A two-phase composite ferrite material and a method of making and using the same

Abstract

The application provides a dual-phase composite ferrite material and a preparation method and application thereof. The dual-phase composite ferrite material is prepared by compounding a SrBaM ferrite phase and a LiZn ferrite phase. The dual-phase composite ferrite material is obtained by compounding the SrBaM ferrite phase and the LiZn ferrite phase, wherein the SrBaM ferrite phase has the advantages of high saturation magnetization, high residual magnetic induction and high coercive force, the LiZn ferrite phase has the advantages of high remanence ratio, low line width and high Curie temperature, and the two phases are synergistically combined to improve the structure and electromagnetic characteristics of the dual-phase composite ferrite, so that the dual-phase composite ferrite has the advantages of low line width, low delta H, high remanence ratio and high Curie temperature, and is suitable for a Ka-band self-biased circulator.

Description

Technical Field

[0001] This invention belongs to the field of ferrite material preparation technology, specifically relating to a two-phase composite ferrite material, its preparation method, and its application. Background Technology

[0002] 5G high-frequency communication demands higher transmission rates and miniaturization to support 5G / 6G network applications in scenarios such as the Industrial Internet, Vehicle-to-Everything (V2X), Extended Reality (XR), and In-flight Internet. Traditional circulators often employ cubic ferrite materials (such as yttrium iron garnet, nickel-based, or lithium-based spinel ferrite). These materials have low magnetocrystalline anisotropy, and the gyromagnetic effect relies on an external permanent magnet to provide a bias magnetic field. The external magnet increases the device's size, severely limiting the miniaturization and integration of communication systems. While some microstrip circulator designs are more compact, they still cannot escape dependence on an external magnetic field, significantly increasing the device's size and greatly limiting the miniaturization of transceiver circuit systems.

[0003] Self-biased circulators eliminate the need for magnet assembly and calibration processes. Self-biased materials avoid magnet aging and demagnetization issues, extending device lifespan and making them suitable for high-reliability applications such as aerospace. The absence of external magnets avoids the risk of magnetic field shift and provides superior temperature stability. The core advantage of self-biasing technology lies in achieving "demagnetization" through material innovation. Self-biased circulators without external magnets avoid the risk of magnetic field shift and provide superior temperature stability. Their breakthrough value is not only reflected in the upgrading of existing communication systems but also provides fundamental material support for future cutting-edge fields such as terahertz (THz) communication and quantum devices.

[0004] Among gyromagnetic ferrites, hexagonal ferrites of the gyromagnetic type (such as M-type hexagonal ferrite SrM) possess high coercivity, high anisotropy, and high remanence. High coercivity preserves the permanent magnet characteristics of hexagonal ferrites, while the high remanence causes the magnetic moment to precess in a strongly anisotropic direction. This allows the magnetic moment to interact with microwaves / millimeter waves and generate ferromagnetic resonance even without an external steady magnetic field or with a very small steady magnetic field, achieving self-biasing characteristics in microwave devices. This eliminates the need for external magnets and significantly reduces the weight and size of microwave devices. However, the high anisotropy of M-type hexagonal ferrites limits their application frequencies, typically to the Ka band and above. Therefore, developing two-phase composite ferrite materials for Ka-band self-biasing devices is of great significance for achieving self-biasing characteristics in Ka-band microwave devices.

[0005] Patent CN116947475A discloses a method for preparing high-performance composite ferrite for self-biased circulators. The preparation method includes: (1) firstly preparing BaM ferrite initial powder and NiCuZnSn ferrite initial powder respectively; (2) mixing BaM ferrite initial powder, NiCuZnSn ferrite initial powder and deionized water in proportion and ball milling in a high-energy ball mill, and then obtaining mixed powder after first pre-firing, second pre-firing and second ball milling treatment; (3) subsequently obtaining high-performance composite ferrite for self-biased circulators by low-temperature magnetic field orientation molding technology and magnetic field heat treatment. This invention uses composite BaM ferrite powder and NiCuZnSn ferrite powder, and increases the saturation magnetization intensity through high-energy ball milling technology, low-temperature magnetic field orientation molding technology and magnetic field heat treatment technology, thereby improving the microstructure and magnetic properties of the two-phase composite ferrite. However, the preparation process requires one room-temperature magnetization molding and one high-temperature magnetization molding, which is complex and the prepared ferrite has a large ΔH (ferromagnetic resonance linewidth). Patent CN118955113A discloses a soft and hard magnetic microwave ferrite coupling material and its preparation method. The ferrite coupling material includes YIG and BaM microwave ferrite. The YIG microwave ferrite material includes 8.5-20.5 mol% Y2O3, 17-29 mol% Bi2O3, 47.5-57.5 mol% Fe2O3, and 5-15 mol% In2O3. The BaM ferrite material includes 6.5-12.5 mol% BaO, 5.5-10.5 mol% La2O3, 5.5-10.5 mol% Bi2O3, and 62.5-73.5 mol% Fe2O3. The soft and hard magnetic microwave ferrite coupling material prepared by this invention has high Mr / Ms and Hc, suitable 4πMs and Ha, and low ΔH and tanδ characteristics. However, YBiIG ferrite has disadvantages such as low remanence and low Curie temperature while having low linewidth, and its compatibility with BaM ferrite is not high.

[0006] Therefore, how to make two-phase composite ferrite materials have advantages such as low linewidth and low ΔH while also having high remanence ratio and high Curie temperature is an urgent technical problem to be solved. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a two-phase composite ferrite material, its preparation method, and its applications. The present invention uses a combination of SrBaM ferrite phase and LiZn ferrite phase to obtain a two-phase composite ferrite material. The SrBaM ferrite phase possesses advantages such as high saturation magnetization, high remanence, and high coercivity, while the LiZn ferrite phase possesses advantages such as high remanence ratio, low linewidth, and high Curie temperature. The synergistic effect of these two phases improves the structure and electromagnetic properties of the two-phase composite ferrite, resulting in a material that combines low linewidth and low ΔH with high remanence ratio and high Curie temperature, making it suitable for Ka-band self-biased circulators.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a dual-phase composite ferrite material, wherein the dual-phase composite ferrite material is obtained by combining a SrBaM ferrite phase and a LiZn ferrite phase.

