Microwave ferrite material with high dielectric constant and low ferromagnetic resonance linewidth, preparation method and application thereof

Abstract

The present application relates to a microwave ferrite material with high dielectric constant and low ferromagnetic resonance linewidth, which is prepared by using a main formula and additives, wherein the main formula is Y2O3, Fe2O3 and Bi2O3, and the additives are ZrO2, CaCO3 and MnCO3, and the components are as follows in terms of mass percentage: Y2O3: 13wt%-18wt%, Fe2O3: 50wt%-55.5wt%, Bi2O3: 27wt%-35wt%, ZrO2: 0.5wt%-1.5wt%, CaCO3: 0.5wt%-2wt% and MnCO3: 0.55wt%-0.95wt%. The microwave ferrite material can be applied to related devices of 5G communication to meet the miniaturization and integration of microwave circulators and isolators.

Description

Technical Field

[0001] This invention relates to a microwave ferrite material with high dielectric constant and low ferromagnetic resonance linewidth, its preparation method and application, belonging to the field of microwave ferrite material technology. Background Technology

[0002] The rapid development of 5G base stations presents new opportunities for microwave ferrite materials and devices, making the integration of various microwave magnetic devices a key research area. Whether for military or civilian electronic equipment, the requirements for material performance parameters are constantly increasing. In the current environment of rapid microwave technology development, electronic device design must meet the demands of increasingly smaller sizes, wider operating bandwidths, and higher safety and stability. Only when the properties of ferrite materials meet these requirements can microwave devices with excellent performance in all aspects be designed. Increasing the dielectric constant of garnet ferrite materials is an effective way to reduce the size of microwave magnetic devices. Furthermore, by reducing its ferromagnetic resonance linewidth and dielectric loss, the overall loss of electronic devices can be reduced.

[0003] Existing microwave ferrites suffer from high resonant linewidth and low dielectric constant, mainly due to unsuitable formulations and preparation processes, resulting in material properties that do not meet requirements.

[0004] CN112745122A discloses a method for preparing high-power, high-dielectric-constant garnet, with the molecular formula: (YBiSmGdCa)3(ZrSnTiGeInVMnAlFe). 5-δ O 12 The iron deficiency δ is 0 ≤ δ ≤ 0.50; through process methods, the degree of solid-phase reaction is promoted, the formation of Bi-rich phase is reduced, and rare earth ions Sm are utilized in the formulation. 3+ This method replaces the low-magnetic-moment garnet ferrite with both low ΔH and high ΔHk, as well as a high dielectric constant ε. However, its synthesis using rare-earth elements results in high price and cost.

[0005] CN116813321A discloses a high-performance, high-dielectric-constant gyromagnetic ferrite material and its preparation method, belonging to the field of microwave ferrite materials. Its chemical formula is: Bi. a Ca 3b Y 3-a-3b Zr b V b Mn c Fe 5-2b O 12 Ferrite materials have a dielectric constant of 22-28 and a saturation magnetization range of 1000G-1600G, exhibiting low electromagnetic loss, which can meet the requirements of miniaturized ferrite devices for high dielectric constant and low electromagnetic loss.

[0006] Therefore, inventing a microwave ferrite material with high dielectric constant and low ferromagnetic resonance linewidth has great significance and market value in practical use and production. Summary of the Invention

[0007] This invention addresses the aforementioned problems by proposing a microwave ferrite material with high dielectric constant and low ferromagnetic resonance linewidth. The material design utilizes a Y, Fe, and Bi series as the base formulation, and the Curie temperature Tc is controlled through the combined action of Zr and Fe. Low power consumption is achieved by reducing the linewidth ΔH through Ca substitution; low loss characteristics are achieved by reducing dielectric loss through a small amount of Mn substitution; and the saturation magnetization 4πMs is adjusted through a combination of Ca and Mn substitution to suit different frequency devices. This material can be applied to 5G communication devices to meet the miniaturization and integration requirements of microwave circulators and isolators.

