Composite ferrite for self-biased circulator and preparation method of composite ferrite

Abstract

According to the composite ferrite for the self-biased circulator and the preparation method of the composite ferrite, BaM ferrite and LiZn ferrite are combined, the LiZn ferrite has the advantages of high remanence ratio, low line width and high Curie temperature, through high-energy wet grinding, magnetic field orientation forming and heat treatment, the grain boundary characteristics of grains are effectively regulated and controlled, the orientation degree is improved, and the self-biased circulator is prepared. The saturation magnetization intensity is increased, and the microstructure and the electromagnetic property of the composite ferrite are improved by matching the types and the substitution quantity of the substitution elements, so that the method is suitable for industrial large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of ferrite material preparation, and in particular to a composite ferrite for a self-biased circulator and a preparation method thereof. Background Art

[0002] A microwave circulator is a non-reciprocal multi-port microwave device that enables unidirectional transmission of electromagnetic waves. This characteristic makes it widely used in radar, communication systems, antenna duplexers, and other applications. Traditional microwave circulators require large internal permanent magnets to provide a DC bias field. As microwave technology develops toward higher frequencies and smaller devices, the presence of permanent magnets makes it difficult to miniaturize the entire transceiver system, limiting the integration and portability of microwave systems.

[0003] Self-bias ferrites possess a large magnetocrystalline anisotropy field, creating a self-biased internal field within the material. This eliminates the need for external permanent magnets to provide a biasing external magnetic field in circulators. This allows the magnetic moment to undergo ferromagnetic resonance with microwaves or millimeter waves in the absence of an external steady-state magnetic field or in the presence of a very small one, achieving self-biasing in the circulator. Devices using self-bias ferrites can be significantly reduced in size and weight, meeting the demands of modern electronic equipment for integrated and lightweight design.

[0004] The research on self-biased ferrite is currently focused on improving its performance and optimizing its preparation process to meet the development needs of high frequency, miniaturization and low loss of microwave devices. CN118955113A discloses a soft and hard magnetic microwave ferrite coupling material and preparation method. The ferrite coupling material includes YIG and BaM microwave ferrite. BaM ferrite and high dielectric YIG raw powder are mixed and ground in different proportions and pre-sintered to make the soft magnetic phase high dielectric YIG ferrite and the hard magnetic phase BaM ferrite mutually coupled, achieving the hard magnetic phase high dielectric constant. r / M s and H c The characteristics are coupled to the high dielectric constant and low loss soft magnetic phase. CN119176714A discloses a C-band ultra-low loss self-biased hexagonal ferrite material and its preparation method, which uses BaM ferrite and high dielectric constant YIG raw powder mixed in different proportions and pre-sintered by ball milling to grow a high M ferrite on the surface of the low-loss high dielectric constant YIG ferrite material particles. r / M s and H c BaM hexagonal ferrite material with unique characteristics, realizing hard magnetic phase with high M r / M s and H cThe properties are combined into a high-dielectric, low-loss soft magnetic phase. However, the high-dielectric YIG ferrites used in the aforementioned methods possess a high dielectric constant but a low Curie temperature, which limits the operating temperature of the device. Furthermore, the formulations in some methods contain In₂O₃, which increases the production cost of the material and limits its practicality. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a composite ferrite for a self-biased circulator and a preparation method thereof, which improves the microstructure and electromagnetic properties of the composite ferrite, so that the composite ferrite has the advantages of high remanence ratio and low line width.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a composite ferrite for a self-biased circulator. Raw materials for preparing the composite ferrite for a self-biased circulator include LiZn ferrite, BaM ferrite, and a dopant.

[0008] The mass ratio of the LiZn ferrite to the BaM ferrite is 1:(1-2.5), for example, 1:1, 1:1.5, 1:2, 1:2.2 or 1:2.5, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0009] The LiZn ferrite is: Li 0.5-0.5a Zn a Fe 2.4-0.5a-b Co b Mn 0.1 O4, among which, 0.27≤a≤0.33, 0.02≤b≤0.06.

