High-dielectric high-power low-loss ferrite material and preparation method thereof

Abstract

The invention discloses a high-dielectric high-power low-loss ferrite material and a preparation method thereof, the matrix structure is yttrium iron garnet, the ferrite material belongs to a gyromagnetic ferrite material, the chemical formula of the ferrite material is Y3-a-b-cBiaCabDycZrbIndFe5-b-d-fO12-1. 5f, a is greater than or equal to 0.9 and less than or equal to 1.55, b is greater than or equal to 0.2 and less than or equal to 0.45, c is greater than or equal to 0 and less than or equal to 0.06, d is greater than or equal to 0 and less than or equal to 0.3, and f is greater than or equal to 0 and less than or equal to 0.2. The invention also discloses a preparation method of the ferrite material, the specific gravity of a liquid phase medium is gradually reduced in two times of ball milling, the particle size of the material is reduced, and the particle uniformity is improved. And a sectional sintering process is combined, so that uniform generation of fine grain ferrite is promoted, and precipitation of a second phase is inhibited. According to the ferrite material prepared by the invention, the dielectric constant is 22-31, the ferromagnetic resonance line width is 70-110 Oe, the saturation magnetization is 1600-1950 Gs, and the electromagnetic loss is tan delta epsilon lt; the ferrite material has good performance stability, and can be applied to a small-size ultra-wideband circulator.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microwave materials, in particular to a high-dielectric high-power low-loss ferrite material and a preparation method thereof. BACKGROUND

[0002] Microwave ferrite material is a kind of metal oxide material that uses its gyromagnetic effect to realize the directional modulation of electromagnetic wave signal transmission process, and is widely used in aerospace, satellite communication, mobile communication and medical treatment and other fields. Especially in the field of aerospace, ferrite is the core component in the circulator for radar. With the new requirements of new generation of radar equipment such as ultra large bandwidth, miniaturization, high power and low insertion loss, the performance of ferrite material needs to be improved to meet the design requirements. Traditional yttrium iron garnet (YIG) has the characteristics of small linewidth and low loss, but its dielectric constant is low (less than 14), which cannot meet the design requirements of miniaturized devices. The spin wave linewidth of intrinsic YIG is small, which makes the device prone to excite nonlinear effects and has low power tolerance.

[0003] CN 118145978 A was published on June 7, 2024, which disclosed a preparation method of a high-dielectric-constant small-line-width yttrium iron garnet ferrite material. The dielectric constant ε' is greater than 20, the dielectric loss tanδε is less than 1x10 -4 , the ferromagnetic resonance linewidth ΔH is less than or equal to 25 Oe, the saturation magnetization 4πMs is greater than 1900G, and the Curie temperature Tc is greater than 240℃. Although the loss of the material is low, the dielectric constant is not high enough and the power tolerance performance of the device is not considered in the material design, and the process of three ball milling and two pre-burning is adopted, which greatly increases the preparation cost and period of the material, which is not conducive to large-scale production. SUMMARY

[0004] In order to solve the above technical problems, the present application provides a high-dielectric high-power low-loss ferrite material and a preparation method thereof.

[0005] A high-dielectric high-power low-loss ferrite material, whose chemical formula is Y 3-a-b-c Bi a Ca b Dy c Zr b In d Fe 5-b-d- f O 12-1.5f , wherein 0.9≤a≤1.55, 0.2≤b≤0.45, 0≤c≤0.06, 0≤d≤0.3, 0≤f≤0.2.

[0006] Further, the raw materials are Y2O3, Bi2O3, CaCO3, ZrO2, In2O3, Dy2O3 and Fe2O3.

[0007] Furthermore, the dielectric constant of the material is 25.5 to 31.

