A preparation method of high dielectric low loss garnet ferrite with high bismuth substitution

Abstract

The application relates to a preparation method of high-intermediate low-loss garnet ferrite with high bismuth substitution, and belongs to the field of microwave ferrite materials. 3+ The application reduces the volatilization of Bi by adding a small amount of H3BO3 and Bi2O3 as additives in the two-milling process, accelerates the growth of the crystal under the driving of the low-melting-point Bi2O3 additive in the sintering process, and accelerates the growth of the crystal under the driving of the low-melting-point Bi2O3 additive in the sintering process. 3+ The volatilization of Bi in the pre-sintering process is reduced by using a lower pre-sintering temperature, the optimal sintering temperature is wider, and the microstructure of the material is effectively improved. 3+ The volatilization of Bi in the sintering process is compensated by using a three-stage progressive holding sintering method in the high-temperature section of the final sintering, the sintering temperature and the holding time are controlled, the crystal grain growth is reduced after the continuous growth of the crystal grain, and the uniformity of the solid-phase reaction is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of microwave ferrite materials, especially ferrite devices applied in radars and 5G communication systems, and particularly relates to a preparation method of high-intermediate high-loss garnet ferrite with high bismuth substitution. BACKGROUND

[0002] The purpose of developing high dielectric constant yttrium iron garnet ferrite material is to solve the problem of miniaturization of ferrite devices. Currently, the dielectric constant of the material is generally improved by Bi 3+ substitution, but the volatilization of Bi 3+ will cause the ferromagnetic resonance line width of the material to increase, and the preparation process has more stringent requirements.

[0003] Currently, the research on high-dielectric low-loss YIG mainly improves the performance of garnet ferrite material through ion substitution and improvement of the preparation process. The patent with the publication number CN11182544A, "High-dielectric constant, high-saturation magnetization garnet ferrite material, its preparation method and application", uses an oxide ceramic process to prepare Bi a Ca b Gd c Y 3-a-b- c Fe 5-d-e-f-g-δ Hf d Zr e V f Sn g O 12 ferrite, wherein a = 1.5, b = 0.45, c = 0, d = 0.33, e = 0.22, f = 0, g = 0, δ = 0.05, 4πM s = 1861Gs, ΔH = 50Oe, ε' = 32.27. The material has high dielectric constant and low ferromagnetic resonance line width, but the large amount of substitution of noble metal Hf will cause the Curie temperature to be too low, only 190-200℃, and the raw material cost is high.

[0004] The patent with the publication number CN113402268A, "Microwave ferrite material and its preparation method and application", discloses a chemical formula Y 3-a-b+d Ca b-d Bi a Ti b Al c Zn d Fe 5-b-c-d O 12The ferrite is of formula: 0≤a≤1.2, 0.6≤b≤1.5, 0≤c≤0.6, 0≤d≤0.7, 0≤e≤0.7, 0≤f≤0.15, 0≤g≤0.5, 0≤δ≤0.3, δ is a process iron deficiency, the dielectric constant of the prepared material is controlled in a range of 14-31, and the saturation magnetization 4πM s is 1200-2000Gs, the Curie temperature is not lower than 200 DEG C, the dielectric loss tangent tan delta is less than or equal to 0.0002, and the ΔH is less than or equal to 50 Oe, but the preparation process and production equipment involved are complex through the combination of temperature rising and cold isostatic pressing and the combination of cold rolling and annealing treatment, which is not conducive to improving industrial production efficiency.

