Ferrite material for self-bias device and preparation method and application thereof

Abstract

This invention provides a ferrite material for self-biased devices, its preparation method, and its application. The ferrite material for self-biased devices comprises a matrix and a dopant, wherein the matrix comprises Ba. 0.88 Ca 0.12 La x Fe 12‑y‑z‑2a Co y Al z (ZnSn) a O 19 Where x is 0.13–0.23, y is 0.15–0.25, z is 0.05–0.1, and a is 0.05–0.15; the dopants include ZnO, SiO2, and B2O3. The ferrite material for self-biased devices described in this invention improves the structure and electromagnetic properties of ferrite by employing specific substrates and dopants, enabling the ferrite material to possess the advantages of low linewidth and high remanence ratio required for self-biased devices.

Description

Technical Field

[0001] This invention belongs to the field of magnetic materials technology, and relates to a ferrite material for self-biased devices, its preparation method and application. Background Technology

[0002] With the widespread application of active phased array radar in modern electronic warfare, microwave devices with characteristics such as high frequency, small size, and low loss have become a research focus in microwave and millimeter-wave technologies. Circulators are indispensable components in transmit / receive (T / R) modules. Traditional circulators require an external permanent magnet to provide a bias field, which restricts the integration of the entire system. Self-biased circulators utilize the high anisotropy of hexagonal ferrite and its permanent magnet properties to replace the role of an external permanent magnet, reducing the height and weight of the circulator and solving the problem of traditional circulators being unsuitable for system integration.

[0003] Self-biased ferrites refer to ferrite materials and related technologies that can maintain their ferromagnetic resonance properties at specific microwave frequencies (usually millimeter-wave bands) without the need for an externally applied constant bias magnetic field. This technology is mainly used in miniaturized, lightweight, and low-power microwave / millimeter-wave devices, such as circulators, isolators, and phase shifters, and has significant advantages, especially in applications sensitive to size, weight, and power consumption, such as aerospace, radar, and satellite communications.

[0004] Among gyromagnetic ferrites, the M-type hexagonal ferrite (BaM) possesses high coercivity, high anisotropy, and high remanence. High coercivity preserves the permanent magnet characteristics of the hexagonal ferrite; the high remanence causes the magnetic moment to precess in a strongly anisotropic direction, enabling ferromagnetic resonance between the magnetic moment and microwaves / millimeter waves without an external steady magnetic field. This achieves self-biasing characteristics in microwave devices, freeing them from the constraints of external magnets and significantly reducing their weight and size. Self-biasing circulators are one of the key enabling technologies for next-generation compact and efficient millimeter-wave systems. However, the high anisotropy of the M-type hexagonal ferrite limits its application frequency to relatively high frequencies, typically Ka-band and above. Therefore, developing two-phase composite ferrite materials for Ka-band self-biasing devices is of great significance for achieving self-biasing characteristics in Ka-band microwave devices.

[0005] For example, CN111732427A discloses a low-ferromagnetic-resonance-linewidth hexagonal ferrite material for self-biased circulators and its preparation method. It includes BaM ferrite made from BaCO3, Ga2O3, and Fe2O3, and CuO, Bi2O3, and B2O3 as dopants. The prepared self-biased ferrite has a high anisotropic field, a high saturation magnetization, a low ferromagnetic-resonance linewidth, and suitable coercivity. However, the preparation requires rare earth oxide Ga2O3, which is costly and not suitable for mass production.

[0006] For example, CN116986891A discloses a method for preparing a dual-ion co-substituted self-biased hexagonal ferrite, which involves adding divalent Zn during the preparation process. 2+ ZnO and tetravalent Sn 4+ SnO2 to replace Fe 3+ BaM ferrite initial powder was prepared by adding rare earth complexes, and then the powder containing divalent Ce was sprayed during the subsequent high-energy ball milling process. 2+ The Ce(PFPC)₂·3H₂O rare earth complex was injected into a ball mill jar, and then subjected to a first pre-calcination, a second pre-calcination, and a second ball milling process to obtain a mixed powder. Subsequently, through magnetic field orientation molding technology and strong magnetic field heat treatment technology, a dual-ion co-substituted self-biased hexagonal ferrite was finally obtained. However, its preparation process requires the addition of Ce-containing compounds. 2+ Ce(PFPC)2·3H2O rare earth elements are expensive and not suitable for mass production.