[0008] A method for preparing a high-dielectric, high-power, low-loss ferrite material, the chemical formula of which is Y. 3-a-b- c Bi a Ca b Dy c Zr b In d Fe 5-b-d-f O 12-1.5f Where 0.9≤a≤1.55, 0.2≤b≤0.45, 0≤c≤0.06, 0≤d≤0.3, and 0≤f≤0.2, its preparation method includes the following steps: (1) Ingredients: Calculate and weigh each raw material according to its chemical formula. The raw materials are Y2O3, Bi2O3, CaCO3, ZrO2, In2O3, Dy2O3, and Fe2O3. (2) First ball milling: Add the various raw materials weighed in step (1) to the dispersant and perform wet ball milling using a ball mill. The dispersant is deionized water or alcohol. The rotation speed is 50-100 r / min and the ball milling time is 18-24 h. (3) Pressing and molding: The slurry obtained after grinding in step (2) is introduced into a container, dried and pressed into blocks; (4) Pre-firing: The block obtained in step (3) is placed in a bell furnace for pre-firing. The pre-firing temperature is 750℃, the holding time is 6-10h, and the cooling method is slow cooling with the furnace. (5) Secondary ball milling: After mechanically crushing the pre-burnt block obtained in step (4), pour it into the ball mill barrel, add a dispersant, and perform secondary wet ball milling using a horizontal ball mill. The dispersant is deionized water, alcohol or an alcohol-water solution. The rotation speed is 50-100 r / min, and the ball milling time is 18-24 h. (6) Drying and granulation: Dry the slurry obtained in step (5), add binder and mix evenly for granulation, and sieve it through a 200-mesh filter. The binder is a polyvinyl alcohol aqueous solution with a concentration of 5wt% to 10wt%. (7) Sample pressing: The powder obtained in step (6) is pressed into a block sample green body with a pressing pressure of 100-150 MPa. (8) Sintering: The sample green blank is placed in a sintering furnace for segmented heating and sintering. The sintering temperature is 950℃~980℃ and the holding time is 10~20h.

[0009] Furthermore, in step (2), during the first ball milling, the mass ratio of ball:material:dispersant is 3.3:0.95:1.

[0010] Furthermore, in step (4), the pre-firing process is a multi-stage sintering process, which involves raising the temperature from room temperature to 200°C for 3 hours and holding it for 2 hours, then raising the temperature to 750°C for 8 hours and holding it for 6 to 10 hours.

[0011] Furthermore, in step (5) the secondary ball milling, the mass ratio of ball:material:dispersant is 3.3:0.95:0.9.

[0012] Furthermore, in step (8), the segmented heating sintering starts from room temperature, heats up to 300°C in 180 minutes, then heats up to 700°C in 430 minutes, and heats up from 700°C to 950°C to 980°C. The heating rate is controlled at 1 to 4°C / min. After reaching the target temperature, the temperature is held for 10 to 20 hours, and then slowly cooled to room temperature with the furnace.

[0013] Compared with existing technologies, the advantages of this technology are as follows: 1. The method for preparing high-dielectric, high-power, and low-loss ferrite materials provided by this invention has a low content of rare earth and expensive metal oxides in the material formulation, and adopts a material preparation process of two ball millings and one pre-firing, which greatly reduces production costs and time; by improving the powder particle size and multi-stage heating process, the nucleation uniformity of the material grains is improved, the generation of the second phase and the abnormal growth of some grains are suppressed, and the stability of the material performance is ensured; 2. The high-dielectric, high-power, and low-loss ferrite material prepared by this invention has a dielectric constant that can vary between 22 and 31 depending on the composition, a ferromagnetic resonance linewidth of 70 to 120 Oe, a saturation magnetization of 1700 to 1950 Gs, and an electromagnetic loss tanδε < 9 × 10⁻⁶. -4 It can meet the requirements of circulator design for balancing high-frequency signal loss and isolation while effectively reducing device size. Attached Figure Description

[0014] Figure 1 The image shows the phase analysis SEM image of the ferrite material in Example 1. Figure 2 XRD patterns of the ferrite materials in Examples 1 and 2; Figure 3 XPS plots of the ferrite materials from Examples 1 and 2; Figure 4 This is the elemental distribution diagram of the phase analysis of the ferrite material in Example 1; Figure 5 SEM images of the ferrite material in Comparative Example 3; Figure 6 The elemental distribution diagram of the phase analysis of the ferrite material in Comparative Example 1 is shown. Figure 7 The magnetic properties of the examples and comparative examples; Figure 8 The particle size after secondary ball milling is shown in the examples and comparative examples. Detailed Implementation

[0015] The present invention will be further described below.

