CN114956800A - High-performance microwave polycrystalline ferrite material - Google Patents
High-performance microwave polycrystalline ferrite material Download PDFInfo
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Abstract
The invention discloses a high-performance microwave polycrystalline ferrite material, which belongs to the technical field of microwave ferrite materials and has the following chemical formula: li 0.5‑0.5a‑0.5d+0.02 Zn a (MgTi) b Mn c Ni d Bi e Fe 2.5‑2b‑0.5a‑0.5d‑c‑δ O 4 Wherein a is more than or equal to 0.1 and less than or equal to 0.35, b is more than or equal to 0 and less than or equal to 0.3, c is more than or equal to 0.02 and less than or equal to 0.08, d is more than or equal to 0.02 and less than or equal to 0.06, e is more than or equal to 0.003 and less than or equal to 0.006, delta is the iron deficiency, delta is more than or equal to 0.06 and less than or equal to 0.12, the invention also discloses a preparation method of the material, the invention adopts a vacuum hot pressing sintering method, and is matched with proper material formula and process parameters, and the saturation magnetization of the obtained ferrite material is 4 pi M s The improvement is 4.5 percent, and the ferromagnetic resonance line width Delta H is reduced15% lower spin linewidth Δ H k The porosity P of the material is reduced from 2.6% to 0.7%, and the comprehensive performance of the obtained microwave polycrystalline ferrite material is remarkably improved.
Description
Technical Field
The invention relates to the technical field of microwave ferrite materials, in particular to a high-performance microwave polycrystalline ferrite material and a preparation method thereof.
Background
The spinel microwave ferrite material has the dominating position in the field of high-frequency microwave application due to the characteristics of low loss and strong power bearing capacity, and the electromagnetic performance of the spinel microwave ferrite material directly determines the relevant performance of microwave devices in the frequency range from X to millimeter wave. Extrinsic parameters of microwave ferrite materials, e.g. ferromagnetic resonance linewidth Δ H, spin linewidth Δ H, of microwave properties associated with high-frequency relaxation k Etc., depending on the microstructure of the material (grain size, porosity, etc.) in addition to the material composition. The spinel microwave polycrystalline ferrite material is a porous structure material, the microstructure of the material is improved through a process, so that the material has high density and low porosity, and the spinel microwave polycrystalline ferrite material is an effective way for improving the extrinsic performance parameters of the material.
In the prior art, generally adopted for improving the compactness of the microwave ferrite material is to carry out isostatic pressing (CIP) re-pressurization treatment or Hot Isostatic Pressing (HIP) treatment after a forming process, but the processes are used for reducing the porosity P of the material and reducing the pore width Delta H p Has certain effect but has a spin linewidth delta H to the material k But is not elevated. Reducing the ferromagnetic resonance line width deltaH, wherein the line width is reduced by adding non-magnetic ions instead of reducing the magnetocrystalline anisotropy constant, but the Curie temperature of the material is reduced due to the non-magnetic ions; improving the spin linewidth Delta H of the material k The fast relaxation ions are mainly added, but the substitution of the fast relaxation ions can increase the effective line width deltaH of the material eff And is not favorable for low-loss design of the device.
In addition, hot-pressing sintering is the most effective means for improving the material compactness, but the current hot-pressing sintering furnace is vacuum or inert atmosphere sintering, and is applicable to soft magnetic materials with sintering atmosphere being vacuum or inert atmosphere sintering, for example, Chinese patent application CN 201711493894.2-a manganese zinc ferrite and preparation method thereof ", CN 202011034841.6-a preparation method of high-compactness manganese zinc ferrite", which all mention the improvement of the compactness of ferrite materials by vacuum hot-pressing sintering. However, microwave ferrite materials that require an air or oxygen atmosphere for the sintering atmosphere may result in poor loss properties of the material.
Furthermore, the inventors of the present application tried to adopt the hot press sintering process parameters disclosed in the above two patents, and as a result, a highly dense, high-performance microwave ferrite material could not be obtained.
