A poor iron manganese zinc ferrite material and a method for producing the same

Abstract

The application provides a kind of lean iron manganese zinc ferrite material and its preparation method, belong to magnetic material technical field.The main component of the lean iron manganese zinc ferrite material includes 48-49 mol% of Fe2O3, 17-18 mol% of ZnO, and the balance is MnO;Auxiliary components include one or more of CaCO3, Co2O3;The Curie temperature Tc of the lean iron manganese zinc ferrite, two-peak temperature Tsp and Fe2O 3 And the content of ZnO meets the relevant formula respectively, the initial magnetic permeability of preparation is more than 4000, the Curie temperature of DC bias drop D L ≤10% is greater than 150 DEG C, and the two-peak temperature is greater than 150 DEG C;The application can quickly determine the main component content based on the Curie temperature and two-peak temperature by exploring the relationship between the main component and the Curie temperature of lean iron manganese zinc ferrite material, two-peak temperature, and the relationship between the auxiliary component and the main component content is proposed, which can be used to guide the formula design, and further combined with preparation process control, the lean iron manganese zinc ferrite material with high Curie temperature, high magnetic permeability and low drop can be obtained.

Description

Technical Field

[0001] This invention relates to the field of magnetic materials technology, specifically to a low-iron-manganese-zinc ferrite material and its preparation method. Background Technology

[0002] High-impedance manganese-zinc materials, as a new era of functional materials, have been widely used in communications, new energy vehicles, office automation equipment, and consumer electronics. With the advancement of technology, the electromagnetic interference (EMI) problem of products has received increasing attention, and the most effective solution is electromagnetic compatibility (EMC) design. Currently, the three common EMC design methods are grounding, shielding, and filtering. Among these three technologies, filtering is currently the most common, effective, and economical means of suppressing EMC, thus requiring a large amount of anti-EMI materials.

[0003] Currently, commonly used electromagnetic interference suppression materials include manganese-zinc ferrite and nickel-zinc ferrite. Compared with nickel-zinc ferrite, manganese-zinc ferrite has lower production costs, higher low-frequency impedance and permeability, lower power consumption, and better stability, meeting the contemporary product design trend towards lighter, thinner, shorter, and smaller designs. In recent years, patent document CN101857426A discloses a broadband high-impedance MnZn ferrite material with a DC resistivity greater than 103 Ω·m, a Curie temperature greater than 115℃, and an initial permeability of 2000; CN111138179A discloses a broadband high-impedance manganese-zinc ferrite material with a Curie temperature greater than 210℃ and an initial permeability of 650; CN110156451A discloses a high-impedance iron-poor manganese-zinc ferrite material with a Curie temperature greater than 160℃ and an initial permeability of 2500; and CN112142457A discloses a broadband high-permeability high-impedance manganese-zinc ferrite material. The Curie temperature is greater than 130℃ and the initial permeability is 4000. CN116891378A discloses a lean iron manganese zinc ferrite material with a Curie temperature greater than 170℃, an initial permeability of 500-1000, and an inductance DC bias drop DL≤15%. However, the main formulation of these materials requires a large number of DOE tests and calculations, which is a complex and tedious process. In practical applications, it was found that the high permeability and high Curie temperature characteristics of these materials cannot be satisfied at the same time. Moreover, after DC bias or equivalent operation, there is a large inductance drop that cannot be recovered on its own, which greatly limits the application of lean iron manganese zinc materials. Summary of the Invention

[0004] Based on extensive practical research, this application explores the relationship between Curie temperature, second peak temperature and the main components of ferrite materials, and provides a lean iron-manganese-zinc ferrite material and its preparation method. This lean iron-manganese-zinc ferrite material can have an initial permeability of over 4000, a Curie temperature of over 150℃, and a DC bias reduction DL ≤ 10% at room temperature.