[0016] Example 1 (1) According to the chemical formula Y of ferrite material 1.1 Bi 1.5 Ca 0.35 Dy 0.05 Zr 0.35 In 0.05 Fe 4.5 O 11.85 The raw materials are Y2O3, Bi2O3, CaCO3, ZrO2, Dy2O3, In2O3, and Fe2O3.

[0017] (2) First ball milling: Add the various raw materials weighed in step (1) into the ball milling barrel, pour in 1000 mL of deionized water, and use a horizontal ball mill for wet ball milling. The ball milling time is 20 h and the rotation speed is 70 r / min. (3) Pressing and molding: The slurry obtained after grinding in step (2) is introduced into a container, dried in an oven at 110°C, and then pressed into blocks using an automatic press. (4) Pre-firing: The block obtained in step (3) is placed in a bell furnace for pre-firing. The pre-firing temperature is 750℃, the heating time is 10h, the holding time is 10h, and the cooling method is slow cooling with the furnace. (5) Secondary ball milling: After mechanically crushing the pre-burnt block obtained in step (4), pour it into the ball mill bucket, add 900 mL of deionized water, and perform secondary wet ball milling using a horizontal ball mill. The ball milling time is 24 h and the rotation speed is 99 r / min. (6) Drying and granulation: Dry the slurry obtained in step (5), add binder and mix evenly for granulation, and sieve it through a 200-mesh filter. The binder is a polyvinyl alcohol aqueous solution with a concentration of 5 wt%. (7) Sample pressing: The powder obtained in step (6) is pressed into a block sample green body of a specific shape using an automatic press. The pressing pressure is 150 MPa. (8) Sintering: The sample green billet is placed in a sintering furnace for segmented heating and sintering. The sintering process is to reach 300℃ from room temperature in 3 hours, then reach 700℃ in 430 minutes, and then increase the temperature to 960℃ at 1.5℃ / min. After holding at the temperature for 15 hours, it is cooled to room temperature with the furnace.

[0018] Example 2 (1) According to the chemical formula Y of ferrite material 1.17 Bi 1.4 Ca0.4 Dy 0.03 Zr 0.4 In 0.1 Fe 4.4 O 11.85 The raw materials are Y2O3, Bi2O3, CaCO3, ZrO2, Dy2O3, In2O3, and Fe2O3.

[0019] (2) First ball milling: Add the various raw materials weighed in step (1) into the ball milling barrel, pour in 1000 mL of deionized water, and use a horizontal ball mill for wet ball milling. The ball milling time is 20 h and the rotation speed is 70 r / min. (3) Pressing and molding: The slurry obtained after grinding in step (2) is introduced into a container, dried in an oven at 110°C, and then pressed into blocks using an automatic press. (4) Pre-firing: The block obtained in step (3) is placed in a bell furnace for pre-firing. The pre-firing temperature is 750℃, the heating time is 10h, the holding time is 10h, and the cooling method is slow cooling with the furnace. (5) Secondary ball milling: After mechanically crushing the pre-burnt block obtained in step (4), pour it into the ball mill bucket, add 900 mL of deionized water, and perform secondary wet ball milling using a horizontal ball mill. The ball milling time is 24 h and the rotation speed is 99 r / min. (6) Drying and granulation: Dry the slurry obtained in step (5), add binder and mix evenly for granulation, and sieve it through a 200-mesh filter. The binder is a polyvinyl alcohol aqueous solution with a concentration of 5 wt%. (7) Sample pressing: The powder obtained in step (6) is pressed into a block sample green body of a specific shape using an automatic press. The pressing pressure is 150 MPa. (8) Sintering: The sample green billet is placed in a sintering furnace for segmented heating and sintering. The sintering process is to reach 300°C from room temperature in 3 hours, then reach 700°C in 430 minutes, and then increase the temperature to 965°C at 2°C / min. After holding at the temperature for 15 hours, it is cooled to room temperature with the furnace.

[0020] Example 3 (1) According to the chemical formula Y of ferrite material 1.1 Bi 1.5 Ca 0.35 Dy 0.05 Zr 0.35 In 0.1 Fe 4.45 O 11.85 The raw materials are Y2O3, Bi2O3, CaCO3, ZrO2, Dy2O3, In2O3, and Fe2O3.