[0010] The 0.27≤a≤0.33 may be, for example, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32 or 0.33, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0011] The 0.02≤b≤0.06 may be, for example, 0.02, 0.03, 0.04, 0.05 or 0.06, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0012] The BaM ferrite is: Ba 1-x-y Ca x La y Fe 12-z Co z O 19 , among which, 0.18≤x≤0.28, 0.34≤y≤0.44, 0.2≤z≤0.3.

[0013] The 0.18≤x≤0.28 may be, for example, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27 or 0.28, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0014] The 0.34≤y≤0.44 may be, for example, 0.34, 0.35, 0.36, 0.38, 0.4, 0.42 or 0.44, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0015] The 0.2≤z≤0.3 may be, for example, 0.2, 0.22, 0.25, 0.26, 0.28 or 0.3, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0016] The composite ferrite for the self-biased circulator provided by the present invention combines BaM ferrite with LiZn ferrite. LiZn ferrite has the advantages of high remanence ratio, low linewidth and high Curie temperature. The microstructure and electromagnetic properties of the composite ferrite are improved by combining the type and amount of substitution elements.

[0017] Preferably, based on the total mass percentage of LiZn ferrite and BaM ferrite, the composition of the dopant includes: Bi2O3 2-2.7wt%, B2O3 0.5-1.5wt%, V2O5 1-1.5wt%, and CuO 1-1.5wt%.

[0018] The mass percentage of Bi2O3 in the dopant is 2-2.7wt% of the total mass percentage of LiZn ferrite and BaM ferrite, for example, it can be 2wt%, 2.1wt%, 2.2wt%, 2.3wt%, 2.4wt%, 2.5wt%, 2.6wt% or 2.7wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] The mass percentage of B2O3 in the dopant is 0.5-1.5wt% of the total mass percentage of LiZn ferrite and BaM ferrite, for example, it can be 0.5wt%, 0.6wt%, 0.8wt%, 1wt%, 1.2wt%, 1.3wt%, 1.4wt% or 1.5wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] The mass percentage of V2O5 in the dopant is 1-1.5wt% of the total mass percentage of LiZn ferrite and BaM ferrite, for example, it can be 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt% or 1.5wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] The mass percentage of CuO in the dopant is 1-1.5 wt % of the total mass percentage of LiZn ferrite and BaM ferrite, for example, it can be 1 wt %, 1.1 wt %, 1.2 wt %, 1.3 wt %, 1.4 wt % or 1.5 wt %, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0022] In a second aspect, the present invention provides a method for preparing the composite ferrite for the self-biased circulator as described in the first aspect, the preparation method comprising the following steps:

[0023] (1) LiZn ferrite and BaM ferrite are first wet-milled and mixed, and the resulting slurry is sequentially dried and pre-calcined to obtain a precursor;

[0024] (2) The formulated dopant is mixed with the precursor obtained in step (1) by a second wet grinding, and the obtained slurry is dehydrated, then subjected to magnetic field orientation molding and sintering in sequence to obtain the composite ferrite for the self-biased circulator.

[0025] The preparation method of the composite ferrite for self-biased circulator provided by the present invention effectively controls the grain boundary characteristics, improves the orientation degree, and increases the saturation magnetization intensity through high-energy wet grinding, magnetic field orientation molding and heat treatment. The microstructure and electromagnetic properties of the composite ferrite are improved by combining the type and amount of substitution elements, and the composite ferrite is suitable for industrial-scale production.

[0026] Preferably, the raw materials for preparing the LiZn ferrite in step (1) include Li2CO3, ZnO, Fe2O3, Co2O3 and Mn3O4.

[0027] Preferably, the raw materials for preparing the BaM ferrite in step (1) include BaCO3, CaCO3, La2O3, Fe2O3 and Co2O3.

[0028] Preferably, the BaM ferrite in step (1) is obtained by wet ball milling, drying and calcining raw materials in a prescribed amount.

[0029] Preferably, the mass ratio of the raw materials, deionized water and zirconia balls in the wet ball milling is 1:(0.9-1.1):(5.5-6.5), for example, it can be 1:0.9:5.5, 1:1:6 or 1:1.1:6.5, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0030] Preferably, the wet ball milling has a rotation speed of 70-90 r / min and a time of 8-12 h.

