Fluoride microwave dielectric ceramic material and preparation method thereof

Abstract

The application discloses a preparation method of a fluoride microwave dielectric ceramic material. NaF powder, NaCl powder and deionized water are heated and stirred, the stirred and dried powder is mixed with MgF2 powder through wet ball milling, drying and molding to obtain a ceramic body, and finally sintering at 600-750 DEG C obtains the fluoride microwave dielectric ceramic material. The application further discloses the fluoride microwave dielectric ceramic material prepared by the preparation method of the fluoride microwave dielectric ceramic material, and the main phase of the fluoride microwave dielectric ceramic material is NaF. The fluoride microwave dielectric ceramic material prepared by the application has the advantages of simple process, low preparation energy consumption, excellent material performance and suitability for being used as a key basic material of a microwave device for LTCC.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials technology, and in particular to a fluoride microwave dielectric ceramic material and its preparation method. Background Technology

[0002] With the ever-increasing demand for information and communication, 5G communication frequency bands are gradually expanding into the millimeter-wave domain, which places higher demands on electronic components in 5G communication. As key components of 5G communication microwave devices (such as resonators, filters, and antennas), the development of microwave dielectric ceramics with low dielectric constant, high quality factor, and near-zero temperature coefficient of resonant frequency can meet the needs of wireless communication development.

[0003] Current research on microwave dielectric materials mainly focuses on oxides, including silicates, germanates, borates, aluminates, and phosphates. Researchers have discovered... The ion polarizability is higher than Due to their low ionic polarizability, fluoride microwave dielectric ceramics have been extensively studied as ultra-low dielectric constant systems. Existing techniques have prepared several fluoride ceramics using the standard solid-state method. While the standard solid-state method is simple, it requires high sintering temperatures, and the low surface energy of fluoride ceramics makes the preparation of dense fluoride ceramics using this method challenging. Although high-density fluoride ceramics can be obtained using cold sintering, the preparation process is complex. Therefore, achieving low dielectric constant, low sintering temperature, and high density in ceramic materials based on traditional solid-state methods is a key technical challenge for the application of fluoride microwave dielectric ceramics in LTCC microwave devices. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, the present invention aims to provide a fluoride microwave dielectric ceramic material and its preparation method, thereby achieving low dielectric constant, low sintering temperature, and high density in the fluoride microwave dielectric ceramic material.

[0005] The technical solution of this invention is: a method for preparing a fluoride microwave dielectric ceramic material, comprising the following steps:

[0006] Step S1: NaF, NaCl and deionized water are magnetically stirred under heating conditions, and then dried into powder after stirring.

[0007] Step S2: The powder obtained in step S1 is wet ball-milled with MgF2, and then dried into powder after ball milling.

[0008] Step S3: After preparing the powder obtained in step S2 into a blank, sinter it at 600-750℃ to obtain fluoride microwave dielectric ceramic material.

[0009] Furthermore, the NaF and NaCl used in step S1 and the MgF2 used in step S2, by percentage of their total mass, are as follows: NaF accounts for 98% to 99%, NaCl accounts for 0.7% to 1.5%, and MgF2 accounts for 0.3% to 0.5%.

[0010] Furthermore, the purity of NaF is 99.9%, and NaCl and MgF2 are of analytical grade.

[0011] Furthermore, the heating conditions in step S1 are: a temperature of 40–60°C, a stirring speed of 300–400 r / min during magnetic stirring, and a stirring time of 30–60 min.

[0012] Furthermore, the wet ball milling parameters in step S2 are: ball milling time of 4 to 6 hours and rotation speed of 200 to 250 r / min.

[0013] Furthermore, the drying parameters in steps S1 and S2 are: drying temperature of 70-90℃ and drying time of 12-24h.

[0014] Furthermore, in step S3, the high-temperature sintering process involves heating to 600-750°C at a rate of 3-5°C / min, holding for 2-4 hours, and then cooling with the furnace.

