A YIG ferrite with high saturation magnetic induction and a preparation method and application thereof

Abstract

This invention discloses a YIG ferrite with high saturation magnetic induction intensity, its preparation method, and its applications, belonging to the field of ferrite material technology. The method for preparing the YIG ferrite with high saturation magnetic induction intensity includes the following steps: plasma-assisted ball milling of oxide mixed powders, drying, obtaining pretreated powder, sieving, pre-sintering treatment, plasma-assisted ball milling, drying, obtaining powder, mixing with polyvinyl alcohol aqueous solution, pressing and molding to obtain ferrite green body, sintering treatment, and obtaining YIG ferrite. This invention, through plasma-assisted ball milling combined with lowering the sintering temperature, reduces the optimal phase formation temperature of YIG ferrite. By altering the physical state of iron ions and stimulating chemical reactions through discharge to enhance their activity, a YIG ferrite with high dielectric constant and high saturation magnetic induction intensity is prepared.

Description

Technical Field

[0001] This invention belongs to the field of ferrite material technology, and particularly relates to a YIG ferrite with high saturation magnetic induction intensity, its preparation method and application. Background Technology

[0002] With the continuous development of wireless communication and network technologies, wireless communication technology has rapidly entered people's daily lives. The application of wireless networks, the Internet of Things (IoT), and many other wireless communication technologies has ushered in the 5G era. Microwave communication devices are used to process and transmit microwave frequency signals and are widely used in electronic equipment in various fields such as radar, communication, navigation, electronic countermeasures, satellite communication, broadcasting, and microwave heating. Circulators and isolators are common electronic devices in microwave and radio frequency technologies, and the magnetic materials used in them are usually ferrites. Garnet ferrite has poor electron mobility, resulting in relatively high permeability and magnetic saturation induction, low conductivity and loss, and good oxidation resistance and magnetic stability. Furthermore, it contains three oxygen polyhedra; by substituting the cations in the oxygen polyhedra, their saturation magnetization, temperature stability, dielectric loss, coercivity, and other properties can be appropriately adjusted to meet the needs of various applications.

[0003] Currently, the demand for non-electronic systems such as radar, base stations, and mobile phones is increasing dramatically, driving the development and application of related components and placing higher demands on ferrite materials. Firstly, an ideal ferrite material should possess sufficient saturation magnetization to ensure it can withstand the required magnetic field strength in a circulator, thereby achieving good magnetic properties. Higher saturation magnetization typically means the material can saturate under relatively weak magnetic fields, which helps improve the magnetic properties and efficiency of the circulator. Furthermore, exploring new synthesis methods is also crucial for improving the microstructure fabrication, surface activity regulation, and particle refinement of the material. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a YIG ferrite with high saturation magnetic induction intensity, its preparation method, and its application. By utilizing plasma-assisted ball milling and lowering the sintering temperature, YIG (garnet) ferrite with small grains and high saturation magnetic induction intensity is prepared.

[0005] To achieve the above objectives, the present invention provides a method for preparing YIG ferrite with high saturation magnetic induction, comprising the following steps:

[0006] S1, oxide mixed powder is first plasma-assisted ball milled and first dried to obtain pretreated powder;

[0007] The pretreated powder described in S2 and S1 is sieved, pre-sintered, secondly plasma-assisted ball milled, and secondly dried to obtain powder.

[0008] S3. The powder described in step S2 is mixed with a polyvinyl alcohol aqueous solution and pressed into shape to obtain a ferrite green body.

[0009] S4. The ferrite green body sintering treatment described in step S3 yields YIG ferrite.

[0010] Preferably, the proportion of the oxide mixed powder in step S1 is according to the chemical formula Y 2.7 Ca 0.3 Fe 4.5- x Sn 0.15 Zr 0.15 In 0.2 O 12-1.5x The calculation is performed, where x is the amount of iron deficiency, 0≤x≤1, and the purity of the oxide mixed powder is ≥99%.