[0031] The rotation speed of the wet ball mill is 70-90 r / min, for example, it can be 70 r / min, 75 r / min, 80 r / min, 85 r / min or 90 r / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0032] The wet ball milling time is 8-12 hours, for example, 8 hours, 9 hours, 10 hours, 11 hours or 12 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0033] Preferably, a dispersant is added to the wet ball milling, and the volume ratio of the dispersant to deionized water is 1:(35-45), for example, it can be 1:35, 1:38, 1:40, 1:42 or 1:45, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0034] Preferably, the dispersant includes any one of ammonia water, sodium hexametaphosphate or sodium tripolyphosphate, or a combination of at least two of them. Typical but non-limiting combinations include a combination of ammonia water and sodium hexametaphosphate, a combination of sodium hexametaphosphate and sodium tripolyphosphate, or a combination of ammonia water, sodium hexametaphosphate and sodium tripolyphosphate.

[0035] Preferably, the drying temperature is 115-125°C, for example, 115°C, 118°C, 120°C, 122°C or 125°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0036] Preferably, after the drying and before the roasting, the step of passing through an 80-mesh sieve is further included.

[0037] Preferably, the calcination temperature is 1180-1250° C. and the calcination time is 1-5 hours.

[0038] The calcination temperature is 1180-1250° C., for example, 1180° C., 1200° C., 1220° C., 1230° C. or 1250° C., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0039] The calcination time is 1-5 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours or 5 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0040] Preferably, the mass ratio of the powder, deionized water and zirconia balls in the first wet grinding mixing in step (1) is 1:(0.9-1.1):(5.5-6.5), for example, it can be 1:0.9:5.5, 1:1:6 or 1:1.1:6.5, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0041] Preferably, the rotation speed of the first wet grinding mixing in step (1) is 60-80 r / min, and the time is 6-10 h.

[0042] The rotation speed of the first wet grinding mixing in step (1) is 60-80 r / min, for example, it can be 60 r / min, 65 r / min, 70 r / min, 75 r / min or 80 r / min, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0043] The time for the first wet grinding and mixing in step (1) is 6-10 hours, for example, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0044] Preferably, a dispersant is added to the first wet grinding mixing in step (1), and the volume ratio of the dispersant to deionized water is 1:(35-45), for example, it can be 1:35, 1:38, 1:40, 1:42 or 1:45, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0045] Preferably, the dispersant includes any one of ammonia water, sodium hexametaphosphate or sodium tripolyphosphate, or a combination of at least two of them. Typical but non-limiting combinations include a combination of ammonia water and sodium hexametaphosphate, a combination of sodium hexametaphosphate and sodium tripolyphosphate, or a combination of ammonia water, sodium hexametaphosphate and sodium tripolyphosphate.

[0046] Preferably, the drying temperature in step (1) is 115-125°C, for example, 115°C, 118°C, 120°C, 122°C or 125°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0047] Preferably, after the drying in step (1) and before the pre-calcination, the step of passing through an 80-mesh sieve is further included.

[0048] Preferably, the pre-calcination temperature in step (1) is 980-1020° C. and the pre-calcination time is 2-6 hours.

[0049] The pre-calcination temperature in step (1) is 980-1020°C, for example, 980°C, 990°C, 1000°C, 1010°C or 1020°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0050] The pre-burning time in step (1) is 2-6 hours, for example, 2 hours, 3 hours, 4 hours, 5 hours or 6 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0051] Preferably, the mass ratio of the powder, deionized water and zirconia balls in the second wet grinding mixing in step (2) is 1:(0.9-1.1):(5.5-6.5), for example, it can be 1:0.9:5.5, 1:1:6 or 1:1.1:6.5, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0052] Preferably, the rotation speed of the second wet grinding mixing in step (2) is 70-90 r / min, and the time is 12-18 h.