Disclosure of Invention
It is an object of the present invention to provide a high performance microwave polycrystalline ferrite material to solve the above problems.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a high-performance microwave polycrystalline ferrite material comprises the following chemical formula: li 0.5-0.5a-0.5d+0.02 Zn a (MgTi) b Mn c Ni d Bi e Fe 2.5-2b-0.5a-0.5d-c-δ O 4 Wherein a is more than or equal to 0.1 and less than or equal to 0.35, b is more than or equal to 0 and less than or equal to 0.3, c is more than or equal to 0.02 and less than or equal to 0.08, d is more than or equal to 0.02 and less than or equal to 0.06, e is more than or equal to 0.003 and less than or equal to 0.006, delta is the iron deficiency, and delta is more than or equal to 0.06 and less than or equal to 0.12.
The invention adopts Li 0.5 Fe 2.5 O 4 As the basic formula, the sintering condition of the traditional microwave ferrite material is generally air or oxygen atmosphere, and in order to avoid the performance reduction of the material by vacuum sintering atmosphere, the invention adopts vacuum hot-pressing sintering, so the Li-rich combined iron-deficiency formula design is adopted and the vacuum hot-pressing sintering is coordinated with proper technological parameters. With a suitable amount of Zn 2+ Substitution (Li) 1+ Fe 3+ ) To increase 4 pi M s Proper amount of (Mg) 2+ Ti 4+ ) Combined substitution of Fe 3+ To reduce 4 pi M s Meanwhile, the loss is reduced; using a suitable amount of Ni 2+ Substitution (Li) 1+ Fe 3+ ) The rectangular magnetic property of the material is improved.
The inventors have analyzed through a number of experiments the reason why a high-density, high-performance microwave ferrite material cannot be obtained by the sintering process of the two patent applications mentioned in the background art, and it is likely that an inappropriate sintering temperature would cause the material to be over-fired, the crystal grains to be enlarged, the grain boundaries to be blurred, the loss of the material to be sharply increased, the ion volatilization causes the porosity to be increased, and the material compactness to be deteriorated.
The second purpose of the present invention is to provide a preparation method of the high-performance microwave polycrystalline ferrite material, which adopts the technical scheme that the preparation method comprises the following steps:
(1) formulation design according to the composition chemical formula Li 0.5-0.5a-0.5d+0.02 Zn a (MgTi) b Mn c Ni d Bi e Fe 2.5-2b-0.5a-0.5d-c-δ O 4 Wherein: a is more than or equal to 0.1 and less than or equal to 0.35, b is more than or equal to 0 and less than or equal to 0.3, c is more than or equal to 0.02 and less than or equal to 0.08, d is more than or equal to 0.02 and less than or equal to 0.06, e is more than or equal to 0.003 and less than or equal to 0.006, delta is the iron deficiency, and delta is more than or equal to 0.06 and less than or equal to 0.12, and the formula design is carried out;
(2) weighing, calculating and weighing various required raw materials according to the formula design result in the step (1), wherein the raw materials are analytically pure Fe 2 O 3 、NiO、ZnO、TiO 2 、MgO、Li 2 CO 3 、MnCO 3 、Bi 2 O 3 ；
(3) Performing primary ball milling, namely mixing the raw materials weighed in the step (2), putting the mixture into a ball milling tank, adding balls and a diluent, and performing primary wet mixing ball milling on the raw materials for 5-10 hours to obtain primary slurry;
(4) pre-burning, drying the primary slurry obtained in the step (3), sieving the primary slurry by a 30-40-mesh sieve to obtain powder, and then putting the powder into a sintering furnace for pre-burning, wherein the pre-burning temperature is 800-900 ℃, and the temperature is kept for 4-6 hours;
(5) performing secondary ball milling, namely filling the powder subjected to the pre-sintering in the step (4) into a ball milling tank, adding balls and a diluent, and performing secondary wet ball milling for 12-24 hours to obtain secondary slurry;
(6) granulating, namely drying the secondary slurry obtained in the step (5), and then adding a granulating agent for granulation;
(7) molding, namely putting the particles obtained in the step (6) into a mold for hydraulic pressing, wherein the pressing pressure is 80-100 MPa, so as to obtain a green blank sample;
(8) hot-pressing sintering, namely putting the green blank sample obtained in the step (7) into a mould to perform vacuum hot-pressing sintering at the sintering temperature of 950-1020 ℃, preserving heat for 2-4 hours, and controlling the pressure in the temperature rise process to be 10-20 MPa; the pressure intensity in the heat preservation process is 5 MPa-10 MPa.
As a preferred technical scheme, the diluents in the step (3) and the step (5) are deionized water.