[0005] To achieve the above objectives, the technical solution provided by the present invention is as follows: In a first aspect, the present invention provides a lean iron-manganese-zinc ferrite material, wherein the raw materials for preparing the lean iron-manganese-zinc ferrite material include a main component and auxiliary components, wherein the main component includes 48-49 mol% Fe2O3, 17-18 mol% ZnO, and the balance is MnO; the auxiliary components include one or more of CaCO3 and Co2O3; the Curie temperature Tc, the second peak temperature Tsp, and the contents of Fe2O3 and ZnO of the lean iron-manganese-zinc ferrite respectively satisfy the following: Tc=6.475×(Fe2O3mol%-2 / 3×ZnO mol%)-83.1; Tsp=4411-83×Fe2O3mol% -2 ZnO mol%.

[0006] The auxiliary components, by weight of each component in the preparation raw materials, respectively satisfy the following conditions: CaCO3= (10200-200×Fe2O3mol%)ppm; Co2O3= (30000-1000×ZnO mol%)ppm.

[0007] Preferably, the impurity content of the main component is less than 1 wt%.

[0008] Preferably, the auxiliary components account for 1.24-1.36 wt% of the total weight of the raw materials used in the preparation.

[0009] Preferably, the Tc of the iron-poor manganese-zinc ferrite material is greater than 150°C.

[0010] Preferably, the initial permeability of the iron-poor manganese-zinc ferrite material is ≥4000; the DC bias at room temperature reduces the drop in magnetic flux density (D). L ≤10%.

[0011] In another aspect, the present invention provides a method for preparing the aforementioned iron-poor manganese-zinc ferrite material, comprising the following steps: (1) Formulation design: First, set the Curie temperature Tc and the second peak temperature Tsp. The formula is: Tc = 6.475 × (Fe₂O₃ mol% - 2 / 3 × ZnO mol%) - 83.1. Tsp=4411-83× Fe2O3mol% -2 ZnO mol%, 48mol% ≤ Fe2O3mol% ≤49 mol%, 17mol% ≤ ZnO mol% ≤18 mol%; The content of the main component is calculated; then, the dosage of the auxiliary component is calculated according to CaCO3 = (10200-200 × Fe2O3 mol%)ppm and Co2O3 = (30000-1000 ZnO mol%)ppm; finally, the materials are prepared according to the calculation results. (2) First-stage milling: The main component, water, and additives (such as dispersants, defoamers, etc.) are mixed to obtain an intermediate product; (3) Pre-calcination: The intermediate product is pre-calcined to obtain the crude product; (4) Secondary ball milling: Add auxiliary components and water to the crude product and ball mill to obtain a slurry; (5) Granulation: Dry the above slurry and add glue to granulate; (6) Molding: The granulated product from (4) is pressed into shape; (6) Sintering: The product formed in (5) is sintered to obtain the final product.

[0012] In step (1), the second peak temperature Tsp is not limited. The main purpose is to make the initial permeability greater than 4000. It can be selected based on experience. For example, in some embodiments, the second peak temperature can be between 300-400℃. As for the Curie temperature, since the desired Curie temperature is as high as possible, it is preferred that in step (1), Tc > 150℃. Preferably, in step (1), the impurity content of the main component is less than 1 wt%.

[0013] Preferably, in step (1), the auxiliary components account for 1.24-1.36 wt% of the total weight of the raw materials.

[0014] Preferably, in step (2), the mixing is carried out by stirring; more preferably, the stirring speed is 800-1200 rpm and the time is 20-40 min.

[0015] Preferably, in step (3), the pre-firing temperature is 780-820℃.

[0016] Preferably, in step (4), the average particle size of the slurry is 0.8-1.2 μm.

[0017] Preferably, in step (4), the ball milling speed is 200-400 rpm.

[0018] Preferably, in step (4), the ball milling time is 40-60 min.

[0019] Preferably, in step (7), a balanced oxygen atmosphere is used for sintering, and the oxygen partial pressure control mode relationship during the sintering process is: LogP O2 =AB / T; where T is the absolute temperature; A takes the value of 8-9, and B takes the value of 13400-13500.