[0010] This invention employs a combination of SrBaM ferrite phase and LiZn ferrite phase to obtain a two-phase composite ferrite material. The SrBaM ferrite phase has advantages such as high saturation magnetization, high remanence, and high coercivity, while the LiZn ferrite phase has advantages such as high remanence ratio, low linewidth, and high Curie temperature. The synergistic effect of the two phases improves the structure and electromagnetic properties of the two-phase composite ferrite, enabling it to possess advantages such as low linewidth, low ΔH, high remanence ratio, and high Curie temperature, making it suitable for Ka-band self-biased circulators.

[0011] It should be noted that the SrBaM ferrite phase refers to a composite ferrite phase of the M-type hexagonal crystal system.

[0012] Preferably, the chemical formula of the SrBaM ferrite phase is: Sr 0.64-0.5x Ba 0.24-0.5x Ca 0.12 La x Fe 12-y- z Co y Al z O 19 Where 0.15≤x≤0.25, for example, it can be 0.15, 0.2 or 0.25, etc.; 0.2≤y≤0.3, for example, it can be 0.2, 0.22, 0.24, 0.26, 0.28 or 0.3, etc.; and 0.05≤z≤0.15, for example, it can be 0.05, 0.1 or 0.15, etc.

[0013] In this invention, SrBaM ferrite provides an internal magnetic field for the circulator, which is the basis for the miniaturization of the circulator.

[0014] Preferably, the chemical formula of the LiZn ferrite phase is: Li 0.45-0.5a-0.5b Zn a Fe 2.4-0.5a- 0.5b Cu b Mn 0.05 Co 0.1 O4, where 0.15≤a≤0.25, for example, can be 0.15, 0.2 or 0.25, etc., and 0.1≤b≤0.2, for example, can be 0.1, 0.12, 0.14, 0.16, 0.18 or 0.2, etc.

[0015] Preferably, the mass ratio of the SrBaM ferrite phase to the LiZn ferrite phase is (1-2.5):1, for example, it can be 1:1, 1.5:1, 2:1 or 2.5:1, etc.

[0016] In this invention, a suitable ratio of SrBaM ferrite phase to LiZn ferrite phase can significantly improve the structure and electromagnetic properties of the two-phase composite ferrite, enabling it to possess advantages such as low linewidth, low ΔH, high remanence ratio, and high Curie temperature. If the mass ratio of SrBaM ferrite phase to LiZn ferrite phase is too small, the internal magnetic field of the ferrite itself will be small, failing to reach the designed internal field. If the mass ratio of SrBaM ferrite phase to LiZn ferrite phase is too large, the linewidth will be too large, which is detrimental to reducing losses.

[0017] Preferably, the dual-phase composite ferrite material further contains a dopant, which includes any one or a combination of at least two of ZnO, SiO2, or B2O3.

[0018] The present invention introduces the above-mentioned dopant into a two-phase composite ferrite material, which helps to reduce porosity and reduce the linewidth caused by pores.

[0019] In a second aspect, the present invention provides a method for preparing a dual-phase composite ferrite material as described in the first aspect, the method comprising the following steps:

[0020] SrBaM ferrite phase powder and LiZn ferrite phase powder are mixed to obtain a mixture. M includes La, Fe, Co, and Al. The mixture is subjected to a first sintering, forming process, and a second sintering to obtain the two-phase composite ferrite material.

[0021] The preparation method provided by this invention can effectively control grain boundary characteristics, improve orientation, and increase saturation magnetization, which is beneficial to improving the structure and electromagnetic properties of two-phase composite ferrites, enabling the composite ferrites to have the advantages of high remanence ratio and low linewidth required by circulators.

[0022] Preferably, before mixing the SrBaM ferrite phase powder and the LiZn ferrite phase powder, the SrBaM ferrite phase powder is pretreated, and the pretreatment steps include grinding and pre-calcination.

[0023] This invention employs grinding and pre-firing to pretreat SrBaM ferrite phase powder, which helps to achieve abnormal growth of SrBaM ferrite grains and enhance the internal magnetic field required for the circulator.

[0024] Preferably, the grinding method includes ball milling. For example, wet ball milling may be used.

[0025] Preferably, the rotational speed of the ball mill is 60-80 rpm, for example, it can be 60 rpm, 65 rpm, 70 rpm, 75 rpm or 80 rpm.

[0026] Preferably, the grinding time is 12-18 hours, for example, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours or 18 hours.

[0027] Preferably, the preheating temperature is 1150-1200℃, for example, it can be 1150℃, 1160℃, 1170℃, 1180℃, 1190℃ or 1200℃.

[0028] Preferably, the preheating time is 2-6 hours, for example, 2 hours, 3 hours, 4 hours, 5 hours or 6 hours.

[0029] Preferably, the mass ratio of the SrBaM ferrite phase powder to the LiZn ferrite phase powder is (1-2.5):1, for example, it can be 1:1, 1.5:1, 2:1 or 2.5:1, etc.

[0030] Preferably, the mixing process is accompanied by grinding.

[0031] Preferably, the grinding method includes ball milling. For example, wet ball milling may be used.

[0032] Preferably, the rotational speed of the ball mill is 60-80 rpm, for example, it can be 60 rpm, 65 rpm, 70 rpm, 75 rpm or 80 rpm.

[0033] Preferably, the grinding time is 12-18 hours, for example, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours or 18 hours.

[0034] Preferably, the atmosphere for the first sintering is an air atmosphere.

[0035] Preferably, the temperature of the first sintering is 900-950℃, for example, it can be 900℃, 910℃, 920℃, 930℃, 940℃ or 950℃.

[0036] Preferably, the heat preservation time of the primary calcining agent is 2-6 hours, for example, it can be 2 hours, 3 hours, 4 hours, 5 hours or 6 hours.

[0037] Preferably, a doping process is performed between the first sintering and the forming process.

[0038] Preferably, the dopant used in the doping process includes any one or a combination of at least two of ZnO, SiO2 or B2O3, and more preferably a combination of ZnO, SiO2 and B2O3.

[0039] In this invention, the combination of ZnO, SiO2 and B2O3 for doping can reduce the sintering temperature and decrease the porosity between grains.

