YIG-mnz composite ferrite material and preparation method thereof

Abstract

This invention relates to the field of ferrite materials technology, specifically to a YIG-MnZn composite ferrite material and its preparation method, comprising a BiCaZr-YIG garnet phase and a (Mn,Zn)Fe2O4 spinel phase; the molar ratio of the BiCaZr-YIG garnet phase and the (Mn,Zn)Fe2O4 spinel phase is 10–1. The saturation magnetization of the invented YIG-MnZn composite ferrite material is ≥2000 Gs, the ferromagnetic resonance linewidth is ≤150 Oe, and the dielectric loss is ≤1×10⁻⁶. ‑3 Meanwhile, the dielectric constant is 16-20. This composite material is simple to synthesize, can increase device bandwidth, reduce device size, and has low cost.

Description

Technical Field

[0001] This invention relates to the field of ferrite materials technology, specifically to a YIG-MnZn composite ferrite material and its preparation method. Background Technology

[0002] Microwave magnetic devices such as circulators and isolators are crucial components in aerospace communication and radar systems, and their performance directly determines the system's microwave frequency reception and transmission performance. Magnetic ferrite substrates, as the core material of circulators / isolators, directly determine the circulator's specifications through their electromagnetic properties, which is also a bottleneck limiting the development of devices towards wideband, low-loss designs. Compared to intercrystalline ferrites, garnet ferrites have a narrower ferromagnetic resonance linewidth and lower dielectric loss. However, the theoretical upper limit of the saturation magnetization of single-phase polycrystalline garnet ferrite is 2100 Gauss. Since the center operating frequency of microwave devices (circulators, isolators) is proportional to the saturation magnetization of the material (fr∝γ.4πMs), this limits the application frequency range of garnet ferrites.

[0003] Currently, intercrystalline ferrite is used to meet the high-frequency requirements of broadband microwave magnetic devices. Although intercrystalline ferrite can provide higher saturation magnetization, its inherent magnetocrystalline anisotropy is large, resulting in a ferromagnetic resonance linewidth that is much wider than that of the garnet system, and the dielectric loss is usually also higher.

[0004] Existing single-phase polycrystalline garnet ferrites are difficult to exceed the theoretical upper limit of 2100 Gauss saturation magnetization. Spinel ferrites with higher saturation magnetization have greater ferromagnetic resonance linewidth and dielectric loss than garnet systems.

[0005] Traditional methods for preparing composite ferrites involve first preparing two single-phase ferrite materials with similar sintering temperatures, then mechanically mixing the different ferrite powders and re-sintering them to obtain the composite ferrite material. Due to the inherent properties of ferrite materials, the composite ferrite after phase formation and mixing is prone to uneven electromagnetic properties and porosity defects, leading to a deterioration in the performance of the composite ferrite. Furthermore, this method of preparing composite ferrites is more complex and costly. Summary of the Invention

[0006] The purpose of this invention is to provide a YIG-MnZn composite ferrite material and its preparation method, thereby solving the technical problem that composite ferrites in the prior art are prone to uneven electromagnetic properties and porosity defects, which leads to the deterioration of the performance of composite ferrites.

[0007] This invention discloses a YIG-MnZn composite ferrite material, comprising a BiCaZr-YIG garnet phase and a (Mn,Zn)Fe2O4 spinel phase; The molar ratio of BiCaZr-YIG garnet phase to (Mn,Zn)Fe2O4 spinel phase is 10–1.

[0008] Furthermore, the BiCaZr-YIG garnet phase composition includes 6.5 mol%–11.5 mol% Bi₂O₃, 23 mol%–30 mol% Y₂O₃, 0 mol%–11.5 mol% CaCO₃, 0 mol%–11.5 mol% Zr₂O₃, and 44.5 mol%–62.5 mol% Fe₂O₃.

[0009] Furthermore, the (Mn,Zn)Fe2O4 spinel phase composition includes: 10 mol% to 40 mol% MnO, 40 mol% to 10 mol% ZnO and 50 mol% Fe2O3.

[0010] Furthermore, its chemical formula is (Bi) a Y 3-a-b Ca b Zr b Fe 5-b-δ ) 1-c ((Mn,Zn)Fe2O4) c Where 0.6≤a≤0.9, 0≤b≤0.5, 0.1≤c≤0.5, 0≤δ≤0.06, and δ is the amount of iron deficiency.

[0011] A method for preparing a YIG-MnZn composite ferrite material includes the following steps: S1. After batching, the ingredients are ball-milled once and then dried; S2. The powder obtained after one ball milling is pre-calcined and then crushed to obtain pre-calcined material; S3. The obtained pre-calcined material is subjected to secondary ball milling; S4. The powder obtained from the second ball milling is dried, then granulated, shaped and sintered to obtain the final product.

[0012] Furthermore, the sintering specifically refers to: It includes two heating processes: the first heating process is at 850-900℃, and the holding time is 1-4 hours; The second heating process is at 1050–1150℃, and the holding time is 20–30 hours.

