Microwave dielectric ceramic material, preparation method and application thereof

Abstract

The application belongs to the technical field of microwave dielectric ceramic, and particularly relates to a microwave dielectric ceramic material and a preparation method thereof, which can be applied to 5G / 6G communication. 1‑x Ge x O3, wherein 0.1 < x < 0.3. The preparation method of the microwave dielectric ceramic material comprises the following steps: step (1), taking MgO, SiO2 and GeO2 as raw materials, and according to the target chemical formula MgSi 1‑x Ge x O3, the amount-of-substance ratio of the three elements of Mg, Si and Ge in the target chemical formula is used to weigh the raw materials, wherein 0.1 < x < 0.3.

Description

Technical Field

[0001] This invention belongs to the field of microwave dielectric ceramic technology, specifically relating to a microwave dielectric ceramic material and its preparation method, which can be applied to 5G / 6G communication. Background Technology

[0002] Microwave dielectric ceramics are highly technical functional materials designed specifically for conducting, resonating, and filtering functions in the microwave frequency band (300MHz–300GHz). These ceramics are considered key foundational materials for 5G / 6G communication. With the rapid advancement of large-scale commercialization of 5G networks globally, strategic planning for 6G research and development has been fully launched. Therefore, developing high-performance microwave dielectric ceramic materials is of significant value. 5G / 6G communication operates at high frequencies and features short signal transmission delays, high signal fidelity, and low attenuation, thus requiring microwave dielectric ceramics to have low dielectric constants and low dielectric losses.

[0003] Silicate ceramics, as a class of common materials with low cost and abundant raw materials, possess inherent characteristics of low dielectric constant and low dielectric loss due to the fundamental properties of the Si-O bond, showing great potential in 5G / 6G applications. Among them, MgSiO3 exhibits excellent microwave dielectric properties, making it an ideal candidate material for 5G / 6G communication. However, MgSiO3 ceramics often suffer from cracking and pulverization during preparation and use. This is due to the crystal structure phase transition that occurs in the ceramic, severely affecting its microwave dielectric properties and thus limiting its practical applications. MgSiO3 commonly has three crystal structures: proto-enstatite (Pbcn, PEN), enstatite (Pbca, OEN), and low-clino-enstatite (P21 / c, CEN). During ceramic fabrication, when the temperature is cooled from a high temperature (above 1000℃) to room temperature, the PEN phase present at high temperatures becomes unstable and transforms into the CEN phase, leading to internal stress and potentially causing cracking and pulverization. Current research, besides introducing sufficient glassy phase, also suggests suppressing the phase transition by introducing A-site ions to replace Mg. However, the latter still presents a significant problem of the simultaneous presence of both PEN and CEN phases, limiting the extent to which microwave dielectric properties can be improved. Summary of the Invention

[0004] To address the problem of microwave dielectric property degradation caused by the PEN→CEN phase transition and the coexistence of two phases during the preparation and use of MgSiO3 microwave dielectric ceramics in existing technologies, this invention focuses on introducing appropriate amounts of other ions to replace silicon ions at the B site to form a solid solution, directly obtaining a stable OEN phase, thereby optimizing microwave dielectric properties. Ultimately, this invention finds a microwave dielectric ceramic material and its preparation method that can be applied to the 5G / 6G communication field.

[0005] During the preparation of MgSiO3 ceramics, the PEN phase, present at high temperatures (above 1000℃), becomes unstable upon cooling to room temperature and transforms into the CEN phase. This leads to internal stress, potentially causing cracks and pulverization, severely impacting microwave dielectric properties and usability. Current research, besides introducing sufficient glassy phase, also suggests suppressing the phase transition by introducing A-site ions to replace Mg. However, the latter still presents a significant challenge of simultaneously exhibiting both PEN and CEN phases, limiting the extent of improvement in microwave dielectric properties.