[0040] Preferably, during the doping process, the doping amount of the dopant is 2.2-3.6 wt%, based on the mass of the sintered material obtained in the first sintering as 100%, for example, it can be 2.2 wt%, 2.4 wt%, 2.6 wt%, 2.8 wt%, 3 wt%, 3.2 wt%, 3.4 wt%, or 3.6 wt%, etc.

[0041] Preferably, when the dopant used in the doping process is a combination of ZnO, SiO2 and B2O3, the mass ratio of ZnO, SiO2 and B2O3 is (1.5-2):(0.5-1):(0.2-0.6). The range of ZnO selected from "1.5-2" can be, for example, 1.5, 1.6, 1.7, 1.8, 1.9 or 2, etc.; the range of SiO2 selected from "0.5-1" can be, for example, 0.5, 0.6, 0.7, 0.8, 0.9 or 1, etc.; and the range of B2O3 selected from "0.2-0.6" can be, for example, 0.2, 0.3, 0.4, 0.5 or 0.6, etc.

[0042] In this invention, ZnO, SiO2 and B2O3 are used in an appropriate mass ratio, which can not only ensure the densification driving force during subsequent sintering, reduce porosity, improve densification effect, reduce pore linewidth, but also help improve the magnetic properties and structural stability of the two-phase composite ferrite material and suppress impurities and defects.

[0043] Preferably, the molding process includes magnetic field-assisted molding.

[0044] Preferably, the atmosphere for the secondary sintering is an air atmosphere.

[0045] Preferably, the temperature of the secondary sintering is 1100-1150℃, for example, it can be 1100℃, 1110℃, 1120℃, 1130℃, 1140℃ or 1150℃.

[0046] Preferably, the holding time for the secondary sintering is 4-8 hours, for example, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours.

[0047] Preferably, the preparation method includes the following steps:

[0048] (1) The SrBaM ferrite phase powder is ball-milled at a speed of 60-80 rpm for 12-18 h to obtain ball milling material. Then the ball milling material is sieved and pre-calcined at a temperature of 1150-1200℃ for 2-6 h to obtain pre-treated SrBaM ferrite phase powder.

[0049] The chemical formula of the SrBaM ferrite phase powder is: Sr 0.64-0.5x Ba 0.24-0.5x Ca 0.12 La x Fe 12-y- z Co y Al z O 19 , where 0.15≤x≤0.25, 0.2≤y≤0.3, and 0.05≤z≤0.15.

[0050] (2) The pretreated SrBaM ferrite phase powder and LiZn ferrite phase powder are ball-milled at a mass ratio of (1-2.5):1. The ball milling speed is 60-80 rpm and the time is 12-18 h to obtain a mixture.

[0051] The chemical formula of the LiZn ferrite phase powder is: Li 0.45-0.5a-0.5b Zn a Fe 2.4-0.5a- 0.5b Cu b Mn 0.05 Co 0.1 O4, where 0.15≤a≤0.25, 0.1≤b≤0.2.

[0052] (3) The mixture is sieved and then sintered in air atmosphere. The temperature of the first sintering is 900-950℃ and the holding time is 2-6h to obtain a sintered powder.

[0053] (4) The calcined powder and the dopant are ball-milled and mixed at a speed of 60-80 rpm (e.g., 60 rpm, 65 rpm, 70 rpm, 75 rpm or 80 rpm) for 14-30 h (e.g., 14 h, 16 h, 18 h, 20 h, 22 h, 24 h, 26 h, 28 h or 30 h). Then, the powder is shaped using a magnetic field-assisted molding method to obtain a shaped blank.

[0054] The dopants include ZnO, SiO2, and B2O3 in a mass ratio of (1.5-2):(0.5-1):(0.2-0.6). Based on the mass of the calcined powder as 100%, the doping amount of ZnO is 1.5-2 wt%, the doping amount of SiO2 is 0.5-1 wt%, and the doping amount of B2O3 is 0.2-0.6 wt%. In the magnetic field-assisted molding method, the magnetic field strength is ≥1.4T (e.g., it can be 1.4T, 1.5T, 2T, 2.5T, or 3T, etc.), and the molding pressure is 2-4MPa (e.g., it can be 2MPa, 2.5MPa, 3MPa, 3.5MPa, or 4MPa, etc.).

[0055] (5) The preform is sintered in air at a temperature of 1100-1150℃ and a holding time of 4-8h to obtain a two-phase composite ferrite material.

[0056] Thirdly, the present invention provides an application of the two-phase composite ferrite material as described in the first aspect in the preparation of a self-biased circulator.

[0057] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] (1) The present invention uses SrBaM ferrite phase and LiZn ferrite phase to obtain two-phase composite ferrite material. SrBaM ferrite phase has the advantages of high saturation magnetization, high remanence induction and high coercivity, while LiZn ferrite phase has the advantages of high remanence ratio, low linewidth and high Curie temperature. The two work together to improve the structure and electromagnetic properties of the two-phase composite ferrite, so that the two-phase composite ferrite has the advantages of low linewidth and low ΔH, as well as high remanence ratio and high Curie temperature, and is suitable for Ka-band self-biased circulators.

[0060] (2) The preparation method provided by the present invention can effectively control the grain boundary characteristics, improve the orientation degree, increase the saturation magnetization intensity, and improve the structure and electromagnetic properties of the two-phase composite ferrite, so that the composite ferrite has the advantages of high remanence ratio and low linewidth required by the circulator. Detailed Implementation

[0061] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0062] Example 1

[0063] This embodiment provides a dual-phase composite ferrite material, which is prepared by combining a SrBaM ferrite phase and a LiZn ferrite phase; wherein, the chemical formula of the SrBaM ferrite phase is: Sr 0.64- 0.5x Ba 0.24-0.5x Ca 0.12 La x Fe 12-y-z Co y Al z O 19 x = 0.15, y = 0.25, z = 0.05; the chemical formula of the LiZn ferrite phase is: Li 0.45-0.5a-0.5b Zn a Fe 2.4-0.5a-0.5b Cu b Mn 0.05 Co 0.1 O4, a = 0.15, b = 0.1; the mass ratio of the SrBaM ferrite phase to the LiZn ferrite phase is 1:1; the dual-phase composite ferrite material also contains dopants, which are combinations of ZnO, SiO2 and B2O3.