[0011] Preferably, in step S1, the first plasma-assisted ball mill uses stainless steel balls as the grinding medium and deionized water as the dispersant. The mass ratio of the oxide mixed powder, stainless steel balls and deionized water in the first plasma-assisted ball mill is 1:(4-6):(4-6). The rotation speed of the first plasma-assisted ball mill is 800-950 rad / min, and the effective time of the first plasma-assisted ball mill is 6-9 h.

[0012] Preferably, in step S1, the effective time of the first plasma ball milling is the time for ball milling. The program of the first plasma ball milling is to mill for 30 minutes, pause for 10 minutes, and cycle 12 times. The raw material oxide powder is mixed evenly through the first plasma ball milling so that the solid phase reaction is complete during pre-sintering.

[0013] More preferably, the mass ratio of the large, medium, and small balls in the stainless steel ball is 2:5:3, the diameter of the ball is 8mm, the diameter of the medium ball is 5mm, and the diameter of the small ball is 3mm.

[0014] Preferably, in step S1, the temperature of the first drying is 80-100°C, and the drying time is 10-12 hours.

[0015] Preferably, the sieve aperture in step S2 is 20-40 mesh; the pre-sintering temperature in step S2 is 1150-1300℃, and the pre-sintering time is 2-3 hours. This high-temperature treatment causes a preliminary chemical reaction in the pre-treated powder after sieving, with a portion transforming into ferrite, ensuring better microstructure of the sintered sample, increasing sintering density, and reducing product shrinkage. In step S2, the second plasma-assisted ball mill uses stainless steel balls as the grinding medium and deionized water as the dispersant. The mass ratio of the pre-treated powder, stainless steel balls, and deionized water in the second plasma-assisted ball mill is 1:(4-6):(4-6). The rotation speed of the second plasma-assisted ball mill is 800-950 rad / min, and the effective time is 6-9 hours. In step S2, the second drying temperature is 80-100℃, and the second drying time is 10-12 hours.

[0016] Preferably, in step S2, the effective time of the second plasma ball milling is the time for ball milling, and the program of the second plasma ball milling is ball milling for 30 minutes, pausing for 10 minutes, and repeating 12 times.

[0017] Preferably, the mixing mass ratio of the powder to the polyvinyl alcohol aqueous solution in step S3 is 1:(0.1-0.15); the concentration of the polyvinyl alcohol aqueous solution in step S3 is 5-7 wt%; the pressing pressure in step S3 is 15-20 MPa; and the pressing time is 2-4 min.

[0018] Preferably, the sintering temperature in step S4 is 1350–1480°C, and the sintering time is 3–5 hours.

[0019] The present invention also provides YIG ferrite prepared by the aforementioned preparation method.

[0020] The present invention also provides the YIG ferrite prepared by the preparation method or the application of the YIG ferrite in the preparation of microwave and / or radio frequency electronic components.

[0021] Compared with the prior art, the present invention has the following advantages and technical effects:

[0022] This invention uses oxide mixed powder as raw material, and through plasma-assisted ball milling, combined with lowering the sintering temperature, the optimal phase formation temperature of YIG ferrite is reduced. After the first and second plasma-assisted ball milling, the ferrite powder has a small particle size and the grain size in the microstructure is significantly reduced. By changing the physical state of iron ions and stimulating chemical reactions through discharge, its activity is improved, and YIG ferrite with high dielectric constant and high saturation magnetic induction intensity is prepared. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 X-ray diffraction patterns of the YIG ferrite prepared in Example 1 and the YIG ferrite prepared in Comparative Example 1;

[0025] Figure 2 Hysteresis loop diagrams of the YIG ferrite prepared in Example 1 and the YIG ferrite prepared in Comparative Example 1.

[0026] Figure 3 The image shows a scanning electron microscope image of the YIG ferrite prepared in Example 1, with a scale bar of 15 μm.

[0027] Figure 4 The image shows a scanning electron microscope image of the YIG ferrite prepared in Comparative Example 1, with a scale bar of 15 μm.

[0028] Figure 5 The particle size distributions of YIG ferrite prepared in Example 1 after first and second plasma-assisted ball milling are shown in Figure 1. In Figure 1, A is the particle size distribution after first plasma-assisted ball milling, and B is the particle size distribution after second plasma-assisted ball milling.