[0013] Furthermore, the first ball milling specifically involves: mixing each raw material with zirconia balls and deionized water, with a ball:material:water mass ratio of 4:1:1.5, ball milling time of 4 to 8 hours, and then drying and passing through a 60-mesh sieve. Furthermore, the pre-firing temperature is 940-980℃, the holding time is 1-5h, and after pre-firing, the material is crushed and sieved.

[0014] Furthermore, in the secondary ball milling, the mass ratio of ball:material:water is 4:1:1.5, the ball milling is carried out for 4 to 8 hours, and then the mixture is dried and passed through a 60-mesh sieve.

[0015] Furthermore, the granulation process involves adding 9 wt% polyvinyl alcohol (PVA) aqueous solution to the powder obtained from the secondary ball milling, granulating the powder, sieving it, and taking granules with a mesh size of 60-80.

[0016] Furthermore, the molding process involves placing the granulated material into a mold and pressing it into shape, with a pressing pressure of 150–200 MPa.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention employs a one-step synthesis method, which introduces an intercrystalline second phase by adding excess manganese, zinc and iron ions to the formulation, thereby controlling the saturation magnetization of the main phase. This significantly improves the saturation magnetization while maintaining low loss characteristics as much as possible, thus preparing a broadband low-loss microwave ferrite material suitable for higher frequency bands.

[0018] 2. The saturation magnetization of the invented YIG-MnZn composite ferrite material is ≥2000 Gs, the ferromagnetic resonance linewidth is ≤150 Oe, and the dielectric loss is ≤1×10⁻⁶. -3 Meanwhile, the dielectric constant is 16-20. This composite material is simple to synthesize, can increase device bandwidth, reduce device size, and has low cost. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a scanning electron microscope image of the ferrite material in Example 1.

[0021] Figure 2 This is a scanning electron microscope image of the ferrite material in Example 2.

[0022] Figure 3 This is a scanning electron microscope image of the ferrite material in Example 3.

[0023] Figure 4 This is a scanning electron microscope image of the ferrite material in Comparative Example 1.

[0024] Figure 5 This is a scanning electron microscope image of the ferrite material in Comparative Example 2. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0026] Example 1 This embodiment discloses a YIG-MnZn composite ferrite material and its preparation method, including the following steps: (1) Ingredients: MnO, ZnO, Bi2O3, CaCO3, Y2O3, ZrO2, and Fe2O3 are used as raw materials, according to the chemical formula (Bi a Y 3-a- b Ca b Zr b Fe 5-b-δ ) 1-c ((Mn,Zn)Fe2O4) c The ingredients were mixed in the following proportions: 0.6≤a≤0.9, 0≤b≤0.5, 0.1≤c≤0.5, 0≤δ≤0.06, where δ represents the iron deficiency, to obtain the YIG-MnZn composite ferrite raw material. The main formulations of the YIG-MnZn composite ferrite raw material in Examples 1-3 are shown in the table below: Table 1

[0027] (2) First ball milling: The raw materials obtained in step 1) are ball milled and mixed evenly, with a ball:material:water mass ratio of 4:1:1.5 and a ball milling time of 4 to 8 hours. After drying, the mixture is passed through a 60-mesh sieve. (3) Pre-firing: The powder obtained in step 2) is pre-firing at 940-980℃ for 1-5 hours; (4) Secondary ball milling: The obtained pre-calcined material is ball-milled and mixed evenly. The mass ratio of ball:material:water is 4:1:1.5, and the ball milling time is 4 to 8 hours. After drying, it is passed through a 60-mesh sieve. (5) Granulation: After drying the powder obtained from the second ball milling, add 9wt% polyvinyl alcohol (PVA) aqueous solution according to the weight percentage for granulation, sieve, and take granules with a mesh size of 60-80. (6) Molding: The granulated material is placed into a mold and pressed into shape. The pressing pressure is 150-200MPa. (7) Sintering: The formed green parts are placed in an air atmosphere sintering furnace and sintered using a multi-step sintering method, including two heating processes: the first heating process is 850-900℃ and the holding time is 1-4 hours; the second heating process is 1050-1150℃ and the holding time is 20-30 hours.

[0028] Test data The basic properties of the YIG-MnZn composite ferrite materials prepared by the above process are shown in the table below for the three examples: Table 2

[0029] From Table 1-2, Figures 1-3 As can be seen, the average grain size of the ferrite material of this invention is between 1.5 μm and 2.5 μm, basically maintaining a polyhedral structure with few pores and good density. This material can not only effectively improve the saturation magnetization intensity, but also ensure low ferromagnetic resonance linewidth and dielectric loss, and the preparation method is simple.

[0030] Comparative Example 1 The only change based on Example 1 is the method of compounding, which includes the following steps: (1) Ball milling: Bi with a molar mass ratio of 9:1 0.7 Y2Ca 0.3 Zr 0.3 Fe 4.7-δ Mn, ZnFe2O4 ferrite was added to a ball mill jar with a ball:material:water mass ratio of 4:1:1.5 and a ball milling time of 4 to 8 hours. After drying, it was passed through a 60-mesh sieve. (2) Granulation: After drying the powder obtained from the second ball milling, add 9wt% polyvinyl alcohol (PVA) aqueous solution according to the weight percentage for granulation, sieve, and take granules with a mesh size of 60-80. (3) Molding: The granulated material is placed into a mold and pressed into shape. The pressing pressure is 150-200MPa. (4) Sintering: The formed green parts are placed in an air atmosphere sintering furnace and sintered using a multi-step sintering method, including two heating processes: the first heating process is 850-900℃ and the holding time is 1-4 hours; the second heating process is 1050-1150℃ and the holding time is 20-30 hours.