[0021] (2) First ball milling: Add the various raw materials weighed in step (1) into the ball milling barrel, pour in 1000 mL of deionized water, and perform wet ball milling using a horizontal ball mill. The ball milling time is 24 h and the rotation speed is 70 r / min. (3) Pressing and molding: The slurry obtained after grinding in step (2) is introduced into a container, dried in an oven at 110°C, and then pressed into blocks using an automatic press. (4) Pre-firing: The block obtained in step (3) is placed in a bell furnace for pre-firing. The pre-firing temperature is 750℃, the heating time is 10h, the holding time is 10h, and the cooling method is slow cooling with the furnace. (5) Secondary ball milling: After mechanically crushing the pre-burnt block obtained in step (4), pour it into the ball mill bucket, add 900 mL of deionized water, and perform secondary wet ball milling using a horizontal ball mill. The ball milling time is 24 h and the rotation speed is 99 r / min. (6) Drying and granulation: Dry the slurry obtained in step (5), add binder and mix evenly for granulation, and sieve it through a 200-mesh filter. The binder is a polyvinyl alcohol aqueous solution with a concentration of 5 wt%. (7) Sample pressing: The powder obtained in step (6) is pressed into a block sample green body of a specific shape using an automatic press. The pressing pressure is 150 MPa. (8) Sintering: The sample green billet is placed in a sintering furnace for segmented heating and sintering. The sintering process is to reach 300°C from room temperature in 3 hours, then reach 700°C in 430 minutes, and then increase the temperature to 955°C at 2°C / min. After holding at the temperature for 15 hours, it is cooled to room temperature with the furnace.

[0022] Example 4 (1) According to the chemical formula Y of ferrite material 1.24 Bi 1.42 Ca 0.3 Dy 0.04 Zr 0.3 In 0.05 Fe 4.6 O 11.925 The raw materials are Y2O3, Bi2O3, CaCO3, ZrO2, Dy2O3, In2O3, and Fe2O3.

[0023] (2) First ball milling: Add the various raw materials weighed in step (1) into the ball milling barrel, pour in 1000 mL of deionized water, and perform wet ball milling using a horizontal ball mill. The ball milling time is 22 h and the rotation speed is 55 r / min. (3) Pressing and molding: The slurry obtained after grinding in step (2) is introduced into a container, dried in an oven at 110°C, and then pressed into blocks using an automatic press. (4) Pre-firing: The block obtained in step (3) is placed in a bell furnace for pre-firing. The pre-firing temperature is 750℃, the heating time is 10h, the holding time is 10h, and the cooling method is slow cooling with the furnace. (5) Secondary ball milling: After mechanically crushing the pre-burnt block obtained in step (4), pour it into the ball mill bucket, add 800 mL of deionized water, and perform secondary wet ball milling using a horizontal ball mill. The ball milling time is 22 h and the rotation speed is 99 r / min. (6) Drying and granulation: Dry the slurry obtained in step (5), add binder and mix evenly for granulation, and sieve it through a 200-mesh filter. The binder is a polyvinyl alcohol aqueous solution with a concentration of 5 wt%. (7) Sample pressing: The powder obtained in step (6) is pressed into a block sample green body of a specific shape using an automatic press. The pressing pressure is 150 MPa. (8) Sintering: The sample green billet is placed in a sintering furnace for segmented heating and sintering. The sintering process is to reach 300℃ from room temperature in 3 hours, then reach 700℃ in 430 minutes, and then increase the temperature to 960℃ at 1.5℃ / min. After holding at the temperature for 15 hours, it is cooled to room temperature with the furnace.

[0024] Example 5 (1) According to the chemical formula Y of ferrite material 1.23 Bi 1.37 Ca 0.35 Dy 0.05 Zr 0.35 In 0.2 Fe 4.35 O 11.85 The raw materials are Y2O3, Bi2O3, CaCO3, ZrO2, Dy2O3, In2O3, and Fe2O3.