[0006] This invention forms a solid solution MgSi by introducing an appropriate amount of B-site ions (Ge) for substitution. 1-x Ge x O3 directly yields a stable OEN phase, which can fundamentally prevent the PEN→CEN phase transition and optimize the microwave dielectric properties of MgSiO3 microwave dielectric ceramics.

[0007] The amount of Ge doped (substituted) is crucial in determining the OEN phase. Simultaneously, the slow cooling step during preparation, at a rate of 1.5℃ / min to 600℃, reduces or avoids internal stress problems that might arise from rapid cooling, thus ensuring a stable OEN phase and excellent microwave dielectric properties.

[0008] This invention provides a microwave dielectric ceramic material with the chemical formula MgSi. 1-x Ge x O3, of which 0.1 <x≤0.3。

[0009] Preferably, the microwave dielectric ceramic material has a dielectric constant of 5.8 to 7.2, a Qf value of 40,500 to 140,000 GHz @ 13 GHz, and a resonant frequency temperature coefficient of -52 to -31 ppm / ℃.

[0010] The method for preparing the microwave dielectric ceramic material includes the following steps:

[0011] Step (1): Using MgO, SiO2, and GeO2 as raw materials, according to the target chemical formula MgSi 1-x Ge xIn O3, the molar ratio of the three elements Mg, Si, and Ge. Weigh the raw materials, where 0.1 < x ≤ 0.3. Mix, ball-mill, dry, sieve, and pre-sinter the weighed raw materials in sequence. Perform secondary ball-milling, drying, and sieving on the pre-sintered powder to obtain the powder.

[0012] Step (2): Granulate, sieve, and form the powder obtained in step (1) to obtain a green body.

[0013] Step (3): Sinter the green body obtained in step (2) at 1300 - 1390 °C to obtain the ceramic.

[0014] Preferably, in step (1), the raw materials are pretreated before weighing. The pretreatment operations include: calcining the MgO at 900 °C for 3 h, and drying the SiO2 and GeO2 at 80 °C for 24 h before weighing.

[0015] Preferably, in step (1), the ball-milling time is 24 h, the rotation speed is 220 r / min, and the direction is changed every 30 min.

[0016] Preferably, in step (1), the pre-sintering process includes: the heating rate is 5 °C / min, heat up to 1250 °C and pre-sinter for 3 h; at a cooling rate of 2 °C / min, cool down to 800 °C; then cool down with the furnace.

[0017] Preferably, in step (2), the granulation process includes: using an aqueous solution of polyvinyl alcohol with a concentration of 10 wt% as the binder, and the addition amount of the binder accounts for 10% of the mass of the powder obtained in step (1); the sieve used is a 40-mesh standard sieve, and the forming uses a steel mold with a diameter of 12 mm, and is pressed into a cylindrical green body with a height of 3 - 5 mm and a diameter of 12 mm under a pressure of 80 - 100 MPa.

[0018] Preferably, in step (3), the sintering process includes: heating up to 650 °C at a rate of 2 °C / min to remove the binder for 3 h, heating up to 1300 - 1390 °C at a rate of 5 °C / min to sinter for 5 h, and cooling down to 600 °C at a rate of 1.5 °C / min and then cooling down with the furnace to room temperature.

[0019] The present invention also provides an application of the microwave dielectric ceramic material in the 5G / 6G communication field. In the high-frequency microwave frequency range, the high-frequency microwave frequency is 13 GHz. The microwave dielectric ceramic material is used for device substrates, resonators, and filters. The application performance parameters of the microwave dielectric ceramic material are: the dielectric constant is 5.8 - 7.2, the Qf value is 40,500 - 140,000 GHz, and the resonant frequency temperature coefficient is -52 - -31 ppm / °C.

