add 3.5 mol / L sodium hydroxide solution, heat to 100 °C, reflux for 5 h, wash the precipitate three times with deionized water and ethanol solution by centrifugation, set the centrifugation speed to 8500 rpm and the centrifugation time to 10 min, and dry the washed precipitate in an oven at 60 °C for 12 h to obtain the RE(OH)3;

[0057] (3) Under an argon atmosphere, Co(OH)2 and Nd(OH)3 were weighed at a molar ratio of 2:17 to obtain the metal precursor mixture; the metal precursor mixture and CaH2 were weighed at a molar ratio of 1:1.5, mixed evenly, and ball-milled at high energy for 3 hours with a ball-to-material ratio of 20:1 and a speed of 500 rpm.

[0058] (4) The mixture after high-energy ball milling is placed in a crucible made of corundum. Under an argon atmosphere, the crucible is placed in a tube furnace for thermal reduction reaction. The temperature is increased from room temperature to 850℃ at 5℃ / min and held for 30min. 2g of ammonium chloride is dissolved in 100mL of methanol solution to obtain a mixed solution of ammonium chloride and methanol. The thermal reduction product is washed with the mixed solution of ammonium chloride and methanol and dried to obtain the rare earth high-frequency soft magnetic material.

[0059] Comparative Example 1

[0060] This invention provides a high-frequency soft magnetic material, wherein the chemical formula of the high-frequency soft magnetic material described in this embodiment is Nd₂Co. 17 .

[0061] The high-frequency soft magnetic material preparation method described in this embodiment includes the following steps:

[0062] (1) Preparation of Co(OH)2: Weigh 0.2207g of anhydrous cobalt chloride, dissolve it in 50mL of deionized water, stir evenly, add 3.5mol / L sodium hydroxide solution, heat to 100℃, reflux for 5h, use deionized water and ethanol solution to centrifuge and wash three times, centrifuge speed set to 8500rpm, centrifuge time for 10min, dry the washed precipitate in an oven at 60℃ for 12h to obtain the Co(OH)2;

[0063] (2) Preparation of Nd(OH)3: Weigh 0.1435 g of anhydrous cobalt chloride, dissolve it in 50 mL of deionized water, stir well, add 3.5 mol / L sodium hydroxide solution, heat to 100 °C, reflux for 5 h, wash the precipitate three times with deionized water and ethanol solution by centrifugation, set the centrifugation speed to 8500 rpm and the centrifugation time to 10 min, and dry the washed precipitate in an oven at 60 °C for 12 h to obtain the RE(OH)3;

[0064] (3) Under an argon atmosphere, Co(OH)2 and Nd(OH)3 were weighed at a molar ratio of 2:17 to obtain the metal precursor mixture; the metal precursor mixture and CaH2 were weighed at a molar ratio of 1:1.5, mixed evenly, and ball-milled at low energy for 2 hours with a ball-to-material ratio of 20:1 and a speed of 80 rpm.

[0065] (4) The mixture after high-energy ball milling was placed in a crucible made of corundum. Under an argon atmosphere, the crucible was placed in a tube furnace for thermal reduction reaction. The temperature was increased from room temperature to 850°C at 5°C / min and held for 30 min. 2g of ammonium chloride was dissolved in 100mL of methanol solution to obtain a mixed solution of ammonium chloride and methanol. The thermal reduction product was washed with deionized water and ethanol solution and dried. The rare earth high-frequency soft magnetic material was not obtained.

[0066] Comparative Example 2

[0067] This invention provides a high-frequency soft magnetic material, wherein the chemical formula of the high-frequency soft magnetic material described in this embodiment is Nd₂Co. 17 .

[0068] The high-frequency soft magnetic material preparation method described in this embodiment includes the following steps:

[0069] (1) Preparation of Co(OH)2: Weigh 0.2207g of anhydrous cobalt chloride, dissolve it in 50mL of deionized water, stir evenly, add 3.5mol / L sodium hydroxide solution, heat to 100℃, reflux for 5h, use deionized water and ethanol solution to centrifuge and wash three times, centrifuge speed set to 8500rpm, centrifuge time for 10min, dry the washed precipitate in an oven at 60℃ for 12h to obtain the Co(OH)2;