[0005] The above patent incorporates a large amount of Bi 3+ in order to obtain a high dielectric constant s , adopts a complex process in order to obtain a low ferromagnetic resonance line width ΔH, greatly increases the production cost, and is not conducive to cost reduction and efficiency improvement; or a large amount of octahedral non-magnetic ions are replaced, the ferromagnetic resonance line width ΔH and the saturation magnetization 4πM 3+ temperature characteristics cannot be considered, and the practicability is limited. At the same time, the doping of high Bi 3+ must lead to serious volatilization in the high-temperature sintering stage, and the requirements for the preparation process are more severe. SUMMARY

[0006] The purpose of the present application is to solve the problems of the prior art that a large amount of Bi 3+ is replaced, Bi a volatilizes seriously in the high-temperature stage, and the microstructure of the sintered body is uneven in grain size, the grain boundary is blurred, the porosity is high, and the composition distribution is uneven, and finally the ferromagnetic resonance line width value of the material is greatly increased.

[0007] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0008] A preparation method of a high-dielectric low-loss garnet ferrite with high Bi substitution, comprising the following steps:

[0009] Step 1, batching:

[0010] Analytically pure Bi2O3, CaCO3, La2O3, Nd2O3, Y2O3, ZrO2, In2O3, SnO2, V2O5 and Fe2O3 are used as raw materials, and the chemical formula Bi a Ca b La c Nd d Y 3-a-b-c-d Zr e In f Sn g Vh Fe 5-e-f-g-h-δ O 12 The stoichiometric ratio of the raw materials is calculated and weighed; wherein 1.4≤a, 0

[0011] Step 2, primary ball milling:

[0012] The powder weighed in step 1 is ball milled with zirconia balls and deionized water in a planetary ball mill, the mass ratio of zirconia balls: raw materials: deionized water is 4:1:1.5, the ball milling time is 5-8h, and after ball milling, drying and 80 mesh sieving are performed;

[0013] Step 3, pre-sintering:

[0014] The primary ball milled material obtained in step 2 is pre-sintered at 810-850℃, the holding time is 1-5h, and after pre-sintering, crushing and sieving are performed;

[0015] Step 4, secondary ball milling:

[0016] 0.01-0.05wt% of H3BO3 and 0.01-0.05wt% of Bi2O3 are added to the pre-sintered material obtained in step 3 as additives, and after mixing, secondary ball milling is performed in a planetary ball mill, the mass ratio of balls: materials: water is 4:1:1.5, the ball milling time is 6-8h, and after drying and 80 mesh sieving are performed;

[0017] Step 5, granulation:

[0018] The secondary ball milled material obtained in step 4 is granulated with 12wt% of polyvinyl alcohol (PVA) according to the weight percentage, sieved, and the granulated material with a mesh size of 80-200 is taken;

[0019] Step 6, molding:

[0020] The granulated material obtained in step 5 is placed in a mold for compression molding, and the compression pressure is 150-200MPa;

[0021] Step 7, sintering:

[0022] The green body obtained by compression molding in step 6 is placed in a sintering furnace for sintering by a multi-step sintering method, and progressive holding is performed in the high temperature zone to obtain the garnet ferrite; wherein the process of the multi-step sintering method is as follows: the sintering temperature of the first process is 400-500℃, and the holding time is 1-5h; the sintering temperature of the second process is 820-900℃, and the holding time is 1-5h; the third process is three-stage progressive holding at 930-1000℃, and the total holding time is 20-40h.

[0023] Further, in step 7, the holding temperature of the first process is 400-500℃, which is the degassing stage; the holding temperature of the second process is 820-900℃, which is set near the melting point of Bi2O3, so as to inhibit the volatilization of Bi2O3 and make up for the lower pre-sintering temperature, so that the raw materials are completely reacted, and the temperature compensation problem due to the volatilization of Bi2O3 is made up; the holding temperature of the third process is 930-1000℃, which is sintered in three stages, specifically, first holding at 930℃ for 6-10h, then heating to 940℃ for 6-10h, and finally heating to 950℃ for 6-10h, so as to continuously grow the grains to the end of continuous growth (grain size 3-7μm, which increases with the increase of Bi 3+ substitution), and before the abnormal growth of the grains, the sintering temperature is reduced according to the increase of Bi 3+ substitution, and at the same time, in order to avoid the thermal stress caused by too fast cooling, the cooling rate is finally reduced to 2℃ / min to 600℃, and then the sample is cooled with the furnace. 3+ 3 +