[0007] Based on the above research, there is a need to provide a ferrite material for self-biased devices, which has advantages such as low linewidth and high remanence ratio. Summary of the Invention

[0008] The purpose of this invention is to provide a ferrite material for self-biased devices, its preparation method, and its application. The ferrite material for self-biased devices improves the structure and electromagnetic properties of ferrite by using a specific matrix and dopants, so that the ferrite material has the advantages of low linewidth and high remanence ratio required by self-biased devices.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a ferrite material for a self-biased device, the ferrite material comprising a matrix and a dopant, the matrix comprising Ba 0.88 Ca 0.12 La x Fe 12-y-z-2a Co y Al z (ZnSn) a O 19Where x is 0.13-0.23, y is 0.15-0.25, z is 0.05-0.1, and a is 0.05-0.15;

[0011] The dopants include ZnO, SiO2, and B2O3.

[0012] The matrix of this invention includes Ba, Ca, La, Fe, Co, Al, Zn, and Sn, making the ferrite a two-phase composite ferrite, wherein La 3+ Replacement can significantly improve the magnetocrystalline anisotropy field, Co 2+ Substitution can reduce magnetic anisotropy inhomogeneity, suppress abnormal grain growth, and thus reduce linewidth. Al 3+ It can reduce the magnetocrystalline anisotropy field, increase resistivity, and reduce 4πMs. Zn-Sn substitution can suppress abnormal grain growth and thus reduce linewidth. Furthermore, the structure and electromagnetic properties of the two-phase composite ferrite are improved by doping with ZnO, SiO2 and B2O3 dopants. Therefore, the ferrite material of the present invention has the advantages of low linewidth and high remanence ratio required for self-biased devices.

[0013] The x is 0.13-0.23, for example, it can be 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22 or 0.23; the y is 0.15-0.25, for example, it can be 0.15, 0.17, 0.19, 0.21, 0.23 or 0.25; the z is 0.05-0.1, for example, it can be 0.05, 0.06, 0.07, 0.08, 0.09 or 0.1; the a is 0.05-0.15, for example, it can be 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14 or 0.15, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0014] In this invention, 'x' represents the amount of La. If 'x' is too large, there will be too much La, resulting in an excessively large magnetocrystalline anisotropy linewidth. If 'x' is too small, there will be too little La, causing the ferrite to fail to provide a sufficient magnetic field, leading to a mismatch between the magnetic field and 4πMs. If 'y' is too large, there will be too much Co, resulting in decreased resistivity and increased eddy current losses. If 'y' is too small, there will be too little Co, leading to abnormal growth of some grains. If 'z' is too large, there will be too much Al, resulting in low 4πMs and a low magnetocrystalline anisotropy field. If 'z' is too small, there will be too little Al, resulting in low resistivity and high eddy current losses. If 'a' is too large, there will be too much Zn and Sn, resulting in a low magnetocrystalline anisotropy field. If 'a' is too small, there will be too little Zn and Sn, resulting in an excessively large linewidth and low resistivity.

[0015] Preferably, the ZnO content in the ferrite material for the self-biasing device is 1.5-2 wt%, for example, it can be 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, or 2 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0016] Preferably, the SiO2 content in the ferrite material for the self-biased device is 0.5-1wt%, for example, it can be 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt% or 1wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0017] Preferably, the B2O3 content in the ferrite material for the self-biasing device is 0.6-1.2 wt%, for example, it can be 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, 1.1 wt%, or 1.2 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] The doping amount of the dopant in this invention affects the performance of ferrite materials. If the dopant content is too low, the dopant will not have a sufficient solubilizing effect on the product, resulting in increased porosity and larger linewidth. If the dopant content is too high, the grains will grow abnormally, and the linewidth will increase.

[0019] In a second aspect, the present invention provides a method for preparing a ferrite material for a self-biased device as described in the first aspect, the method comprising the following steps:

[0020] (1) According to the formula, the raw materials of the matrix are ball-milled and pre-fired once to obtain a pre-fired material;

[0021] (2) The pre-calcined material described in step (1) is subjected to secondary ball milling and secondary pre-calcination in sequence to obtain secondary pre-calcined material;

[0022] (3) The secondary pre-burned material and dopant described in step (2) are ball-milled three times and then pressed into a green embryo. The green embryo is sintered to obtain the ferrite material for the self-biased device.

[0023] This invention effectively controls grain boundary characteristics, improves orientation, and increases saturation magnetization through multiple ball milling, two pre-firing processes, and pressing followed by sintering. Combined with the incorporation of other elements after the second pre-firing, it improves the structure and electromagnetic properties of the two-phase composite ferrite, enabling the composite ferrite to possess the advantages of high remanence ratio and low linewidth required for circulators.