[0064] This embodiment also provides a method for preparing the above-mentioned dual-phase composite ferrite material, the method comprising the following steps:

[0065] (1) The SrBaM ferrite phase powder was placed in a ball mill and wet ball milled according to the weight ratio of SrBaM ferrite phase powder: deionized water: steel balls = 1000:1100:5500. The ball milling speed was 60 rpm and the time was 14 h to obtain ball milled wet material. Then the ball milled wet material was placed in an oven at 100℃ to dry it. Then it was sieved with an 80 mesh screen and then placed in a pre-calcination furnace for pre-calcination. The pre-calcination temperature was 1200℃ and the holding time was 2 h to obtain pre-treated SrBaM ferrite phase powder.

[0066] The chemical formula of the SrBaM ferrite phase powder is: Sr0.64-0.5x Ba 0.24-0.5x Ca 0.12 La x Fe 12-y- z Co y Al z O 19 x = 0.15, y = 0.25, z = 0.05; 12 mL of dispersant, namely ammonia, is also added during the wet ball milling process.

[0067] (2) The pretreated SrBaM ferrite phase powder and LiZn ferrite phase powder are put into a ball mill at a mass ratio of 1:1 and wet ball milling is carried out according to the weight ratio of grinding material: deionized water: steel balls = 1000:1100:5500. The ball milling speed is 60 rpm and the time is 14 h to obtain the mixed wet material.

[0068] The chemical formula of the LiZn ferrite phase powder is: Li 0.45-0.5a-0.5b Zn a Fe 2.4-0.5a- 0.5b Cu b Mn 0.05 Co 0.1 O4, a = 0.15, b = 0.1; 12 mL of dispersant, namely ammonia, is also added during the wet ball milling process.

[0069] (3) The mixed wet material is placed in an oven at 100°C to dry, then sieved through an 80-mesh sieve, and then placed in an air atmosphere sintering furnace for a first sintering at a temperature of 950°C for 2 hours to obtain a sintered powder.

[0070] (4) The powder and dopant are placed in a ball mill and wet ball milling is carried out according to the weight ratio of powder to be ground: deionized water: steel balls = 1000: 1100: 5500. The ball milling speed is 60 rpm and the time is 14 h. Then the slurry is dehydrated so that the water content after dehydration is 25%. Then the magnetic field assisted molding method is used to press the slurry under the magnetic field press to obtain the shaped blank.

[0071] The dopants include ZnO, SiO2, and B2O3 in a mass ratio of 1.5:0.7:0.2. Based on the mass of the calcined powder as 100%, the doping amount of ZnO is 1.5wt%, the doping amount of SiO2 is 0.7wt%, and the doping amount of B2O3 is 0.2wt%. In the magnetic field-assisted molding method, the magnetic field strength is 1.4T and the molding pressure is 3MPa.

[0072] (5) The shaped blank is placed in an air atmosphere sintering furnace and the shaped blank is sintered for a second time. The temperature of the second sintering is 1100℃ and the holding time is 8h to obtain a two-phase composite ferrite material.

[0073] Example 2

[0074] This embodiment provides a dual-phase composite ferrite material, which is obtained by combining a SrBaM ferrite phase and a LiZn ferrite phase; wherein, the chemical formula of the SrBaM ferrite phase is: Sr 0.64-0.5x Ba 0.24- 0.5x Ca 0.12 La x Fe 12-y-z Co y Al z O 19 x = 0.2, y = 0.25, z = 0.1; the chemical formula of the LiZn ferrite phase is: Li 0.45-0.5a-0.5b Zn a Fe 2.4-0.5a-0.5b Cu b Mn 0.05 Co 0.1 O4, a = 0.2, b = 0.15; the mass ratio of the SrBaM ferrite phase to the LiZn ferrite phase is 1:1.7; the dual-phase composite ferrite material also contains dopants, which are combinations of ZnO, SiO2 and B2O3.

[0075] This embodiment also provides a method for preparing the above-mentioned dual-phase composite ferrite material, the method comprising the following steps:

[0076] (1) The SrBaM ferrite phase powder was placed in a ball mill and wet ball milled according to the weight ratio of SrBaM ferrite phase powder: deionized water: steel balls = 1000: 1100: 5500. The ball milling speed was 60 rpm and the time was 16 h to obtain ball milled wet material. Then the ball milled wet material was placed in an oven at 100°C to dry it. Then it was sieved with an 80-mesh sieve and then placed in a pre-calcination furnace for pre-calcination. The pre-calcination temperature was 1170°C and the holding time was 4 h to obtain pre-treated SrBaM ferrite phase powder.

[0077] The chemical formula of the SrBaM ferrite phase powder is: Sr 0.64-0.5x Ba 0.24-0.5x Ca 0.12 La x Fe 12-y- z Co y Al z O 19x = 0.2, y = 0.25, z = 0.1; 12 mL of dispersant, namely ammonia, is also added during the wet ball milling process.

[0078] (2) The pretreated SrBaM ferrite phase powder and LiZn ferrite phase powder were placed in a ball mill at a mass ratio of 1:1.7 and wet ball milled according to the weight ratio of material to be ground:deionized water:steel balls = 1000:1100:5500. The ball milling speed was 60 rpm and the time was 16 h to obtain the mixed wet material.

[0079] The chemical formula of the LiZn ferrite phase powder is: Li 0.45-0.5a-0.5b Zn a Fe 2.4-0.5a- 0.5b Cu b Mn 0.05 Co 0.1 O4, a = 0.2, b = 0.15; 12 mL of dispersant, namely ammonia, is also added during the wet ball milling process.

[0080] (3) The mixed wet material is placed in an oven at 100°C to dry, then sieved through an 80-mesh sieve, and then placed in an air atmosphere sintering furnace for a first sintering at a temperature of 900°C for a holding time of 6 hours to obtain a sintered powder.