[0025] (2) First ball milling: Add the various raw materials weighed in step (1) into the ball milling barrel, pour in 1000 mL of deionized water, and perform wet ball milling using a horizontal ball mill. The ball milling time is 22 h and the rotation speed is 55 r / min. (3) Pressing and molding: The slurry obtained after grinding in step (2) is introduced into a container, dried in an oven at 110°C, and then pressed into blocks using an automatic press. (4) Pre-firing: The block obtained in step (3) is placed in a bell furnace for pre-firing. The pre-firing temperature is 750℃, the heating time is 10h, the holding time is 10h, and the cooling method is slow cooling with the furnace. (5) Secondary ball milling: After mechanically crushing the pre-burnt block obtained in step (4), pour it into the ball mill bucket, add 800 mL of deionized water, and perform secondary wet ball milling using a horizontal ball mill. The ball milling time is 22 h and the rotation speed is 99 r / min. (6) Drying and granulation: Dry the slurry obtained in step (5), add binder and mix evenly for granulation, and sieve it through a 200-mesh filter. The binder is a polyvinyl alcohol aqueous solution with a concentration of 5 wt%. (7) Sample pressing: The powder obtained in step (6) is pressed into a block sample green body of a specific shape using an automatic press. The pressing pressure is 150 MPa. (8) Sintering: The sample green billet is placed in a sintering furnace for segmented heating and sintering. The sintering process is to reach 300°C from room temperature in 3 hours, then reach 700°C in 430 minutes, and then increase the temperature to 960°C at 3°C / min. After holding at the temperature for 15 hours, it is cooled to room temperature with the furnace.

[0026] Comparative Example 1 According to the chemical formula Y of ferrite materials 1.1 Bi 1.5 Ca 0.35 Dy 0.05 Zr 0.35 In 0.05 Fe 4.5 O 11.85 The components were configured differently from those in Example 1, except that the dispersant used in the first and second ball milling was alcohol, the ball milling speed was 60 r / min in the first milling and 60 r / min in the second milling, and the other process parameters were the same as in Example 1.

[0027] Comparative Example 2 According to the chemical formula Y of ferrite materials 1.17 Bi 1.4 Ca 0.4 Dy 0.03 Zr 0.4 In 0.1 Fe 4.4 O 11.85 The components were configured, and the sintering process was as follows: room temperature for 3 hours to reach 300°C, 300°C for 12 hours to reach 960°C, and then held at 960°C for 15 hours before being slowly cooled to room temperature in the furnace. The remaining process parameters were the same as in Example 2.

[0028] Comparative Example 3 According to the chemical formula Y of ferrite materials 1.1 Bi 1.5 Ca 0.35 Dy 0.05 Zr 0.35 In 0.1 Fe 4.45 O 11.85The components were configured, and the sintering process was as follows: room temperature for 3 hours to reach 300°C, 300°C for 6 hours to reach 550°C, 550°C was increased to 960°C at a rate of 5°C / min, and the temperature was held at 960°C for 15 hours before being slowly cooled to room temperature in the furnace. The remaining process parameters were the same as in Example 1.

[0029] The sintered samples from all examples and comparative examples were tested for saturation magnetization, ferromagnetic resonance linewidth, spin wave linewidth, dielectric constant, and dielectric loss. The results are as follows: Figure 7 As shown: Comparing the particle size of powders before sintering in different embodiments and comparative samples, the particle size after secondary ball milling is as follows: Figure 8 As shown: As can be seen from Examples 1-5, the garnet ferrite prepared by this patent has the characteristics of low linewidth and high dielectric constant. Furthermore, the material exhibits stable saturation magnetization and low dielectric loss, which can meet the design requirements of miniaturized, low-loss circulators. Simultaneously, the material's high spin wavelinewidth makes it difficult to excite nonlinear effects, thus meeting the high power requirements of the device.

[0030] like Figure 8 As shown in the comparison between Example 1 and Comparative Example 1, when the material composition is consistent, the dispersant used in ball milling determines the particle size of the material after ball milling. When water is used as the dispersant, its fluidity is higher than that of alcohol, resulting in a significantly lower particle size after ball milling. Smaller particle size promotes nucleation during the material's crystallization process, preventing the formation of large pores, thus significantly reducing the ferromagnetic resonance linewidth of the material.

[0031] Comparing Example 1 and Comparative Example 3, and Example 2 and Comparative Example 2, it can be found that when the material composition is consistent and the particle size is similar, the heating rate has a significant impact on the ferromagnetic resonance linewidth of the material at the same sintering temperature. The process used in this patent involves a heating rate of 1–4 °C / min at 700–900 °C. This heating rate can effectively promote uniform nucleation of the material and thus inhibit Bi... 3+ To prevent component segregation, and at the same time avoid porosity caused by excessively rapid heating rate.