[0024] Preferably, the rotation speed of the ball mill in step (1) is 60-80 r / min, for example, 60 r / min, 65 r / min, 70 r / min, 75 r / min or 80 r / min, and the time is 8-12 h, for example, 8 h, 9 h, 10 h, 11 h or 12 h, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] Preferably, after the ball milling in step (1), the material is first dried and sieved, and then pre-fired.

[0026] Preferably, the temperature of the first preheating in step (1) is 1050-1100℃, for example, it can be 1050℃, 1060℃, 1070℃, 1080℃, 1090℃ or 1100℃, and the time is 2-4h, for example, it can be 2h, 2.5h, 3h, 3.5h or 4h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0027] Preferably, the rotation speed of the secondary ball mill in step (2) 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, and the time is 10-16 h, for example, it can be 10 h, 11 h, 12 h, 13 h, 14 h, 15 h or 16 h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] Preferably, after the secondary ball milling in step (2), the material is first dried and sieved, and then pre-fired a second time.

[0029] Preferably, the temperature of the secondary preheating in step (2) is 800-900℃, for example, 800℃, 820℃, 840℃, 860℃, 880℃ or 900℃, and the time is 3-6h, for example, 3h, 4h, 5h or 6h, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] Preferably, the rotation speed of the three ball milling operations in step (3) 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, and the time is 14-20 h, for example, it can be 14 h, 15 h, 16 h, 17 h, 18 h, 19 h or 20 h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] Preferably, a dispersant is added independently after the first ball milling in step (1), the second ball milling in step (2), and the third ball milling in step (3).

[0032] Preferably, the dispersant is ammonia.

[0033] Preferably, after the three ball millings in step (3), the mixture is first dehydrated and then pressed into shape.

[0034] Preferably, the moisture content of the dehydrated material is 20wt%-30wt%, for example, it can be 20wt%, 22wt%, 24wt%, 26wt%, 28wt% or 30wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] Preferably, the pressing and molding process described in step (3) is carried out in a magnetic field.

[0036] Preferably, the magnetic field strength is above 1.4T, for example, it can be 1.4T, 1.45T, 1.5T, 1.55T, 1.6T, 1.65T, 1.7T, 1.75T or 1.8T, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0037] Preferably, the sintering temperature in step (3) is 1150-1200℃, for example, it can be 1150℃, 1160℃, 1170℃, 1180℃, 1190℃ or 1200℃, and the time is 6-12h, for example, it can be 6h, 7h, 8h, 9h, 10h, 11h or 12h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0038] Thirdly, the present invention provides an application of the ferrite material for self-biased devices as described in the first aspect, the application including its use in self-biased circulators.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The matrix of the present invention includes Ba, Ca, La, Fe, Co, Al, Zn and Sn, making the ferrite a two-phase composite ferrite. The structure and electromagnetic properties of the two-phase composite ferrite are improved by doping with ZnO, SiO2 and B2O3 dopants. Therefore, the ferrite material of the present invention has the advantages of low linewidth and high remanence ratio required for self-biased devices. Detailed Implementation

[0041] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0042] Example 1

[0043] This embodiment provides a ferrite material for a self-biased device, the ferrite material comprising a matrix and a dopant, the matrix comprising Ba. 0.88 Ca 0.12 La x Fe 12-y-z-2a Co y Al z (ZnSn) a O 19 Where x is 0.13, y is 0.25, z is 0.05, and a is 0.07;

[0044] The dopants include ZnO, SiO2 and B2O3, and the content of ZnO in the ferrite material is 1.5wt%, the content of SiO2 is 0.5wt%, and the content of B2O3 is 0.8wt%.

[0045] The method for preparing the ferrite material for the self-biased device includes the following steps:

[0046] (1) According to the formula amount of the matrix, BaCO3, CaCO3, La2O3, Fe2O3, Co2O3, Al2O3, ZnO and SnO2 are mixed to obtain raw materials. The raw materials are placed in a ball mill jar and mixed using a ball mill. The raw materials, deionized water and zirconium balls are fed in a weight ratio of 1000:1100:6500. The ball milling is carried out once. The speed of the ball milling is 60 r / min and the time is 10 hours. After the ball milling, 12 mL of dispersant (specifically ammonia water) is added.

[0047] (2) The slurry obtained in step (1) is dried in an oven at 100°C and then passed through an 80-mesh sieve. The powder is then placed in a pre-firing furnace at 1050°C for a first pre-firing for 4 hours to obtain a first pre-firing material.