[0081] (4) The powder and dopant are placed in a ball mill and wet ball milling is carried out according to the weight ratio of the powder to be ground: deionized water: steel balls = 1000: 1100: 5500. The ball milling speed is 60 rpm and the time is 16 h. Then the slurry is dehydrated so that the water content after dehydration is 30%. Then the magnetic field assisted molding method is used to press the slurry under the magnetic field press to obtain the shaped blank.

[0082] The dopants include ZnO, SiO2, and B2O3 in a mass ratio of 1.7:0.5:0.4. Based on the mass of the calcined powder as 100%, the doping amount of ZnO is 1.7 wt%, the doping amount of SiO2 is 0.5 wt%, and the doping amount of B2O3 is 0.4 wt%. In the magnetic field-assisted molding method, the magnetic field strength is 1.4 T and the molding pressure is 3 MPa.

[0083] (5) The shaped blank is placed in an air atmosphere sintering furnace and the shaped blank is sintered for a second time. The temperature of the second sintering is 1120℃ and the holding time is 6h to obtain a two-phase composite ferrite material.

[0084] Example 3

[0085] This embodiment provides a dual-phase composite ferrite material, which is obtained by combining a SrBaM ferrite phase and a LiZn ferrite phase; wherein, the chemical formula of the SrBaM ferrite phase is: Sr 0.64-0.5x Ba 0.24- 0.5x Ca 0.12 La x Fe 12-y-z Co y Al z O 19 x = 0.25, y = 0.2, z = 0.15; the chemical formula of the LiZn ferrite phase is: Li 0.45-0.5a-0.5b Zn a Fe 2.4-0.5a-0.5b Cu b Mn 0.05 Co 0.1 O4, a = 0.25, b = 0.15; the mass ratio of the SrBaM ferrite phase to the LiZn ferrite phase is 1:2.5; the dual-phase composite ferrite material also contains dopants, which are combinations of ZnO, SiO2 and B2O3.

[0086] This embodiment also provides a method for preparing the above-mentioned dual-phase composite ferrite material, the method comprising the following steps:

[0087] (1) The SrBaM ferrite phase powder was placed in a ball mill and wet ball milled according to the weight ratio of SrBaM ferrite phase powder: deionized water: steel balls = 1000:1100:5500. The ball milling speed was 80 rpm and the time was 12 h to obtain ball milled wet material. Then the ball milled wet material was placed in an oven at 100℃ to dry it. Then it was sieved with an 80 mesh screen and then placed in a pre-calcination furnace for pre-calcination. The pre-calcination temperature was 1200℃ and the holding time was 2 h to obtain pre-treated SrBaM ferrite phase powder.

[0088] The chemical formula of the SrBaM ferrite phase powder is: Sr 0.64-0.5x Ba 0.24-0.5x Ca 0.12 La x Fe 12-y- z Co y Al z O 19 x = 0.25, y = 0.2, z = 0.15; 12 mL of dispersant, ammonia water, is also added during the wet ball milling process.

[0089] (2) The pretreated SrBaM ferrite phase powder and LiZn ferrite phase powder are put into a ball mill at a mass ratio of 1:2.5 and wet ball milling is carried out according to the weight ratio of material to be ground:deionized water:steel balls = 1000:1100:5500. The ball milling speed is 80 rpm and the time is 12 h to obtain the mixed wet material.

[0090] The chemical formula of the LiZn ferrite phase powder is: Li 0.45-0.5a-0.5b Zn a Fe 2.4-0.5a- 0.5b Cu b Mn 0.05 Co 0.1 During the wet ball milling process described in O4, a = 0.25, b = 0.15, 12 mL of a dispersant, namely ammonia, is also added.

[0091] (3) The mixed wet material is placed in an oven at 100°C to dry, then sieved through an 80-mesh sieve, and then placed in an air atmosphere sintering furnace for a first sintering at a temperature of 920°C for 4 hours to obtain a sintered powder.

[0092] (4) The powder and dopant are placed in a ball mill and wet ball milling is carried out according to the weight ratio of the powder to be ground: deionized water: steel balls = 1000: 1100: 5500. The ball milling speed is 80 rpm and the time is 12 h. Then the slurry is dehydrated so that the water content after dehydration is 20%. Then the magnetic field assisted molding method is used to press the slurry under the magnetic field press to obtain the shaped blank.

[0093] The dopants include ZnO, SiO2, and B2O3 in a mass ratio of 2:0.8:0.2. Based on the mass of the calcined powder as 100%, the doping amount of ZnO is 2wt%, the doping amount of SiO2 is 0.8wt%, and the doping amount of B2O3 is 0.2wt%. In the magnetic field-assisted molding method, the magnetic field strength is 1.4T and the molding pressure is 3MPa.

[0094] (5) The shaped blank is placed in an air atmosphere sintering furnace and the shaped blank is sintered for a second time. The temperature of the second sintering is 1100℃ and the holding time is 8h to obtain a two-phase composite ferrite material.

[0095] Example 4

[0096] This embodiment provides a dual-phase composite ferrite material, which is obtained by combining a SrBaM ferrite phase and a LiZn ferrite phase; wherein, the chemical formula of the SrBaM ferrite phase is: Sr 0.64-0.5x Ba 0.24-0.5x Ca 0.12 La x Fe 12-y-z Co y Al z O 19 x = 0.15, y = 0.3, z = 0.15; the chemical formula of the LiZn ferrite phase is: Li 0.45-0.5a-0.5b Zn a Fe 2.4-0.5a-0.5b Cu b Mn 0.05 Co 0.1 O4, a = 0.2, b = 0.2; the mass ratio of the SrBaM ferrite phase to the LiZn ferrite phase is 1:1.4; the dual-phase composite ferrite material also contains dopants, which are combinations of ZnO, SiO2 and B2O3.

[0097] This embodiment also provides a method for preparing the above-mentioned dual-phase composite ferrite material, the method comprising the following steps:

[0098] (1) The SrBaM ferrite phase powder was placed in a ball mill and wet ball milled according to the weight ratio of SrBaM ferrite phase powder: deionized water: steel balls = 1000: 1100: 5500. The ball milling speed was 70 rpm and the time was 16 h to obtain ball milled wet material. Then the ball milled wet material was placed in an oven at 100℃ to dry it. Then it was sieved with an 80 mesh screen and then placed in a pre-calcination furnace for pre-calcination. The pre-calcination temperature was 1150℃ and the holding time was 6 h to obtain pre-treated SrBaM ferrite phase powder.