[0053] The rotation speed of the second wet grinding mixing in step (2) is 70-90 r / min, for example, it can be 70 r / min, 75 r / min, 80 r / min, 85 r / min or 90 r / min, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0054] The time for the second wet grinding and mixing in step (2) is 12-18 hours, for example, 12 hours, 14 hours, 16 hours or 18 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0055] Preferably, the dehydration in step (2) is to a slurry with a water content of 20-30%, for example, 20%, 22%, 25%, 28% or 30%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0056] Preferably, the magnetic field for the magnetic field orientation molding in step (2) is ≥1.4T, for example, it can be 1.4T, 1.5T, 1.6T, 1.7T or 1.8T, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0057] Preferably, the pressure of the magnetic field orientation molding in step (2) is 2.5-3.5 MPa, for example, it can be 2.5 MPa, 2.8 MPa, 3 MPa, 3.2 MPa or 3.5 MPa, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0058] Preferably, the sintering temperature in step (2) is 1150-1200° C. and the sintering time is 2-6 hours.

[0059] The sintering temperature in step (2) is 1150-1200°C, for example, 1150°C, 1160°C, 1170°C, 1180°C or 1200°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0060] The sintering time in step (2) is 2-6 hours, for example, 2 hours, 3 hours, 4 hours, 5 hours or 6 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0061] Compared with the prior art, the present invention has the following beneficial effects:

[0062] The composite ferrite for a self-biased circulator provided by the present invention combines BaM ferrite with LiZn ferrite. LiZn ferrite has the advantages of high remanence ratio, low linewidth, and high Curie temperature. Through high-energy wet grinding, magnetic field orientation molding, and heat treatment, the grain boundary characteristics are effectively regulated, the orientation degree is improved, and the saturation magnetization intensity is increased. The microstructure and electromagnetic properties of the composite ferrite are improved by combining the type and amount of substitution elements, making it suitable for industrial-scale production. DETAILED DESCRIPTION

[0063] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0064] Example 1

[0065] This embodiment provides a composite ferrite for a self-biased circulator. Raw materials for preparing the composite ferrite for a self-biased circulator include LiZn ferrite, BaM ferrite, and a dopant. The mass ratio of the LiZn ferrite to the BaM ferrite is 1:1.

[0066] The LiZn ferrite is: Li 0.365 Zn 0.27 Fe 2.225 Co 0.04 Mn 0.1 O4, BaM ferrite is: Ba 0.46 Ca 0.18 La 0.36 Fe 11.78 Co 0.22 O 19; Based on the total mass percentage of LiZn ferrite and BaM ferrite, the composition of the dopant includes: Bi2O3 2.2wt%, B2O3 0.5wt%, V2O5 1.2wt%, CuO 1wt%.

[0067] The method for preparing the composite ferrite for the self-biased circulator comprises the following steps:

[0068] (1) The raw materials prepared in the formula amount are wet-milled at a rotation speed of 80 r / min for 10 hours, wherein the mass ratio of the raw materials, deionized water and zirconia balls in the wet ball milling is 1:1:6, and sodium hexametaphosphate is added in the wet ball milling, wherein the volume ratio of sodium hexametaphosphate to deionized water is 1:40; then, BaM ferrite is obtained after being dried at 120°C, passed through an 80-mesh sieve and calcined at 1200°C for 3 hours; the raw materials prepared include BaCO3, CaCO3, La2O3, Fe2O3 and Co2O3.

[0069] BaM ferrite and LiZn ferrite are first wet-milled and mixed at a speed of 70 r / min for 8 hours. The mass ratio of powder, deionized water and zirconia balls in the first wet-milling mixture is 1:1:6. Sodium hexametaphosphate is added to the first wet-milling mixture, and the volume ratio of sodium hexametaphosphate to deionized water is 1:40. The obtained slurry is successively dried at 120°C, passed through an 80-mesh sieve and pre-calcined at 1000°C for 4 hours to obtain a precursor. The raw materials for preparing the LiZn ferrite include Li2CO3, ZnO, Fe2O3, Co2O3 and Mn3O4.