[0008] The technical means adopted by the present invention to solve the above problems are as follows:

[0009] A microwave ferrite material with high dielectric constant and low ferromagnetic resonance linewidth is disclosed, which is composed of a main formulation and additives. The main formulation consists of Y₂O₃, Fe₂O₃, and Bi₂O₃, and the additives consist of ZrO₂, CaCO₃, and MnCO₃, with their components expressed as mass percentages as follows:

[0010] Y2O3: 13wt%-18wt%, Fe2O3: 50wt%-55.5wt%, Bi2O3: 27wt%-35wt%, ZrO2: 0.5wt%-1.5wt%, CaCO3: 0.5wt%-2wt%, and MnCO3: 0.55wt%-0.95wt%.

[0011] In the microwave ferrite material with high dielectric constant and low ferromagnetic resonance linewidth of this invention, the non-magnetic ion Bi 3+ The saturation magnetization can be changed because it is the magnetic energy torque per unit volume. Changes in cell parameters and density can lead to changes in magnetization. (Bi) 3+ The doping enhances the superexchange effect of Fe-O-Fe, thus increasing both the saturation magnetization and Curie temperature of the material. Furthermore, Bi... 3+ Substitution of ions can increase the dielectric constant of the product; adjusting the Bi content of the substituted Y can make its dielectric constant reach above 23; Mn 3+ Ion substitution reduces dielectric loss performance. Secondly, by using composite substitution with ions such as Bi and Ca, the combined requirements of increasing material density and reducing ferromagnetic resonance linewidth are better met.

[0012] Another objective of this invention is to disclose a method for preparing the aforementioned microwave ferrite material with high dielectric constant and low ferromagnetic resonance linewidth. By using a combination of main formulation and additives, a new Bi-doped YIG ferrite material with high dielectric constant and low ferromagnetic resonance linewidth is synthesized by employing a pre-calcination temperature of 850-950℃ and a grinding process, along with a low-temperature sintering temperature of 1000℃-1100℃.

[0013] Furthermore, the specific steps include:

[0014] S1. Ingredients: First, mix the main formula evenly, then add appropriate amounts of additives CaCO3, ZrO2 and MnCO3 and ball mill. The ball milling rate is 240rpm-300rpm, the grinding time is 10h-15h, and the particle size reaches 1.5μm±0.2μm.

[0015] S2. Pre-firing: Pre-firing process, temperature is 850℃-950℃, holding time is 4h-8h; then secondary ball milling is performed;

[0016] S3. Spray Granulation: Add 7wt%-10wt% of 8%-10% PVA adhesive; spray granulate into 60-200µm particles; polyvinyl alcohol (PVA) in the adhesive increases viscosity. After adding PVA, its molecular chains interact with other components in the adhesive, forming a three-dimensional network structure. This structure increases the adhesive's viscosity, making it more viscous during application or coating, thus improving its adhesive properties. PVA has a certain promoting effect on the adhesive properties of the adhesive. The PVA molecular chains in the adhesive have a certain polarity, allowing them to interact with many material surfaces through hydrogen bonds or other chemical bonds, thereby enhancing the adhesion between the adhesive and the bonded materials. In this way, the adhesive can better adhere to the surface of the bonded materials during the bonding process, improving the bond strength.

[0017] S4. The product is dry-pressed into a suitable shape and then sintered at a low temperature for a total time of 16-30 hours.

[0018] Furthermore, the sintering in step S4 is segmented sintering: the temperature is increased from room temperature to 500℃-700℃ at a rate of 1℃ / min-2℃ / min, held for 1h-3h, and then increased to the maximum sintering temperature of 1000℃-1100℃ at a rate of 1℃ / min-3℃ / min, held for 3h-10h, and then cooled with the furnace.

[0019] Further, in step S1, the ball-to-material ratio of the first ball mill is (5-7):1:(1-2), the ball milling time is 12h-24h, and the ball milling speed is 260rpm-300rpm; after the first ball milling, a drying is performed, the drying temperature is 160℃-220℃, and the drying time is 6h-10h.

[0020] Furthermore, after the initial drying, a primary crushing process is performed, wherein the ball milling rate for the primary crushing is 20 rpm to 50 rpm, and the grinding time is 0.5 h to 2 h.

[0021] Further, in step S2, the ball-to-material ratio of the secondary ball mill is (5-7):1:(1-2), the ball milling time is 15h-24h, and the ball milling speed is 240rpm-300rpm; after the secondary ball milling, a secondary drying is performed, the secondary drying temperature is 150℃-240℃, and the secondary drying time is 5h-12h.

