Hexaaluminate-based medium microwave dielectric ceramic material and preparation method thereof

Abstract

The invention belongs to the technical field of microwave dielectric ceramic materials, and particularly relates to a hexaaluminate-based intermediate microwave dielectric ceramic material and a preparation method thereof. The chemical expression of the hexaaluminate-based intermediate microwave dielectric ceramic material is A1-xBxTi2 + xAl9-xO19, A is La or Y, B is Sr or Ba, and x is greater than or equal to 0 and less than or equal to 1.0, the hexaaluminate-based intermediate microwave dielectric ceramic material has a high quality factor and a resonant frequency temperature coefficient close to zero, is suitable for preparing communication devices such as resonators and dielectric filters, can effectively broaden the use temperature interval of communication equipment, and can be applied to the field of communication equipment. And meanwhile, the working loss of an equipment system is effectively reduced, the heating value is reduced, the stability is improved, and the use requirement of communication equipment in a high-temperature or low-temperature extreme environment is met.

Description

Technical Field

[0001] This application belongs to the technical field of microwave dielectric ceramic materials, and more specifically, relates to a hexaaluminate-based intermedium microwave dielectric ceramic material and a preparation method thereof. Background Art

[0002] In recent years, with the improvement of the social development level and the rise of short videos and live broadcasts, the per capita video playback duration has increased sharply, which puts higher requirements on the capacity, communication quality, and transmission speed of communication devices. At the same time, the realization of new communication technologies such as industrial Internet and Internet of Things also requires higher transmission speed, connection stability, and high response speed. 5G communication technology has the advantages of high bandwidth, high transmission speed, and low latency. However, higher operating frequencies mean increased heat generation in devices, and temperature changes cause fluctuations in the center frequency of communication devices, resulting in a significant increase in signal loss. To achieve high-speed and low-loss transmission of communication signals, it is urgent to improve the thermal stability of communication devices and ensure the stable operation of communication equipment.

[0003] Microwave dielectric ceramics are a type of ceramic materials used to manufacture core devices such as antennas, resonators, and filters in communication equipment, and their operating frequencies range from 300 MHz to 300 GHz. The microwave dielectric properties of microwave dielectric ceramic materials have an important impact on the performance of devices. Among them, a high quality factor can effectively reduce the power loss during signal transmission, and the temperature coefficient of resonant frequency directly affects the thermal stability of communication equipment. A near-zero temperature coefficient means a larger operating temperature range, which can balance the high heat generation of 5G communication and is conducive to the use of communication equipment in extreme environments, and is of great significance to the development of communication technology.

[0004] Existing single-phase microwave dielectric ceramic materials often do not have a near-zero temperature coefficient of resonant frequency. Usually, they need to be compounded with another material with an opposite temperature coefficient of resonant frequency to adjust the temperature coefficient to near zero, and new phases may be generated by the reaction of the two phases during the compounding process, resulting in uncontrollable dielectric properties.

[0005] Therefore, it is urgent to develop an intermedium microwave dielectric ceramic material with an intermediate dielectric constant, a near-zero temperature coefficient of resonant frequency, and a high quality factor. Summary of the Invention

[0006] Aiming at the defects of the existing technology, the purpose of this application is to provide a hexaaluminate-based intermedium microwave dielectric ceramic material and a preparation method thereof, aiming to solve the problems that existing microwave dielectric ceramic materials do not have a near-zero temperature coefficient of resonant frequency and need to be compounded with other materials.

[0007] To achieve the above object, in a first aspect, the present application provides a hexaaluminate-based intermedium microwave dielectric ceramic material, and the chemical formula of the hexaaluminate-based intermedium microwave dielectric ceramic material is A 1-x B x Ti 2+x Al 9-x O 19 , where A is La or Y, B is Sr or Ba, and 0 ≤ x ≤ 1.0.