[0070] (2) The formulated dopant and the precursor obtained in step (1) are mixed by a second wet grinding at a rotation speed of 80 r / min for 16 hours, wherein the mass ratio of the powder, deionized water and zirconia balls in the second wet grinding is 1:1:6; the obtained slurry is dehydrated to a water content of 25%, and then subjected to magnetic field orientation molding under a magnetic field of 1.6 T and a pressure of 3 MPa, and sintered at 1180° C. for 4 hours to obtain the composite ferrite for the self-biased circulator.

[0071] Example 2

[0072] This embodiment provides a composite ferrite for a self-biased circulator. The raw materials for preparing the composite ferrite for the self-biased circulator include LiZn ferrite, BaM ferrite, and a dopant. The mass ratio of the LiZn ferrite to the BaM ferrite is 1:1.5.

[0073] The LiZn ferrite is: Li 0.335 Zn 0.33 Fe 2.205 Co 0.03 Mn 0.1 O4, BaM ferrite is: Ba 0.4 Ca0.22 La 0.38 Fe 11.8 Co 0.2 O 19 Based on the total mass percentage of LiZn ferrite and BaM ferrite, the composition of the dopant includes: Bi2O3 2wt%, B2O3 1.1wt%, V2O5 1wt%, CuO 1.3wt%.

[0074] The method for preparing the composite ferrite for the self-biased circulator comprises the following steps:

[0075] (1) The raw materials prepared in the formula amount are wet-milled at a rotation speed of 70 r / min for 12 hours, wherein the mass ratio of the raw materials, deionized water and zirconia balls in the wet ball milling is 1:0.9:5.5, and ammonia water is added during the wet ball milling, wherein the volume ratio of ammonia water to deionized water is 1:35; then, BaM ferrite is obtained after being dried at 115°C, passed through an 80-mesh sieve and calcined at 1180°C for 5 hours; the raw materials prepared include BaCO3, CaCO3, La2O3, Fe2O3 and Co2O3.

[0076] BaM ferrite and LiZn ferrite are first wet-milled and mixed at a speed of 60 r / min for 10 hours. The mass ratio of powder, deionized water and zirconia balls in the first wet-milling mixture is 1:0.9:5.5. Ammonia water is added to the first wet-milling mixture, and the volume ratio of ammonia water to deionized water is 1:35. The obtained slurry is dried at 115°C, passed through an 80-mesh sieve and pre-calcined at 980°C for 6 hours to obtain a precursor. The raw materials for preparing the LiZn ferrite include Li2CO3, ZnO, Fe2O3, Co2O3 and Mn3O4.

[0077] (2) The formulated dopant and the precursor obtained in step (1) are mixed by a second wet grinding at a rotation speed of 70 r / min for 18 hours, wherein the mass ratio of the powder, deionized water and zirconia balls in the second wet grinding is 1:0.9:5.5; the obtained slurry is dehydrated to a water content of 20%, and then subjected to magnetic field orientation molding at a magnetic field of 1.5 T and a pressure of 2.5 MPa, and sintered at 1150° C. for 6 hours to obtain the composite ferrite for the self-biased circulator.

[0078] Example 3

[0079] This embodiment provides a composite ferrite for a self-biased circulator. Raw materials for preparing the composite ferrite for the self-biased circulator include LiZn ferrite, BaM ferrite, and a dopant. The mass ratio of the LiZn ferrite to the BaM ferrite is 1:2.

[0080] The LiZn ferrite is: Li 0.35 Zn 0.3 Fe2.23 Co 0.02 Mn 0.1 O4, BaM ferrite is: Ba 0.32 Ca 0.26 La 0.42 Fe 11.72 Co 0.28 O 19 Based on the total mass percentage of LiZn ferrite and BaM ferrite, the composition of the dopant includes: Bi2O3 2.7wt%, B2O3 1.1wt%, V2O51.2wt%, CuO 1.5wt%.

[0081] The method for preparing the composite ferrite for the self-biased circulator comprises the following steps:

[0082] (1) The raw materials prepared in the formula amount are wet ball milled at a rotation speed of 90r / min for 8h, and the mass ratio of the raw materials, deionized water and zirconia balls in the wet ball milling is 1:1.1:6.5. Sodium tripolyphosphate is added in the wet ball milling, and the volume ratio of sodium tripolyphosphate to deionized water is 1:45; then, BaM ferrite is obtained after being dried at 125℃, passed through an 80-mesh sieve and calcined at 1250℃ for 1h; the raw materials prepared include BaCO3, CaCO3, La2O3, Fe2O3 and Co2O3.