[0020] Preferably, in step (7), the sintering temperature is T = 1490-10 ZnO mol% ℃.

[0021] Compared with the prior art, the advantages of the present invention are as follows: By exploring the relationship between the main components and Curie temperature and second-peak temperature of lean iron-manganese-zinc ferrite materials, the main components of lean iron-manganese-zinc ferrites were rapidly determined based on the Curie temperature and second-peak temperature. At the same time, the relationship between the content of auxiliary components and main components was proposed to guide the formulation design of lean iron-manganese-zinc ferrites with high Curie temperature, high permeability and low drop. Furthermore, by combining the control of the preparation process, especially the sintering atmosphere and temperature, the resulting lean iron-manganese-zinc ferrite materials have a high initial permeability of over 4000, a Curie temperature of over 150℃, and a DC bias drop reduction (DL) of ≤10% at room temperature. Attached Figure Description

[0022] Figure 1 The results of temperature permeability testing of the iron-manganese-zinc ferrite in this embodiment of the invention; Figure 2 The results of the dispersion loss test of the iron-manganese-zinc ferrite in the embodiment of the present invention; Figure 3 The high-frequency impedance test results of the iron- and manganese-zinc ferrite in this embodiment of the invention; Figure 4 Magnetization curves of the iron-depleted manganese-zinc ferrite at different temperatures in embodiments of the present invention; Figure 5 The results of incremental permeability testing of the iron-poor manganese-zinc ferrite in this embodiment of the invention are shown. Detailed Implementation

[0023] The following description, in conjunction with specific embodiments, illustrates the points. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by the present invention.

[0024] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0025] Example 1 Referring to Table 1, this embodiment provides a lean iron-manganese-zinc ferrite material, the preparation method of which includes the following steps: (1) Formulation design First, set Tc=154, Tsp=393, and solve the Curie temperature formula: Tc=6.475×(Fe2O3mol%-2 / 3×ZnOmol%)-83.1 and the second peak temperature formula: Tsp=4411-83×Fe2O3mol%-2ZnOmol% to obtain: the main components include: 48mol% Fe2O3, 17mol% ZnO, and the balance is MnO.

[0026] Then the contents of auxiliary components were calculated: CaCO3 was (10200-200 × Fe2O3 mol%) = 600 ppm; Co2O3 was (30000-1000 ZnO mol%) = 13000 ppm, and the auxiliary components accounted for 1.24 wt% of the MnZn material.

[0027] Control the impurity content of the main component to be less than 1 wt%, and prepare the raw materials for the main component and auxiliary components according to the above results.

[0028] (2) The main components, water, and magnetic material special dispersant (model BWY-507) (mass ratio of the three is 49:49:2) are mixed and ground in a sand mill at a speed of 1000 rpm for 30 min to obtain an intermediate product; (3) The intermediate product was transferred into a muffle furnace for pre-calcination for 2.5 h at a pre-calcination temperature of 800 °C to obtain the crude product; (4) Place the crude product in a ball mill and add auxiliary components according to the above mass fraction, then ball mill at a speed of 350 rpm for 48 min to obtain a slurry with an average particle size of 1 ± 0.1 μm. (5) Dry the slurry and add 8% of the powder weight of glue for granulation; (6) The granulated product is pressed into shape to obtain a standard sample green body of 25 mm × 15 mm × 8 mm. (7) The pressed sample green body is arranged and placed in a bell furnace for sintering under a balanced oxygen atmosphere: the sintering temperature is T=1490-10 ZnO mol% ℃=1320℃; the oxygen content is controlled by the balanced oxygen partial pressure method during the cooling process, and the oxygen content is determined according to the balanced oxygen partial pressure formula LogPO2= AB / T (T is the absolute temperature): A is 8.55 and B is 13436.