As a preferable technical scheme, the granulating agent in the step (6) is polyvinyl alcohol adhesive, the concentration is 6-10 wt%, and the adding amount is 10% of the mass of the secondary powder (powder after the slurry is dried).
Preferably, the material of the mold in the step (8) is silicon carbide or aluminum oxide.
The vacuum hot-pressing sintering of the invention ensures that the material is compact and uniform, has small grain size and can effectively improve the extrinsic performance parameters of the microwave ferrite material, thus the vacuum hot-pressing sintering is an effective way for preparing high-performance ferrite material. The hot-pressing sintering temperature range is wide, and the material has good performance at 950-1020 ℃. The application improves Delta H by refining grains of microwave ferrite k The grain refinement is related to the hot pressing process, and is also closely related to the process parameters such as sintering temperature and heat preservation time, and the grain growth can be caused by the over-high sintering temperature and the over-long heat preservation time, so that the purpose of grain refinement can not be achieved. The magnetic properties of the two prior patents are different in the pursuit of the two prior patents, the process control is different in the pursuit of different magnetic properties, the hot-pressing sintering of the prior patents is material powder, the sintering of the prior patents is a green body after the material is molded, and the process parameters are greatly different.
The performance of the microwave ferrite material is obtained by perfectly combining a formula and a process, the two processes are not necessary, as mentioned above, the sintering condition of the microwave ferrite material is generally air or oxygen atmosphere, the Li-rich combined iron-deficient formula design is adopted in the microwave ferrite material to be matched with and coordinated with vacuum hot-pressing sintering, the material has a compact, uniform and single-phase microstructure, the performance of the material can be improved, and the compactness of the material is improved by showing that rho of the material is increased app Increase, P decrease, ρ app Enlarging the materialWith a higher 4 pi M s P reduction makes the material less lossy; vacuum hot-pressing sintering is adopted, so that the material has a compact, uniform and single-phase microstructure, the grains are refined, and rho is improved app 、ΔH、ΔH k The precondition is that the hot pressing technological parameter is properly designed, and not only the vacuum hot pressing sintering is adopted, the P can be reduced to 0.7%, the material loss can be reduced, and the power bearing capacity is improved.
Compared with the prior art, the invention has the advantages that:
compared with the existing material, the microwave polycrystalline ferrite material which is sintered by adopting vacuum hot pressing and is improved by combining the formula has the saturation magnetization of 4 pi M s Improved by 4.5%, reduced by 15% in ferromagnetic resonance line width Delta H, and spin wave line width Delta H k The porosity P of the material is reduced from 2.6% to 0.7%, and the comprehensive performance of the obtained microwave polycrystalline ferrite material is remarkably improved.
Drawings
FIG. 1 is an SEM image of a microwave polycrystalline ferrite material prepared in example 1 of the present invention;
FIG. 2 is an SEM image of a microwave polycrystalline ferrite material prepared in example 2 of the present invention;
FIG. 3 is an SEM image of a microwave polycrystalline ferrite material prepared in example 1 of the present invention;
FIG. 4 is a diagram of a sample of microwave polycrystalline ferrite material prepared in examples 1-3;
FIG. 5 is an XRD pattern of the microwave polycrystalline ferrite material prepared in examples 1-3.
Detailed Description
The invention will be further explained with reference to the drawings.