[0048] (3) After passing the pre-burned material obtained in step (2) through an 80-mesh sieve, put it into a ball mill jar and mix it with a ball mill. The pre-burned material, deionized water and zirconium balls are added in a weight ratio of 1000:1100:6500. The ball mill is then carried out at a speed of 60 r / min for 12 hours. After the ball milling, 12 mL of dispersant (specifically ammonia water) is added.

[0049] (4) The slurry obtained in step (3) is placed in an oven and dried at 100°C. After passing through an 80-mesh sieve, the powder is placed in a pre-firing furnace at 900°C for a second pre-firing for 3 hours to obtain a second pre-firing material.

[0050] (5) After passing the secondary pre-burned material obtained in step (4) through an 80-mesh sieve, it is mixed with dopants ZnO, SiO2 and B2O3 in a ball mill jar and a ball mill is used. The secondary pre-burned material and dopants are fed in a weight ratio of 1000:1100:6500, and the mixture is ball-milled three times. The ball milling speed is 60 r / min and the time is 14 hours. After the three ball millings, 12 mL of dispersant (specifically ammonia water) is added.

[0051] (6) Dehydrate the slurry obtained in step (7), and control the water content to 25% after dehydration. Press it into shape under a magnetic field press. The forming magnetic field is 1.4T and the forming pressure is 3MPa.

[0052] (7) The green blank obtained in step (6) is placed in a sintering furnace for sintering at a temperature of 1150°C and a holding time of 12 hours to obtain the ferrite material for the self-biased device.

[0053] Example 2

[0054] This embodiment provides a ferrite material for a self-biased device, the ferrite material comprising a matrix and a dopant, the matrix comprising Ba. 0.88 Ca 0.12 La x Fe 12-y-z-2a Co y Al z (ZnSn) a O 19 Where x is 0.16, y is 0.18, z is 0.07, and a is 0.1;

[0055] The dopants include ZnO, SiO2 and B2O3, and the content of ZnO in the ferrite material is 1.7 wt%, the content of SiO2 is 0.7 wt%, and the content of B2O3 is 0.6 wt%.

[0056] The method for preparing the ferrite material for the self-biased device includes the following steps:

[0057] (1) According to the formula amount of the matrix, BaCO3, CaCO3, La2O3, Fe2O3, Co2O3, Al2O3, ZnO and SnO2 are mixed to obtain raw materials. The raw materials are placed in a ball mill jar and mixed using a ball mill. The raw materials, deionized water and zirconium balls are fed in a weight ratio of 1000:1100:6500. The ball milling is carried out once. The speed of the ball milling is 70 r / min and the time is 10 hours. After the ball milling, 12 mL of dispersant (specifically ammonia water) is added.

[0058] (2) The slurry obtained in step (1) is dried in an oven at 100°C and then passed through an 80-mesh sieve. The powder is then placed in a pre-firing furnace at 1070°C for 3 hours to obtain a pre-firing material.

[0059] (3) After passing the pre-burned material obtained in step (2) through an 80-mesh sieve, put it into a ball mill jar and mix it with a ball mill. The pre-burned material, deionized water and zirconium balls are added in a weight ratio of 1000:1100:6500. The ball mill is then carried out at a speed of 70 r / min for 12 hours. After the ball milling, 12 mL of dispersant (specifically ammonia water) is added.

[0060] (4) The slurry obtained in step (3) is placed in an oven and dried at 100°C. After passing through an 80-mesh sieve, the powder is placed in a pre-firing furnace at 850°C for a second pre-firing for 4 hours to obtain a second pre-firing material.

[0061] (5) After passing the secondary pre-burned material obtained in step (4) through an 80-mesh sieve, it is mixed with dopants ZnO, SiO2 and B2O3 in a ball mill jar and a ball mill is used. The secondary pre-burned material and dopants are fed in a weight ratio of 1000:1100:6500, and the mixture is ball-milled three times. The ball milling speed is 70 r / min and the time is 18 hours. After the three ball millings, 12 mL of dispersant (specifically ammonia water) is added.

[0062] (6) Dehydrate the slurry obtained in step (7), and control the water content to 20% after dehydration. Press it into shape under a magnetic field press. The forming magnetic field is 1.5T and the forming pressure is 3MPa.

[0063] (7) The green blank obtained in step (6) is placed in a sintering furnace for sintering at a temperature of 1170°C and a holding time of 10h to obtain the ferrite material for the self-biased device.