[0024] Further, in step 3, the pre-sintering temperature is relatively low, and the holding time is 1-5h, so as to obtain a wider sintering interval and reduce the volatilization of Bi2O3 in the pre-sintering stage; in step 4, a small amount of H3BO3 and Bi2O3 is added as a fluxing agent, so as to improve the microstructure of the final sintered body and further inhibit the volatilization of Bi2O3; in step 7, the volatilization of Bi2O3 is further inhibited by placing a sample identical to the sample around the sample, or stacking a bottom sheet and a top sheet identical to the sample on the upper and lower layers of the sample. 3+ 3+ 3+

[0025] The application provides a preparation method of high-intermediate-loss stone molybdenum ferrite with high Bi substitution, in which a small amount of H3BO3 and Bi2O3 is added as an additive in the second grinding process, so as to reduce the volatilization of Bi2O3 on one hand, and on the other hand, under the driving of high reaction activation energy, the crystals are fused with each other and accelerated to grow under the capillary driving of the low-melting-point Bi2O3 additive. In addition, the volatilization of Bi2O3 in the pre-sintering stage is reduced by using a lower pre-sintering temperature, and a wider optimal sintering temperature can be obtained by using a lower pre-sintering temperature. Moreover, Bi2O3 as a low-melting-point substance can reduce the sintering temperature required by the ferrite material, but the volatilization of Bi2O3 will reduce this effect, so a three-stage progressive holding sintering is used in the high-temperature stage of the final sintering to make up for the volatilization of Bi2O3 in the sintering and holding stage. 3+ 3+ 3+ 3+ 3+ ​​​​​​​​​The temperature compensation required for volatilization can effectively improve the microstructure of the material, and the sintering temperature and holding time are controlled to make the grain growth to the end of continuous growth, and then the temperature is lowered, and the uniformity of the solid phase reaction is improved.

[0026] The polycrystalline ferrite material obtained by the traditional ceramic solid phase sintering process through high-temperature ion diffusion has problems of uneven chemical composition and corresponding micro-area magnetization strength gradient, etc. The garnet ferrite material can be divided into two stages according to the grain size growth during the long-time holding sintering process, one is the continuous grain growth stage in the early stage of long-time holding, and the other is the abnormal grain growth stage in the late stage of long-time holding. The key to obtaining a small linewidth material lies in the end of the continuous grain growth before the abnormal grain growth. During the continuous grain growth, the grain boundary continuously migrates back and forth, which promotes the homogenization of the composition and improves the degree of completion of the solid phase reaction. During the abnormal grain growth, the grain boundary only passes once and cannot produce such homogenization. If the sintering temperature is too low, it is not conducive to the continuous growth of the grain, and if the temperature is too high, the grain will abnormally grow. Therefore, Bi 3+ The volatilization of Bi can be compensated by slowly increasing the sintering temperature in three stages, so that the holding stage ends at the end of the continuous grain growth (grain size 3-7 mu, according to the increase of Bi substitution), the homogenization of the continuous grain growth is improved, and the ferrimagnetic resonance linewidth performance is improved.

[0027] Compared with the prior art, the beneficial effects of the present application are:

[0028] The garnet ferrite of the present application uses Bi 3+ , Ca 2+ , La 3+ , Nd 3+ , Zr 4+ , In 3+ , Sn 4+ , V 5+ ion combined control, and at the same time, for the volatilization problem of high Bi 3+ , a small amount of H3BO3 and Bi2O3 are added as additives in the second grinding process, and through control of the sintering process, the volatilization of Bi 3+ is effectively utilized, and the microstructure of the sintered body is regulated by three-stage progressive holding sintering, so as to obtain a ferrite material with dielectric constant ε' ≥ 30, and at the same time, high saturation magnetization 4πM s ≥ 1800Gs, low ferrimagnetic resonance linewidth ΔH ≤ 30Oe, and high Curie temperature T c ≥ 250℃. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1The scanning electron microscope photo of the garnet ferrite material obtained in Example 1 is shown in the following figure:

[0030] Figure 2 The scanning electron microscope photo of the garnet ferrite material obtained in Example 2 is shown in the following figure:

[0031] Figure 3 The scanning electron microscope photo of the garnet ferrite material obtained in Example 3 is shown in the following figure:

[0032] Figure 4 The scanning electron microscope photo of the garnet ferrite material obtained in Example 4 is shown in the following figure. DETAILED DESCRIPTION

[0033] The present application provides a preparation method of high-bismuth-substituted high-dielectric low-loss garnet ferrite, which will be described in more details through specific embodiments, but the protection scope of the present application is not limited to these embodiments.

[0034] Example 1

[0035] A preparation method of high-bismuth-substituted high-dielectric low-loss garnet ferrite, specifically comprising the following steps:

[0036] Step 1, batching:

[0037] Analytically pure Bi2O3, CaCO3, La2O3, Nd2O3, Y2O3, ZrO2, In2O3, SnO2, V2O5 and Fe2O3 are used as raw materials, and the raw materials are calculated and weighed according to the stoichiometric ratio of the chemical formula Bi a Ca b La c Nd d Y 3-a-b-c-d Zr e In f Sn g V h Fe 5-e-f-g-h-δ O 12 ; wherein a = 1.4, b = 0.35, c = 0.1, d = 0.1, e = 0.35, f = 0.1, g = 0, h = 0, and δ = 0.1, wherein δ is the amount of iron deficiency;

[0038] Step 2, primary ball milling:

[0039] The powder weighed in step 1 and zirconia balls and deionized water are ball milled in a planetary ball mill. The ball mill tank is made of stainless steel to reduce the wear of Fe into the material during ball milling. The mass ratio of zirconia balls, raw materials and deionized water is 4:1:1.5. The ball milling time is 5h. After ball milling, the material is dried and sieved through an 80 mesh sieve, and then loaded into a special corundum crucible.

[0040] Step 3, pre-sintering:

[0041] Put the corundum crucible filled with the powder obtained in step 2 into a box furnace in an air atmosphere for pre-sintering, the pre-sintering temperature is 830℃, and the holding time is 4h, and after pre-sintering, crushing and sieving are performed;

[0042] Step 4, secondary ball milling:

[0043] In the pre-sintered material obtained in step 3, 0.01wt% of H3BO3 and 0.01wt% of Bi2O3 are added as additives according to the mass ratio, and after mixing, secondary ball milling is performed in a planetary ball mill, the mass ratio of ball:material:water is 4:1:1.5, ball milling is performed for 6h, and drying and sieving through an 80 mesh sieve are performed;

[0044] Step 5, granulation:

[0045] The secondary ball milled material obtained in step 4 is granulated by adding 12wt% of polyvinyl alcohol (PVA) according to the weight percentage, sieved, and the granulated material between 80-200 meshes is taken;

[0046] Step 6, molding:

[0047] The granulated material obtained in step 5 is placed into a mold for compression molding, and the compression pressure is 150-200MPa;

[0048] Step 7, sintering:

[0049] The green body obtained by compression molding in step 6 is placed in a sintering furnace for sintering by a multi-step sintering method, and progressive holding is performed in the high temperature zone, to obtain the garnet ferrite; wherein the process of the multi-step sintering method is: the sintering temperature of the first process is 400-500℃, and the holding time is 1h; the sintering temperature of the second process is 835℃, and the holding time is 2h; the third process is three-stage progressive holding at 930-1000℃, specifically, first holding at 930℃ for 6-10h, then heating to 950℃ for 6-10h, and finally heating to 970℃ for 6-10h, and finally cooling to 600℃ at a rate of 2℃ / min and cooling with the furnace.