[0008] Preferably, in the chemical formula of the above hexaaluminate-based intermedium microwave dielectric ceramic material, 0 ≤ x < 0.6, or 0.8 < x ≤ 1.0.

[0009] In a second aspect, the present application provides a preparation method of the above hexaaluminate-based intermedium microwave dielectric ceramic material, including the following steps: S1. Obtain raw material components according to the stoichiometric ratio of metal elements in the chemical formula A 1-x B x Ti 2+x Al 9-x O 19 , where A is La or Y, B is Sr or Ba, 0 ≤ x ≤ 1.0, mix the above raw materials and grind them into a mixed powder; S2. Pre-sinter the above mixed powder to obtain a pre-sintered powder body, and grind the above pre-sintered powder body into a pre-sintered powder; S3. Mix the above pre-sintered powder and a binder for granulation and press them into a green body, and then perform sintering treatment on the above green body to obtain the above hexaaluminate-based intermedium microwave dielectric ceramic material.

[0010] Preferably, in step S1, the above raw material components are metal element oxides or carbonates, etc.

[0011] Preferably, in step S1, the above grinding is wet ball milling treatment.

[0012] Preferably, in step S1, the above wet ball milling treatment includes the following steps: after mixing the above raw materials, ball mill for 20 h to 30 h under the condition that the mass ratio of the mixed raw materials, ball milling balls and the solvent is 1:(3 - 7):(1 - 2), dry and then screen to obtain a mixed powder.

[0013] Preferably, in step S2, the temperature of the above pre-sintering is 1200 °C to 1300 °C, and the time of the pre-sintering is 4 h to 6 h.

[0014] Preferably, in step S2, the above grinding is wet ball milling treatment.

[0015] Preferably, in step S2, the wet ball milling treatment includes the following steps: ball milling the pre-sintered powder, ball milling balls, and solvent for 20 h to 30 h under the condition of a mass ratio of 1:(3 to 7):(1 to 2), drying and then sieving to obtain pre-sintered powder materials.

[0016] Preferably, in steps S1 and S2, the wet ball milling treatment can be carried out in a planetary ball mill.

[0017] Preferably, in steps S1 and S2, the solvent can be anhydrous ethanol.

[0018] Preferably, in steps S1 and S2, the drying temperature is 75°C to 90°C, and the drying time is 8 h to 12 h.

[0019] Preferably, in step S3, the mass ratio of the pre-sintered powder material to the binder is 1:(0.05 to 0.08).

[0020] Preferably, in step S3, the pressing pressure is 100 MPa to 300 MPa.

[0021] Preferably, in step S3, the sintering temperature is 1350°C to 1550°C, and the sintering time is 3 h to 5 h.

[0022] In a third aspect, the present application provides a microwave dielectric ceramic device. The raw material components for preparing the microwave dielectric ceramic device include the above-mentioned hexaaluminate-based intermedium microwave dielectric ceramic material, or the microwave dielectric ceramic material is prepared by the above-mentioned preparation method.

[0023] Generally speaking, compared with the prior art by the above technical solutions conceived by the present application, the following technical advantages are mainly achieved: (1) The hexaaluminate-based intermedium microwave dielectric ceramic material provided by the present application has a chemical formula of A 1-x B x Ti 2+ x Al 9-x O 19 , where A is La or Y, B is Sr or Ba, 0 ≤ x ≤ 1.0. It has a high quality factor and a resonance frequency temperature coefficient close to zero, is suitable for preparing communication devices such as resonators and dielectric filters, can effectively broaden the operating temperature range of communication equipment, and at the same time effectively reduce the loss of the equipment system during operation, reduce the heat generation, and improve the stability, meeting the requirements for use in extreme environments of high temperature or low temperature of communication equipment.

