BaM ferrite material based on common substitution of samarium and copper and preparation method of BaM ferrite material

Abstract

The invention discloses a BaM ferrite material based on common substitution of samarium and copper and a preparation method thereof, and belongs to the technical field of ferrite materials, the molecular formula of the ferrite material is Ba < 1-x > Sm < x > Fe < 12-x > Cu < x > O19, x is more than 0 and less than or equal to 0.25, and a preparation method combining a wet solid-phase reaction method and magnetic field orientation is adopted. The preparation method comprises the following specific steps: proportioning according to a reaction formula, carrying out primary ball milling, drying, sieving, pre-sintering, adding 8wt% of a sodium polynaphthalene sulfonate dispersing agent, carrying out secondary ball milling, orienting and sintering. According to the invention, the magnetic performance of the ferrite is adjusted by adding different amounts of substitutes, the remanence ratio of all materials is greater than 0.5, which indicates that the ferrite has a single domain or quasi-single domain state, and when the substitution amount x is 0.10, the material obtains the remanence ratio of 0.83. High-frequency ferromagnetic resonance linewidth measurement is carried out on the material, and it is found that the material has the low linewidth of 800 Oe in the 55GHz frequency band.

Description

Technical Field

[0001] This invention relates to the field of ferrite materials technology, and in particular to a BaM ferrite material based on samarium and copper co-substitution and its preparation method. Background Technology

[0002] With the continuous evolution of 5G mobile communication technology, low-orbit satellite internet, and autonomous driving vehicle radar systems towards the millimeter-wave band, the radio frequency front-end places more stringent demands on the high-frequency performance and integration of core non-reciprocal components such as circulators. Traditional circulators based on garnet or spinel ferrite, due to their low magnetocrystalline anisotropy field, must rely on bulky external permanent magnets to provide the necessary bias magnetic field in the millimeter-wave band. This has become a fundamental obstacle to achieving miniaturization, low power consumption, and high reliability in the system.

[0003] In this context, M-type hexagonal ferrites (such as BaFe) 12 O 19 SrFe 12 O 19 With its strong uniaxial magnetocrystalline anisotropy field of up to 1.7T, it exhibits unique self-biasing characteristics, providing an ideal material platform for realizing millimeter-wave circulators with no permanent magnets and high temperature stability. However, its inherent high anisotropy field, while granting high-frequency self-biasing capability, also leads to excessively high ferromagnetic resonance frequencies, making it difficult to effectively cover and optimize performance in key millimeter-wave windows such as Ka-band (26.5-40GHz) and even U-band (40-60GHz). To solve this high-frequency adaptability problem, Co... 2+ -Ti 4+ Zn 2+ -Zr 4+ Plasma against Fe 3+ Selective doping has become a core technical means to precisely control its high-frequency magnetic properties: this strategy can finely adjust the anisotropic field of the magnetocrystalline structure without significantly sacrificing the saturation magnetization, thereby "customizing" its ferromagnetic resonance frequency in a specific millimeter-wave band; at the same time, doping effectively optimizes the gyromagnetic properties and remanence ratio of the material, which is directly related to the reduction of insertion loss and the improvement of isolation of the millimeter-wave circulator.

[0004] Therefore, the profound significance of ion doping M-type hexagonal ferrite lies in transforming this high-performance material from a "candidate" with fixed properties into an "engineering material" with designable and optimizable performance in the millimeter-wave band, providing a key material solution for overcoming the technical bottlenecks of future millimeter-wave integrated radio frequency front-ends. Summary of the Invention

[0005] One of the objectives of this invention is to provide a BaM ferrite material based on samarium and copper co-substitution to solve the above-mentioned problems.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A BaM ferrite material based on samarium and copper co-substituted ferrite, wherein the molecular formula of the ferrite material is: Ba 1- x Sm x Fe 12-x Cu x O 19 , where 0 < x ≤ 0.25.

[0007] Compared to Chinese patent application CN109206131A, which uses Sm-doped material... 3+ and Cu 2+ Combined substitution of Sr in strontium ferrite 2 + and Fe 3+ This invention uses a barium ferrite matrix: First, barium ions (Ba 2+ It has a larger ionic radius, and its lattice sites are larger trivalent rare earth ions, samarium (Sm). 3+ The substitution provides a more relaxed and compatible crystal environment. This substitution can more effectively introduce lattice distortion and enhance magnetocrystalline anisotropy, thereby providing a structural basis for improving coercivity, a key permanent magnetic property, and avoiding phase instability caused by excessive lattice mismatch.