[0099] The chemical formula of the SrBaM ferrite phase powder is: Sr 0.64-0.5x Ba 0.24-0.5x Ca 0.12 La x Fe 12-y- z Co y Al z O 19 x = 0.15, y = 0.3, z = 0.15; 12 mL of dispersant, namely ammonia, is also added during the wet ball milling process.

[0100] (2) The pretreated SrBaM ferrite phase powder and LiZn ferrite phase powder were placed in a ball mill at a mass ratio of 1:1.4 and wet ball milling was carried out at a weight ratio of 1000:1100:5500 for grinding material:deionized water:steel balls. The ball milling speed was 70 rpm and the time was 16 h to obtain the mixed wet material.

[0101] The chemical formula of the LiZn ferrite phase powder is: Li 0.45-0.5a-0.5b Zn a Fe 2.4-0.5a- 0.5b Cu b Mn 0.05 Co 0.1 O4, a = 0.2, b = 0.2; 12 mL of dispersant, namely ammonia, is also added during the wet ball milling process.

[0102] (3) The mixed wet material is placed in an oven at 100°C to dry, then sieved through an 80-mesh sieve, and then placed in an air atmosphere sintering furnace for a first sintering at a temperature of 900°C for 4 hours to obtain a sintered powder.

[0103] (4) The powder and dopant are placed in a ball mill and wet ball milling is carried out according to the weight ratio of powder to be ground: deionized water: steel balls = 1000: 1100: 5500. The ball milling speed is 70 rpm and the time is 16 h. Then the slurry is dehydrated so that the water content after dehydration is 25%. Then the magnetic field assisted molding method is used to press the slurry under the magnetic field press to obtain the shaped blank.

[0104] The dopants include ZnO, SiO2, and B2O3 in a mass ratio of 1.6:1:0.6. Based on the mass of the calcined powder as 100%, the doping amount of ZnO is 1.6 wt%, the doping amount of SiO2 is 1 wt%, and the doping amount of B2O3 is 0.6 wt%. In the magnetic field-assisted molding method, the magnetic field strength is 1.4 T and the molding pressure is 3 MPa.

[0105] (5) The shaped blank is placed in an air atmosphere sintering furnace and the shaped blank is sintered for a second time. The temperature of the second sintering is 1150℃ and the holding time is 2h to obtain a two-phase composite ferrite material.

[0106] Example 5

[0107] This embodiment provides a dual-phase composite ferrite material, which is obtained by combining a SrBaM ferrite phase and a LiZn ferrite phase; wherein, the chemical formula of the SrBaM ferrite phase is: Sr 0.64-0.5x Ba 0.24- 0.5x Ca 0.12 La x Fe 12-y-z Co y Al z O 19 x = 0.22, y = 0.28, z = 0.13; the chemical formula of the LiZn ferrite phase is: Li0.45-0.5a-0.5b Zn a Fe 2.4-0.5a-0.5b Cu b Mn 0.05 Co 0.1 O4, a = 0.18, b = 0.15; the mass ratio of the SrBaM ferrite phase to the LiZn ferrite phase is 1:2.3; the dual-phase composite ferrite material also contains dopants, which are combinations of ZnO, SiO2 and B2O3.

[0108] This embodiment also provides a method for preparing the above-mentioned dual-phase composite ferrite material, the method comprising the following steps:

[0109] (1) The SrBaM ferrite phase powder was placed in a ball mill and wet ball milled according to the weight ratio of SrBaM ferrite phase powder: deionized water: steel balls = 1000:1100:5500. The ball milling speed was 65 rpm and the time was 18 h to obtain ball milled wet material. Then the ball milled wet material was placed in an oven at 100°C to dry it. Then it was sieved with an 80-mesh sieve and then placed in a pre-calcination furnace for pre-calcination. The pre-calcination temperature was 1180°C and the holding time was 3 h to obtain pre-treated SrBaM ferrite phase powder.

[0110] The chemical formula of the SrBaM ferrite phase powder is: Sr 0.64-0.5x Ba 0.24-0.5x Ca 0.12 La x Fe 12-y- z Co y Al z O 19 x = 0.22, y = 0.28, z = 0.13; 12 mL of dispersant, ammonia water, is also added during the wet ball milling process.

[0111] (2) The pretreated SrBaM ferrite phase powder and LiZn ferrite phase powder were placed in a ball mill at a mass ratio of 1:2.3 and wet ball milling was carried out at a weight ratio of 1000:1100:5500 for grinding material:deionized water:steel balls. The ball milling speed was 65 rpm and the time was 18 h to obtain the mixed wet material.

[0112] The chemical formula of the LiZn ferrite phase powder is: Li 0.45-0.5a-0.5b Zn a Fe 2.4-0.5a- 0.5b Cu b Mn 0.05 Co 0.1O4, a = 0.18, b = 0.15; 12 mL of dispersant, namely ammonia, is also added during the wet ball milling process.

[0113] (3) The mixed wet material is placed in an oven at 100°C to dry, then sieved through an 80-mesh sieve, and then placed in an air atmosphere sintering furnace for a first sintering at a temperature of 940°C for 3 hours to obtain a sintered powder.

[0114] (4) The powder and dopant are placed in a ball mill and wet ball milling is carried out according to the weight ratio of powder to be ground: deionized water: steel balls = 1000: 1100: 5500. The ball milling speed is 65 rpm and the time is 18 h. Then the slurry is dehydrated so that the water content after dehydration is 25%. Then the magnetic field assisted molding method is used to press the slurry under the magnetic field press to obtain the shaped blank.

[0115] The dopants include ZnO, SiO2, and B2O3 in a mass ratio of 1.8:0.8:0.5. Based on the mass of the calcined powder as 100%, the doping amount of ZnO is 1.8 wt%, the doping amount of SiO2 is 0.8 wt%, and the doping amount of B2O3 is 0.5 wt%. In the magnetic field-assisted molding method, the magnetic field strength is 1.4 T and the molding pressure is 3 MPa.