[0070] (2) Preparation of Nd(OH)3: Weigh 0.1435 g of anhydrous cobalt chloride, dissolve it in 50 mL of deionized water, stir well, add 3.5 mol / L sodium hydroxide solution, heat to 100 °C, reflux for 5 h, wash the precipitate three times with deionized water and ethanol solution by centrifugation, set the centrifugation speed to 8500 rpm and the centrifugation time to 10 min, and dry the washed precipitate in an oven at 60 °C for 12 h to obtain the RE(OH)3;

[0071] (3) Under an argon atmosphere, Co(OH)2 and Nd(OH)3 were weighed at a molar ratio of 2:17 to obtain the metal precursor mixture; the metal precursor mixture and CaH2 were weighed at a molar ratio of 1:1.5, mixed evenly, and mechanically stirred for 2 hours.

[0072] (4) The mixture after high-energy ball milling was placed in a crucible made of corundum. Under an argon atmosphere, the crucible was placed in a tube furnace for thermal reduction reaction. The temperature was increased from room temperature to 850°C at 5°C / min and held for 30 min. 2g of ammonium chloride was dissolved in 100mL of methanol solution to obtain a mixed solution of ammonium chloride and methanol. The thermal reduction product was washed with the mixed solution of ammonium chloride and methanol and dried. The rare earth high-frequency soft magnetic material was not obtained.

[0073] Preparation of cyclic samples

[0074] Weigh the rare earth high-frequency soft magnetic material and paraffin prepared in Example 1, with a mass ratio of 4:1. Add cyclohexane to disperse the material and sonicate for 40 min to fully disperse the paraffin around the magnetic powder. Dry the powder sample at room temperature for 12 h. Place the powder sample in a mold with an inner diameter of 3.04 mm and an outer diameter of 7.00 mm to press a ring with a thickness of 1.5–2.5 mm. Test the microwave magnetism of the obtained ring sample in an Agilent vector network analyzer.

[0075] Performance Tests and Results

[0076] Comparing Example 1 of the present invention with Comparative Example 1, the high-energy ball milling method of the present invention can prepare rare earth high-frequency soft magnetic materials with excellent performance, while the mechanical stirring and low-energy ball milling methods failed to obtain the rare earth high-frequency soft magnetic materials of the present invention. This indicates that the mechanical stirring and low-energy ball milling methods cannot pre-reduce the rare earth metals and Co in the metal precursor mixture, which is not conducive to the subsequent thermal reduction reaction.

[0077] X-ray powder diffraction phase analysis was performed on samples from different steps of the preparation method of rare earth high-frequency soft magnetic materials in Example 1 of this invention. Figure 1 The X-ray diffraction pattern of the metal precursor mixture is shown. Figure 2 The X-ray diffraction pattern of the metal precursor mixture after high-energy ball milling is shown. Figure 3 These are the X-ray diffraction patterns of the heat-treated product before and after washing. From... Figure 2 It is evident that the metal precursor mixture after high-energy ball milling contains small amounts of CoO and Nd₂O₃, indicating that 2 hours of high-energy ball milling can decompose some of the Co(OH)₂ and Nd(OH)₃ in the metal precursor mixture, which is beneficial to the subsequent reduction reaction. Figure 3 It can be seen that the rare earth high-frequency soft magnetic material Nd2Co was prepared using the method of the present invention. 17 The alloy contained a large amount of calcium oxide impurities before washing. Excess calcium oxide was removed using a methanol solution containing ammonium chloride, resulting in a relatively pure rare-earth high-frequency soft magnetic material, Nd₂Co. 17 alloy.

[0078] Figure 4 The image shows a SEM image of a rare-earth high-frequency soft magnetic material prepared using the method of this invention. As can be seen from the image, the rare-earth high-frequency soft magnetic material prepared by this invention has uniform size and the grain size is controlled between 4 and 6 μm.

[0079] Figures 5-7 The results are the magnetoelectric parameters of a ring-shaped sample made of rare-earth high-frequency soft magnetic material prepared using the method of this invention, tested using an Agilent vector network analyzer.