[0008] Secondly, in this invention, copper ions (Cu) 2+ ) for iron position (Fe 3+ The substitution of strontium ferrite with copper ions aims to optimize intrinsic magnetism through the modulation of valence state and magnetic moment. The crystal field environment of the barium ferrite matrix differs subtly from that of strontium ferrite, and its interaction with copper ions is more conducive to promoting densification and grain refinement during sintering, while effectively suppressing abnormal grain growth. This creates favorable conditions for achieving the uniform, fine-grained microstructure necessary for high coercivity.

[0009] This invention selects barium ferrite as the matrix based on its deep synergistic effect with the specific doping strategies of "Sm-Ba site substitution" and "Cu-Fe site substitution". This method can more fully utilize the compatibility advantage of large-radius Ba sites with rare-earth doping, and combine it with its unique crystal field environment to optimize the microstructure control effect of transition metal doping. This synergistically improves the material's magnetocrystalline anisotropy and coercivity while ensuring structural stability and process feasibility. This overcomes the limitations of dopant ion solid solubility and microstructure control that may be encountered when simply pursuing strontium ferrite as the matrix, providing a unique and efficient technical path for realizing high-performance ferrite permanent magnet materials.

[0010] As the preferred technical solution, x=0.1.

[0011] The second objective of this invention is to provide a method for preparing the aforementioned BaM ferrite material based on samarium and copper co-substitution, the technical solution of which includes the following steps: S1. Ingredients: BaCO3, Sm2O3, Fe2O3, and CuO are selected as raw materials, according to the molecular formula Ba 1-x Sm x Fe 12-x Cu x O 19 Perform calculations and accurately weigh the ingredients; S2. First ball milling: Mix the weighed ingredients from step S1 with deionized water and perform a first ball milling. After the ball milling is completed, a first ball milling slurry is obtained. S3. Pre-calcination: The slurry obtained after ball milling in step S2 is dried, sieved, and placed in a high-temperature box furnace. It is heated and kept at a temperature in air atmosphere, and then cooled to room temperature with the furnace to obtain pre-calcined powder. S4. Add sintering aid: Weigh the pre-sintered powder obtained in step S3 and add 8wt% sodium polynaphthalene sulfonate dispersant for mixing and batching; S5. Secondary ball milling: Mix the weighed ingredients from step S4 with a measured amount of deionized water and perform secondary ball milling. After the ball milling is completed, a secondary ball milling slurry is obtained. S6. Orientation pressing of green body: The slurry obtained in step S5 is poured into a mold and pressed into a cylindrical green body under pressure. At the same time, a magnetic field parallel to the pressure is applied to magnetize the single-domain particles and orient them in the direction of the external magnetic field. S7. Sintering: The cylindrical green billet obtained in step S6 is placed in a high-temperature box furnace for sintering. The temperature is raised and held in an air atmosphere, and then cooled to room temperature with the furnace.

[0012] The synthesis method of this invention is novel. First, the main components and substitutes are mixed evenly and ball-milled once. After drying, they are pre-fired in a box furnace at a suitable temperature of 1200℃ for 4 hours. Then, the material is weighed and a dispersant of 8wt% of the pre-fired powder is added. The mixture is then ball-milled a second time. The resulting slurry is poured into a mold and pressed into a cylindrical green body while a magnetic field parallel to the pressure is applied. Finally, a suitable sintering temperature of 1000℃ is selected and the holding time is 4 hours to prepare BaM hexagonal ferrite with high remanence ratio and low ferromagnetic resonance linewidth.

[0013] This invention synthesizes a new BaCO3 compound with high remanence and low ferromagnetic resonance linewidth by ball milling a mixture of main ingredients (BaCO3, Fe2O3) and substitutes (Sm2O3, CuO) for 12 hours, pre-calcining at a suitable temperature (1200℃), adding a dispersant of a certain mass fraction of the pre-calcined powder, ball milling for another 24 hours, and finally sintering at a suitable temperature (1000℃). 0.9 Sm 0.1 Fe 11.9 Cu 0.1 O 19 Ferrite materials; their remanence ratio can reach 0.83, and their DH is as low as 800 Oe.

[0014] As a preferred technical solution: In step S2, the mass of the added deionized water is 150% to 250% of the raw material, and the ball milling is carried out at a speed of 300 r / min for 12 hours.

[0015] As a preferred technical solution: In step S3, the temperature is increased to 1200℃ at a rate of 2-5℃ / min, and the holding time is 4h.

[0016] As a preferred technical solution: in step S4, the added dispersant accounts for 8wt% to 10% of the pre-calcined powder.