[0022] Furthermore, after secondary drying, secondary crushing is carried out, with a ball milling rate of 20rpm-50rpm and a grinding time of 0.5h-3h.

[0023] The microwave ferrite material prepared by the method of the present invention, which has a high dielectric constant and low ferromagnetic resonance linewidth, can be used in isolators or circulators of microstrip devices.

[0024] The microwave ferrite material of the present invention, with its high dielectric constant and low ferromagnetic resonance linewidth, achieves both by rationally proportioning the chemical components of the raw materials. This provides a foundation for the further miniaturization of microwave ferrite devices and is highly beneficial for the research and development and production of miniaturized circulators and isolators.

[0025] In the microwave ferrite material of this invention, the non-magnetic ion Bi 3+ Substitution can alter the saturation magnetization because the saturation magnetization is the magnetic moment per unit volume. Although the molecular magnetic moment does not change before and after ionic substitution, changes in unit cell parameters and density can lead to changes in magnetization. (Bi) 3+ The doping enhances the superexchange effect of Fe-O-Fe, thus increasing both the saturation magnetization and Curie temperature of the material. Furthermore, Bi... 3+ Substitution of ions can increase the dielectric constant of the product; adjusting the Bi content of the substituted Y can make its dielectric constant reach above 23; Mn 3+ Ion substitution reduces dielectric loss performance. Secondly, by using composite substitutions of ions such as Bi and Ca, the combined requirements of increasing material density and reducing ferromagnetic resonance linewidth are better met.

[0026] With innovative compositional formulation, Bi₂O₃ can also form a liquid-phase sintering, lowering the sintering temperature, increasing the sintering density, and reducing the porosity between grains and grain boundaries. CaCO₃ can form a high-resistivity layer at grain boundaries, increasing the resistivity of grain boundaries and reducing eddy current losses; Y 3+After ion doping, Y₂O₃ can enter the ferrite lattice. Appropriate Y₂O₃ doping is beneficial for improving the saturation magnetization and initial permeability of the sample, reducing coercivity, and improving the magnetic properties of ferrite materials. Fe₂O₃ is the main component, with a honeycomb crystal structure being preferred. It exhibits strong chemical reactivity, complete solid-state reaction, and low levels of chemical impurities and soluble salts. It is suitable for preparing ferrite magnetic materials by solid-state reaction composite oxides of oxides, hydroxides, carbonates, or oxalates of one or more other metallic elements. 2+ It can replace Fe at the a-site of the octahedron 3+ Reduce the impact of conductive ions on Fe 2+ -Fe 3+ This increases grain resistivity and reduces losses. The role of MnCO3 is to reduce Fe... 2+ The generation of this reduces the resonant linewidth.

[0027] The additive, nano-calcium carbonate, is located at the grain boundaries. Its fine nanoparticle size increases the activation energy, forming a grain boundary layer with high resistivity, which helps reduce ferrite loss. Nanomaterials have very small particle radii; even with equal amounts of the same impurities of different particle sizes, the total volume of the nanomaterial is larger, making it easier to disperse uniformly into the ferrite material. This contributes to the uniform grain growth of the ferrite material. Therefore, adding nano-additives can yield high-performance ferrites with uniform grains.

[0028] The beneficial effects of this invention are:

[0029] 1. The microwave ferrite material of the present invention, characterized by high dielectric constant and low ferromagnetic resonance linewidth, utilizes a Y, Fe, and Bi series as the base formulation in its raw material design. The Curie temperature Tc is controlled through the combined action of Zr and Fe. Low power consumption is achieved by reducing the linewidth ΔH through Ca substitution; low loss is achieved by reducing dielectric loss through a small amount of Mn substitution; and the saturation magnetization 4πMs is adjusted through a combination of Ca and Mn substitution to suit different frequency devices. It can be applied to related devices in 5G communication to meet the miniaturization and integration requirements of microwave circulators and isolators.