[0024] (2) By adjusting the content of metal elements such as La, Y, Sr, Ba, Ti, and Al in the hexaaluminate-based intermedium microwave dielectric ceramic material of the present application, a tunable dielectric constant between 16.67 and 17.79, and a quality factor range Q × f is tunable between 20200 GHz and 33851 GHz, and the temperature coefficient of resonance frequency τ f is tunable between -8.24 ppm / °C and 0.11 ppm / °C. The hexaaluminate-based intermedium microwave dielectric ceramic material has the advantages of excellent microwave dielectric properties and stable performance.

[0025] (3) The preparation method of the hexaaluminate-based intermedium microwave dielectric ceramic material provided by the present application is simple, with low production cost, suitable for large-scale production, and conducive to the practical application of the hexaaluminate-based intermedium microwave dielectric ceramic material. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic flow chart of the preparation method of the hexaaluminate-based intermedium microwave dielectric ceramic material provided by the embodiment of the present application; Figure 2 is the XRD pattern of the hexaaluminate-based intermedium microwave dielectric ceramics prepared in Examples 1 to 11 of the present application; Figure 3 is the SEM image of the hexaaluminate-based intermedium microwave dielectric ceramic prepared in Example 1 of the present application; Figure 4 is the SEM image of the hexaaluminate-based intermedium microwave dielectric ceramic prepared in Example 2 of the present application; Figure 5 is the SEM image of the hexaaluminate-based intermedium microwave dielectric ceramic prepared in Example 3 of the present application; Figure 6 is the SEM image of the hexaaluminate-based intermedium microwave dielectric ceramic prepared in Example 4 of the present application; Figure 7 is the SEM image of the hexaaluminate-based intermedium microwave dielectric ceramic prepared in Example 5 of the present application; Figure 8 is the SEM image of the hexaaluminate-based intermedium microwave dielectric ceramic prepared in Example 6 of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] In order to make the objectives, technical solutions, and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0028] In the description of the embodiments of the present application, words such as "exemplary" or "for example" are used to represent examples, illustrations, or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the embodiments of the present application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of words such as "exemplary" or "for example" is intended to present relevant concepts in a specific manner.

[0029] In the description of the embodiments of the present application, unless otherwise specified, the meaning of "a plurality" refers to two or more.

[0030] The term "intermediate microwave dielectric ceramic material" refers to a microwave dielectric ceramic material with an intermediate dielectric constant.

[0031] The present application provides a hexaaluminate-based intermediate microwave dielectric ceramic material, and the chemical formula of the hexaaluminate-based intermediate microwave dielectric ceramic material is A 1-x B x Ti 2+x Al 9-x O 19 , where A is La or Y, B is Sr or Ba, and 0 ≤ x ≤ 1.0.

[0032] In some embodiments, in the chemical formula of the above-mentioned hexaaluminate-based intermediate microwave dielectric ceramic material, 0 ≤ x < 0.6, or 0.8 < x ≤ 1.0. Through the synergistic cooperation of each component in the A 1-x B x Ti 2+x Al 9-x O 19 The hexaaluminate-based intermediate microwave dielectric ceramic material has an intermediate dielectric constant, a resonance frequency temperature coefficient close to zero, and a high quality factor. Its dielectric constant ε r is adjustable between 16.67 and 17.79, and the quality factor Q × f is adjustable between 20200 GHz and 33851 GHz. The resonance frequency temperature coefficient τ f is adjustable between -8.24 ppm / °C and 0.11 ppm / °C, having excellent microwave dielectric properties and better application performance.

[0033] On the other hand, as Figure 1 shown, the present application also provides a preparation method for the above-mentioned hexaaluminate-based intermediate microwave dielectric ceramic material, including the following steps: S1. According to the chemical formula A 1-x B x Ti 2+x Al 9-x O 19Obtain the raw material components with the stoichiometric ratio of metal elements, where A is La or Y, B is Sr or Ba, 0 ≤ x ≤ 1.0, and mix the above raw materials and grind them into a mixed powder; S2. Pre-sinter the above mixed powder to obtain a pre-sintered powder body, and grind the above pre-sintered powder body into a pre-sintered powder; S3. Mix the above pre-sintered powder and a binder for granulation and press them into a green body, and then perform a sintering treatment on the above green body to obtain the above hexaaluminate-based intermediate microwave dielectric ceramic material.