Claims

1. A high-dielectric, high-power, low-loss ferrite material, characterized in that, Its chemical formula is Y 3-a-b- c Bi a Ca b Dy c Zr b In d Fe 5-b-d-f O 12-1.5f , where 0.9≤a≤1.55, 0.2≤b≤0.45, 0≤c≤0.06, 0≤d≤0.3, and 0≤f≤0.

2.

2. The high-dielectric, high-power, low-loss ferrite material according to claim 1, characterized in that, The raw materials are Y2O3, Bi2O3, CaCO3, ZrO2, In2O3, Dy2O3, and Fe2O3.

3. The high-dielectric, high-power, low-loss ferrite material according to claim 1, characterized in that, The dielectric constant of the material is 22 to 31.

4. A method for preparing a high-dielectric, high-power, low-loss ferrite material, characterized in that, Its chemical formula is Y 3-a-b- c Bi a Ca b Dy c Zr b In d Fe 5-b-d-f O 12-1.5f Where 0.9≤a≤1.55, 0.2≤b≤0.45, 0≤c≤0.06, 0≤d≤0.3, and 0≤f≤0.2, its preparation method includes the following steps: (1) Ingredients: Calculate and weigh each raw material according to its chemical formula. The raw materials are Y2O3, Bi2O3, CaCO3, ZrO2, In2O3, Dy2O3, and Fe2O3. (2) First ball milling: Add the various raw materials weighed in step (1) to the dispersant and perform wet ball milling using a ball mill. The dispersant is deionized water or alcohol. The rotation speed is 50-100 r / min and the ball milling time is 18-24 h. (3) Pressing and molding: The slurry obtained after grinding in step (2) is introduced into a container, dried and pressed into blocks; (4) Pre-firing: The block obtained in step (3) is placed in a bell furnace for pre-firing. The pre-firing temperature is 750℃, the holding time is 6-10h, and the cooling method is slow cooling with the furnace. (5) Secondary ball milling: After mechanically crushing the pre-burnt block obtained in step (4), pour it into the ball mill barrel, add a dispersant, and perform secondary wet ball milling using a horizontal ball mill. The dispersant is deionized water, alcohol or an alcohol-water solution. The rotation speed is 50-100 r / min, and the ball milling time is 18-24 h. (6) Drying and granulation: Dry the slurry obtained in step (5), add binder and mix evenly for granulation, and sieve it through a 200-mesh filter. The binder is a polyvinyl alcohol aqueous solution with a concentration of 5wt% to 10wt%. (7) Sample pressing: The powder obtained in step (6) is pressed into a block sample green body with a pressing pressure of 100-150 MPa. (8) Sintering: The sample green blank is placed in a sintering furnace for segmented heating and sintering. The sintering temperature is 950℃~980℃ and the holding time is 10~20h.

5. The method for preparing the high-dielectric, high-power, low-loss ferrite material according to claim 3, characterized in that, In step (2), the mass ratio of ball:material:dispersant in a single ball mill is 3.3:0.95:

1.

6. The method for preparing the high-dielectric, high-power, low-loss ferrite material according to claim 3, characterized in that, Step (4) is a multi-stage sintering process, which involves raising the temperature from room temperature to 200℃ for 3 hours and holding it for 2 hours, then raising the temperature to 660-810℃ for 8 hours and holding it for 6-10 hours.

7. The method for preparing high-dielectric, high-power, low-loss ferrite material according to claim 3, characterized in that... In step (5), during the secondary ball milling, the mass ratio of ball:material:dispersant is 3.3:0.95:0.

9.

8. The method for preparing high-dielectric, high-power, low-loss ferrite material according to claim 3, characterized in that... In step (8), the segmented heating sintering starts from room temperature and is heated to 300℃ in 180 minutes, then to 700℃ in 430 minutes. When the temperature is raised from 700℃ to 950℃~980℃, the heating rate is controlled to be 1~4℃ / min. After reaching the target temperature, the temperature is held for 10~20 hours, and then slowly cooled to room temperature with the furnace.

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