[0015] Another technical solution of the present invention is: a fluoride microwave dielectric ceramic material, which is prepared by the aforementioned method for preparing fluoride microwave dielectric ceramic materials, wherein the main phase of the fluoride microwave dielectric ceramic material is NaF.

[0016] Furthermore, the relative permittivity of the fluoride microwave dielectric ceramic material is 4.67–5.25, the quality factor is 61368–76846 GHz, and the temperature coefficient of the resonant frequency is -61 to -76 ppm / ℃.

[0017] The advantages of this invention compared to the prior art are:

[0018] 1. The use of NaCl and MgF2 as composite additives not only improves the material's quality factor but also improves the material's temperature coefficient of resonant frequency.

[0019] 2. The matrix NaF and the additive NaCl were premixed in an aqueous system and sintered at high temperature to obtain a ceramic material with a building block-like particle morphology, which greatly improved the sintering density of the ceramic block and thus improved the quality factor of the material. Attached Figure Description

[0020] Figure 1 The image shows the XRD pattern of the fluoride microwave dielectric ceramic material prepared in Example 3 of this invention.

[0021] Figure 2 This is a SEM image of the fluoride microwave dielectric ceramic material prepared in Example 3 of the present invention.

[0022] Figure 3 This is a SEM image of the ceramic material prepared in Comparative Example 4. Detailed Implementation

[0023] The present invention will be further described below with reference to embodiments, but these are not intended to limit the scope of the invention.

[0024] Example 1

[0025] Weigh 39.2g of NaF powder, 0.60g of NaCl powder, and 59.70g of deionized water, and add each to a 250ml beaker. Place the beaker on a magnetic stirrer and heat and stir at 300 rpm at 40°C for 30 minutes. After stirring, place the beaker in a 70°C oven to dry for 12 hours. Mix the dried powder with 0.2g of MgF2 powder and then perform wet ball milling for 4 hours at 200 rpm. After drying and pressing the wet-milled powder, sinter it in a high-temperature muffle furnace. The temperature is increased to 600°C at a rate of 3°C / min and held for 2 hours. After holding, cool with the furnace to obtain the fluoride microwave dielectric ceramic material described in this invention.

[0026] Example 2

[0027] Weigh 39.28g of NaF powder, 0.56g of NaCl powder, and 63.74g of deionized water, and add them separately to 250ml beakers. Place the beakers on a magnetic stirrer and heat and stir at 350r / min at 45℃ for 45min. After stirring, place the beakers in a 75℃ oven to dry for 14h. Mix the dried powder with 0.16g of MgF2 powder and then wet ball mill for 5h at 225r / min. After drying and pressing the wet ball-milled powder, sinter it in a high-temperature muffle furnace. The temperature is increased to 650℃ at a rate of 4℃ / min and held for 3h. After holding, cool with the furnace to obtain the fluoride microwave dielectric ceramic material of this invention.

[0028] Example 3

[0029] Weigh 39.36g of NaF powder, 0.52g of NaCl powder, and 67.80g of deionized water, and add each to a 250ml beaker. Place the beaker on a magnetic stirrer and heat and stir at 400 rpm at 50°C for 60 minutes. After stirring, place the beaker in an oven at 80°C for 16 hours to dry. Mix the dried powder with 0.12g of MgF2 powder and then wet ball mill for 6 hours at 250 rpm. After drying and pressing the wet-ball-milled powder, sinter it in a high-temperature muffle furnace. The temperature is increased to 700°C at a rate of 5°C / min and held for 4 hours. After holding, cool with the furnace to obtain the fluoride microwave dielectric ceramic material of this invention.

[0030] Example 4

[0031] Weigh 39.44g of NaF powder, 0.40g of NaCl powder, and 71.71g of deionized water, and add them separately to 250ml beakers. Place the beakers on a magnetic stirrer and heat and stir at 350r / min at 55℃ for 45min. After stirring, place the beakers in an oven at 85℃ for 18h to dry. Mix the dried powder with 0.16g of MgF2 powder and then wet ball mill for 5h at 200r / min. After wet ball milling, dry and press the powder into a compact, then sinter it in a high-temperature muffle furnace. The temperature is increased to 750℃ at a rate of 4℃ / min and held for 2h. After holding, cool with the furnace to obtain the fluoride microwave dielectric ceramic material of this invention.