[0030] 2. This microwave ferrite material possesses excellent comprehensive properties: resonant linewidth ≤ 80 Oe, dielectric constant ≥ 27, and its dielectric loss tanδε is less than 2 × 10⁻⁶. -4 Based on the optimized additive content, it can be used in the field of 5G communication equipment. Detailed Implementation

[0031] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited thereto.

[0032] Density was measured using the water displacement method, saturation magnetization Ms was measured using a magnetic balance, Curie temperature Tc was measured using a vibrating sample magnetometer, and saturation magnetic induction Bs, remanent magnetic induction Br, and coercivity He were measured using an SMT-600 hysteresis loop tester. The ferromagnetic resonance linewidth, dielectric constant, and dielectric loss of the material were tested according to GB / T9633-1998 "Test Methods for the Properties of Rotary Magnetite Ferrite Materials for Microwave Frequency Applications".

[0033] The microwave ferrite material of the present invention, characterized by high dielectric constant and low ferromagnetic resonance linewidth, is composed of a main formulation and additives. The main formulation consists of Y₂O₃, Fe₂O₃, and Bi₂O₃, while the additives are ZrO₂, CaCO₃, and MnCO₃, with their components expressed as mass percentages as follows:

[0034] Y2O3: 13wt%-18wt%, Fe2O3: 50wt%-55.5wt%, Bi2O3: 27wt%-35wt%, ZrO2: 0.5wt%-1.5wt%, CaCO3: 0.5wt%-2wt%, and MnCO3: 0.55wt%-0.95wt%.

[0035] The raw materials are first ball-milled, dried and pre-fired; then ball-milled and dried again, and a binder is added to granulate and form the pellet. The green pellet density is further improved by isostatic pressing, and finally sintered.

[0036] Example 1

[0037] The method for preparing microwave ferrite materials with high dielectric constant and low ferromagnetic resonance linewidth in this embodiment uses Y2O3, Fe2O3, and Bi2O3, with ZrO2, CaCO3, and MnCO3 as additives as initial raw materials, and is designed according to the component formulation in Table 1, including the following steps:

[0038] S1. Batching: Bi2O3, Y2O3, CaCO3, ZrO2, MnCO3 and Fe2O3 are used as initial raw materials for batching; then the materials are mixed in a ball mill, and dried for the first time after one ball milling; the ball-to-material-to-water ratio of the first ball milling is 6:1:1.2; the temperature of the first drying is 180-220℃, and the temperature is maintained for 4-8 hours.

[0039] S2. After crushing the dried material obtained in step S1, compact and punch holes, heat to 850℃-870℃ for pre-firing, hold for 7h-8h, and cool to room temperature with the furnace to obtain pre-fired material; after secondary crushing, the pre-fired material is ball-milled for 15h-16h at a ball mill speed of 240rpm-260rpm; after ball milling until the average particle size of the powder is below 1.2μm, it is dried a second time; the ball-to-material-to-water ratio is 6:1:1; the temperature of the second drying is 160-200℃, and the holding time is 6h-8h.

[0040] S3. Add 7% by weight of a binder solution to the secondary ball-milled and dried material obtained in step S2 to granulate, and grind evenly into a slurry in a ball mill; wherein the binder is preferably 8%-10% PVA adhesive. The resulting slurry is then spray-granulated; the wet-mixed mixture is placed in an atomizing device at 150-180℃ for spray granulation; the particle size of the spray-granulated material is 60-200 μm.

[0041] S4. The sprayed granules obtained in step S3 are molded into green bodies using pressure molding: the temperature is raised to 65-80℃, held for 10 minutes, and then held under pressure of 22-26 MPa for 10 minutes to further improve the density of the green body. The resulting green body is then sintered by raising the temperature to 350℃ at a rate of 1℃ / min and holding for 2 hours to drain the material. Then, the temperature is raised to 700℃ at a rate of 1-2℃ / min and held for 2 hours to drain the binder. Finally, the temperature is raised to 1020-1100℃ at a rate of 1.5℃ / min and held for 10 hours. The total sintering time is 16-20 hours.

[0042] The performance test structure of the microwave ferrite material with high dielectric constant and low ferromagnetic resonance linewidth prepared by the method of this embodiment is shown in Table 2.