Example 1
A high-performance polycrystal microwave ferrite material has a spinel structure as its main phase structure and Li as its chemical formula 0.5-0.5a-0.5d+0.02 Zn a (MgTi) b Mn c Ni d Bi e Fe 2.5-2b-0.5a-0.5d-c-δ O 4 Wherein: a =0.1, b =0.3, c =0.02, d =0.06, e =0.003, δ = 0.12;
the preparation method comprises the following steps:
(1) formulation design, namely performing formulation design according to the composition chemical formula;
(2) weighing, calculating and weighing various required raw materials according to formula design, wherein the raw materials are analytically pure Fe 2 O 3 、NiO、ZnO、TiO 2 、MgO、Li 2 CO 3 、MnCO 3 、Bi 2 O 3 ；
(3) Performing primary ball milling, namely mixing various raw materials weighed according to the formula, putting the raw materials into a ball milling tank, adding balls and a diluent, wherein the diluent is deionized water, and performing primary wet mixing ball milling on the raw materials for 10 hours;
(4) pre-burning, drying the primary ball-milling slurry, sieving the dried primary ball-milling slurry by a 30-40 mesh sample sieve to obtain powder, and then putting the powder into a sintering furnace for pre-burning, wherein the pre-burning temperature is 900 ℃, and the temperature is kept for 4 hours;
(5) performing secondary ball milling, namely filling the pre-sintered powder into a ball milling tank, adding balls and a diluent, wherein the diluent is deionized water, and performing secondary wet ball milling for 24 hours to obtain slurry;
(6) granulating, namely drying the slurry subjected to secondary ball milling, and then adding 10% of polyvinyl alcohol adhesive with the concentration of 10wt% for granulation;
(7) molding, namely putting the granulated particles into a mold for hydraulic pressing, wherein the pressing pressure is 100MPa, so as to obtain a green blank sample;
(8) hot-pressing sintering, namely putting the green blank sample into a silicon carbide mould for vacuum hot-pressing sintering, wherein the sintering temperature is 1020 ℃, the temperature is kept for 2 hours, and the pressure in the temperature rise process is 20 MPa; the pressure intensity in the heat preservation process is 10 MPa.
Electromagnetic performance test of the material is carried out according to GB/T9633-2012, and the test result is shown in Table 1;
the SEM image of the resulting material is shown in FIG. 1, the sample image is shown in FIG. 4, and the XRD image is shown in FIG. 5.
Comparative example 1
Compared with the embodiment 1, the comparative example only adopts the step (8) to sinter in a common air sintering furnace, the sintering temperature is 1020 ℃, the heat preservation is carried out for 4 hours, and the rest is the same as the embodiment 1.
The performance results of example 1 and comparative example 1 show that the saturation magnetization of the hot-pressed sintered material is 4 π M s Improved by 4.6%, reduced by 16.5% in ferromagnetic resonance line width Delta H, and spin wave line width Delta H k The porosity P is reduced by 73%, and the Curie temperature is almost unchanged.
Example 2
A high-performance microwave polycrystalline ferrite material has a spinel structure as its main phase structure and Li as its chemical formula 0.5-0.5a-0.5d+0.02 Zn a (MgTi) b Mn c Ni d Bi e Fe 2.5-2b-0.5a-0.5d-c-δ O 4 Wherein: a =0.2, b =0.15, c =0.05, d =0.04, e =0.003, δ = 0.08;
the preparation method comprises the following steps:
(1) formulation design, namely performing formulation design according to the composition chemical formula;
(2) weighing, calculating and weighing various required raw materials according to formula design, wherein the raw materials are analytically pure Fe 2 O 3 、NiO、ZnO、TiO 2 、MgO、Li 2 CO 3 、MnCO 3 、Bi 2 O 3 ；
(3) Performing primary ball milling, namely mixing various raw materials weighed according to the formula, putting the raw materials into a ball milling tank, adding balls and a diluent, wherein the diluent is deionized water, and performing primary wet mixing ball milling on the raw materials for 10 hours;
(4) pre-burning, drying the primary ball-milling slurry, sieving the dried primary ball-milling slurry by a 30-40 mesh sample sieve to obtain powder, and then putting the powder into a sintering furnace for pre-burning, wherein the pre-burning temperature is 900 ℃, and the temperature is kept for 4 hours;
(5) performing secondary ball milling, namely filling the pre-sintered powder into a ball milling tank, adding balls and a diluent, wherein the diluent is deionized water, and performing secondary wet ball milling for 24 hours to obtain slurry;
(6) granulating, namely drying the slurry subjected to secondary ball milling, and then adding 10% of polyvinyl alcohol adhesive with the concentration of 8wt% for granulation;
(7) molding, namely putting the granulated particles into a mold for hydraulic pressing, wherein the pressing pressure is 100MPa, so as to obtain a green blank sample;
(8) hot-pressing sintering, namely putting the green blank sample into an alumina mould for vacuum hot-pressing sintering, wherein the sintering temperature is 1020 ℃, the temperature is kept for 4 hours, and the pressure in the temperature rise process is 10 MPa; the pressure intensity in the heat preservation process is 5 MPa.
(9) The electromagnetic performance of the material was tested according to GB/T9633-2012, the results of which are shown in Table 2.
The SEM image of the resulting material is shown in FIG. 2, the sample image is shown in FIG. 4, and the XRD image is shown in FIG. 5.