[0116] (5) The shaped blank is placed in an air atmosphere sintering furnace and the shaped blank is sintered for a second time. The temperature of the second sintering is 1130℃ and the holding time is 6h to obtain a two-phase composite ferrite material.

[0117] Example 6

[0118] The difference between this embodiment and Embodiment 1 is that the mass ratio of the SrBaM ferrite phase to the LiZn ferrite phase is 1:3.

[0119] The remaining preparation methods and parameters are consistent with those in Example 1.

[0120] Example 7

[0121] The difference between this embodiment and Embodiment 1 is that the mass ratio of the SrBaM ferrite phase to the LiZn ferrite phase is 3:1.

[0122] The remaining preparation methods and parameters are consistent with those in Example 1.

[0123] Example 8

[0124] The difference between this embodiment and embodiment 1 is that no dopant is added in step (4).

[0125] The remaining preparation methods and parameters are consistent with those in Example 1.

[0126] Example 9

[0127] The difference between this embodiment and embodiment 1 is that the dopant B2O3 in step (4) is replaced with an equal mass of SiO2, that is, the two-phase composite ferrite material is not doped with element B.

[0128] The remaining preparation methods and parameters are consistent with those in Example 1.

[0129] Example 10

[0130] The difference between this embodiment and embodiment 1 is that the doping amounts of ZnO, SiO2 and B2O3 are adjusted proportionally so that the total doping amount of the dopant in step (4) is 1.5wt%.

[0131] The remaining preparation methods and parameters are consistent with those in Example 1.

[0132] Example 11

[0133] The difference between this embodiment and embodiment 1 is that the doping of ZnO, SiO2 and B2O3 is adjusted proportionally so that the total doping amount of the dopant in step (4) is 4wt%.

[0134] The remaining preparation methods and parameters are consistent with those in Example 1.

[0135] Example 12

[0136] The difference between this embodiment and embodiment 1 is that step (1) is not performed, that is, the SrBaM ferrite phase powder is not pretreated.

[0137] The remaining preparation methods and parameters are consistent with those in Example 1.

[0138] Example 13

[0139] The difference between this embodiment and embodiment 1 is that the temperature of the first sintering in step (3) is 800°C.

[0140] The remaining preparation methods and parameters are consistent with those in Example 1.

[0141] Example 14

[0142] The difference between this embodiment and embodiment 1 is that the temperature of the first sintering in step (3) is 1000℃.

[0143] The remaining preparation methods and parameters are consistent with those in Example 1.

[0144] Comparative Example 1

[0145] The difference between this comparative example and Example 1 is that the SrBaM ferrite phase powder in step (1) is replaced with BaM' ferrite powder, so that the two-phase composite ferrite material is obtained by combining BaM' ferrite phase and LiZn ferrite phase.

[0146] The initial BaM' ferrite powder is prepared from BaCO3, La2O3 and Fe2O3 as raw materials, in a ratio of "5mol% BaCO3, 10mol% La2O3 and 85mol% Fe2O3".

[0147] The remaining preparation methods and parameters are consistent with those in Example 1.

[0148] Comparative Example 2

[0149] The difference between this comparative example and Example 1 is that the chemical formula of the SrBaM ferrite phase is: Sr 0.64- 0.5x Ba 0.24-0.5x Ca 0.12 La x Fe 12-y-z Co y Al z O 19 , x=0.15, y=0, z=0.05.

[0150] The remaining preparation methods and parameters are consistent with those in Example 1.

[0151] Comparative Example 3

[0152] The difference between this comparative example and Example 1 is that the chemical formula of the SrBaM ferrite phase is: Sr 0.64- 0.5x Ba 0.24-0.5x Ca 0.12 La x Fe 12-y-z Co y Al z O 19 , x=0.15, y=0.25, z=0.

[0153] The remaining preparation methods and parameters are consistent with those in Example 1.

[0154] Performance testing

[0155] The magnetic properties of the two-phase composite ferrite materials prepared in the above embodiments and comparative examples were tested, including characterizing the saturation magnetization 4πMs, remanence ratio Mr / Ms, and coercivity Hc using a LakeShore 8604 vibrating sample magnetometer (USA), and characterizing the ferromagnetic resonance linewidth ΔH and dielectric constant ε using a CK-XW-100 high-frequency integrated measurement system. r .

[0156] The test results are shown in Table 1.

[0157] Table 1

[0158] Example 1 3979 0.9 309 15.3 3128 Example 2 3968 0.92 309 15.2 3143 Example 3 3856 0.89 307 15.4 3141 Example 4 3915 0.9 302 15.1 3100 Example 5 3864 0.89 307 15.1 3172 Example 6 3976 0.85 254 15.1 2027 Example 7 3971 0.92 510 15.0 3269 Example 8 3510 0.91 530 15.2 3204 Example 9 3888 0.9 480 15.3 3270 Example 10 3872 0.92 535 15.1 3159 Example 11 3990 0.91 563 15.1 3170 Example 12 4009 0.91 572 15.3 3197 Example 13 3954 0.92 564 15.3 3280 Example 14 3968 0.91 552 15.3 3165 Comparative Example 1 3865 0.85 304 15.0 2526 Comparative Example 2 3928 0.84 321 15.3 2335 Comparative Example 3 3888 0.9 304 15.3 2854

[0159] analyze:

[0160] A comparison of Examples 1 and 6-7 shows that if the mass ratio of SrBaM ferrite phase to LiZn ferrite phase is too small, the remanence ratio and coercivity will be low; if the mass ratio of SrBaM ferrite phase to LiZn ferrite phase is too large, the linewidth will be large.

[0161] As can be seen from the comparison between Example 1 and Examples 8-9, if the two-phase composite ferrite material is not doped, the linewidth becomes larger; if the two-phase composite ferrite material is not doped with element B, the linewidth becomes larger and the synergistic effect is not achieved.

[0162] A comparison of Example 1 and Examples 10-11 shows that if the total doping amount of the dopant is too small, the linewidth will be larger; if the total doping amount of the dopant is too large, the linewidth will be larger.

[0163] A comparison of Example 1 and Example 12 shows that if the SrBaM ferrite phase powder is not pretreated, it will be difficult to reduce the linewidth.