[0029] Figure 6 The particle size distributions of YIG ferrite prepared in Comparative Example 1 after first and second plasma-assisted ball milling are shown in Figure 1. In Figure 1, A is the particle size distribution after first plasma-assisted ball milling, and B is the particle size distribution after second plasma-assisted ball milling.

[0030] Figure 7 Dielectric constant diagrams of the YIG ferrite prepared in Example 1 and the YIG ferrite prepared in Comparative Example 1. Detailed Implementation

[0031] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0032] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0033] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0034] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0035] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0036] Y2O3 powder was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., CaCO3 powder from Tianjin Aubokai Chemical Co., Ltd., SnO2 powder from Shanghai Aladdin Biochemical Technology Co., Ltd., ZrO2 powder from Tianjin Xiens Biochemical Technology Co., Ltd., In2O3 powder from Shanghai Maclean Biochemical Technology Co., Ltd., Fe2O3 powder from Tianjin Aubokai Chemical Co., Ltd., plasma ball mill (model PBM200) from Guangzhou Huagong Optoelectronic Technology Co., Ltd., polyvinyl alcohol from Sinopharm Chemical Reagent Co., Ltd., and hydraulic sample preparation machine (model SDJ) from Xiangtan Instrument Co., Ltd.

[0037] Example 1

[0038] S1, Oxide Mixed Powder (mixing ratio according to chemical formula Y) 2.7 Ca 0.3 Fe 4.3 Sn 0.15 Zr 0.15 In 0.2 O 11.7Calculate and weigh out the following powders (Y2O3 powder, CaCO3 powder, SnO2 powder, ZrO2 powder, In2O3 powder, and Fe2O3 powder) according to the specified proportions. Load them into a plasma ball mill, using stainless steel balls as the grinding medium and deionized water as the dispersant. Perform a first plasma-assisted ball milling at a speed of 895 rad / min for 6 hours. The ball milling mode is cyclic discharge with a discharge frequency of 30.5 kHz and a discharge power of 15 W. Mix the oxide mixed powder, stainless steel balls (large, medium, and small balls with diameters of 8 mm, 5 mm, and 3 mm respectively, and a mass ratio of 2:5:3 for large, medium, and small balls), and deionized water at a mass ratio of 1:5:4. The ball milling program is: ball milling for 30 minutes, pause for 10 minutes, cycle 12 times, and then dry at 100℃ for 10 hours to obtain the pretreated powder.

[0039] S2. The pretreated powder is passed through a 30-mesh sieve and pre-sintered in a muffle furnace at 1200℃ for 3 hours. Using stainless steel balls as the grinding medium and deionized water as the dispersant, a second plasma-assisted ball milling is performed at a speed of 895 rad / min for 6 hours. The ball milling mode is cyclic discharge with a discharge frequency of 30.5 kHz and a discharge power of 15 W. The pretreated powder after sieving, stainless steel balls (large, medium and small balls with diameters of 8 mm, 5 mm and 3 mm respectively, and a mass ratio of large, medium and small balls of 2:5:3) and deionized water are mixed at a mass ratio of 1:5:4. The ball milling program is 30 min, pause for 10 min, cycle 12 times, and then dry at 100℃ for 10 hours to obtain the powder.

[0040] S3. The powder and a 5wt% polyvinyl alcohol aqueous solution are mixed at a mass ratio of 1:0.12. The 5wt% polyvinyl alcohol aqueous solution is added dropwise while being manually ground. Then, the powder is passed through a 40-mesh sieve. 6.5g of the sieved powder is weighed and pressed into shape for 3 minutes under a pressure of 18MPa using a hydraulic sample making machine to obtain a ferrite green body.

[0041] S4. The ferrite green blank is placed in a muffle furnace for sintering treatment. The procedure is as follows: 20℃, 1h to 150℃, hold for 1h to drain, 2h to 550℃, hold for 1h to remove the binder, sinter at 1400℃ for 3h, hold for 4h, then 3h to 500℃ and cool naturally to obtain YIG ferrite.