[0083] BaM ferrite and LiZn ferrite are first wet-milled and mixed at a speed of 80 r / min for 6 hours. The mass ratio of powder, deionized water and zirconia balls in the first wet-milling mixture is 1:1.1:6.5. Sodium tripolyphosphate is added to the first wet-milling mixture, and the volume ratio of sodium tripolyphosphate to deionized water is 1:45. The obtained slurry is dried at 125°C, passed through an 80-mesh sieve and pre-calcined at 1020°C for 2 hours to obtain a precursor. The raw materials for preparing the LiZn ferrite include Li2CO3, ZnO, Fe2O3, Co2O3 and Mn3O4.

[0084] (2) The formulated dopant and the precursor obtained in step (1) are mixed by a second wet grinding at a rotation speed of 90 r / min for 12 hours, wherein the mass ratio of the powder, deionized water and zirconia balls in the second wet grinding is 1:1.1:6.5; the obtained slurry is dehydrated to a water content of 30%, and then subjected to magnetic field orientation molding under a magnetic field of 1.4 T and a pressure of 3.5 MPa, and sintered at 1200° C. for 2 hours to obtain the composite ferrite for the self-biased circulator.

[0085] Example 4

[0086] This embodiment provides a composite ferrite for a self-biased circulator. The difference from embodiment 1 is that the LiZn ferrite is adjusted to Li 0.355 Zn 0.29 Fe2.205 Co 0.05 Mn 0.1 O4, BaM ferrite adjusted to Ba 0.38 Ca 0.28 La 0.34 Fe 11.7 5Co 0.25 O 19 The mass ratio of the LiZn ferrite to the BaM ferrite is adjusted to 1:2.5, and the sodium hexametaphosphate in step (1) is adjusted to sodium hexametaphosphate and sodium tripolyphosphate mixed in a mass ratio of 1:1. The rest is the same as in Example 1.

[0087] Example 5

[0088] This embodiment provides a composite ferrite for a self-biased circulator. The difference from embodiment 1 is that the LiZn ferrite is adjusted to Li 0.345 Zn 0.31 Fe 2.215 Co 0.03 Mn 0.1 O4, BaM ferrite adjusted to Ba 0.36 Ca 0.2 La 0.44 Fe 11.7 Co 0.3 O 19 The mass ratio of the LiZn ferrite to the BaM ferrite is adjusted to 1:1.8, the sodium hexametaphosphate in step (1) is adjusted to a mixture of ammonia water and sodium tripolyphosphate in a mass ratio of 1:1, and the rest are the same as in Example 1.

[0089] Example 6

[0090] This embodiment provides a composite ferrite for a self-biased circulator. The difference between the preparation method of the composite ferrite for a self-biased circulator and that of Example 1 is that, except that the pre-firing temperature in step (1) is adjusted to 950°C and the sodium hexametaphosphate in step (1) is adjusted to a mixture of sodium hexametaphosphate, ammonia water and sodium tripolyphosphate in a mass ratio of 1:1:1, the rest is the same as that of Example 1.

[0091] Example 7

[0092] This embodiment provides a composite ferrite for a self-biased circulator. The difference between the preparation method of the composite ferrite for a self-biased circulator and that of Example 1 is that, except that the pre-firing temperature in step (1) is adjusted to 1050°C and the sodium hexametaphosphate in step (1) is adjusted to a mixture of sodium hexametaphosphate, ammonia water and sodium tripolyphosphate in a mass ratio of 1:1:1, the rest is the same as that of Example 1.

[0093] Example 8

[0094] This embodiment provides a composite ferrite for a self-biased circulator. The difference between the preparation method of the composite ferrite for a self-biased circulator and that of Example 1 is that sodium hexametaphosphate is not added to the first wet grinding mixing in step (1), and the rest is the same as that of Example 1.