[0020] The beneficial effects of this invention are as follows:

[0021] This invention directly obtains a stable OEN phase by substituting appropriate amounts of B-site ions to form a solid solution, thus fundamentally avoiding the PEN→CEN phase transition and optimizing the microwave dielectric properties of MgSiO3 microwave dielectric ceramics. It achieves a low dielectric constant (5.8–7.2) and a high Qf value (40,500–140,000 GHz @ 13 GHz), with a resonant frequency temperature coefficient of -52 to -29 ppm / ℃, making it applicable to 5G / 6G communication fields. These characteristics give this invention significant industrial application value. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Some specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings in an exemplary and non-limiting manner. The same reference numerals in the drawings indicate the same or similar parts or components. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0023] Figure 1 The X-ray diffraction (XRD) patterns of Comparative Examples 1-2 and Examples 1-4 are shown.

[0024] Figure 2 Microwave dielectric properties (dielectric constant, Qf value and temperature coefficient of resonant frequency) of Comparative Examples 1-2 and Examples 1-4. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. In this invention, unless otherwise specified, the raw materials and equipment used are commercially available or commonly used in the art. The methods in the embodiments, unless otherwise specified, are conventional methods in the art.

[0026] The present invention will be further illustrated below with reference to examples and comparative examples.

[0027] Example 1:

[0028] MgSi 0.88 Ge 0.12 O3 microwave dielectric ceramic material and its preparation method, the preparation process includes the following steps:

[0029] (1) Weighing and mixing: Weigh the pretreated MgO, SiO2 and GeO2 raw materials (all with a purity greater than 99.5%) according to the chemical formula MgSi0.88 Ge 0.12 O3 is used for weighing and mixing ingredients;

[0030] (2) One-time ball milling, drying and sieving: Transfer the weighed raw material into a ball mill jar, add anhydrous ethanol and zirconium dioxide balls, and ball mill in a ball mill for 24 hours at a speed of 220 r / min. After ball milling, dry at 80℃ for 24 hours and sieve with a 120 mesh standard sieve.

[0031] (3) Pre-firing: Pre-firing at 1250℃ with a heating rate of 5℃ / min, holding for 3 hours, cooling down at a rate of 2℃ / min to 800℃, and then cooling down with the furnace.

[0032] (4) Secondary ball milling, drying, granulation and molding: The slurry after secondary ball milling is dried at 80℃ for 24h, 10wt% PVA solution is added as a binder, and after thorough mixing and grinding, it is passed through a 40-mesh standard sieve. Then the granulated powder is poured into a steel mold and pressed into a green body with a diameter of 12mm and a height of 3-5mm under a pressure of 80MPa to 100MPa.

[0033] (5) Debinding and sintering: The green body is heated from room temperature to 650℃ at a rate of 2℃ / min and held for 3h to remove the binder. Then, it is heated to 1300℃, 1325℃, 1350℃, 1375℃ and 1390℃ at a rate of 5℃ / min and held for 5h. Then, it is cooled to 600℃ at a rate of 1.5℃ / min and then cooled naturally to room temperature to obtain microwave dielectric ceramic.

[0034] In this embodiment, the dielectric constant is 5.8 to 6.9, the quality factor is 43,000 to 63,000, and the temperature coefficient of the resonant frequency is -45 to -29 ppm / ℃.

[0035] Example 2

[0036] MgSi 0.85 Ge 0.15 O3 microwave dielectric ceramic material and its preparation method, the preparation process includes the following steps:

[0037] Steps (2), (3), (4), and (5) are the same as in Example 1, except that in this example, the ratio of raw materials in step (1) is based on the chemical formula MgSi. 0.85 Ge 0.15 O3 was weighed.

[0038] In this embodiment, the dielectric constant is 6.1 to 6.9, the quality factor is 86,000 to 140,000, and the temperature coefficient of the resonant frequency is -49 to -36 ppm / ℃.

[0039] Example 3

[0040] MgSi 0.8 Ge 0.2 O3 microwave dielectric ceramic material and its preparation method, the preparation process includes the following steps:

[0041] Steps (2), (3), (4), and (5) are the same as in Example 1, except that in this example, the ratio of raw materials in step (1) is based on the chemical formula MgSi. 0.8 Ge 0.2 O3 was weighed.