[0042] Example 2

[0043] S1, Oxide Mixed Powder (mixing ratio according to chemical formula Y) 2.7 Ca 0.3 Fe 4.3 Sn 0.15 Zr 0.15 In 0.2 O 11.7Calculate and weigh out the following powders (Y2O3 powder, CaCO3 powder, SnO2 powder, ZrO2 powder, In2O3 powder, and Fe2O3 powder) according to the specified proportions. Load them into a plasma ball mill, using stainless steel balls as the grinding medium and deionized water as the dispersant. Perform a first plasma-assisted ball milling at a speed of 800 rad / min for 6 hours. The ball milling mode is cyclic discharge with a discharge frequency of 30.5 kHz and a discharge power of 15 W. Mix the oxide mixed powder, stainless steel balls (large, medium, and small balls with diameters of 8 mm, 5 mm, and 3 mm respectively, and a mass ratio of 2:5:3 for large, medium, and small balls), and deionized water at a mass ratio of 1:4:5. The ball milling program is: ball milling for 30 minutes, pause for 10 minutes, cycle 12 times, and then dry at 80℃ for 12 hours to obtain the pretreated powder.

[0044] S2. The pretreated powder is passed through a 20-mesh sieve and pre-sintered in a muffle furnace at 1150℃ for 3 hours. Using stainless steel balls as the grinding medium and deionized water as the dispersant, a second plasma-assisted ball milling is performed at a speed of 800 rad / min for 6 hours. The ball milling mode is cyclic discharge with a discharge frequency of 30.5 kHz and a discharge power of 15 W. The pretreated powder after sieving, stainless steel balls (large, medium and small balls with diameters of 8 mm, 5 mm and 3 mm respectively, and a mass ratio of large, medium and small balls of 2:5:3) and deionized water are mixed at a mass ratio of 1:6:6. The ball milling program is 30 min, pause for 10 min, cycle 12 times, and then dry at 80℃ for 12 hours to obtain the powder.

[0045] S3. The powder and a 6wt% polyvinyl alcohol aqueous solution are mixed at a mass ratio of 1:0.1. The 6wt% polyvinyl alcohol aqueous solution is added dropwise while being manually ground. Then, the powder is passed through a 40-mesh sieve. 6.5g of the sieved powder is weighed and pressed into shape for 4 minutes under a pressure of 15MPa using a hydraulic sample making machine to obtain a ferrite green body.

[0046] S4. The ferrite green blank is placed in a muffle furnace for sintering treatment. The procedure is as follows: 20℃, 1h to 150℃, hold for 1h to drain, 2h to 550℃, hold for 1h to remove the binder, sinter at 1350℃ for 5h, hold for 4h, then 3h to 500℃ and cool naturally to obtain YIG ferrite.

[0047] Example 3

[0048] S1, Oxide Mixed Powder (mixing ratio according to chemical formula Y) 2.7 Ca 0.3 Fe 4.3 Sn 0.15 Zr 0.15 In 0.2 O 11.7Calculate and weigh out the following powders (Y2O3 powder, CaCO3 powder, SnO2 powder, ZrO2 powder, In2O3 powder, and Fe2O3 powder) according to the specified proportions. Load them into a plasma ball mill, using stainless steel balls as the grinding medium and deionized water as the dispersant. Perform a first plasma-assisted ball milling at a speed of 950 rad / min for 6 hours. The ball milling mode is cyclic discharge with a discharge frequency of 30.5 kHz and a discharge power of 15 W. Mix the oxide mixed powder, stainless steel balls (large, medium, and small balls with diameters of 8 mm, 5 mm, and 3 mm respectively, and a mass ratio of 2:5:3 for large, medium, and small balls), and deionized water at a mass ratio of 1:5:5. The ball milling program is: ball milling for 30 minutes, pause for 10 minutes, cycle 12 times, and then dry at 90℃ for 11 hours to obtain the pretreated powder.