Comparative example 2
Compared with the embodiment 2, the comparative example only adopts the step (8) to sinter in a common air sintering furnace, the sintering temperature is 1050 ℃, the temperature is kept for 6 hours, and the rest is the same as the embodiment 2;
the electromagnetic performance test results of the high-performance microwave polycrystalline ferrite material are shown in table 2.
The performance results of example 2 and comparative example 2 show that the saturation magnetization of the hot-pressed sintered material is 4 π M s Improved by 4.0%, reduced by 21.8% in ferromagnetic resonance line width Delta H, and spin wave line width Delta H k The porosity P is reduced by 73%, and the Curie temperature is almost unchanged.
Example 3
A high-performance microwave polycrystalline ferrite material has a spinel structure as its main phase structure and Li as its chemical formula 0.5-0.5a-0.5d+0.02 Zn a (MgTi) b Mn c Ni d Bi e Fe 2.5-2b-0.5a-0.5d-c-δ O 4 Wherein: a =0.3, b =0, c =0.08, d =0.06, e =0.006, δ = 0.06.
The preparation method comprises the following steps:
(1) formulation design, namely performing formulation design according to the composition chemical formula;
(2) weighing, calculating and weighing various required raw materials according to formula design, wherein the raw materials are analytically pure Fe 2 O 3 、NiO、ZnO、Li 2 CO 3 、MnCO 3 、Bi 2 O 3 ；
(3) Performing primary ball milling, namely mixing various raw materials weighed according to the formula, putting the raw materials into a ball milling tank, adding balls and a diluent, wherein the diluent is deionized water, and performing primary wet mixing ball milling on the raw materials for 5 hours;
(4) pre-burning, drying the primary ball-milling slurry, sieving the dried primary ball-milling slurry by a 30-40 mesh sample sieve to obtain powder, and then putting the powder into a sintering furnace for pre-burning, wherein the pre-burning temperature is 800 ℃, and the temperature is kept for 6 hours;
(5) performing secondary ball milling, namely filling the pre-sintered powder into a ball milling tank, adding balls and a diluent, wherein the diluent is deionized water, and performing secondary wet ball milling for 12 hours to obtain slurry;
(6) granulating, namely drying the slurry subjected to secondary ball milling, and then adding 10% of polyvinyl alcohol adhesive with the concentration of 8wt% for granulation;
(7) molding, namely putting the granulated particles into a mold for hydraulic pressing, wherein the pressing pressure is 80MPa, so as to obtain a green blank sample;
(8) hot-pressing sintering, namely putting the green blank sample into a silicon carbide mould for vacuum hot-pressing sintering, wherein the sintering temperature is 950 ℃, the temperature is kept for 4 hours, and the pressure in the temperature rise process is 10 MPa; the pressure intensity in the heat preservation process is 10 MPa;
(9) the electromagnetic performance of the material was tested according to GB/T9633-2012, and the results are shown in Table 3.
The SEM image of the resulting material is shown in FIG. 3, the sample image is shown in FIG. 4, and the XRD image is shown in FIG. 5.
Comparative example 3
Compared with the above example 3, the comparative example only adopts the step (8) to sinter in a common air sintering furnace, the sintering temperature is 1000 ℃, the temperature is kept for 6 hours, and the rest is the same as the example 3.
Comparative example 4
This comparative example compares with example 3 aboveThe chemical formula of the formula only in the step (1) is Li 0.5-0.5a-0.5d Zn a (MgTi) b Mn c Ni d Bi e Fe 2.5-2b-0.5a-0.5d-c-δ O 4 Wherein: a =0.3, b =0, c =0.08, d =0.06, e =0.006, δ =0 (this comparative example is intended to demonstrate the technical effect of the change in the amount of iron deficiency, compared to example 3 above, example 3 was formulated with "lithium rich + iron deficiency" and comparative example 4 was formulated with normal lithium content + normal iron content), and the rest was the same as example 3.
The measured material properties are shown in table 3 below,
the performance results of example 3 and comparative example 3 show that the saturation magnetization of the hot-pressed sintered material is 4 π M s Improved by 4.6%, reduced by 22.0% in ferromagnetic resonance line width Delta H, and spin wave line width Delta H k The porosity P is reduced by 75%, and the Curie temperature is almost unchanged. The performance results of example 3 and comparative example 4 show that the Δ H of the material can be significantly reduced by adopting the Li-rich combined iron-deficiency formulation design, thereby effectively reducing the loss of the material.