[0050] Example 2

[0051] A preparation method of a high-intermediate low-loss garnet ferrite with high bismuth substitution, specifically comprising the following steps:

[0052] Step 1, batching:

[0053] Analytically pure Bi2O3, CaCO3, La2O3, Nd2O3, Y2O3, ZrO2, In2O3, SnO2, V2O5, and Fe2O3 are used as raw materials, and the chemical formula Bi a Ca b La c Ndd Y 3-a-b-c-d Zr e In f Sn g V h Fe 5-e-f-g-h-δ O 12 The stoichiometric ratio of the raw materials is calculated and weighed; wherein a = 1.4, b = 0.4, c = 0, d = 0, e = 0.4, f = 0, g = 0, h = 0, δ = 0.15, and δ is the amount of iron deficiency;

[0054] Step 2, primary ball milling:

[0055] The powder weighed in step 1 is ball milled with zirconia balls and deionized water in a planetary ball mill. The ball mill tank is made of stainless steel to reduce the wear of Fe into the material during ball milling. The mass ratio of zirconia balls, raw materials, and deionized water is 4:1:1.5. The ball milling time is 5 h. After ball milling, the material is dried and sieved through an 80-mesh sieve, and then loaded into a special corundum crucible.

[0056] Step 3, pre-sintering:

[0057] The corundum crucible containing the powder obtained in step 2 is placed in a box furnace in an air atmosphere for pre-sintering. The pre-sintering temperature is 840°C, and the holding time is 3 h. After pre-sintering, the material is broken and sieved.

[0058] Step 4, secondary ball milling:

[0059] 0.02wt% H3BO3 and 0.02wt% Bi2O3 are added to the pre-sintered material obtained in step 3 as additives. After mixing, secondary ball milling is performed in a planetary ball mill. The mass ratio of balls, material, and water is 4:1:1.5. The ball milling time is 8 h. The material is dried and sieved through an 80-mesh sieve.

[0060] Step 5, granulation:

[0061] The secondary ball milled material obtained in step 4 is granulated with 12wt% polyvinyl alcohol (PVA) by weight percentage. The granulated material is sieved, and the granulated material with a mesh size of 80-200 is taken.

[0062] Step 6, shaping:

[0063] The granulated material obtained in step 5 is placed in a mold for compression molding. The compression pressure is 150-200 MPa.

[0064] Step 7, sintering:

[0065] The green compact of step 6 is placed in a sintering furnace to be sintered by a multi-step sintering method, and is progressively kept warm in a high temperature zone to obtain the garnet ferrite; wherein the process of the multi-step sintering method is as follows: the sintering temperature of the first process is 400-500 DEG C, and the keeping warm time is 1 h; the sintering temperature of the second process is 840 DEG C, and the keeping warm time is 2 h; the third process is three-stage progressive keeping warm at 930-960 DEG C, specifically, keeping warm at 930 DEG C for 6-10 h, then increasing the temperature to 940 DEG C for 6-10 h, and finally increasing the temperature to 950 DEG C for 6-10 h, and finally decreasing the temperature to 600 DEG C at a rate of 2 DEG C / min and cooling with the furnace.

[0066] Example 3

[0067] A preparation method of high-intermediate low-loss garnet ferrite for high bismuth substitution, specifically comprising the following steps:

[0068] Step 1, batching:

[0069] Analytically pure Bi2O3, CaCO3, La2O3, Nd2O3, Y2O3, ZrO2, In2O3, SnO2, V2O5 and Fe2O3 are used as raw materials, and the raw materials are calculated and weighed according to the stoichiometric ratio of the chemical formula Bi a Ca b La c Nd d Y 3-a-b-c-d Zr e In f Sn g V h Fe 5-e-f-g-h-δ O 12 ; wherein a = 1.4, b = 0.5, c = 0.02, d = 0.25, e = 0, f = 0, g = 0.075, h = 0, and δ = 0.15, wherein δ is the amount of iron deficiency;