[0017] As a preferred technical solution: In step S5, the mass of the added deionized water is 150% to 250% of the raw material, and the secondary ball milling is carried out at a speed of 500 r / min for 24 hours.

[0018] As a preferred technical solution: in step S6, the magnetic field strength during pressing is 10 kOe and the molding pressure is 4 MPa.

[0019] As a preferred technical solution: In step S7, the temperature is increased to 1000℃ at a rate of 2-5℃ / min, and the holding time is 4h.

[0020] Compared with existing technologies, the advantages of this invention are as follows: By substituting appropriate amounts of Sm and Cu ions, the invention solves the problems of low remanence and large ferromagnetic resonance lines found in existing technologies. First, the main material and the substituents are mixed and ball-milled once. After ball milling, the mixture is dried and pre-fired at a suitable pre-fired temperature. Then, the pre-fired material is weighed and mixed with sintering aids and dispersants. After pre-fired, it is ball-milled a second time. The slurry is then poured into a mold for orientation and pressed into a cylindrical shape. Finally, sintering is performed at a suitable temperature, successfully preparing Ba with excellent gyromagnetic properties and high remanence. 0.9 Sm 0.1 Fe 11.9 Cu 0.1 O 19 Ferrite materials can achieve a remanence ratio of up to 0.83 and a DH as low as 800 Oe. Attached Figure Description

[0021] Figure 1 The images show the XRD patterns of the ferrite materials prepared in Examples 1-6 of this invention. Figure 2 The remanence ratio trend diagrams are shown for the ferrite materials prepared in Examples 1-6 of this invention. Figure 3 SEM images of the ferrite materials prepared in Examples 1-6 of this invention; Figure 4 The image shows the linewidth fitting diagram of the ferrite material prepared in Example 3 of this invention at frequencies of 50–65 GHz. Detailed Implementation

[0022] To explain the technical content, objectives, and effects of the present invention in detail, the following specific embodiments further illustrate the content of the present invention. However, the content of the present invention is far more than the following embodiments.

[0023] Example 1 A method for preparing a BaM ferrite material based on samarium and copper co-substituted materials includes the following steps: S1. Ingredients: According to Ba 1-x Sm x Fe 12-x Cu x O 19 Weigh out the molecular formulas: BaCO3, Fe2O 3， Sm₂O₃, CuO, substitution amount x = 0.00; S2. First ball milling: Add the raw material weighed in step S1 to 200% of the raw material mass of deionized water and perform a first ball milling for 12 hours; S3. Pre-calcination: After taking the material, dry it in an oven at 100℃. After drying, sieve it through a 45-mesh sieve. Put the sieved powder into a sintering furnace, heat it to 1200℃ at a rate of 2-5℃ / min and keep it at that temperature for 4 hours. Then let it cool naturally to room temperature to obtain the pre-calcined material. S4. Secondary batching: Add 8 wt% sodium polynaphthalene sulfonate dispersant to the pre-burned material obtained in step S3 to reduce agglomeration effect; S5. Secondary ball milling: Using the batch obtained in step S4 as a reference, add 200% deionized water by mass and perform secondary ball milling for 24 hours at a speed of 500 r / min. After the ball milling is completed, the secondary ball milled material is obtained. S6. Orientation molding: The secondary ball milling slurry obtained in step S5 is pressed into cylindrical samples under an electric field strength of 10 Oe and a pressure of 4 MPa. S7. Sintering: The sample obtained in step S6 is sintered. First, it is sintered at 1000℃ for 4 hours. After cooling to room temperature in the furnace, the BaM ferrite material based on samarium and copper co-substitution is obtained.

[0024] Example 2 A BaM ferrite material based on samarium and copper co-substitution is prepared by a method that is basically the same as that in Example 1, except that the substitution amount x in step S1 is 0.05. Example 3

[0025] A BaM ferrite material based on samarium and copper co-substitution is prepared by a method that is basically the same as that in Example 1, except that the substitution amount x in step S1 is 0.10. Example 4

[0026] A BaM ferrite material based on samarium and copper co-substitution is prepared by a method that is basically the same as that in Example 1, except that the substitution amount x in step S1 is 0.15. Example 5

[0027] A BaM ferrite material based on samarium and copper co-substitution is prepared by a method that is basically the same as that in Example 1, except that the substitution amount x in step S1 is 0.20. Example 6