[0034] In some embodiments, in step S1, in the chemical expression of the above hexaaluminate-based intermediate microwave dielectric ceramic material, 0 ≤ x < 0.6, or 0.8 < x ≤ 1.0.

[0035] In some embodiments, in step S1, the above raw material components are oxides or carbonates of metal elements, etc. In the specific embodiments of the present application, the above raw material components include La2O3, Y2O3, SrCO3, BaCO3, TiO2 and Al2O3.

[0036] In some embodiments, the purity of the above raw material components is greater than or equal to 99.5%, which can effectively reduce the introduction of impurity components and avoid the influence of raw material impurities on the purity and electrochemical performance of the hexaaluminate-based intermediate microwave dielectric ceramic material.

[0037] In some embodiments, in step S1, the above grinding is wet ball milling treatment.

[0038] In some embodiments, the above wet ball milling treatment includes the following steps: After mixing the above raw materials, ball mill for 20 h to 30 h under the condition that the mass ratio of the mixed raw materials, ball milling balls and solvent is 1:(3 - 7):(1 - 2), dry and then screen to obtain a mixed powder. Through the wet ball milling treatment, each raw material component is further refined and homogenized, and is fully mixed evenly during the grinding process.

[0039] In some embodiments, in step S1, the above solvent can be but is not limited to anhydrous ethanol.

[0040] In some embodiments, in step S1, the temperature of the above drying is 75°C to 90°C, and the time of drying is 8 h to 12 h to fully remove the moisture in the mixed powder and obtain a dried mixed powder. It can be understood that those skilled in the art can adaptively increase or decrease the drying temperature and extend or shorten the drying time according to different drying methods, which are all within the protection scope of the present application.

[0041] In some embodiments, in step S2, the temperature of the above-mentioned pre-sintering is 1200°C to 1300°C, and the time of pre-sintering is 4h to 6h, which can enable the mixed powder to be fully mixed and dissolved, forming a pre-sintered powder with uniformly dispersed components. In some specific embodiments, the above-mentioned mixed powder can be sintered for 4h to 5h, 5h to 6h, etc. at temperatures such as 1200°C to 1250°C and 1250°C to 1300°C to obtain a pre-sintered powder with uniformly dispersed components.

[0042] In some embodiments, in step S2, the above-mentioned grinding is wet ball milling treatment, and the wet ball milling treatment includes the following steps: ball milling the above-mentioned pre-sintered powder, ball milling balls and solvent for 20h to 30h under the condition of a mass ratio of 1:(3 to 7):(1 to 2), drying and then sieving to obtain pre-sintered powder. In some embodiments, the above-mentioned wet ball milling treatment can be carried out in a planetary ball mill.

[0043] In some embodiments, in step S2, the above-mentioned solvent can be, but is not limited to, anhydrous ethanol.

[0044] In some embodiments, in step S2, the temperature of the above-mentioned drying is 75°C to 90°C, and the time of drying is 8h to 12h.

[0045] In some embodiments, step S3 includes the following steps: S3-1. Mix and granulate the above-mentioned pre-sintered powder and binder to obtain granulated powder; S3-2. Place the above-mentioned granulated powder in a mold and press it into a green body; S3-3. Sinter the above-mentioned green body to obtain a sintered body, that is, the above-mentioned microwave dielectric ceramic material.

[0046] In some embodiments, in step S3-1, the above-mentioned binder includes at least one of polyvinyl alcohol PVA and polyethylene glycol PEG, which can improve the bonding performance between components and is beneficial to forming the powder into a device product.