[0029] Example 2 Referring to Table 1, this embodiment provides a lean iron-manganese-zinc ferrite material. First, Tc = 161, Tsp = 310. The Curie temperature formula is: Tc = 6.475 × (Fe₂O₃ mol% - 2 / 3 × ZnO mol%) - 83.1, and the second peak temperature formula is: Tsp = 4411 - 83 × Fe₂O₃ mol% - 2 ZnO mol%. The main components consist of 49 mol% Fe₂O₃, 17 mol% ZnO, and the balance is MnO. The impurity content of the main components is less than 1 wt%. The auxiliary components account for 1.24 wt% of the MnZn material. Specifically, the auxiliary components are: CaCO₃ (10200 - 200 × Fe₂O₃ mol%) = 400 ppm; Co₂O₃ (30000 - 1000 ZnO mol%) = 13000 ppm.

[0030] The preparation method of this material includes the following steps: (1) The main components, water, and magnetic material special dispersant (model BWY-507) (mass ratio of the three is 49:49:2) are mixed and ground in a sand mill at a speed of 1000 rpm for 30 min to obtain an intermediate product; (2) The intermediate product was transferred into a muffle furnace for pre-calcination for 2.5 h at a pre-calcination temperature of 800 °C to obtain the crude product; (3) Place the crude product in a ball mill and add auxiliary components according to the above mass fraction, then ball mill at a speed of 350 rpm for 48 min to obtain a slurry with an average particle size of 1±0.1 μm. (4) Dry the slurry and add 8% of the powder weight of glue for granulation; (5) The granulated product is pressed into shape to obtain a standard sample green body of 25 mm × 15 mm × 8 mm. (6) The pressed sample green body is arranged and placed in a bell furnace for sintering under a balanced oxygen atmosphere: the sintering temperature is T=1490-10 ZnO mol% ℃=1320℃; the oxygen content is controlled by the balanced oxygen partial pressure method during the cooling process, and the oxygen content is determined according to the balanced oxygen partial pressure formula LogPO2= AB / T (T is the absolute temperature): A is 8.55 and B is 13436.

[0031] Example 3 Referring to Table 1, this embodiment provides a lean iron-manganese-zinc ferrite material. First, Tc = 150, Tsp = 391. The Curie temperature formula is: Tc = 6.475 × (Fe₂O₃ mol% - 2 / 3 × ZnO mol%) - 83.1, and the second peak temperature formula is: Tsp = 4411 - 83 × Fe₂O₃ mol% - 2 ZnO mol%. The resulting material contains: 48 mol% Fe₂O₃, 18 mol% ZnO, with the balance being MnO. The impurity content of the main components is less than 1 wt%. The auxiliary components account for 1.36 wt% of the MnZn material. Specifically, the auxiliary components are: CaCO₃ (10200 - 200 × Fe₂O₃ mol%) = 600 ppm; Co₂O₃ (30000 - 1000 ZnO mol%) = 12000 ppm.

[0032] The preparation method of this material includes the following steps: (1) The main components, water, and magnetic material special dispersant (model BWY-507) (mass ratio of the three is 49:49:2) are mixed and ground in a sand mill at a speed of 1000 rpm for 30 min to obtain an intermediate product; (2) The intermediate product was transferred into a muffle furnace for pre-calcination for 2.5 h at a pre-calcination temperature of 800 °C to obtain the crude product; (3) Place the crude product in a ball mill and add auxiliary components according to the above mass fraction, then ball mill at a speed of 350 rpm for 48 min to obtain a slurry with an average particle size of 1±0.1 μm. (4) Dry the slurry and add 8% glue by weight of powder for granulation; (5) The granulated product is pressed into shape to obtain a standard sample green body of 25 mm × 15 mm × 8 mm. (6) The pressed sample green body is arranged and placed in a bell furnace for sintering under a balanced oxygen atmosphere: the sintering temperature is T=1490-10 ZnO mol% ℃=1310℃; the oxygen content is controlled by the balanced oxygen partial pressure method during the cooling process, and the oxygen content is determined according to the balanced oxygen partial pressure formula LogPO2= AB / T (T is the absolute temperature): A is 8.55 and B is 13436.