[0032] Example 5

[0033] Weigh 39.52g of NaF powder, 0.36g of NaCl powder, and 75.77g of deionized water, and add each to a 250ml beaker. Place the beaker on a magnetic stirrer and heat and stir at 300 rpm at 60°C for 30 minutes. After stirring, place the beaker in a 90°C oven to dry for 20 hours. Mix the dried powder with 0.12g of MgF2 powder and then wet ball mill for 4 hours at 250 rpm. After drying and pressing the wet-ball-milled powder, sinter it in a high-temperature muffle furnace. The temperature is increased to 700°C at a rate of 3°C / min and held for 3 hours. After holding, cool with the furnace to obtain the fluoride microwave dielectric ceramic material of this invention.

[0034] Example 6

[0035] Weigh 39.6g of NaF powder, 0.28g of NaCl powder, and 79.76g of deionized water, and add each to a 250ml beaker. Place the beaker on a magnetic stirrer and heat and stir at 350 rpm at 55°C for 45 minutes. After stirring, place the beaker in a 75°C oven to dry for 24 hours. Mix the dried powder with 0.12g of MgF2 powder and then wet ball mill for 6 hours at 200 rpm. After drying and pressing the wet-ball-milled powder, sinter it in a high-temperature muffle furnace. The temperature is increased to 600°C at a rate of 4°C / min and held for 4 hours. After holding, cool with the furnace to obtain the fluoride microwave dielectric ceramic material of this invention.

[0036] Comparative Example 1

[0037] Weigh 39.36g of NaF powder and 67.80g of deionized water, and add them separately to 250ml beakers. Place the beakers on a magnetic stirrer and heat and stir at 400 rpm at 50℃ for 60 min. After stirring, place the beakers in an oven at 80℃ to dry. Perform wet ball milling on the dried powder for 6 hours at 250 rpm. After drying and pressing the wet-milled powder, sinter it in a high-temperature muffle furnace. Increase the temperature to 700℃ at a rate of 5℃ / min and hold for 4 hours. After holding, cool with the furnace to obtain the fluoride microwave dielectric ceramic material of this invention.

[0038] Comparative Example 2

[0039] Weigh 39.36g of NaF powder, 0.52g of NaCl powder, and 67.80g of deionized water, and add each to a 250ml beaker. Place the beaker on a magnetic stirrer and heat and stir at 400 rpm at 50°C for 60 minutes. After stirring, place the beaker in an oven at 80°C to dry. Perform wet ball milling on the dried powder for 6 hours at 250 rpm. After drying and pressing the wet-milled powder, sinter it in a high-temperature muffle furnace. The temperature is increased to 700°C at a rate of 5°C / min and held for 4 hours. After holding, cool with the furnace to obtain the fluoride microwave dielectric ceramic material described in this invention.

[0040] Comparative Example 3

[0041] Weigh 39.36g of NaF powder and 67.80g of deionized water, and add them separately to 250ml beakers. Place the beakers on a magnetic stirrer and heat and stir at 50℃ for 60min at 400r / min. After stirring, place the beakers in an oven at 80℃ to dry. Mix the dried powder with 0.12g of MgF2 powder and then perform wet ball milling for 6h at 250r / min. After drying and pressing the wet-milled powder, sinter it in a high-temperature muffle furnace, heating it to 700℃ at a rate of 5℃ / min and holding it for 4h. After holding, cool it with the furnace to obtain the fluoride microwave dielectric ceramic material of this invention.