[0064] Example 3

[0065] This embodiment provides a ferrite material for a self-biased device, the ferrite material comprising a matrix and a dopant, the matrix comprising Ba. 0.88 Ca 0.12 La x Fe 12-y-z-2a Co y Al z (ZnSn) a O 19 Where x is 0.2, y is 0.15, z is 0.05, and a is 0.13;

[0066] The dopants include ZnO, SiO2 and B2O3, and the content of ZnO in the ferrite material is 2wt%, the content of SiO2 is 1wt%, and the content of B2O3 is 0.6wt%.

[0067] The method for preparing the ferrite material for the self-biased device includes the following steps:

[0068] (1) According to the formula amount of the matrix, BaCO3, CaCO3, La2O3, Fe2O3, Co2O3, Al2O3, ZnO and SnO2 are mixed to obtain raw materials. The raw materials are placed in a ball mill jar and mixed using a ball mill. The raw materials, deionized water and zirconium balls are fed in a weight ratio of 1000:1100:6500. The ball milling is carried out once. The speed of the ball milling is 80 r / min and the time is 8 hours. After the ball milling, 12 mL of dispersant (specifically ammonia water) is added.

[0069] (2) The slurry obtained in step (1) is dried in an oven at 100°C and then passed through an 80-mesh sieve. The powder is then placed in a pre-firing furnace at 1100°C for 2 hours to obtain a pre-firing material.

[0070] (3) After passing the pre-burned material obtained in step (2) through an 80-mesh sieve, put it into a ball mill jar and mix it with a ball mill. The pre-burned material, deionized water and zirconium balls are added in a weight ratio of 1000:1100:6500. The ball mill is then carried out at a speed of 80 r / min for 16 hours. After the ball mill, 12 mL of dispersant (specifically ammonia water) is added.

[0071] (4) The slurry obtained in step (3) is placed in an oven and dried at 100°C. After passing through an 80-mesh sieve, the powder is placed in a pre-firing furnace at 800°C for a second pre-firing for 6 hours to obtain a second pre-firing material.

[0072] (5) After passing the secondary pre-burned material obtained in step (4) through an 80-mesh sieve, it is mixed with dopants ZnO, SiO2 and B2O3 in a ball mill jar and a ball mill is used. The material is fed in a weight ratio of 1000:1100:6500 for the total weight of the secondary pre-burned material and dopants, and deionized water and zirconium balls. The ball milling is carried out three times. The speed of the ball milling is 80 r / min and the time is 18 hours. After the ball milling is completed, 12 mL of dispersant (specifically ammonia water) is added.

[0073] (6) Dehydrate the slurry obtained in step (7), and control the water content to 30% after dehydration. Press it into shape under a magnetic field press. The forming magnetic field is 1.4T and the forming pressure is 3MPa.

[0074] (7) The green blank obtained in step (6) is placed in a sintering furnace for sintering at a temperature of 1200℃ and a holding time of 6h to obtain the ferrite material for the self-biased device.

[0075] Example 4

[0076] This embodiment provides a ferrite material for a self-biased device, the ferrite material comprising a matrix and a dopant, the matrix comprising Ba. 0.88 Ca 0.12 La x Fe 12-y-z-2a Co y Al z (ZnSn) a O 19 Where x is 0.23, y is 0.2, z is 0.1, and a is 0.05;

[0077] The dopants include ZnO, SiO2 and B2O3, and the content of ZnO in the ferrite material is 1.5wt%, the content of SiO2 is 0.5wt%, and the content of B2O3 is 1.2wt%.

[0078] The method for preparing the ferrite material for the self-biased device includes the following steps:

[0079] (1) According to the formula amount of the matrix, BaCO3, CaCO3, La2O3, Fe2O3, Co2O3, Al2O3, ZnO and SnO2 are mixed to obtain raw materials. The raw materials are placed in a ball mill jar and mixed using a ball mill. The raw materials, deionized water and zirconium balls are fed in a weight ratio of 1000:1100:6500. The ball milling is carried out once. The speed of the ball milling is 70 r / min and the time is 8 hours. After the ball milling, 12 mL of dispersant (specifically ammonia water) is added.

[0080] (2) The slurry obtained in step (1) is dried in an oven at 100°C and then passed through an 80-mesh sieve. The powder is then placed in a pre-firing furnace at 1080°C for 3 hours to obtain a pre-firing material.

[0081] (3) After passing the pre-burned material obtained in step (2) through an 80-mesh sieve, put it into a ball mill jar and mix it with a ball mill. The pre-burned material, deionized water and zirconium balls are added in a weight ratio of 1000:1100:6500. The ball mill is then carried out at a speed of 60 r / min for 16 hours. After the ball milling, 12 mL of dispersant (specifically ammonia water) is added.