[0047] In some embodiments, in step S3-1, the mass ratio of the above-mentioned pre-sintered powder to the above-mentioned binder is 1:(0.05 to 0.08), which can ensure the combined forming performance between the pre-sintered powders, is beneficial to preparing granulated powder with high particle size uniformity, and at the same time avoids the subsequent green body being too hard due to excessive binder, affecting the physical and chemical properties of the subsequent ceramic material, etc.

[0048] In some embodiments, in step S3-2, the pressure of the above pressing is 100MP~300MPa, which is beneficial to the sufficient contact of the above granulated powder, shrinkage and pore exclusion, and the formation of a stable ceramic green body. In some specific embodiments, the pressure of the above pressing can be 100~150MPa, 150MPa~200MPa, 200MPa~250MPa, 250MPa~300MPa, etc.

[0049] In some embodiments, in step S3-3, the temperature of the above sintering treatment is 1350℃~1550℃, and the time of the sintering treatment is 3h~5h, so that the components in the ceramic green body react to form a hexaaluminate-based intermedium microwave dielectric ceramic material with excellent performance, and at the same time have an intermedium dielectric constant, a resonance frequency temperature coefficient close to zero and a high quality factor. In some specific embodiments, the above ceramic green body can be sintered at temperatures such as 1350℃~1400℃, 1400℃~1450℃, 1450℃~1500℃, 1500℃~1550℃ for durations such as 3h~3.5h, 3.5h~4h, 4.5h~5h, 4h~4.5h, etc. to obtain a hexaaluminate-based intermedium microwave dielectric ceramic material with excellent microwave dielectric properties.

[0050] This application also provides a microwave dielectric ceramic device. The raw material components for preparing the microwave dielectric ceramic device include the above hexaaluminate-based intermedium microwave dielectric ceramic material, or the microwave dielectric ceramic material is prepared by the above preparation method.

[0051] The microwave dielectric ceramic device provided by this application is made of the above hexaaluminate-based intermedium microwave dielectric ceramic material which simultaneously has an intermedium dielectric constant, a resonance frequency temperature coefficient close to zero and a high quality factor, so that the microwave dielectric ceramic device also has properties such as an intermedium dielectric constant, a frequency temperature coefficient close to zero and a high quality factor.

[0052] It should be understood that materials with the same or similar types, models, qualities, properties or functions as the reagents and instruments used in the following embodiments can be used to implement this application. The experimental methods used in the following embodiments are all conventional methods unless otherwise specified. The materials, reagents, etc. used in the following embodiments can be obtained from commercial channels unless otherwise specified.

[0053] The following are examples: Examples 1~11 Examples 1~11 of this application respectively provide a hexaaluminate-based intermedium microwave dielectric ceramic material, and its chemical formula is A 1-x B x Ti 2+x Al 9-x O 19, where the elements corresponding to A, the elements corresponding to B, and the specific values of x are shown in Table 1.

[0054] The preparation method of the hexaaluminate-based intermedium microwave dielectric ceramic material provided by the embodiment of the present application includes the following steps: S1. Prepare mixed powder: According to the chemical expressions in Table 1, the powder raw materials of La2O3, Y2O3, SrCO3, BaCO3, TiO2 and Al2O3 are proportioned, and the purities of the powder raw materials of La2O3, Y2O3, SrCO3, BaCO3, TiO2 and Al2O3 are all 99.5%. After mixing the prepared above-mentioned powder raw materials, add them together with anhydrous ethanol into a polyurethane ball milling tank equipped with zirconium balls for wet ball milling treatment, where the mass ratio of the mixed powder raw materials, zirconium balls and anhydrous ethanol is 1:3:1, and then ball mill for 20 h in a planetary ball mill. Place the ball-milled mixed raw materials in a blast drying oven at 80 °C for drying for 12 h, and then pass through a 40-mesh standard sieve to obtain the mixed powder.