[0095] Example 9

[0096] This embodiment provides a composite ferrite for a self-biased circulator. The difference between the preparation method of the composite ferrite for a self-biased circulator and that of Example 1 is that the magnetic field of the magnetic field orientation molding in step (2) is adjusted to 1.2T, and the rest is the same as that of Example 1.

[0097] Comparative Example 1

[0098] This comparative example provides a composite ferrite for a self-biased circulator. The difference from Example 1 is that the LiZn ferrite is adjusted to Li 0.35 Zn 0.3 Fe 2.21 Co 0.04 Mn 0.1 O4, BaM ferrite adjusted to Ba 0.42 Ca 0.2 La 0.38 Fe 11.76 Co 0.24 O 19 The mass ratio of the LiZn ferrite to the BaM ferrite is adjusted to 1:4, and the rest are the same as in Example 1.

[0099] Comparative Example 2

[0100] This comparative example provides a composite ferrite for a self-biased circulator. The difference from Example 1 is that the LiZn ferrite is adjusted to Li 0.365 Zn 0.27 Fe 2.215 Co 0.05 Mn 0.1 O4, BaM ferrite adjusted to Ba 0.34 Ca 0.24 La 0.42 Fe 11.7 4Co 0.26 O 19 The mass ratio of the LiZn ferrite to the BaM ferrite is adjusted to 1:0.5, and the rest are the same as in Example 1.

[0101] The self-biased circulators provided in Examples 1-9 and Comparative Examples 1 and 2 were prepared using composite ferrites to test the saturation magnetization intensity 4πM. s , remanence ratio M r / M s , ferromagnetic resonance linewidth △H, dielectric constant εr , coercive force H c The results are shown in Table 1.

[0102] Table 1

[0103] <![CDATA[4πM s (Gs)]]> <![CDATA[M r / M s ]]> △H(Oe) <![CDATA[ε r ]]> <![CDATA[H c (You)]]> Example 1 4113 0.92 304 15.3 2622 Example 2 4056 0.9 317 15.3 2628 Example 3 4198 0.9 324 15.4 2636 Example 4 4076 0.91 308 15.2 2639 Example 5 4181 0.92 329 15.6 2644 Example 6 4076 0.87 562 15.3 2038 Example 7 4091 0.86 537 15.2 1845 Example 8 4123 0.82 769 15.2 1846 Example 9 4056 0.84 467 15.3 1756 Comparative Example 1 4073 0.9 342 15.6 2851 Comparative Example 2 4053 0.9 286 15 2336

[0104] It can be seen from Table 1 that the composite ferrite for the self-biased circulator provided by the present invention has the advantages of high saturation magnetization, high remanence ratio, low line width, high dielectric constant and high coercive force.

[0105] By comparing Example 1 with Examples 6 and 7, it can be seen that if the pre-firing temperature is too low or too high, the line width will increase and the coercive force will decrease; by comparing Example 1 with Example 8, it can be seen that if no dispersant is added during wet ball milling, the composition will be offset, the line width will increase, and the remanence and coercive force will decrease; by comparing Example 1 with Example 9, it can be seen that if the magnetic field of magnetic field orientation molding is too low, the remanence and coercive force will decrease.

[0106] By comparing Example 1 with Comparative Examples 1 and 2, it can be seen that when the content of each component in LiZn ferrite and BaM ferrite exceeds the specified range, the comprehensive electromagnetic performance will be reduced, thereby affecting their application in the self-biased circulator.

[0107] In summary, the composite ferrite for self-biased circulator provided by the present invention combines BaM ferrite and LiZn ferrite. LiZn ferrite has the advantages of high remanence ratio, low line width and high Curie temperature. Through high-energy wet grinding, magnetic field orientation molding and heat treatment, the grain boundary characteristics are effectively regulated, the orientation degree is improved, and the saturation magnetization intensity is increased. By combining the type and amount of substitution elements, the microstructure and electromagnetic properties of the composite ferrite are improved, which is suitable for industrial-scale production.