[0049] S2. The pretreated powder is passed through a 40-mesh sieve and pre-sintered in a muffle furnace at 1300℃ for 2 hours. Using stainless steel balls as the grinding medium and deionized water as the dispersant, a second plasma-assisted ball milling is performed at a speed of 950 rad / min for 6 hours. The ball milling mode is cyclic discharge with a discharge frequency of 30.5 kHz and a discharge power of 15 W. The pretreated powder after sieving, stainless steel balls (large, medium and small balls with diameters of 8 mm, 5 mm and 3 mm respectively, and a mass ratio of large, medium and small balls of 2:5:3) and deionized water are mixed at a mass ratio of 1:5:6. The ball milling program is 30 min, pause for 10 min, cycle 12 times, and then dry at 90℃ for 11 hours to obtain the powder.

[0050] S3. The powder and a 7wt% polyvinyl alcohol aqueous solution are mixed at a mass ratio of 1:0.15. The 7wt% polyvinyl alcohol aqueous solution is added dropwise while being manually ground. Then, the mixture is passed through a 40-mesh sieve. 6.5g of the sieved powder is weighed and pressed into shape for 2 minutes under a pressure of 20MPa using a hydraulic sample making machine to obtain a ferrite green body.

[0051] S4. The ferrite green blank is placed in a muffle furnace for sintering treatment. The procedure is as follows: 20℃, 1h to 150℃, hold for 1h to drain, 2h to 550℃, hold for 1h to remove the binder, sinter at 1480℃ for 3h, hold for 4h, then 3h to 500℃ and cool naturally to obtain YIG ferrite.

[0052] Comparative Example 1

[0053] S1, Oxide Mixed Powder (mixing ratio according to chemical formula Y) 2.7 Ca 0.3 Fe 4.3 Sn 0.15 Zr 0.15 In 0.2 O 11.7Calculate and weigh out the following powders (Y2O3 powder, CaCO3 powder, SnO2 powder, ZrO2 powder, In2O3 powder, and Fe2O3 powder) according to the specified proportions. Load them into a plasma ball mill, using stainless steel balls as the grinding medium and deionized water as the dispersant. Perform a first plasma-assisted ball milling for 6 hours at a speed of 895 rad / min. The ball milling mode is cyclic vibration. Mix the oxide powder, stainless steel balls (large, medium, and small ball diameters are 8 mm, 5 mm, and 3 mm respectively, with a mass ratio of 2:5:3 for large, medium, and small balls), and deionized water at a mass ratio of 1:5:4. The ball milling program is: ball milling for 30 minutes, pause for 10 minutes, cycle 12 times, and then dry at 100℃ for 12 hours to obtain the pretreated powder.

[0054] S2. The pretreated powder is passed through a 30-mesh sieve and pre-sintered in a muffle furnace at 1250℃ for 3 hours. Then, it is subjected to a second plasma-assisted ball milling at a speed of 895 rad / min for 6 hours using stainless steel balls as the grinding medium and deionized water as the dispersant. The ball milling mode is cyclic vibration. The pretreated powder after sieving, stainless steel balls (large, medium and small balls with diameters of 8 mm, 5 mm and 3 mm respectively, and a mass ratio of large, medium and small balls of 2:5:3) and deionized water are mixed at a mass ratio of 1:5:4. The ball milling program is 30 min, pause for 10 min, cycle 12 times, and then dry at 100℃ for 12 hours to obtain the powder.

[0055] S3. The powder and a 5wt% polyvinyl alcohol aqueous solution are mixed at a mass ratio of 1:0.12. The 5wt% polyvinyl alcohol aqueous solution is added dropwise while being manually ground. Then, the powder is passed through a 40-mesh sieve. 6.5g of the sieved powder is weighed and pressed into shape for 3 minutes under a pressure of 18MPa using a hydraulic sample making machine to obtain a ferrite green body.

[0056] S4. The ferrite green blank is placed in a muffle furnace for sintering treatment. The procedure is as follows: 20℃, 1h to 150℃, hold for 1h to drain, 2h to 550℃, hold for 1h to remove the binder, sinter at 1450℃ for 3h, hold for 4h, then 3h to 500℃ and cool naturally to obtain YIG ferrite.