[0070] Step 2, primary ball milling:

[0071] The powder weighed in step 1 and zirconia balls and deionized water are ball milled in a planetary ball mill, and a stainless steel ball mill tank is used to reduce the wear of Fe into the material during ball milling, the mass ratio of zirconia balls, raw materials and deionized water is 4:1:1.5, the ball milling time is 5 h, and after ball milling, the powder is dried and sieved through an 80-mesh sieve and then loaded into a special corundum crucible;

[0072] Step 3, pre-sintering:

[0073] The corundum crucible loaded with the powder obtained in step 2 is placed in an air atmosphere box furnace for pre-sintering, the pre-sintering temperature is 850 DEG C, and the keeping warm time is 2 h, and after pre-sintering, the powder is crushed and sieved;

[0074] Step 4, secondary ball milling:

[0075] The pre-sintered material obtained in step 3 is mixed with 0.03wt% of H3BO3 and 0.03wt% of Bi2O3 as additives, and then secondary ball milling is performed in a planetary ball mill with a mass ratio of ball:material:water of 4:1:1.5 for 7h, and then dried and sieved through an 80-mesh screen;

[0076] Step 5, granulation:

[0077] The secondary ball milled material obtained in step 4 is granulated with 12wt% of polyvinyl alcohol (PVA) by weight percentage, sieved, and the granulated material with a mesh size of 80-200 is taken;

[0078] Step 6, molding:

[0079] The granulated material obtained in step 5 is placed in a mold for compression molding with a compression pressure of 200MPa;

[0080] Step 7, sintering:

[0081] The green body obtained in step 6 is placed in a sintering furnace for sintering using a multi-step sintering method, and progressive holding is performed in the high temperature zone to obtain the garnet ferrite; wherein the process of the multi-step sintering method is as follows: the sintering temperature of the first process is 400-500℃, and the holding time is 1h; the sintering temperature of the second process is 850℃, and the holding time is 2h; the third process is three-stage progressive holding at 950-1000℃, specifically, holding at 950℃ for 6-10h, then increasing the temperature to 970℃ for 6-10h, and finally increasing the temperature to 990℃ for 6-10h, and finally decreasing the temperature to 600℃ at a rate of 2℃ / min and cooling with the furnace.

[0082] Example 4

[0083] A preparation method of a high-intermediate low-loss garnet ferrite with high bismuth substitution, specifically comprising the following steps:

[0084] Step 1, batching:

[0085] Analytically pure Bi2O3, CaCO3, La2O3, Nd2O3, Y2O3, ZrO2, In2O3, SnO2, V2O5, and Fe2O3 are used as raw materials, and the chemical formula Bi a Ca b La c Nd d Y 3-a-b-c-d Zr e In f Sn g V h Fe 5-e-f-g-h-δ O 12stoichiometric ratio calculation and weighing of raw materials; wherein a = 1.5, b = 0.5, c = 0.1, d = 0.1, e = 0.3, f = 0.1, g = 0.1, h = 0.05, δ = 0.15, δ is the amount of iron deficiency;

[0086] Step 2, primary ball milling:

[0087] The powder weighed in step 1 is ball milled with zirconia balls and deionized water in a planetary ball mill. The ball mill tank is made of stainless steel to reduce the wear of Fe into the material during ball milling. The mass ratio of zirconia balls: raw materials: deionized water is 4:1:1.5. The ball milling time is 8h. After ball milling, the material is dried and sieved through an 80 mesh sieve, and then loaded into a special corundum crucible.

[0088] Step 3, pre-sintering:

[0089] The corundum crucible containing the powder obtained in step 2 is placed in a box furnace in an air atmosphere for pre-sintering. The pre-sintering temperature is 850℃, and the holding time is 2h. After pre-sintering, the material is crushed and sieved.

