A soft and hard magnetic microwave ferrite coupling material and preparation method

Abstract

A soft and hard magnetic microwave ferrite coupling material and a preparation method thereof, belonging to the technical field of ferrite material preparation. The ferrite coupling material comprises YIG and BaM microwave ferrites, the YIG microwave ferrite material comprises 8.5-20.5 mol% Y2O3, 17-29 mol% Bi2O3, 47.5-57.5 mol% Fe2O3, 5-15 mol% In2O3, and the BaM ferrite material comprises 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 the present invention has both high M r / M s and H c , suitable 4π M s and H a , low Δ H and tan d ε characteristic.

Description

Technical Field

[0001] The invention belongs to the technical field of ferrite material preparation, and in particular relates to a soft and hard magnetic microwave ferrite coupling material and a preparation method thereof. Background Art

[0002] Circulators are microwave devices designed based on the gyromagnetic properties of ferrites. They have the advantages of high power carrying capacity and low loss, and are widely used in the microwave field. Microwave ferrites can be divided into spinel, garnet and magnetoplumbite ferrites according to their crystal structure. Among them, circulators designed based on spinel and garnet ferrites (commonly known as soft magnetic microwave ferrites) require external magnetic steel to provide a bias field for them to work properly, which is not conducive to the development of small and lightweight and planar integration of the entire system. Magneto-plumbite hexagonal ferrite (commonly known as hard magnetic microwave ferrite) has high coercivity. H c , high anisotropy field H a and high remanence ratio M r / M s ;high H c Can maintain permanent magnetic properties, high M r / M s The magnetic moment can be made to tend to precess in the direction of strong anisotropy, and then the magnetic moment can produce ferromagnetic resonance with microwave / millimeter waves in the absence of an external steady magnetic field or a very small steady magnetic field, thereby realizing the self-bias characteristic of the circulator, getting rid of the constraints of external magnetic steel, significantly reducing the weight and volume of microwave devices, and facilitating miniaturization and integration.

[0003] However, the application frequency of hexagonal ferrite is usually in the range of 40~60 GHz, which is much higher than the industrial application frequency range in radar and wireless communication fields. One of the keys to reduce the application frequency of hexagonal ferrite is to reduce the 4π M s and H a Ion substitution is usually used to regulate the 4π M s and H a , for example, Sc 3+ , Cu 2+ andIn 3+ Single ion substitution and Zn 2+ -Sn 4+ and Mg 2+ -Ti 4+However, the corresponding magnetic properties deteriorate seriously, which is not conducive to the application of self-biased circulators. Therefore, finding a preparation method that can effectively regulate the anisotropy field of hexagonal ferrite and keep the self-biased properties of the material is of great significance to the development of miniaturization and integration of microwave devices.

[0004] For microwave ferrite materials used in self-biased circulators, Y. Chen et al. used solid phase sintering to prepare hexagonal ferrite materials, which have a high c Axis orientation, M r / M s is 0.92, H c 1300 Oe, H a is 8.45 kOe, and the ferromagnetic resonance line width Δ H 530 Oe, dielectric loss tan is not reported d ε ; The prepared materials H c Smaller, Δ H Y. Li et al. prepared hexagonal ferrite materials by tape casting. The 4π M s is 3.81 kGs, M r / M s is 0.85, and when the resonant frequency is 45 GHz, Δ H 383Oe, not reported H c and tan d ε V. Sharma et al. used a one-step sol-gel method to prepare (1- x )BaFe 12 O 19 / x Y3Fe5O 12 (0≤x≤1) soft and hard magnetic microwave ferrite coupling material, 4π M s 、4π M r and H c As the YIG content of the soft magnetic phase increases, it decreases, but the introduction of YIG can effectively reduce Δ H H. Yang et al. used the same method to prepare BaM / YIG soft and hard magnetic microwave ferrite coupling materials. M r / M sand H c 0.59 and 3766 Oe respectively, 4π is not reported M s , Δ H and tan d ε ; The prepared materials M r / M s Small. The above materials cannot have both high M r / M s and H c , suitable 4π M s and H a , low Δ H and tan d ε Characteristics to meet the engineering application requirements of self-bias circulators.

[0005] Based on the above, the present invention proposes a soft and hard magnetic microwave ferrite coupling material and a preparation method, realizes the coupling of soft and hard magnetic microwave ferrite materials through formulation and process design, and develops a soft and hard magnetic microwave ferrite material with high M r / M s and H c , suitable 4π M s and H a , low Δ H and tan d ε Characteristics of microwave ferrite materials. Summary of the invention

[0006] The purpose of the present invention is to propose a soft and hard magnetic microwave ferrite coupling material and a preparation method, in view of the fact that the microwave ferrite materials involved in the current technology are difficult to meet the engineering application requirements of the self-biased circulator. M r / M s and H c , suitable 4π M s and H a , low Δ H and tan d εCharacteristics, fundamentally solving the existing circulator miniaturization and integration problems.