[0042] Comparative Example 4

[0043] 39.36 g of NaF powder, 0.52 g of NaCl powder, and 0.12 g of MgF2 powder were weighed, mixed, and then wet-milled for 6 hours at a speed of 250 r / min. The wet-milled powder was dried, pressed into a compact, and sintered in a high-temperature muffle furnace. The temperature was increased to 700°C at a rate of 5°C / min and held for 4 hours. After holding, the mixture was cooled in the furnace to obtain the fluoride microwave dielectric ceramic material described in this invention.

[0044] The material properties obtained from each embodiment and comparative example are as follows:

[0045]

[0046]

[0047] In this invention, Examples 1-6 describe the microwave dielectric properties of fluoride ceramic materials. Among them, the ceramic sample prepared in Example 3 has the highest quality factor and the best temperature coefficient of resonant frequency. The phase composition is shown in the attached figure. Figure 1 As shown, the main phase is NaF, and no second phase is formed. Based on Example 3, Comparative Example 1 synthesized a ceramic sample without any additives, Comparative Example 2 synthesized a ceramic sample with only NaCl added, Comparative Example 3 synthesized a ceramic sample with only MgF2 added, and Comparative Example 4 did not use a preheating and stirring process, but directly mixed and sintered multiple powders. Figure 2 The image shown is a SEM image of the cross-section of the ceramic sample from Example 3. Figure 3 The SEM images of the cross-section of the ceramic sample in Comparative Example 4 are shown. Comparison between the two images demonstrates that heating and premixing the matrix NaF and additive NaCl in an aqueous system can form a building block-like ceramic particle morphology, promoting the sintering density of the ceramic material. The table shows that the introduction of the composite additive and the preheating and stirring process can both significantly increase the quality factor and improve the temperature coefficient of the resonant frequency.

Claims

1. A method for preparing a fluoride microwave dielectric ceramic material, characterized in that, Includes the following steps: Step S1: NaF, NaCl and deionized water are magnetically stirred under heating conditions, and then dried into powder after stirring. Step S2: The powder obtained in step S1 is wet ball-milled with MgF2, and then dried into powder after ball milling. Step S3: After preparing the powder obtained in step S2 into a blank, sinter it at 600-750℃ to obtain a fluoride microwave dielectric ceramic material. The NaF, NaCl, and MgF2 used in step S1 and step S2 are respectively, by mass percentage, NaF accounts for 98%-99%, NaCl accounts for 0.7%-1.5%, and MgF2 accounts for 0.3%-0.5%.

2. The method for preparing fluoride microwave dielectric ceramic material according to claim 1, characterized in that, The purity of NaF is 99.9%, and NaCl and MgF2 are of analytical grade.

3. The method for preparing fluoride microwave dielectric ceramic material according to claim 1, characterized in that, The heating conditions in step S1 are: temperature of 40-60℃, stirring speed of 300-400 r / min and stirring time of 30-60 min when using magnetic stirring.

4. The method for preparing fluoride microwave dielectric ceramic material according to claim 1, characterized in that, The wet ball milling parameters for step S2 are: ball milling time of 4-6 hours and rotation speed of 200-250 r / min.

5. The method for preparing fluoride microwave dielectric ceramic material according to claim 1, characterized in that, The drying parameters in steps S1 and S2 are: drying temperature of 70-90℃ and drying time of 12-24h.

6. The method for preparing fluoride microwave dielectric ceramic material according to claim 1, characterized in that, In step S3, the sintering process involves heating the temperature at 3-5°C / min to 600-750°C, holding it at that temperature for 2-4 hours, and then cooling it in the furnace.

7. A fluoride microwave dielectric ceramic material, characterized in that, The fluoride microwave dielectric ceramic material is prepared by any one of claims 1 to 6, wherein the main phase of the fluoride microwave dielectric ceramic material is NaF.

8. The fluoride microwave dielectric ceramic material according to claim 7, characterized in that, The relative permittivity of the fluoride microwave dielectric ceramic material is 4.67–5.25, the quality factor is 61368–76846 GHz, and the temperature coefficient of the resonant frequency is -61 to -76 ppm / ℃.

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