[0043] Example 2

[0044] The method for preparing microwave ferrite materials with high dielectric constant and low ferromagnetic resonance linewidth in this embodiment uses Y2O3, Fe2O3, and Bi2O3, with ZrO2, CaCO3, and MnCO3 as additives as initial raw materials, and is designed according to the component formulation in Table 1, including the following steps:

[0045] S1. Batching: Bi2O3, Y2O3, CaCO3, ZrO2, MnCO3 and Fe2O3 are used as initial raw materials for batching; then the materials are mixed in a ball mill, and dried for the first time after one ball milling; the ball-to-material-to-water ratio of the first ball milling is 7:1:1; the temperature of the first drying is 180℃-220℃, and the temperature is maintained for 4h-8h.

[0046] S2. After crushing the dried material obtained in step S1, compact and punch holes, heat it to 900℃-950℃ for pre-firing, hold it at that temperature for 5h-7h, and then cool it to room temperature with the furnace to obtain pre-fired material; after the obtained pre-fired material is crushed a second time, it is then ball-milled a second time in a ball mill until the average particle size of the powder is below 1.2μm, and then dried a second time; the ball-to-material-to-water ratio is 5:1:1; the temperature of the second drying is 180-220℃, and the holding time is 6h-10h.

[0047] S3. Add 10% by weight of a binder solution to the secondary ball-milled and dried material obtained in step S2 to granulate, and grind evenly into a slurry in a ball mill; wherein the binder is preferably 8%-10% PVA adhesive. The resulting slurry is then spray-granulated; the wet-mixed mixture is placed in an atomizing device at 150℃-180℃ for spray granulation; the particle size of the spray-granulated material is 60μm-200μm.

[0048] S4. The sprayed granules obtained in step S3 are molded into green bodies using pressure molding: the temperature is raised to 65℃-80℃, held for 10 min, and then held under pressure of 22MPa-26MPa for 10 min to further improve the density of the green body. The resulting green body is then sintered by raising the temperature to 300℃ at a rate of 2℃ / min and holding for 3 h to drain the binder. Then, the temperature is raised to 700℃ at a rate of 2-3℃ / min and held for 2 h to drain the binder. Finally, the temperature is raised to 1050-1100℃ at a rate of 1.5℃ / min and held for 8-10 h. The total sintering time is 22-25 h. The high dielectric constant and low ferromagnetic resonance linewidth microwave ferrite material prepared using the method of this embodiment has the following performance test structure, as shown in Table 2.

[0049] Example 3

[0050] The preparation method of the microwave ferrite material with high dielectric constant and low ferromagnetic resonance linewidth in this embodiment uses Y2O3, Fe2O3 and Bi2O3 as initial raw materials, and ZrO2, CaCO3 and MnCO3 as additives. The preparation method is designed according to the component formula in Table 1. The preparation method is generally the same as that in Embodiment 1, except that the formula is different.

[0051] The performance test structure of the microwave ferrite material with high dielectric constant and low ferromagnetic resonance linewidth prepared by the method of this embodiment is shown in Table 2.

[0052] Example 4

[0053] The preparation method of the microwave ferrite material with high dielectric constant and low ferromagnetic resonance linewidth in this embodiment uses Y2O3, Fe2O3 and Bi2O3 as initial raw materials, and ZrO2, CaCO3 and MnCO3 as additives. The preparation method is designed according to the component formula in Table 1. The preparation method is generally the same as that in Embodiment 1. The main difference is the different formula.

[0054] The performance test structure of the microwave ferrite material with high dielectric constant and low ferromagnetic resonance linewidth prepared by the method of this embodiment is shown in Table 2.

[0055] Comparative Examples 1-12

[0056] Comparative Examples 1-12 were formulated according to the components in Table 1. The microwave ferrite materials with high dielectric constant and low ferromagnetic resonance linewidth were designed according to the components in Table 1, and their preparation method was the same as that of Example 3. The performance test structure of the microwave ferrite materials with high dielectric constant and low ferromagnetic resonance linewidth prepared using the method of this comparative example is shown in Table 2.