[0033] Example 4 Referring to Table 1, this embodiment provides a lean iron-manganese-zinc ferrite material. First, Tc = 157, Tsp = 308. The Curie temperature formula is: Tc = 6.475 × (Fe₂O₃ mol% - 2 / 3 × ZnO mol%) - 83.1, and the second peak temperature formula is: Tsp = 4411 - 83 × Fe₂O₃ mol% - 2 ZnO mol%. The main components consist of 48 mol% Fe₂O₃, 18 mol% ZnO, and the balance is MnO. The impurity content of the main components is less than 1 wt%. The auxiliary components account for 1.36 wt% of the MnZn material. Specifically, the auxiliary components are: CaCO₃ (10200 - 200 × Fe₂O₃ mol%) = 400 ppm; Co₂O₃ (30000 - 1000 ZnO mol%) = 12000 ppm.

[0034] The preparation method of this material includes the following steps: (1) The main components, water, and magnetic material special dispersant (model BWY-507) (mass ratio of the three is 49:49:2) are mixed and ground in a sand mill at a speed of 1000 rpm for 30 min to obtain an intermediate product; (2) The intermediate product was transferred into a muffle furnace for pre-calcination for 2.5 h at a pre-calcination temperature of 800 °C to obtain the crude product; (3) Place the crude product in a ball mill and add auxiliary components according to the above mass fraction, then ball mill at a speed of 350 rpm for 48 min to obtain a slurry with an average particle size of 1±0.1 μm. (4) Dry the slurry and add 8% glue by weight of powder for granulation; (5) The granulated product is pressed into shape to obtain a standard sample green body of 25 mm × 15 mm × 8 mm. (6) The pressed sample green body is arranged and placed in a bell furnace for sintering under a balanced oxygen atmosphere: the sintering temperature is T=1490-10 ZnO mol% ℃=1310℃; the oxygen content is controlled by the balanced oxygen partial pressure method during the cooling process, and the oxygen content is determined according to the balanced oxygen partial pressure formula LogPO2= AB / T (T is the absolute temperature): A is 8.55 and B is 13436.

[0035] Comparative Example 1 Referring to Table 1, the main components and preparation methods of Comparative Example 1 and Example 1 are the same. The only difference is that the components of Comparative Example 1 include CaCO3 at 700 ppm and Co2O3 at 14000 ppm.

[0036] Comparative Example 2 Referring to Table 1, Comparative Example 2 and Example 2 have the same component types and preparation methods. The only difference is that Comparative Example 2 sets Tc=166, Tsp=270. The Curie temperature formula is: Tc=6.475×(Fe2O3mol%-2 / 3×ZnO mol%)-83.1 and the two-peak temperature formula is: Tsp=4411-83×Fe2O3mol%-2ZnO mol%. The result is: 49.5 mol% Fe2O3 as the main component, 16.5 mol% ZnO as the main component, and the balance is MnO.

[0037] Comparative Example 3 Referring to Table 1, Comparative Example 3 and Example 3 have the same component types and preparation methods. The only difference is that Comparative Example 3 sets Tc=145, Tsp=432. The Curie temperature formula is: Tc=6.475×(Fe2O3mol%-2 / 3×ZnO mol%)-83.1 and the two-peak temperature formula is: Tsp=4411-83×Fe2O3mol%-2ZnO mol%. The result is: 47.5 mol% Fe2O3 as the main component, 18.5 mol% ZnO as the main component, and the balance is MnO.

[0038] Comparative Example 4 Referring to Table 1, the main components and preparation methods of Comparative Example 4 and Example 4 are the same. The only difference is that the components of Comparative Example 3 include CaCO3 at 300 ppm and Co2O3 at 11000 ppm.