[0090] Step 4, secondary ball milling:

[0091] 0.04wt% H3BO3 and 0.04wt% Bi2O3 are added to the pre-sintered material obtained in step 3 as additives. After mixing, secondary ball milling is carried out in a planetary ball mill. The mass ratio of balls: material: water is 4:1:1.5. The ball milling time is 6h. The material is dried and sieved through an 80 mesh sieve.

[0092] Step 5, granulation:

[0093] The secondary ball milled material obtained in step 4 is granulated with 12wt% polyvinyl alcohol (PVA) by weight percentage. The granulated material is sieved, and the granulated material with a size of 80-200 mesh is taken.

[0094] Step 6, shaping:

[0095] The granulated material obtained in step 5 is placed in a mold for compression molding. The compression pressure is 200MPa.

[0096] Step 7, sintering:

[0097] The green compact of step 6 is placed in a sintering furnace to be sintered by a multi-step sintering method, and is progressively kept at high temperature zone to obtain the garnet ferrite; wherein the process of the multi-step sintering method is as follows: the sintering temperature of the first step is 400-500℃, and the keeping time is 2h; the sintering temperature of the second step is 840℃, and the keeping time is 2h; the third step is three-stage progressive keeping at 930-950℃, specifically, keeping at 930℃ for 6-10h, then increasing the temperature to 940℃ for 6-10h, and finally increasing the temperature to 950℃ for 6-10h, and finally decreasing the temperature to 600℃ at a rate of 2℃ / min, and then cooling with the furnace.

[0098] The properties of the garnet ferrite obtained in examples 1-4 are shown in the following table:

[0099]

Claims

1. A method for preparing high dielectric low loss garnet ferrite with high Bi substitution, characterized in that, The method comprises the following steps: Step 1, batching: Bi2O3, CaCO3, La2O3, Nd2O3, Y2O3, ZrO2, In2O3, SnO2, V2O5, Fe2O3 as raw materials, according to the chemical formula Bi a Ca b La c Nd d Y 3-a-b-c-d Zr e In f Sn g V h Fe 5-e-f-g-h-δ O 12 The raw materials are calculated and weighed; wherein, 1.4≤a, 0 Step 2, primary ball milling: The powder weighed in step 1 is subjected to primary ball milling for 5-8 hours, and then is dried and sieved after the ball milling; Step 3, pre-sintering: The primary ball milled material obtained in step 2 is pre-sintered at 810-850℃ for 1-5 hours, and then is crushed and sieved after the pre-sintering; Step 4, secondary ball milling: 0.01-0.05wt% of H3BO3 and 0.01-0.05wt% of Bi2O3 are added to the pre-sintered material obtained in step 3 as additives, and then the mixture is subjected to secondary ball milling for 6-8 hours, and then is dried and sieved; Step 5, granulation: Polyvinyl alcohol is added to the secondary ball milled material obtained in step 4 for granulation, and then is sieved, and the granulated material with a mesh size of 80-200 is taken; Step 6, molding: The granulated material obtained in step 5 is subjected to compression molding at a compression pressure of 150-200MPa; Step 7, sintering: The green compact obtained in step 6 is placed in a sintering furnace and sintered by a multi-step sintering method to obtain the garnet ferrite; wherein the process of the multi-step sintering method is as follows: the sintering temperature of the first step is 400-500℃, and the holding time is 1-5 hours; the sintering temperature of the second step is 820-900℃, and the holding time is 1-5 hours; the third step is three-stage progressive holding at 930-1000℃, and the total holding time is 20-40 hours.

2. The method of claim 1, wherein the high Bi-substituted high dielectric low loss garnet ferrite is characterized by, In step 7, the third step is holding at 930℃ for 6-10 hours, then heating to 940℃ for 6-10 hours, and finally heating to 950℃ for 6-10 hours, and then cooling to 600℃ at a rate of 2℃ / min and cooling with the furnace.

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