[0031] Comparative Example 2 Based on Example 1, step (7) is modified. The specific sintering process is as follows: the formed green part is placed in an air atmosphere sintering furnace and sintered using a multi-step sintering method, including two heating processes: the first heating process is 850-900℃ and the holding time is 1-4 hours; the second heating process is 1150-1250℃ and the holding time is 20-30 hours.

[0032] The basic properties of the YIG-MnZn composite ferrite materials prepared by the above process are shown in the table below for two comparative samples: Table 3

[0033] From Table 3, Figures 4-5 It can be seen that under the traditional solid-state reaction method, it is extremely difficult to achieve simultaneous densification of the two phases, which often leads to problems such as interfacial reaction, high porosity, and non-uniformity of the composite phase, which seriously affect the density and magnetic properties of the composite material. When the sintering temperature is not matched, the compatibility of the two phases co-firing is difficult to guarantee, which affects the density and magnetic properties of the composite material.

[0034] The above are the embodiments listed in this example. However, this example is not limited to the optional embodiments described above. Those skilled in the art can arbitrarily combine the above methods to obtain other various embodiments. Anyone can derive other various forms of embodiments based on the inspiration of this example. The above specific embodiments should not be construed as limiting the scope of protection of this example. The scope of protection of this example should be determined by the claims, and the specification can be used to interpret the claims.

Claims

1. A YIG-MnZn composite ferrite material, characterized in that: Including BiCaZr-YIG garnet phase and (Mn,Zn)Fe2O4 spinel phase; The molar ratio of BiCaZr-YIG garnet phase to (Mn,Zn)Fe2O4 spinel phase is 10–1.

2. The YIG-MnZn composite ferrite material according to claim 1, characterized in that: The BiCaZr-YIG garnet phase composition includes 6.5 mol%–11.5 mol% Bi₂O₃, 23 mol%–30 mol% Y₂O₃, 0 mol%–11.5 mol% CaCO₃, 0 mol%–11.5 mol% Zr₂O₃, and 44.5 mol%–62.5 mol% Fe₂O₃.

3. The YIG-MnZn composite ferrite material according to claim 1, characterized in that: The (Mn,Zn)Fe2O4 spinel phase composition includes: 10 mol% to 40 mol% MnO, 40 mol% to 10 mol% ZnO and 50 mol% Fe2O3.

4. The YIG-MnZn composite ferrite material according to claim 1, characterized in that: Its chemical formula is (Bi) a Y 3-a-b Ca b Zr b Fe 5-b-δ ) 1-c ((Mn,Zn)Fe2O4) c Where 0.6≤a≤0.9, 0≤b≤0.5, 0.1≤c≤0.5, 0≤δ≤0.06, and δ is the amount of iron deficiency.

5. A method for preparing a YIG-MnZn composite ferrite material according to any one of claims 1-4, characterized in that: Includes the following steps: S1. After batching, the ingredients are ball-milled once and then dried; S2. The powder obtained after one ball milling is pre-calcined and then crushed to obtain pre-calcined material; S3. The obtained pre-calcined material is subjected to secondary ball milling; S4. The powder obtained from the second ball milling is dried, then granulated, shaped and sintered to obtain the final product.

6. The method for preparing a YIG-MnZn composite ferrite material according to claim 5, characterized in that: The sintering specifically refers to: It includes two heating processes: the first heating process is at 850-900℃, and the holding time is 1-4 hours; The second heating process is at 1050–1150℃, and the holding time is 20–30 hours.

7. The method for preparing a YIG-MnZn composite ferrite material according to claim 5, characterized in that: The first ball milling process specifically involves mixing each raw material with zirconia balls and deionized water, with a ball:material:water mass ratio of 4:1:1.5, and milling for 4 to 8 hours. After drying, the mixture is then passed through a 60-mesh sieve.

8. The method for preparing a YIG-MnZn composite ferrite material according to claim 5, characterized in that: The pre-firing temperature is 940-980℃, the holding time is 1-5h, and after pre-firing, the material is crushed and sieved.

9. The method for preparing a YIG-MnZn composite ferrite material according to claim 8, characterized in that: In the secondary ball milling, the mass ratio of ball:material:water is 4:1:1.5, and the ball milling is carried out for 4 to 8 hours. Then, the material is dried and passed through a 60-mesh sieve.

10. The method for preparing a YIG-MnZn composite ferrite material according to claim 5, characterized in that: The granulation process involves adding 9 wt% polyvinyl alcohol aqueous solution to the powder obtained from the secondary ball milling, granulating it, sieving it, and taking granules with a mesh size of 60-80. And / or, the molding process is as follows: the granulated material is placed into a mold and pressed into shape, with a pressing pressure of 150-200 MPa.

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