The invention obtains that the saturation magnetization of the microwave polycrystalline ferrite material sintered by vacuum hot pressing is 4 pi larger than that of the common sintered material through 3 examples and corresponding comparative example performance testsM s 4.5% improvement, 15% reduction of ferromagnetic resonance line width delta H, spin wave line width delta H k The porosity P of the material is reduced from 2.6% to 0.7%. The hot-pressing sintering ensures that the material is compact and uniform, has small grain size, can effectively improve the overall performance index of the material, and is an effective way for preparing high-performance microwave polycrystalline ferrite material.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (4)
1. A high-performance microwave polycrystalline ferrite material is characterized by comprising the following chemical formula: li 0.5-0.5a-0.5d+0.02 Zn a (MgTi) b Mn c Ni d Bi e Fe 2.5-2b-0.5a-0.5d-c-δ O 4 Wherein a is more than or equal to 0.1 and less than or equal to 0.35, b is more than or equal to 0 and less than or equal to 0.3, c is more than or equal to 0.02 and less than or equal to 0.08, d is more than or equal to 0.02 and less than or equal to 0.06, e is more than or equal to 0.003 and less than or equal to 0.006, delta is the iron deficiency, and delta is more than or equal to 0.06 and less than or equal to 0.12, and the preparation method comprises the following steps:
(1) formulation design according to the formula of Li 0.5-0.5a-0.5d+0.02 Zn a (MgTi) b Mn c Ni d Bi e Fe 2.5-2b-0.5a-0.5d-c-δ O 4 Wherein: a is more than or equal to 0.1 and less than or equal to 0.35, b is more than or equal to 0 and less than or equal to 0.3, c is more than or equal to 0.02 and less than or equal to 0.08, d is more than or equal to 0.02 and less than or equal to 0.06, e is more than or equal to 0.003 and less than or equal to 0.006, delta is the iron deficiency, and delta is more than or equal to 0.06 and less than or equal to 0.12, and the formula design is carried out;
(2) weighing, calculating and weighing various required raw materials according to the formula design result in the step (1), wherein the raw materials are analytically pure Fe 2 O 3 、NiO、ZnO、TiO 2 、MgO、Li 2 CO 3 、MnCO 3 、Bi 2 O 3 ；
(3) Performing primary ball milling, namely mixing the raw materials weighed in the step (2), putting the mixture into a ball milling tank, adding balls and a diluent, and performing primary wet mixing ball milling on the raw materials for 5-10 hours to obtain primary slurry;
(4) pre-burning, drying the primary slurry obtained in the step (3), sieving the primary slurry by a 30-40-mesh sieve to obtain powder, and then putting the powder into a sintering furnace for pre-burning, wherein the pre-burning temperature is 800-900 ℃, and the temperature is kept for 4-6 hours;
(5) performing secondary ball milling, namely filling the powder subjected to the pre-sintering in the step (4) into a ball milling tank, adding balls and a diluent, and performing secondary wet ball milling for 12-24 hours to obtain secondary slurry;
(6) granulating, namely drying the secondary slurry obtained in the step (5), and then adding a granulating agent for granulation;
(7) molding, namely putting the particles obtained in the step (6) into a mold for hydraulic pressing, wherein the pressing pressure is 80-100 MPa, so as to obtain a green blank sample;
(8) hot-pressing sintering, namely putting the green blank sample obtained in the step (7) into a mould to perform vacuum hot-pressing sintering at the sintering temperature of 950-1020 ℃, preserving heat for 2-4 hours, and controlling the pressure in the temperature rise process to be 10-20 MPa; the pressure intensity in the heat preservation process is 5 MPa-10 MPa.
2. A high performance microwave polycrystalline ferrite material according to claim 1, wherein the diluent in step (3) and step (5) is deionized water.
3. The microwave polycrystalline ferrite material with high performance as claimed in claim 1, wherein the granulating agent in step (6) is polyvinyl alcohol adhesive with concentration of 6-10 wt%, and the addition amount is 10% of the mass of the secondary drying powder.
4. The microwave polycrystalline ferrite material with high performance as claimed in claim 1, wherein the material of the mold in step (8) is silicon carbide or aluminum oxide.
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