[0164] As can be seen from the comparison between Example 1 and Examples 13-14, if the temperature of the first sintering in step (3) is too low, the linewidth will increase; if the temperature of the first sintering in step (3) is too high, the linewidth will increase.

[0165] As can be seen from the comparison between Example 1 and Comparative Example 1, if the dual-phase composite ferrite material is obtained by combining BaM' ferrite phase and LiZn ferrite phase, then an additional room temperature magnetization molding and a high temperature magnetization molding are required in the preparation process, which is complicated and the ferrite ΔH is large.

[0166] As can be seen from the comparison between Example 1 and Comparative Examples 2-3, if the SrBaM ferrite phase does not contain Co, the coercivity is lower; if the SrBaM ferrite phase does not contain Al, the coercivity is lower.

[0167] It should be noted that the present invention is illustrated through the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A two-phase composite ferrite material, characterized in that, The dual-phase composite ferrite material is prepared by combining a SrBaM ferrite phase and a LiZn ferrite phase; the chemical formula of the SrBaM ferrite phase is: Sr 0.64-0.5x Ba 0.24- 0.5x Ca 0.12 La x Fe 12-y-z Co y Al z O 19 Where 0.15≤x≤0.25, 0.2≤y≤0.3, 0.05≤z≤0.15; the chemical formula of the LiZn ferrite phase is: Li 0.45-0.5a-0.5b Zn a Fe 2.4-0.5a-0.5b Cu b Mn 0.05 Co 0.1 O4, where 0.15≤a≤0.25, 0.1≤b≤0.2; The mass ratio of the SrBaM ferrite phase to the LiZn ferrite phase is (1-2.5):1; the dual-phase composite ferrite material also contains dopants, which include a combination of ZnO, SiO2 and B2O3. The preparation method of the dual-phase composite ferrite material includes the following steps: SrBaM ferrite phase powder and LiZn ferrite phase powder are mixed to obtain a mixture; the mixture is then sintered once at a temperature of 900-950℃. Before mixing the SrBaM ferrite phase powder and the LiZn ferrite phase powder, the SrBaM ferrite phase powder is pretreated. The pretreatment steps include grinding and pre-calcination. The doping process is performed after the first sintering; during the doping process, the doping amount of the dopant is 2.2-3.6 wt%, based on the mass of the sintered material obtained from the first sintering as 100%.

2. A method for preparing a dual-phase composite ferrite material as described in claim 1, characterized in that, The preparation method includes the following steps: SrBaM ferrite phase powder and LiZn ferrite phase powder are mixed to obtain a mixture; the mixture is subjected to a first sintering, doping treatment, molding treatment and a second sintering to obtain the two-phase composite ferrite material.

3. The preparation method according to claim 2, characterized in that, The grinding method includes ball milling.

4. The preparation method according to claim 2, characterized in that, The pre-firing temperature is 1150-1200℃.

5. The preparation method according to claim 2, characterized in that, The preheating time is 2-6 hours.

6. The preparation method according to claim 2, characterized in that, The mixing process is accompanied by grinding.

7. The preparation method according to claim 6, characterized in that, The grinding method includes ball milling.

8. The preparation method according to claim 2, characterized in that, The atmosphere for the first sintering is an air atmosphere.

9. The preparation method according to claim 2, characterized in that, The holding time for the first sintering is 2-6 hours.

10. The preparation method according to claim 2, characterized in that, When the dopant used in the doping process is a combination of ZnO, SiO2 and B2O3, the mass ratio of ZnO, SiO2 and B2O3 is (1.5-2):(0.5-1):(0.2-0.6).

11. The preparation method according to claim 2, characterized in that, The molding process includes magnetic field-assisted molding.

12. The preparation method according to claim 2, characterized in that, The atmosphere for the secondary sintering is an air atmosphere.

13. The preparation method according to claim 2, characterized in that, The temperature for the secondary sintering is 1100-1150℃.

14. The preparation method according to claim 2, characterized in that, The holding time for the secondary sintering is 4-8 hours.

15. The preparation method according to claim 2, characterized in that, The preparation method includes the following steps: (1) SrBaM ferrite phase powder is ball-milled at a speed of 60-80 rpm for 12-18 h to obtain ball milling material. Then, the ball milling material is sieved and pre-calcined at a temperature of 1150-1200℃ for 2-6 h to obtain pre-treated SrBaM ferrite phase powder. The chemical formula of the SrBaM ferrite phase powder is: Sr 0.64-0.5x Ba 0.24-0.5x Ca 0.12 La x Fe 12-y-z Co y Al z O 19 Where 0.15≤x≤0.25, 0.2≤y≤0.3, and 0.05≤z≤0.15; (2) The pretreated SrBaM ferrite phase powder and LiZn ferrite phase powder are ball-milled at a mass ratio of (1-2.5):

1. The ball milling speed is 60-80 rpm and the time is 12-18 h to obtain a mixture. The chemical formula of the LiZn ferrite phase powder is: Li 0.45-0.5a-0.5b Zn a Fe 2.4-0.5a-0.5b Cu b Mn 0.05 Co 0.1 O4, where 0.15≤a≤0.25, 0.1≤b≤0.2; (3) The mixture is sieved and then sintered in air atmosphere. The temperature of the first sintering is 900-950℃ and the holding time is 2-6h to obtain a sintered powder. (4) The powder and dopant are ball-milled and mixed at a speed of 60-80 rpm for 14-30 h. Then, the powder is shaped using a magnetic field-assisted molding method to obtain a shaped blank. The dopants include ZnO, SiO2, and B2O3 in a mass ratio of (1.5-2):(0.5-1):(0.2-0.6). Based on the mass of the calcined powder as 100%, the doping amount of ZnO is 1.5-2wt%, the doping amount of SiO2 is 0.5-1wt%, and the doping amount of B2O3 is 0.2-0.6wt%. In the magnetic field-assisted molding method, the magnetic field strength is ≥1.4T, and the molding pressure is 2-4MPa. (5) The preform is sintered in air at a temperature of 1100-1150℃ and a holding time of 4-8h to obtain a two-phase composite ferrite material.

16. The application of the two-phase composite ferrite material as described in claim 1 in the preparation of a self-biased circulator.