[0082] (4) The slurry obtained in step (3) is placed in an oven and dried at 100°C. After passing through an 80-mesh sieve, the powder is placed in a pre-firing furnace at 830°C for a second pre-firing for 5 hours to obtain a second pre-firing material.

[0083] (5) After passing the secondary pre-burned material obtained in step (4) through an 80-mesh sieve, it is mixed with dopants ZnO, SiO2 and B2O3 in a ball mill jar and mixed using a ball mill. The material is fed in a weight ratio of 1000:1100:6500 for the total weight of the secondary pre-burned material and dopants, and deionized water and zirconium balls. The ball milling is carried out three times at a speed of 70 r / min for 17 hours. After the three ball millings, 12 mL of dispersant (specifically ammonia water) is added.

[0084] (6) Dehydrate the slurry obtained in step (7), and control the water content to 25% after dehydration. Press it into shape under a magnetic field press. The forming magnetic field is 1.4T and the forming pressure is 3MPa.

[0085] (7) The green blank obtained in step (6) is placed in a sintering furnace for sintering at a temperature of 1160°C and a holding time of 10h to obtain the ferrite material for the self-biased device.

[0086] Example 5

[0087] This embodiment provides a ferrite material for a self-biased device, the ferrite material comprising a matrix and a dopant, the matrix comprising Ba. 0.88 Ca 0.12 La x Fe 12-y-z-2a Co y Al z (ZnSn) a O 19 Where x is 0.19, y is 0.23, z is 0.1, and a is 0.15;

[0088] The dopants include ZnO, SiO2 and B2O3, and the content of ZnO in the ferrite material is 1.7wt%, the content of SiO2 is 0.5wt%, and the content of B2O3 is 0.8wt%.

[0089] The method for preparing the ferrite material for the self-biased device includes the following steps:

[0090] (1) According to the formula amount of the matrix, BaCO3, CaCO3, La2O3, Fe2O3, Co2O3, Al2O3, ZnO and SnO2 are mixed to obtain raw materials. The raw materials are placed in a ball mill jar and mixed using a ball mill. The raw materials, deionized water and zirconium balls are fed in a weight ratio of 1000:1100:6500. The ball milling is carried out once. The speed of the ball milling is 80 r / min and the time is 10 hours. After the ball milling, 12 mL of dispersant (specifically ammonia water) is added.

[0091] (2) The slurry obtained in step (1) is dried in an oven at 100°C and then passed through an 80-mesh sieve. The powder is then placed in a pre-firing furnace at 1090°C for 3 hours to obtain a pre-firing material.

[0092] (3) After passing the pre-burned material obtained in step (2) through an 80-mesh sieve, put it into a ball mill jar and mix it with a ball mill. The pre-burned material, deionized water and zirconium balls are added in a weight ratio of 1000:1100:6500. The ball mill is then carried out at a speed of 80 r / min for 10 hours. After the ball milling, 12 mL of dispersant (specifically ammonia water) is added.

[0093] (4) The slurry obtained in step (3) is placed in an oven and dried at 100°C. After passing through an 80-mesh sieve, the powder is placed in a pre-firing furnace at 870°C for a second pre-firing for 4 hours to obtain a second pre-firing material.

[0094] (5) After passing the secondary pre-burned material obtained in step (4) through an 80-mesh sieve, it is mixed with dopants ZnO, SiO2 and B2O3 in a ball mill jar and a ball mill is used. The secondary pre-burned material and dopants are fed in a weight ratio of 1000:1100:6500, and the mixture is ball-milled three times. The ball milling speed is 80 r / min and the time is 14 hours. After the three ball millings, 12 mL of dispersant (specifically ammonia water) is added.

[0095] (6) Dehydrate the slurry obtained in step (7), and control the water content to 25% after dehydration. Press it into shape under a magnetic field press. The forming magnetic field is 1.4T and the forming pressure is 3MPa.

[0096] (7) The green blank obtained in step (6) is placed in a sintering furnace for sintering at a temperature of 1190°C and a holding time of 8 hours to obtain the ferrite material for the self-biased device.

[0097] Example 6

[0098] This embodiment provides a ferrite material for a self-biased device. Except for the ZnO content being 1 wt%, the SiO2 content being 0.2 wt%, and the B2O3 content being 0.2 wt%, the ferrite material for the self-biased device is the same as that in Embodiment 1.