[0039] Table 1 Formulations of Examples and Comparative Examples

[0040] The inductance L1 of the sample was measured at 10 kHz and 25 °C using an Agilent-4284A precision LCR instrument, and the initial permeability μ of the sample was calculated. i At a Curie temperature Tc of 10 kHz, the sample magnetic ring was subjected to a 10 A DC bias test using an Agilent-4284A precision LCR instrument with a TH1778AS DC bias source. The inductance L2 of the sample magnetic ring at 10 kHz and 25 °C was then directly measured, and the DC bias reduction D was calculated. L =(L1-L2) / L1.

[0041] The test results are shown in Table 2.

[0042] Table 2 Performance test data for the examples and comparative examples

[0043] Table 2 shows that in the illustrated embodiments, the components of Examples 1-4 are all within the scope defined by this invention, and the material performance indicators fully meet the standards. This is because the composition is the basis of MnZn ferrite materials. For materials, the composition basically determines the magnetic permeability and Curie temperature. The level of magnetic permeability depends partly on the amount of ZnO in the main formula. From the Curie temperature formula: Tc=6.475×(Fe2O3-2 / 3×ZnO)-83.1 and the second peak temperature formula: Tsp=4411-83×Fe2O3-2ZnO, we know that the levels of Curie temperature and second peak temperature simultaneously determine the amounts of Fe2O3 and ZnO in the composition. However, in Comparative Examples 2-3, the Fe2O3 and ZnO contents exceed the scope defined by this invention, resulting in a lower Curie temperature in Comparative Example 3 and a lower magnetic permeability in Comparative Example 2, which do not meet the target requirements. In Comparative Examples 1 and 4, the Ca content exceeds the scope defined by this invention. 2+ Co 2+ Exceeding the limits of CaCO3=(10200-200 ×Fe2O3mol%)ppm and Co2O3=(30000-1000 ZnO mol%)ppm leads to a mismatch between the auxiliary components and the main components of the material. This causes K1, λ and σ to tend to increase, and the final result is a significant decrease in the initial permeability, which does not meet the target requirement of high initial permeability.

[0044] Figure 1-5 The paper illustrates the performance test indicators of lean iron manganese zinc ferrite materials according to some typical embodiments of the present invention. Figure 1 The temperature permeability test results of some embodiments of the present invention show that the iron-poor manganese-zinc ferrite material prepared in the embodiments of the present invention has a Curie temperature ≥150℃, an initial permeability μi>4000, and high permeability from room temperature to 140℃, and outstanding high temperature resistance. Figure 2 These are the dispersion loss test results of some embodiments of the present invention; Figure 3 These are high-frequency impedance test results for some embodiments of the present invention; Figure 4 The magnetization curves of some embodiments of the present invention at different temperatures show that the iron-poor manganese-zinc ferrite material of the present invention has a Bs≈420mT at room temperature, and the saturation magnetic flux decreases at high temperature. Figure 5 The incremental permeability test results of some embodiments of the present invention show that the iron-poor manganese-zinc ferrite of the present invention has good resistance to DC bias below 10A.

[0045] In summary, this invention explores the relationship between the main components and Curie temperature and second-peak temperature of lean iron-manganese-zinc ferrite materials. Based on the Curie temperature and second-peak temperature, the main components of lean iron-manganese-zinc ferrites can be quickly determined. At the same time, the relationship between the content of auxiliary components and main components is proposed, which can be used together to guide the formulation design of lean iron-manganese-zinc ferrites. Furthermore, combined with the control of the preparation process, especially the sintering atmosphere and temperature, the resulting lean iron-manganese-zinc ferrite materials have a high initial permeability of over 4000, a Curie temperature of over 150°C, and a DC bias reduction DL ≤ 10% at room temperature.

[0046] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

[0047] The above description is merely a preferred embodiment of the present invention. It should not be construed as limiting the scope of the invention; any simple equivalent changes and modifications made to the content described in the claims and specification of the present invention shall still fall within the scope of the claims. Furthermore, the abstract and headings are merely for assisting in patent document searching and are not intended to limit the scope of the present invention.