[0007] The core idea of ​​the present invention is that the hard magnetic microwave ferrite material BaM has both high M r / M s and H c Features, in high M r / M s and H c Under the action of BaM, the magnetic moment rotation of the low-loss soft magnetic microwave ferrite material YIG will be affected by BaM, so after the external magnetic field is removed, the material can still maintain a high M r / M s and H c Features. In terms of formula, Bi 3+ It has strong spin-orbit coupling and covalent bonding ability, which enhances the dielectric properties of YIG. 3+ Reduce the anisotropy of YIG and reduce Δ H and tan d ε , while Bi 3+ Regulate the ion occupancy distribution of BaM. In addition, Y 3+ Ion diffusion facilitates access to the BaM crystal structure, enhancing the bridging between elements and dangling bonds in the two phases and optimizing 4π M s and H a ,improve M r / M s In terms of pre-sintering, according to the difference in the growth temperature range of YIG and BaM grains, the two microwave ferrite raw materials are synthesized in one pot by combining the solid phase reaction method, which reduces the distance between the magnetic moments of the soft and hard magnetic phases, enhances the exchange coupling effect, and thus improves M r / M s and H c In terms of dopants, low-melting-point Bi2O3 and high-melting-point SiO2 are used to regulate the grain boundary characteristics and achieve uniform and dense growth of soft and hard magnetic microwave ferrite coupling materials.

[0008] The key technical problem solved by the present invention is that the microwave ferrite material used in the self-biased circulator cannot have both high Mr / M s and H c , suitable 4π M s and H a , low Δ H and tan d ε The technical problem of the characteristics of the soft and hard magnetic microwave ferrite coupling material and preparation method are provided. The soft and hard magnetic microwave ferrite coupling material developed has both high M r / M s and H c , suitable 4π M s and H a , low Δ H and tan d ε Characteristics. The technical solution adopted by the present invention is as follows:

[0009] A soft and hard magnetic microwave ferrite coupling material, characterized in that it comprises a main phase and a dopant;

[0010] The main phase includes YIG microwave ferrite material and BaM microwave ferrite material, wherein 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, and the BaM microwave 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 mass ratio of the YIG microwave ferrite material to the BaM microwave ferrite material is 1:7-1:1;

[0011] The weight percentage of dopants in the main phase, calculated as oxides, is: 0.2~0.6 wt.% Bi2O3 and 0.2~0.6 wt.% SiO2.

[0012] A method for preparing a soft and hard magnetic microwave ferrite coupling material comprises the following steps:

[0013] Step 1: Ingredients

[0014] Weigh the YIG microwave ferrite raw material according to the ratio of "8.5-20.5 mol% Y2O3, 17-29 mol% Bi2O3, 47.5-57.5 mol% Fe2O3, 5-15 mol% In2O3"; weigh the BaM ferrite raw material according to the ratio of "6.5-12.5 mol% BaO, 5.5-10.5 mol% La2O3, 5.5-10.5 mol% Bi2O3, 62.5-73.5 mol% Fe2O3"; mix the YIG and BaM ferrite raw materials in a mass ratio of 1:7-1:1 to obtain a mixed ferrite powder;

[0015] Step 2: First ball milling

[0016] The mixed ferrite powder obtained in step 1 is ball milled by a ball mill for 2 to 8 h;

[0017] Step 3: Primary sintering

[0018] The ball mill obtained in step 2 is dried and sieved, and the temperature is first raised to 1000-1100°C and kept at this temperature for 3-6 hours; then the temperature is quickly raised to 1200-1300°C and kept at this temperature for 1-3 hours;

[0019] Step 4: Doping

[0020] In the mixed sintered powder obtained in step 3, dopants are added according to the weight percentage of the mixed ferrite powder: 0.2-0.6 wt.% Bi2O3 and 0.2-0.6 wt.% SiO2;

[0021] Step 5: Secondary ball milling

[0022] The mixture obtained in step 4 was ball-milled in a ball mill for 12-18 h, and the particle size of the powder was controlled between 0.7-0.9 μm;

[0023] Step 6: Magnetic field forming

[0024] The ball mill obtained in step 5 is pressed and molded in a magnetic field molding machine, the molding magnetic field is 0.7-1.2 T, and the molding pressure is 90-150 MPa;

[0025] Step 7: Secondary sintering

[0026] The green body obtained in step 6 is subjected to secondary sintering at a sintering temperature of 1200-1300° C. for a holding time of 4-10 hours. After sintering, the green body is naturally cooled to room temperature and taken out to obtain the soft and hard magnetic microwave ferrite coupling material.