[0055] S2. Prepare pre-sintered powder: Pre-sinter the above-mentioned mixed powder at 1300 °C for 4 h to obtain a pre-sintered powder body. Then ball mill the above-mentioned pre-sintered powder body, zirconium balls and anhydrous ethanol in a planetary ball mill according to a mass ratio of 1:3:1 for 20 h. Place the ball-milled powder in a blast drying oven at 80 °C for drying for 12 h, and then pass through a 40-mesh standard sieve to obtain the pre-sintered powder.

[0056] S3. Prepare the hexaaluminate-based intermedium microwave dielectric ceramic material: Mix the above-mentioned pre-sintered powder and a binder (aqueous solution of polyvinyl alcohol, the mass percentage of PVA is 5wt%) according to a mass ratio of 1:0.05 for granulation to obtain a granulated powder body. Then place the above-mentioned granulated powder body in a mold and press it into a ceramic green body with a diameter of 12 mm and a height of 6.5 mm under a pressure of 100 MPa. Sinter the above-mentioned ceramic green body at different sintering temperatures for 3 h to obtain a sintered body, that is, the hexaaluminate-based intermedium microwave dielectric ceramic material.

[0057] Table 1 A 1-x B x Ti 2+x Al 9-x O 19 Parameter information of and the sintering temperature during the preparation process

[0058] The phase analysis of the hexaaluminate-based intermedium microwave dielectric ceramic materials prepared in Examples 1 to 11 was carried out by using an X-ray diffractometer, and the XRD patterns are shown in Figure 2 . And observe the micro-morphologies of the hexaaluminate-based intermedium microwave dielectric ceramic materials prepared in Examples 1 to 6, and the SEM images are respectively shown in Figure 3 , Figure 4 ,Figure 5 , Figure 6 , Figure 7 , Figure 8 。

[0059] The microwave dielectric properties of the hexaaluminate-based intermedium microwave dielectric ceramic materials prepared in Examples 1 to 11 were tested. The test method is as follows: The hexaaluminate-based intermedium microwave dielectric ceramic materials prepared in the examples were polished on a 1000-mesh SiC grinding disc, and ultrasonically cleaned and dried in pure water. The parallel plate resonator method was used to analyze and test the dielectric constant ε r of the hexaaluminate-based intermedium microwave dielectric ceramic materials, and the test frequency was 7 GHz to 10 GHz; the quality factor Q×f was tested by the resonator method, and the test frequency was 8 GHz; the test method of the temperature coefficient of resonance frequency τ f was the same as that of the dielectric constant test method. The resonator was placed in a high and low temperature test chamber, and the test temperature range was (30 °C to 80 °C). The change of the resonance frequency with temperature was measured to obtain the temperature coefficient of resonance frequency τ f 。

[0060] The microwave dielectric properties of the hexaaluminate-based intermedium microwave dielectric ceramic materials prepared in Examples 1 to 11 of this application are shown in Table 2.

[0061] Table 2 Microwave dielectric properties of the hexaaluminate-based intermedium microwave dielectric ceramic materials prepared in the examples

[0062] The test results of the microwave dielectric properties show that the hexaaluminate-based intermedium microwave dielectric ceramic materials prepared in Examples 1 to 11 of this application have excellent microwave dielectric properties and a resonance frequency temperature coefficient close to zero. The dielectric constant ε r is 16.67 to 17.79, the quality factor Q × f is 20200 GHz to 33851 GHz, and the temperature coefficient of resonance frequency τ f is -14.66 ppm / °C to 0.11 ppm / °C. Among them, the high quality factor can reduce the loss of the system operation, and the resonance frequency temperature coefficient close to zero can broaden the operating temperature range of the device, ensuring that the device can operate stably at high or low temperatures.