[0099] The preparation method of the ferrite material for the self-biased device is the same as that in Example 1, except that the formulation amount is adapted to change.

[0100] Example 7

[0101] This embodiment provides a ferrite material for a self-biased device. Except for the ZnO content being 2.5wt%, the SiO2 content being 1.5wt%, and the B2O3 content being 1.5wt%, the ferrite material for the self-biased device is the same as that in Embodiment 1.

[0102] The preparation method of the ferrite material for the self-biased device is the same as that in Example 1, except that the formulation amount is adapted to change.

[0103] Comparative Example 1

[0104] This comparative example provides a ferrite material comprising a matrix and a dopant, wherein the matrix comprises Ba. 0.88 Ca 0.12 La x Fe 12-y-z-2a Co y Al z (ZnSn) a O 19 Where x is 0.13, y is 0.25, z is 0.05, and a is 0.07;

[0105] The dopants include ZnO, SiO2 and B2O3, and the content of ZnO in the ferrite material is 1.5wt%, the content of SiO2 is 0.5wt%, and the content of B2O3 is 0.8wt%.

[0106] The method for preparing the ferrite material includes the following steps:

[0107] (1) According to the formula amount of the matrix, BaCO3, CaCO3, La2O3, Fe2O3, Co2O3, Al2O3, ZnO and SnO2 are mixed to obtain raw materials. The raw materials are placed in a ball mill jar and mixed using a ball mill. The raw materials, deionized water and zirconium balls are fed in a weight ratio of 1000:1100:6500. The ball milling is carried out once. The speed of the ball milling is 60 r / min and the time is 10 hours. After the ball milling, 12 mL of dispersant (specifically ammonia water) is added.

[0108] (2) The slurry obtained in step (1) is dried in an oven at 100°C and then passed through an 80-mesh sieve. The powder is then placed in a pre-firing furnace at 1050°C for a first pre-firing for 4 hours to obtain a first pre-firing material.

[0109] (3) After passing the pre-burned material obtained in step (2) through an 80-mesh sieve, mix it with dopants ZnO, SiO2 and B2O3 in a ball mill jar and use a ball mill. Add the pre-burned material and dopants in a weight ratio of 1000:1100:6500, and perform a second ball mill. The ball milling speed is 60 r / min and the time is 14 hours. After the second ball milling, add 12 mL of dispersant (specifically ammonia water).

[0110] (4) Dehydrate the slurry obtained in step (3), and control the water content to 25% after dehydration. Press it into shape under a magnetic field press. The forming magnetic field is 1.4T and the forming pressure is 3MPa.

[0111] (5) The green blank obtained in step (4) is placed in a sintering furnace for sintering at a temperature of 1150°C and a holding time of 12 hours to obtain the ferrite material for the self-biased device.

[0112] Comparative Example 2

[0113] This comparative example provides a ferrite material, which is the same as that in Example 1 except that x is 0.25, y is 0.3, z is 0.15, and a is 0.2.

[0114] The preparation method of the ferrite material described in this comparative example is the same as that in Example 1, except that the raw materials are adapted according to the formula amount.

[0115] Comparative Example 3

[0116] This comparative example provides a ferrite material, which is the same as that in Example 1 except that x is 0.1, y is 0.1, z is 0.03, and a is 0.02.

[0117] The preparation method of the ferrite material described in this comparative example is the same as that in Example 1, except that the raw materials are adapted according to the formula amount.

[0118] Comparative Example 4

[0119] This comparative example provides a ferrite material that is identical to that of Example 1 except that it does not contain dopants.

[0120] The preparation method of the ferrite material described in this comparative example is the same as that in Example 1, except that no dopant is added in step (5).

[0121] The saturation magnetization 4πMs and remanence ratio M of the ferrite materials in the above embodiments and comparative examples were tested. r / M s Ferromagnetic resonance linewidth ΔH, dielectric constant ε r Coercivity H cThe test results are shown in Table 1:

[0122] Table 1

[0123] Example 1 3741 0.89 347 14.7 2186 Example 2 3716 0.87 348 15 2201 Example 3 3724 0.9 341 15 2151 Example 4 3745 0.89 349 15.2 2154 Example 5 3716 0.89 332 14.7 2199 Example 6 3788 0.89 565 15.1 2185 Example 7 3878 0.84 602 14.9 1898 Comparative Example 1 3747 0.92 583 14.9 2871 Comparative Example 2 3703 0.91 528 14.9 2813 Comparative Example 3 3486 0.84 608 15.1 1756 Comparative Example 4 3237 0.82 607 14.9 1856