[0108] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A composite ferrite for a self-biased circulator, characterized in that: The raw materials for preparing the composite ferrite for the self-biased circulator include LiZn ferrite, BaM ferrite and a dopant; the mass ratio of the LiZn ferrite to the BaM ferrite is 1:(1-2.5); The LiZn ferrite is: Li 0.5-0.5a Zn a Fe 2.4-0.5a-b Co b Mn 0.1 O4, where 0.27≤a≤0.33, 0.02≤b≤0.06; The BaM ferrite is: Ba 1-x-y Ca x La y Fe 12-z Co z O 19 , among which, 0.18≤x≤0.28, 0.34≤y≤0.44, 0.2≤z≤0.

3.

2. The composite ferrite for self-biased circulator according to claim 1, characterized in that: Calculated based on the total mass percentage of LiZn ferrite and BaM ferrite, the dopant comprises: Bi2O3 2-2.7wt%, B2O3 0.5-1.5wt%, V2O5 1-1.5wt%, and CuO 1-1.5wt%.

3. A method for preparing the composite ferrite for a self-biased circulator according to claim 1 or 2, characterized in that: The preparation method comprises the following steps: (1) LiZn ferrite and BaM ferrite are first wet-milled and mixed, and the resulting slurry is sequentially dried and pre-calcined to obtain a precursor; (2) The formulated dopant is mixed with the precursor obtained in step (1) by a second wet grinding, and the obtained slurry is dehydrated, then subjected to magnetic field orientation molding and sintering in sequence to obtain the composite ferrite for the self-biased circulator.

4. The preparation method according to claim 3, characterized in that The raw materials for preparing the LiZn ferrite in step (1) include Li2CO3, ZnO, Fe2O3, Co2O3 and Mn3O4; Preferably, the raw materials for preparing the BaM ferrite in step (1) include BaCO3, CaCO3, La2O3, Fe2O3 and Co2O3.

5. The preparation method according to claim 3 or 4, characterized in that The BaM ferrite in step (1) is obtained by wet ball milling, drying and calcining the raw materials in a prescribed amount; Preferably, the mass ratio of the raw materials, deionized water and zirconia balls in the wet ball milling is 1:(0.9-1.1):(5.5-6.5); Preferably, the wet ball milling speed is 70-90 r / min and the time is 8-12 h; Preferably, a dispersant is added during the wet ball milling, and the volume ratio of the dispersant to deionized water is 1:(35-45); Preferably, the drying temperature is 115-125°C; Preferably, the calcination temperature is 1180-1250° C. and the calcination time is 1-5 hours.

6. The preparation method according to any one of claims 3 to 5, characterized in that In step (1), the mass ratio of the powder, deionized water, and zirconium oxide balls in the first wet grinding mixture is 1:(0.9-1.1):(5.5-6.5); Preferably, in step (1), the rotation speed of the first wet grinding mixing is 60-80 r / min, and the time is 6-10 h; Preferably, in step (1), a dispersant is added to the first wet grinding mixing, and the volume ratio of the dispersant to deionized water is 1:(35-45).

7. The preparation method according to any one of claims 3 to 6, characterized in that The drying temperature in step (1) is 115-125° C. Preferably, the pre-calcination temperature in step (1) is 980-1020° C. and the pre-calcination time is 2-6 hours.

8. The preparation method according to any one of claims 3 to 7, characterized in that In step (2), the mass ratio of the powder, deionized water, and zirconium oxide balls in the second wet grinding mixture is 1:(0.9-1.1):(5.5-6.5); Preferably, the rotation speed of the second wet grinding mixing in step (2) is 70-90 r / min, and the time is 12-18 h.

9. The preparation method according to any one of claims 3 to 8, characterized in that Step (2) of dehydrating the slurry until the water content is 20-30%; Preferably, the magnetic field of the magnetic field orientation molding in step (2) is ≥1.4T; Preferably, the pressure of the magnetic field orientation molding in step (2) is 2.5-3.5 MPa.

10. The preparation method according to any one of claims 3 to 9, characterized in that: The sintering temperature in step (2) is 1150-1200° C. and the sintering time is 2-6 hours.