Claims

1. A lean iron-manganese-zinc ferrite material, characterized in that: The raw materials for preparing the lean iron-manganese-zinc ferrite material include main components and auxiliary components. The main components include 48-49 mol% Fe₂O₃, 17-18 mol% ZnO, and the balance being MnO. The auxiliary components include one or more of CaCO₃ and Co₂O₃. The Curie temperature Tc and the second peak temperature Tsp of the lean iron-manganese-zinc ferrite, along with the contents of Fe₂O₃ and ZnO, respectively satisfy the following conditions: Tc=6.475×(Fe2O3 mol%-2 / 3×ZnO mol%)-83.1; Tsp=4411-83×Fe2O3 mol% -2 ZnO mol%; The auxiliary components, by weight of each component in the preparation raw materials, respectively satisfy the following conditions: CaCO3= (10200-200×Fe2O3 mol%)ppm; Co2O3 = (30000-1000×ZnO mol%)ppm.

2. The lean iron manganese zinc ferrite material according to claim 1, characterized in that: The impurity content of the main component is less than 1 wt%; And / or, the auxiliary components account for 1.24-1.36 wt% of the total weight of the raw materials used in the preparation.

3. The lean iron-manganese-zinc ferrite material according to claim 1, characterized in that: The Tc of the aforementioned iron-manganese-zinc ferrite material is greater than 150℃.

4. The lean iron manganese zinc ferrite material according to claim 1, characterized in that: The initial permeability of the iron-manganese-zinc ferrite material is ≥4000; the DC bias at room temperature reduces the drop in magnetic flux density (D). L ≤10%.

5. A method for preparing a lean iron-manganese-zinc ferrite material, characterized in that, Includes the following steps: (1) Formulation design: First, set the Curie temperature Tc and the second peak temperature Tsp. The formula is: Tc = 6.475 × (Fe₂O₃ mol% - 2 / 3 × ZnO mol%) - 83.

1. Tsp=4411-83× Fe2O3 mol% -2 ZnO mol%, 48mol% ≤ Fe2O3 mol% ≤49 mol%, 17mol% ≤ ZnO mol% ≤18 mol%; The content of the main component is calculated; then, the dosage of the auxiliary component is calculated according to CaCO3 = (10200-200 × Fe2O3 mol%)ppm and Co2O3 = (30000-1000 ZnO mol%)ppm; finally, the materials are prepared according to the calculation results. (2) First-time milling: The main component, water, and additives are mixed to obtain an intermediate product; (3) Pre-calcination: The intermediate product is pre-calcined to obtain the crude product; (4) Secondary ball milling: Add auxiliary components and water to the crude product and ball mill to obtain a slurry; (5) Granulation: Dry the above slurry and add glue to granulate; (6) Molding: The granulated product from (5) is pressed into shape; (7) Sintering: The product formed in (6) is sintered to obtain the final product.

6. The preparation method according to claim 5, characterized in that, In step (1), Tc > 150℃; And / or, the impurity content of the main component is less than 1 wt%; And / or, the auxiliary components account for 1.24-1.36 wt% of the total weight of the raw materials used in the preparation.

7. The preparation method according to claim 5, characterized in that, In step (2), the mixing is carried out by stirring; preferably, the stirring speed is 800-1200 rpm and the time is 20-40 min.

8. The preparation method according to claim 5, characterized in that, In step (4), the average particle size of the slurry is 0.8-1.2 μm; And / or, the ball milling speed is 200-400 rpm; And / or, the ball milling time is 40-60 min.

9. The preparation method according to claim 5, characterized in that, In step (7), sintering is performed using a balanced oxygen atmosphere. The oxygen partial pressure control mode relationship during the sintering process is: LogP O2 =AB / T; where T is the absolute temperature; A takes the value of 8-9, and B takes the value of 13400-13500.

10. The preparation method according to claim 5, characterized in that, In step (7), the sintering temperature is T = 1490 - 10 × ZnO mol% ℃.

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