[0027] The performance test of the soft and hard magnetic microwave ferrite coupling material obtained in step 7 is carried out: saturation magnetization intensity 4π Ms , residual magnetization 4π M r , coercivity H c Measured using the American LakeShore 8604 vibrating sample magnetometer; ferromagnetic resonance line width Δ H and dielectric loss tan d ε The anisotropic field is measured using the CK-XW-100 high-frequency integrated measurement system. H a The final technical indicators of the soft and hard magnetic microwave ferrite coupling material prepared by the present invention are as follows:

[0028] Saturation magnetization 4π M s ≥2800 Gs;

[0029] Remanence ratio M r / M s ≥0.90;

[0030] Coercivity H c ≥3300 Oe;

[0031] Anisotropy Field H a ≤12 kOe;

[0032] Ferromagnetic resonance line width Δ H ≤300 Oe;

[0033] Dielectric loss tan d ε ≤2.0×10 -3 .

[0034] Furthermore, in step 3, the temperature is increased to 1200-1300°C at a heating rate of 15°C / min and kept at this temperature for 1-3 h.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The present invention mixes and sinters two microwave ferrite raw materials, YIG and BaM, in one pot, and adopts a multi-step sintering technology. During the mixed sintering process, YIG in YIG 3+ Ions can easily enter the BaM crystal structure through diffusion, enhance the bridging between the elements and dangling bonds in the two phases, and reduce the distance between the magnetic moments of the soft and hard magnetic phases, enhance the exchange coupling effect, and improve the coupling material. M r / M s andH c At the same time, during mixed sintering, the YIG and BaM grains are more evenly distributed and staggered by utilizing the fluidity of chemical reactions, resulting in a higher density of the coupling material, corresponding to Δ H and tan d ε Smaller. DETAILED DESCRIPTION

[0037] The present invention is described in detail below in conjunction with specific examples and comparative examples. This example is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the present invention is not limited to the following examples.

[0038] A method for preparing a soft and hard magnetic microwave ferrite coupling material comprises the following steps:

[0039] Step 1: Ingredients

[0040] Weigh the YIG microwave ferrite raw material according to the ratio of "17 mol% Y2O3, 20.5 mol% Bi2O3, 55.5 mol% Fe2O3, 7 mol% In2O3"; weigh the BaM ferrite raw material according to the ratio of "11.5 mol% BaO, 8.5 mol% La2O3, 9.5 mol% Bi2O3, 70.5 mol% Fe2O3"; mix the YIG and BaM ferrite raw materials, the mixing ratio is shown in the table below, and obtain a mixed ferrite powder;

[0041]

[0042] Step 2: First ball milling

[0043] The mixed ferrite powder obtained in step 1 is ball milled for 6 h;

[0044] Step 3: Primary sintering

[0045] The ball mill obtained in step 2 was dried and sieved, and the temperature was first raised to 1050°C and kept at this temperature for 4 h; then the temperature was quickly raised to 1250°C and kept at this temperature for 2 h;

[0046] Step 4: Doping

[0047] In the mixed sintered powder obtained in step 3, dopants are added according to the weight percentage of the mixed ferrite powder: 0.35 wt.% Bi2O3 and 0.25 wt.% SiO2;

[0048] Step 5: Secondary ball milling

[0049] The mixture obtained in step 4 was ball-milled in a ball mill for 16 h, and the particle size of the powder was controlled between 0.7 and 0.9 μm;

[0050] Step 6: Magnetic field forming

[0051] The ball mill obtained in step 5 is pressed and molded in a magnetic field molding machine, the molding magnetic field is 0.9 T, and the molding pressure is 120 MPa;

[0052] Step 7: Secondary sintering

[0053] The green body obtained in step 6 is subjected to secondary sintering at a sintering temperature of 1250°C and a holding time of 8 h. After sintering, it is naturally cooled to room temperature and taken out to obtain a soft and hard magnetic microwave ferrite coupling material.

[0054] The performance test of the soft and hard magnetic microwave ferrite coupling material obtained in step 7 is carried out: saturation magnetization intensity 4π M s , residual magnetization 4π M r , coercivity H c Measured using the American LakeShore 8604 vibrating sample magnetometer; ferromagnetic resonance line width Δ H and dielectric loss tan d ε The anisotropic field is measured using the CK-XW-100 high-frequency integrated measurement system. H a It is derived from Kittel's formula.

[0055] In comparative example 1, step 3 is heated to 1250°C and kept warm for 2 hours; in step 4, dopant and BaM ferrite raw material are added simultaneously during doping. In comparative example 2, step 3 is heated to 1250°C and kept warm for 2 hours; in step 4, dopant and YIG ferrite raw material are added simultaneously during doping.