[0028] A BaM ferrite material based on samarium and copper co-substitution is prepared by a method that is basically the same as that in Example 1, except that the substitution amount x = 0.25 in step S1. The performance test data of the ferrite materials prepared in Examples 1 to 6 above are shown in Table 1: Table 1. Remanence ratio and saturation magnetization Ms of materials prepared in different embodiments. project <![CDATA[M r / M s ]]> <![CDATA[M s (emu / g)]]> Example 1 80% 74.82 Example 2 65% 70.43 Example 3 83% 66.09 Example 4 82% 63.10 Example 5 79% 60.55 Example 6 68% 55.10 The characterization of the BaM ferrite materials prepared in Examples 1, 2, 3, 4, 5, and 6, and the XRD results are as follows: Figure 1 As shown: when x ≤ 0.10, the sample is a pure BaM phase; when x > 0.10, trace amounts of the second phase α-Fe₂O₃ are observed in the sample. The presence of the second phase α-Fe₂O₃ when the doping concentration is greater than 0.10 may be due to incomplete reaction leading to excess reactants as the doping concentration increases. Figure 2 As can be seen, the remanence ratio of the sample changed nonlinearly as the substitution proceeded. When x=0.10, the sample reached the maximum remanence ratio of 0.83. The high remanence ratio helps to reduce the insertion loss of the circulator, which shows that the formulation of the present invention is feasible. Figure 3 The image shows the microstructure of a series of samples. It can be seen from the image that the addition of Sm and Cu improves the microstructure of the samples.

[0029] like Figure 4 As shown, Example 3 of the present invention and reference standards yielded the ferromagnetic resonance linewidth values ​​of the ferrite material. From Figure 4 As can be seen, the ferromagnetic resonance linewidth of Example 3 is lowest at 55 GHz, with ΔH of 800 Oe. The experimental results show that the reduced ferromagnetic resonance linewidth ΔH meets the process requirements.

[0030] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A BaM ferrite material based on samarium and copper co-substitution, characterized in that, The molecular formula of the ferrite material is: Ba 1-x Sm x Fe 12-x Cu x O 19， Where 0 < x ≤ 0.

25.

2. The BaM ferrite material based on samarium and copper co-substitution according to claim 1, characterized in that, x=0.1。 3. The method for preparing BaM ferrite material based on samarium and copper co-substitution as described in claim 1 or 2, characterized in that, Includes the following steps: S1. Ingredients: BaCO3, Sm2O3, Fe2O3, and CuO are selected as raw materials, according to the molecular formula Ba 1-x Sm x Fe 12-x Cu x O 19 Perform calculations and accurately weigh the ingredients; S2. First ball milling: Mix the weighed ingredients from step S1 with deionized water and perform a first ball milling. After the ball milling is completed, a first ball milling slurry is obtained. S3. Pre-calcination: The slurry obtained after ball milling in step S2 is dried, sieved, and placed in a high-temperature box furnace. It is heated and kept at a temperature in air atmosphere, and then cooled to room temperature with the furnace to obtain pre-calcined powder. S4. Add sintering aid: Weigh the pre-sintered powder obtained in step S3 and add 8wt% sodium polynaphthalene sulfonate dispersant for mixing and batching; S5. Secondary ball milling: Mix the weighed ingredients from step S4 with a measured amount of deionized water and perform secondary ball milling. After the ball milling is completed, a secondary ball milling slurry is obtained. S6. Orientation pressing of green body: The slurry obtained in step S5 is poured into a mold and pressed into a cylindrical green body under pressure. At the same time, a magnetic field parallel to the pressure is applied to magnetize the single-domain particles and orient them in the direction of the external magnetic field. S7. Sintering: The cylindrical green billet obtained in step S6 is placed in a high-temperature box furnace for sintering. The temperature is raised and held in an air atmosphere, and then cooled to room temperature with the furnace.

4. The preparation method according to claim 3, characterized in that: In step S2, the mass of deionized water added is 150% to 250% of the raw material, and the ball milling is carried out at a speed of 300 r / min for 12 hours.

5. The preparation method according to claim 3, characterized in that: In step S3, the temperature is increased to 1200°C at a rate of 2-5°C / min, and the holding time is 4 hours.

6. The preparation method according to claim 3, characterized in that: In step S4, the added dispersant accounts for 8 wt% to 10% of the pre-calcined powder.

7. The preparation method according to claim 3, characterized in that: In step S5, the mass of deionized water added is 150% to 250% of the raw material, and the secondary ball milling is carried out at a speed of 500 r / min for 24 hours.

8. The preparation method according to claim 3, characterized in that: In step S6, the magnetic field strength during pressing is 10 kOe and the molding pressure is 4 MPa.

9. The preparation method according to claim 3, characterized in that: In step S7, the temperature is increased to 1000°C at a rate of 2-5°C / min, and the holding time is 4 hours.

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