[0042] In this embodiment, the dielectric constant is 6.1 to 7.0, the quality factor is 56,000 to 74,300, and the temperature coefficient of the resonant frequency is -44 to -35 ppm / ℃.

[0043] Example 4

[0044] MgSi 0.7 Ge 0.3 O3 microwave dielectric ceramic material and its preparation method, the preparation process includes the following steps:

[0045] Steps (2), (3), (4), and (5) are the same as in Example 1, except that in this example, the ratio of raw materials in step (1) is based on the chemical formula MgSi. 0.7 Ge 0.3 O3 was weighed.

[0046] In this embodiment, the dielectric constant is 6.2 to 7.2, the quality factor is 40,500 to 60,500, and the temperature coefficient of the resonant frequency is -52 to -43 ppm / ℃.

[0047] Comparative Example 1:

[0048] MgSiO3 microwave dielectric ceramic material and its preparation method, the preparation process includes the following steps:

[0049] (1) Weighing and batching: Weigh and batch the pretreated MgO and SiO2 raw materials (both with a purity greater than 99.5%) according to the chemical formula MgSiO3;

[0050] (2) One-time ball milling, drying and sieving: Transfer the weighed raw material into a ball mill jar, add anhydrous ethanol and zirconium dioxide balls, and ball mill in a ball mill for 24 hours at a speed of 220 r / min. After ball milling, dry at 80℃ for 24 hours and sieve with a 120 mesh standard sieve.

[0051] (3) Pre-firing: Pre-firing at 1250℃ with a heating rate of 5℃ / min, holding for 3 hours, cooling down at a rate of 2℃ / min to 800℃, and then cooling down with the furnace.

[0052] (4) Secondary ball milling, drying, granulation and molding: The slurry after secondary ball milling is dried at 80℃ for 24h, 10wt% PVA solution is added as a binder, and after thorough mixing and grinding, it is passed through a 40-mesh standard sieve. Then the granulated powder is poured into a steel mold and pressed into a green body with a diameter of 12mm and a height of 3-5mm under a pressure of 80MPa to 100MPa.

[0053] (5) Debinding and sintering: The green body is heated from room temperature to 650℃ at a rate of 2℃ / min and held for 3h to remove the binder. Then, it is heated to 1300℃, 1325℃, 1350℃, 1375℃ and 1390℃ at a rate of 5℃ / min and held for 5h. Then, it is cooled to 600℃ at a rate of 1.5℃ / min and then cooled naturally to room temperature to obtain microwave dielectric ceramic.

[0054] The dielectric constant of this comparative example is 5.5 to 6.1, the quality factor is 9,600 to 37,800, and the temperature coefficient of the resonant frequency is -39 to -31 ppm / ℃.

[0055] Comparative Example 2:

[0056] MgSi 0.9 Ge 0.1 O3 microwave dielectric ceramic material and its preparation method, the preparation process includes the following steps:

[0057] Steps (2), (3), (4), and (5) are the same as in Example 1, except that in this example, the ratio of raw materials in step (1) is based on the chemical formula MgSi. 0.9 Ge 0.1 O3 was weighed.

[0058] The dielectric constant of this comparative example is 5.6 to 6.5, the quality factor is 22,800 to 58,100, and the temperature coefficient of the resonant frequency is -43 to -26 ppm / ℃.

[0059] Appendix Figure 1 X-ray diffraction patterns of Comparative Examples 1-2 and Examples 1-4 are shown. Comparative Example 1 shows the CEN phase, while the other comparative examples show the coexistence of CEN and OEN phases. As the amount of Ge ions added at the B site increases to x > 0.1, the OEN phase appears; Examples 1-4 all show the OEN phase. The OEN phase is relatively stable.