[0057] Table 1

[0058]

[0059]

[0060] Table 2

[0061]

[0062] The microwave ferrite material of this invention, characterized by high dielectric constant and low ferromagnetic resonance linewidth, exhibits excellent comprehensive performance: resonance linewidth ≤ 80 Oe, dielectric constant 27-33, and dielectric loss tanδε less than 2 × 10⁻⁶. -4 Based on comparative performance testing results, the performance of this invention better meets the usage requirements, and with its optimized additive content, it can be used in the field of 5G communication equipment. Those skilled in the art can make various changes or modifications without departing from the spirit and scope of this invention; therefore, all equivalent technical solutions should also fall within the protection scope of this invention, which should be defined by the claims.

Claims

1. A method for preparing a microwave ferrite material with high dielectric constant and low ferromagnetic resonance linewidth, characterized in that, It is used in combination with a main formulation and additives. The main formulation consists of Y₂O₃, Fe₂O₃, and Bi₂O₃, and the additives consist of ZrO₂, CaCO₃, and MnCO₃, with their components expressed as mass percentages as follows: A novel Bi-doped YIG ferrite material with high dielectric constant and low ferromagnetic resonance linewidth was synthesized by using a combination of main formulation and additives, employing a pre-calcination temperature of 850-950℃ and a grinding process, along with a sintering temperature of 1000℃-1100℃. The composition of Y2O3 was 13wt%-18wt%, Fe2O3 was 50wt%-55.5wt%, Bi2O3 was 27wt%-35wt%, ZrO2 was 0.5wt%-1.5wt%, CaCO3 was 0.5wt%-2wt%, and MnCO3 was 0.55wt%-0.95wt%.

2. The method for preparing microwave ferrite material with high dielectric constant and low ferromagnetic resonance linewidth according to claim 1, characterized in that, The specific steps include: S1. Ingredients: First, mix the main formula evenly, then add appropriate amounts of additives CaCO3, ZrO2 and MnCO3 and ball mill. The ball milling rate is 240rpm-300rpm, the grinding time is 10h-15h, and the particle size reaches 1.5μm±0.2μm. S2. Pre-firing: Pre-firing process, temperature is 850℃-950℃, holding time is 4h-8h; then secondary ball milling is performed; S3. Spray granulation: Add 7wt%-10wt% of 8%-10% PVA adhesive; spray granulate into 60-200um granules; S4. The product is dry-pressed into a suitable shape and then sintered at a low temperature.

3. The method for preparing microwave ferrite material with high dielectric constant and low ferromagnetic resonance linewidth according to claim 2, characterized in that, The sintering in step S4 is segmented sintering: the temperature is increased from room temperature to 300℃-700℃ at a rate of 1℃ / min-2℃ / min, held for 1h-3h, and then increased to the highest sintering temperature of 1000℃-1100℃ at a rate of 1℃ / min-3℃ / min, held for 3h-10h, and then cooled with the furnace.

4. The method for preparing the microwave ferrite material with high dielectric constant and low ferromagnetic resonance linewidth according to claim 3, characterized in that, In step S1, the ball-to-material ratio of the first ball mill is (5-7):1:(1-2), the ball milling time is 12h-24h, and the ball milling speed is 260rpm-300rpm; after the first ball milling, a drying is performed, the drying temperature is 160℃-220℃, and the drying time is 6h-10h.

5. The method for preparing the microwave ferrite material with high dielectric constant and low ferromagnetic resonance linewidth according to claim 4, characterized in that, After drying, the material is crushed once. The ball milling rate for the first crushing is 20 rpm to 50 rpm, and the grinding time is 0.5 h to 2 h.

6. The method for preparing the microwave ferrite material with high dielectric constant and low ferromagnetic resonance linewidth according to claim 5, characterized in that, In step S2, the ball milling time for the second ball milling is 15h-24h, and the ball milling rate is 240rpm-300rpm; after the second ball milling, a second drying is performed, with a second drying temperature of 150℃-240℃ and a second drying time of 5h-12h.

7. The method for preparing the microwave ferrite material with high dielectric constant and low ferromagnetic resonance linewidth according to claim 6, characterized in that, After secondary drying, secondary crushing is carried out. The ball milling rate for secondary crushing is 20rpm-50rpm, and the grinding time is 0.5h-3h.

8. A microwave ferrite material with high dielectric constant and low ferromagnetic resonance linewidth prepared by any one of claims 2-7 is used in isolators or circulators of microstrip devices.

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