[0057] Experimental Example

[0058] X-ray diffraction patterns of the YIG ferrite prepared in Example 1 and the YIG ferrite prepared in Comparative Example 1 were determined. The X-ray diffraction was performed using an X-ray diffractometer (SmartLsbSE, JpanRIGAKUCORPORATION) with CuKa rays, a step size of 0.01° within 2θ, and a scanning rate of 10 (°) / min. The Xrd spectra in the 2θ range of 20° to 80° were recorded.

[0059] The hysteresis loops of the YIG ferrite prepared in Example 1 and the YIG ferrite prepared in Comparative Example 1 were measured. The test was conducted using a soft magnetic DC test system (TS4000, Tunkia Co.) with a saturated applied magnetic field strength of 1590 A / m.

[0060] Scanning electron microscope (SEM) images of the YIG ferrite prepared in Example 1 and Comparative Example 1 were obtained using a scanning electron microscope (JSM-7900F, Japan), with a voltage of 15 kV, a magnification of 8500x, and a scale bar of 15 μm.

[0061] The particle size distribution of the YIG ferrite prepared in Example 1 and the YIG ferrite prepared in Comparative Example 1 after plasma-assisted ball milling was determined. The particle size distribution was measured by a laser particle size analyzer (BT-9000ST, Dandong Better Instruments Co., Ltd.). The material selected was ferric oxide and the medium was water.

[0062] Dielectric constant diagrams of the YIG ferrite prepared in Example 1 and the YIG ferrite prepared in Comparative Example 1 were determined; the results were obtained using a vector network analyzer (VNA, ZNA43, Rohde & Schwarz GmbH, Germany) using the coaxial method.

[0063] like Figure 1 The image shows the XRD patterns of the YIG ferrite prepared in Example 1 and the YIG ferrite prepared in Comparative Example 1, compared with those of Y3Fe5O. 12 A comparison with standard PDF cards showed no extraneous peaks, indicating that all formed a single garnet phase.

[0064] like Figure 2 As shown, the hysteresis loop diagrams of the YIG ferrite prepared in Example 1 and the YIG ferrite prepared in Comparative Example 1 are shown. Through plasma-assisted ball milling, the saturation magnetic induction intensity and remanent magnetic induction intensity of the YIG ferrite prepared in Example 1 are both greater than those of the YIG ferrite prepared in Comparative Example 1, indicating better magnetic properties.

[0065] like Figure 3 As shown, this is a scanning electron microscope image of the YIG ferrite prepared in Example 1. Figure 4 The image shown is a scanning electron microscope image of the YIG ferrite prepared in Comparative Example 1. Under the same magnification and scale, the grain size of the YIG ferrite prepared in Example 1 was significantly smaller than that of Comparative Example 1 by plasma-assisted ball milling.

[0066] like Figure 5 As shown, Figure 5 In Figure A, the particle size distribution of the YIG ferrite prepared in Example 1 after a single ball milling is shown. Figure 5 In Figure B, the particle size distribution of the YIG ferrite prepared in Example 1 after secondary ball milling is shown. The powder obtained through two ball milling processes has a smaller particle size, as shown in Figure B. Figure 6 As shown, Figure 6Figure A shows the particle size distribution of the YIG ferrite prepared in Comparative Example 1 after a single ball milling process. Figure 6 Figure B shows the particle size distribution of the YIG ferrite prepared in Comparative Example 1 after secondary ball milling. Through plasma-assisted ball milling, the particle size of the YIG ferrite powder in Example 1 after each ball milling is smaller than that of the YIG ferrite in Comparative Example 1, resulting in finer powder.

[0067] like Figure 7 The figure shows the dielectric constant of the YIG ferrite prepared in Example 1 and the YIG ferrite prepared in Comparative Example 1 at 2-8 GHz. The dielectric properties of the YIG ferrite prepared in Example 1 are better than those of the YIG ferrite prepared in Comparative Example 1. The dielectric constant of YIG is about 14.5. The dielectric constant can be improved by plasma-assisted ball milling.