[0080] Figure 5This is a graph showing the complex permeability versus frequency of a ring-shaped sample prepared using the rare-earth high-frequency soft magnetic material of this invention. From the real part curve μ′ of the permeability, it can be seen that the attenuation rate of the rare-earth high-frequency soft magnetic material is relatively slow with increasing frequency, and shows a brief increase near 10 GHz, indicating that the rare-earth high-frequency soft magnetic material prepared by the method of this invention maintains good performance at high frequencies. From the imaginary part curve μ″ of the permeability, it can be seen that the rare-earth high-frequency soft magnetic material prepared by this invention still has good magnetic loss with increasing frequency, reducing the rate of decrease of the imaginary part of the permeability, thus preserving the absorption performance as much as possible at high frequencies, thereby improving the absorption performance of the rare-earth high-frequency soft magnetic material across the entire frequency band. In summary, the rare-earth high-frequency soft magnetic material prepared by the method of this invention exhibits good absorption performance across the entire frequency band.

[0081] Figure 6 The figure shows the complex dielectric constant versus frequency relationship of a ring-shaped sample prepared using the rare-earth high-frequency soft magnetic material of Example 1. As can be seen from the figure, the real part ε′ of the dielectric constant of the rare-earth high-frequency soft magnetic material prepared by the method of this invention hardly decreases with increasing frequency in the frequency band from 1 to 7.06 GHz, and a significant peak appears at 0.10 GHz. A corresponding peak also appears in the imaginary part ε″ of the dielectric constant, with the overall value varying between 1 and 18 GHz. In summary, the rare-earth high-frequency soft magnetic material prepared by this invention has a low dielectric constant, which is beneficial for achieving better impedance matching and thus better absorption performance.

[0082] Figure 7 The graph shows the relationship between reflection loss and frequency of a ring-shaped sample prepared using the rare-earth high-frequency soft magnetic material of Example 1. As can be seen from the graph, the absorption performance of the rare-earth high-frequency soft magnetic material prepared by the method of the present invention is concentrated in the frequency range of 1-18 GHz. Furthermore, the rare-earth high-frequency soft magnetic material has a relatively thin thickness (1.4-3.0 mm) and strong absorption (absorption rate exceeding -10 dB is higher than 90%, even reaching -48.8 dB at 1.4 mm, and bandwidth reaching 4 GHz at a thickness of 1.8 mm). Therefore, the rare-earth high-frequency soft magnetic material prepared by the present invention can effectively suppress electromagnetic interference in high-frequency applications without increasing the application volume.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a rare-earth high-frequency soft magnetic material, characterized in that, The chemical formula of the rare-earth high-frequency soft magnetic material is RE2Co. 17 The RE is at least one of Nd, Ce, Y, and Pr; The preparation method of the rare earth high-frequency soft magnetic material is as follows: weigh the metal precursor mixture and the reducing agent, mix them evenly by high-energy ball milling under an argon atmosphere, anneal, wash, and dry to obtain the rare earth high-frequency soft magnetic material; the metal precursor mixture includes Co(OH)2 and RE(OH)3; the reducing agent is CaH2; the annealing temperature is 750-900℃, and the annealing time is 10-60 min; the washing solution includes a mixed solution of ammonium chloride and methanol.

2. The method for preparing rare-earth high-frequency soft magnetic materials as described in claim 1, characterized in that, The method for preparing RE(OH)3 of the metal precursor mixture is as follows: dissolve RECl3 in deionized water, add sodium hydroxide solution with a concentration of 3-5 mol / L, heat under reflux, wash and dry to obtain RE(OH)3 of the metal precursor mixture; the RECl3 includes at least one of NdCl3, CeCl3, YCl3 and PrCl3.

3. The method for preparing rare-earth high-frequency soft magnetic materials as described in claim 1, characterized in that, The high-energy ball milling time is 1 to 3 hours.

4. The method for preparing rare-earth high-frequency soft magnetic materials as described in claim 2, characterized in that, The temperature of the heating reflux is 30℃~100℃.

5. The method for preparing rare-earth high-frequency soft magnetic materials as described in claim 1, characterized in that, The molar ratio of the metal precursor mixture to the reducing agent is metal precursor mixture: reducing agent = 1:(1~2).

6. The method for preparing rare-earth high-frequency soft magnetic materials as described in claim 1, characterized in that, The molar ratio of Co(OH)2 to RE(OH)3 in the metal precursor mixture is RE(OH)3:Co(OH)2 = 2:

17.

7. The application of the method for preparing rare earth high-frequency soft magnetic materials as described in any one of claims 1 to 6 in the fields of high-frequency magnetic devices and communications.

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