[0056] The performance parameters of the soft and hard magnetic microwave ferrite coupling materials prepared based on the above process steps, Examples 1 to 4 and Comparative Examples 1 to 2 are as follows:

[0057]

[0058] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art of the present invention, several equivalent substitutions or obvious variations can be made without departing from the concept of the present invention, and the performance or use is the same, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A soft and hard magnetic microwave ferrite coupling material, characterized in that: including a main phase and a dopant; The main phase includes YIG microwave ferrite material and BaM microwave ferrite material, wherein 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, and the BaM microwave 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 mass ratio of the YIG microwave ferrite material to the BaM microwave ferrite material is 1:7-1:1; The weight percentage of dopants in the main phase, calculated as oxides: 0.2~0.6 wt.% Bi2O3 and 0.2~0.6 wt.% SiO2; The soft and hard magnetic microwave ferrite coupling material is prepared by the following steps: Step 1: Ingredients Weigh the YIG microwave ferrite raw material according to the ratio of "8.5-20.5 mol% Y2O3, 17-29 mol% Bi2O3, 47.5-57.5 mol% Fe2O3, 5-15 mol% In2O3"; weigh the BaM microwave ferrite raw material according to the ratio of "6.5-12.5 mol% BaO, 5.5-10.5 mol% La2O3, 5.5-10.5 mol% Bi2O3, 62.5-73.5 mol% Fe2O3"; mix the YIG and BaM ferrite raw materials in a mass ratio of 1:7-1:1 to obtain a mixed ferrite powder; Step 2: First ball milling The mixed ferrite powder obtained in step 1 is ball-milled for 2 to 8 h; Step 3: Primary sintering The ball mill obtained in step 2 is dried and sieved, and then sintered by step sintering; Step 4: Doping In the mixed sintered powder obtained in step 3, dopants are added according to the weight percentage of the mixed ferrite powder: 0.2-0.6 wt.% Bi2O3 and 0.2-0.6 wt.% SiO2; Step 5: Secondary ball milling The mixture obtained in step 4 was ball-milled for 12-18 h, and the particle size of the powder was controlled between 0.7-0.9 μm; Step 6: Magnetic field forming The ball mill obtained in step 5 is pressed into a mold, the molding magnetic field is 0.7-1.2 T, and the molding pressure is 90-150 MPa; Step 7: Secondary sintering The green body obtained in step 6 is subjected to secondary sintering at a sintering temperature of 1200-1300 °C and a heat preservation time of 4-10 h. After sintering, it is naturally cooled to room temperature and taken out to obtain a soft and hard magnetic microwave ferrite coupling material.

2. A method for preparing a soft and hard magnetic microwave ferrite coupling material, characterized in that: The following steps are involved: Step 1: Ingredients Weigh the YIG microwave ferrite raw material according to the ratio of "8.5-20.5 mol% Y2O3, 17-29 mol% Bi2O3, 47.5-57.5 mol% Fe2O3, 5-15 mol% In2O3"; weigh the BaM microwave ferrite raw material according to the ratio of "6.5-12.5 mol% BaO, 5.5-10.5 mol% La2O3, 5.5-10.5 mol% Bi2O3, 62.5-73.5 mol% Fe2O3"; mix the YIG and BaM ferrite raw materials in a mass ratio of 1:7-1:1 to obtain a mixed ferrite powder; Step 2: First ball milling The mixed ferrite powder obtained in step 1 is ball-milled for 2 to 8 h; Step 3: Primary sintering The ball mill obtained in step 2 is dried and sieved, and then sintered by step sintering; Step 4: Doping In the mixed sintered powder obtained in step 3, dopants are added according to the weight percentage of the mixed ferrite powder: 0.2-0.6 wt.% Bi2O3 and 0.2-0.6 wt.% SiO2; Step 5: Secondary ball milling The mixture obtained in step 4 was ball-milled for 12-18 h, and the particle size of the powder was controlled between 0.7-0.9 μm; Step 6: Magnetic field forming The ball mill obtained in step 5 is pressed into a mold, the molding magnetic field is 0.7-1.2 T, and the molding pressure is 90-150 MPa; Step 7: Secondary sintering The green body obtained in step 6 is subjected to secondary sintering at a sintering temperature of 1200-1300° C. for a holding time of 4-10 h. After sintering, the green body is naturally cooled to room temperature and taken out to obtain the soft and hard magnetic microwave ferrite coupling material.

3. The method for preparing the soft and hard magnetic microwave ferrite coupling material according to claim 2, characterized in that: During the step-by-step sintering in step 3, first raise the temperature to 1000-1100 °C and keep it for 3-6 h; then raise the temperature to 1200-1300 °C and keep it for 1-3 h.

4. The method for preparing the soft and hard magnetic microwave ferrite coupling material according to claim 3, characterized in that: The temperature was raised to 1200-1300 °C at a heating rate of 15 °C / min and kept at this temperature for 1-3 h.

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