[0068] Table 1 Comparison of ferrite preparation data between Example 1 and Comparative Example 1

[0069] Group Components Is it single-phase? ball milling method Sintering temperature Bs(Gs) Example 1 <![CDATA[Y 2.7 Ca 0.3 Fe 4.3 Sn 0.15 Zr 0.15 In 0.2 O 11.7 ]]> yes Cyclic discharge 1400℃ 1887 Comparative Example 1 <![CDATA[Y 2.7 Ca 0.3 Fe 4.3 Sn 0.15 Zr 0.15 In 0.2 O 11.7 ]]> yes Circulatory vibration 1450℃ 1736

[0070] As shown in Table 1, the magnetic properties of the YIG ferrite obtained by plasma-assisted ball milling in Example 1 are better than those of the YIG ferrite obtained by conventional ball milling in Comparative Example 1, and the optimal sintering temperature is lower.

[0071] In summary, the preparation method of the present invention reduces the optimal phase formation temperature of garnet ferrite by plasma-assisted ball milling. After one and two millings, the ferrite powder has a small particle size and the grain size in the microstructure is significantly reduced. By changing the physical state of iron ions and stimulating chemical reactions through discharge, its activity is improved, thus preparing YIG ferrite with high dielectric constant and high saturation magnetic induction intensity.

[0072] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method of producing a YIG ferrite having a high saturation magnetic induction, characterized by, Includes the following steps: S1, oxide mixed powder is first plasma-assisted ball milled and first dried to obtain pretreated powder; The pretreated powder described in S2 and S1 is sieved, pre-sintered, secondly plasma-assisted ball milled, and secondly dried to obtain powder. S3. The powder described in step S2 is mixed with a polyvinyl alcohol aqueous solution and pressed into shape to obtain a ferrite green body. S4. The ferrite green body sintering process described in step S3 yields YIG ferrite. The proportion of the oxide mixed powder in step S1 is according to the chemical formula Y 2.7 Ca 0.3 Fe 4.5- x Sn 0.15 Zr 0.15 In 0.2 O 12-1.5x Calculate, where x is the amount of iron deficiency, 0≤x≤1, and the purity of the oxide mixed powder is ≥99%; The ball milling modes of the first and second plasma-assisted ball mills are cyclic discharge.

2. The method of claim 1, wherein, In step S1, the first plasma-assisted ball mill uses stainless steel balls as the grinding medium and deionized water as the dispersant. The mass ratio of the oxide mixed powder, stainless steel balls and deionized water in the first plasma-assisted ball mill is 1:(4~6):(4~6). The rotation speed of the first plasma-assisted ball mill is 800~950 rad / min, and the effective time of the first plasma-assisted ball mill is 6~9 h.

3. The preparation method according to claim 2, characterized in that, The mass ratio of large, medium, and small balls in the stainless steel ball is 2:5:

3.

4. The preparation method according to claim 1, characterized in that, In step S1, the temperature of the first drying is 80~100℃, and the drying time is 10~12h.

5. The method of claim 1, wherein the step of forming the first and second layers is performed by a process selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. The sieve aperture in step S2 is 20-40 mesh; the pre-sintering temperature in step S2 is 1150-1300℃, and the pre-sintering time is 2-3h; in step S2, the second plasma-assisted ball mill uses stainless steel balls as the grinding medium and deionized water as the dispersant, the mass ratio of the pretreated powder after sieving, stainless steel balls and deionized water in the second plasma-assisted ball mill is 1:(4-6):(4-6), the rotation speed of the second plasma-assisted ball mill is 800-950 rad / min, and the effective time of the second plasma-assisted ball mill is 6-9h; the second drying temperature in step S2 is 80-100℃, and the second drying time is 10-12h.

6. The preparation method according to claim 1, characterized in that, The mass ratio of the powder to the polyvinyl alcohol aqueous solution in step S3 is 1:(0.1~0.15); the concentration of the polyvinyl alcohol aqueous solution in step S3 is 5~7wt%; the pressing pressure in step S3 is 15~20MPa, and the pressing time is 2~4min.

7. The preparation method according to claim 1, characterized in that, The sintering temperature in step S4 is 1350~1480℃, and the sintering time is 3~5h.

8. YIG ferrite prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the YIG ferrite prepared by the preparation method according to any one of claims 1 to 7 or the YIG ferrite according to claim 8 in the preparation of microwave and / or radio frequency electronic components.

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