[0060] Appendix Figure 2The microwave dielectric properties (dielectric constant, Qf value, and temperature coefficient of resonant frequency) of Comparative Examples 1-2 and Examples 1-4 are shown. It can be observed that the addition of the B-site ion Ge has little effect on the dielectric constant; the dielectric constant of the comparative examples is in the range of 5.5-6.5, while that of the examples is slightly improved, in the range of 5.8-7.2. However, it has a significant effect on the Qf value. As the amount of Ge added increases (i.e., the x value increases), the Qf value gradually increases, reaching a maximum at x = 0.15, and then decreases. The Qf values ​​of Examples 1-4 are generally greater than those of Comparative Examples 1-2, indicating that the addition of the B-site ion Ge forms a stable OEN phase, which is less prone to phase transition and is beneficial for obtaining a higher Qf value. Furthermore, the temperature coefficient of resonant frequency of Examples 1-4 is generally larger (negative temperature coefficient) than that of Comparative Examples 1-2.

Claims

1. A method for preparing a microwave dielectric ceramic material, characterized in that, The microwave dielectric ceramic material has a chemical formula of MgSi x Ge x O3, where 0.1 < x ≤ 0.

3. The preparation method includes the following steps: Step (1): Using MgO, SiO2, and GeO2 as raw materials, according to the molar ratio of Mg, Si, and Ge in the target chemical formula MgSi 1-x Ge x O3, weigh the raw materials, where 0.1 < x ≤ 0.

3. Mix, ball-mill, dry, sieve, and pre-burn the weighed raw materials in sequence. Then, perform secondary ball-milling, drying, and sieving on the pre-burned powder to obtain the powder. Step (2): Granulate, sieve, and shape the powder obtained in step (1) to obtain a green body; Step (3): Sinter the green body obtained in step (2) at 1300~1390℃ to obtain ceramic; The sintering process includes: heating to 650°C at a rate of 2°C / min for 3 hours to remove the binder, heating to 1300~1390°C at a rate of 5°C / min for 5 hours to sinter, and cooling to 600°C at a rate of 1.5°C / min and then cooling to room temperature in the furnace.

2. The method for preparing microwave dielectric ceramic material according to claim 1, characterized in that, In step (1), the raw materials are pretreated before weighing. The pretreatment includes calcining the MgO at 900°C for 3 hours and drying the SiO2 and GeO2 at 80°C for 24 hours before weighing.

3. The method for preparing microwave dielectric ceramic material according to claim 1, characterized in that, In step (1), the ball milling time is 24 hours, the rotation speed is 220 r / min, and the direction is reversed every 30 minutes.

4. The method for preparing microwave dielectric ceramic material according to claim 1, characterized in that, In step (1), the pre-firing process includes: heating at a rate of 5°C / min to 1250°C for 3 hours; cooling at a rate of 2°C / min to 800°C; and then cooling down with the furnace.

5. The method for preparing microwave dielectric ceramic material according to claim 1, characterized in that, In step (2), the granulation process includes: using a 10wt% polyvinyl alcohol aqueous solution as a binder, the amount of the binder added is 10% of the mass of the powder obtained in step (1); the sieving is done using a 40-mesh standard sieve; the molding is done using a steel mold with a diameter of 12mm, and pressing it into a cylindrical blank with a height of 3-5mm and a diameter of 12mm under a pressure of 80-100MPa.

6. The microwave dielectric ceramic material prepared by the method according to claim 1, characterized in that, The dielectric constant is 5.8 ~ 7.

2. Qf The value is 40,500~140,000GHz@13GHz, and the temperature coefficient of resonant frequency is -52 ~ -31 ppm / ℃.

7. The application of the microwave dielectric ceramic material according to claim 6 in the field of 5G / 6G communication, characterized in that, Within the high-frequency microwave range, specifically 13 GHz, the microwave dielectric ceramic material is used in device substrates, resonators, and filters. The performance parameters of the microwave dielectric ceramic material are: dielectric constant of 5.8 ~ 7.

2. Qf The value is 40,500~140,000GHz@13GHz, and the temperature coefficient of resonant frequency is -52 ~ -31 ppm / ℃.

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