[0063] As can be seen from Table 1, in Examples 1 to 3, x is from 0 to 0.4. As the content of La element in the hexaaluminate-based intermedium microwave dielectric ceramic material gradually decreases and the content of Sr element gradually increases, the dielectric constant of the prepared intermedium microwave dielectric ceramic material gradually increases, the temperature coefficient of resonant frequency gradually increases, and the quality factor shows a slight decrease but still remains at a relatively good level. In Examples 4 to 5, x is from 0.6 to 0.8. The content of La element continues to decrease compared with Examples 1 to 3, and the content of Sr element continues to increase compared with Examples 1 to 3. The temperature coefficient of resonant frequency of the prepared intermedium microwave dielectric ceramic material shows a decreasing trend. In Examples 6 to 9, x is 1. The temperature coefficient of resonant frequency of the prepared intermedium microwave dielectric ceramic material is close to zero, the quality factor is high, and it has excellent microwave dielectric properties.

[0064] It is easy for those skilled in the art to understand that the above are only the preferred embodiments of the present application, and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A hexaaluminate-based intermediate microwave dielectric ceramic material, characterized in that, The chemical expression of the hexaaluminate-based intermediate microwave dielectric ceramic material is: 1-x B x Ti 2+x Al 9-x O 19 , wherein A is La or Y, B is Sr or Ba, and 0≤x≤1.

0.

2. The hexaaluminate-based intermedium microwave dielectric ceramic material according to claim 1, wherein In the chemical formula of the hexaaluminate-based intermediate microwave dielectric ceramic material, 0 ≤ x < 0.6, or 0.8 < x ≤ 1.

0.

3. A preparation method of the hexaaluminate-based intermediate microwave dielectric ceramic material as described in claim 1 or 2, characterized in that, It includes the following steps: S1. Obtain the raw material components according to the stoichiometric ratio of metal elements in the chemical formula A 1-x B x Ti 2+x Al 9-x O 19 wherein, A is La or Y, B is Sr or Ba, 0 ≤ x ≤ 1.

0. Mix the raw materials and grind them into a mixed powder S2. Pre-sinter the mixed powder to obtain a pre-sintered powder body, and grind the pre-sintered powder body into a pre-sintered powder. S3. Mix the pre-sintered powder and a binder for granulation and press it into a green body, and then perform a sintering treatment on the green body to obtain the hexaaluminate-based intermediate microwave dielectric ceramic material.

4. The preparation method according to claim 3, characterized in that, In step S1, the grinding conditions include: after mixing the raw materials, ball-milling for 20 h to 30 h under the condition that the mass ratio of the mixed raw materials, ball-milling balls and solvent is 1:(3 - 7):(1 - 2), drying and then sieving to obtain a mixed powder.

5. The preparation method according to claim 3, wherein In step S2, the pre-sintering temperature is 1200°C to 1300°C, and the pre-sintering time is 4 h to 6 h. The grinding conditions include: ball-milling the pre-sintered powder body, ball-milling balls and solvent for 20 h to 30 h under the condition that the mass ratio is 1:(3 - 7):(1 - 2), drying and then sieving to obtain a pre-sintered powder.

6. The preparation method according to claim 4 or 5, characterized in that The drying temperature is 75°C to 90°C, and the drying time is 8 h to 12 h.

7. The preparation method according to claim 3, characterized in that, In step S3, the mass ratio of the pre-sintered powder and the binder is 1:(0.05 - 0.08).

8. The preparation method according to claim 3, characterized in that, In step S3, the pressing pressure is 100 MPa to 300 MPa.

9. The preparation method according to claim 3, characterized in that In step S3, the sintering treatment temperature is 1350°C to 1550°C, and the sintering treatment time is 3 h to 5 h.

10. A microwave dielectric ceramic device, characterized in that, The raw material components for preparing the microwave dielectric ceramic device include the hexaaluminate-based intermediate microwave dielectric ceramic material as described in claim 1 or 2, or the microwave dielectric ceramic material prepared by the method as described in any one of claims 3 to 9.

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