[0124] As can be seen from Table 1:

[0125] As shown in Examples 1-5 and Comparative Example 1, the present invention can improve the performance of ferrite materials through multiple ball milling and two pre-firing processes. As shown in Examples 1 and Comparative Examples 2-3, the x, y, z, and a in the matrix of the present invention are within a specific range, thereby ensuring that the elements in the matrix are within a suitable range and guaranteeing the performance of the ferrite material. As shown in Examples 1 and Comparative Example 4, the present invention can improve the structure and electromagnetic properties of ferrite by adding specific dopants, thereby enhancing the performance of the ferrite material. As shown in Examples 1 and Examples 6-7, the present invention preferably uses dopants with a suitable content, which can further guarantee the performance of the ferrite material.

[0126] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A ferrite material for self-biased devices, characterized in that, The ferrite material for the self-biased device includes a matrix and a dopant, wherein the matrix includes Ba. 0.88 Ca 0.12 La x Fe 12-y-z-2a Co y Al z (ZnSn) a O 19 Where x is 0.13-0.23, y is 0.15-0.25, z is 0.05-0.1, and a is 0.05-0.15, the dopant includes ZnO, SiO2, and B2O3; The ZnO content in the ferrite material for the self-biasing device is 1.5-2 wt%. The SiO2 content in the ferrite material used in the self-biased device is 0.5-1 wt%. The ferrite material used in the self-biased device contains 0.6-1.2 wt% B2O3. The method for preparing the ferrite material for the self-biased device includes the following steps: (1) According to the formula, the raw materials of the matrix are ball-milled and pre-fired once to obtain a pre-fired material; (2) The pre-fired material described in step (1) is subjected to secondary ball milling and secondary pre-firing in sequence to obtain secondary pre-fired material; (3) The pre-burned material and dopant in step (2) are ball-milled three times and then pressed into a green embryo. The green embryo is sintered to obtain the ferrite material for the self-biased device.

2. A method for preparing the ferrite material for a self-biased device as described in claim 1, characterized in that, The preparation method includes the following steps: (1) According to the formula, the raw materials of the matrix are ball-milled and pre-fired once to obtain a pre-fired material; (2) The pre-fired material described in step (1) is subjected to secondary ball milling and secondary pre-firing in sequence to obtain secondary pre-fired material; (3) The pre-burned material and dopant in step (2) are ball-milled three times and then pressed into a green embryo. The green embryo is sintered to obtain the ferrite material for the self-biased device.

3. The preparation method according to claim 2, characterized in that, In step (1), the rotation speed of the ball mill is 60-80 r / min and the time is 8-12 h.

4. The preparation method according to claim 2, characterized in that, After the ball milling in step (1), the material is first dried and sieved, and then pre-fired.

5. The preparation method according to claim 2, characterized in that, The temperature of the first pre-firing in step (1) is 1050-1100℃ and the time is 2-4h.

6. The preparation method according to claim 2, characterized in that, The rotation speed of the secondary ball mill in step (2) is 60-80 r / min, and the time is 10-16 h.

7. The preparation method according to claim 2, characterized in that, After the secondary ball milling in step (2), the material is first dried and sieved, and then pre-fired a second time.

8. The preparation method according to claim 2, characterized in that, The temperature of the secondary pre-firing in step (2) is 800-900℃ and the time is 3-6h.

9. The preparation method according to claim 2, characterized in that, In step (3), the rotation speed of the three ball milling processes is 60-80 r / min, and the time is 14-20 h.

10. The preparation method according to claim 2, characterized in that, Dispersants were added independently after the first ball milling in step (1), the second ball milling in step (2), and the third ball milling in step (3).

11. The preparation method according to claim 10, characterized in that, The dispersant is ammonia.

12. The preparation method according to claim 2, characterized in that, After the three ball millings in step (3), the mixture is first dehydrated and then pressed into shape.

13. The preparation method according to claim 12, characterized in that, The moisture content of the dehydrated material is 20wt%-30wt%.

14. The preparation method according to claim 2, characterized in that, Step (3) involves pressing and molding in a magnetic field.

15. The preparation method according to claim 14, characterized in that, The magnetic field strength is above 1.4T.

16. The preparation method according to claim 2, characterized in that, The sintering temperature in step (3) is 1150-1200℃ and the time is 6-12h.

17. An application of the ferrite material for a self-biased device as described in claim 1, characterized in that, The applications include those used in self-biased circulators.