A Mg3TiO5 microwave dielectric material and its preparation method

Abstract

This application discloses a Mg3TiO5 microwave dielectric material and its preparation method, belonging to the field of microwave dielectric materials. The microwave dielectric material has the chemical formula Mg3TiO5 with a Q×f of 198000GHz and a microwave dielectric property fluctuation of less than or equal to 5% in the range of -50℃ to 200℃. The preparation method steps are as follows: (1) MgO or basic magnesium carbonate and TiO2 with a purity of more than 99% and a particle size of 400-600nm are mixed according to the elemental composition of the product to obtain the initial powder; (2) The initial powder obtained in step (1) is ball-milled, dried, sieved and pre-calcined, and then ball-milled, dried and sieved again; (3) The powder obtained in step (2) is granulated by adding polyvinyl alcohol solution according to the powder, and then pressed into shape. The obtained green embryo is sintered in an atmospheric atmosphere at 1320-1440℃ to obtain the Mg3TiO5 microwave dielectric material.

Description

Technical Field

[0001] This invention belongs to the field of electronic ceramics and their manufacturing, and specifically relates to a microwave dielectric ceramic that is resistant to high and low temperatures and has ultra-low loss, and its preparation method. Background Technology

[0002] Microwave dielectric ceramics, as a crucial functional material for microwave and radio frequency devices, are widely used in key areas such as dielectric resonators, filters, dielectric antennas, base station radio frequency components, and satellite communications. With the rapid development of high-speed communication technologies such as 5G, millimeter-wave radar, satellite internet, and the Internet of Things, microwave devices face increasingly stringent requirements regarding signal stability, miniaturization, and wide-temperature adaptability under high-frequency conditions. Particularly in high-reliability scenarios such as aerospace, polar research, and military electronics, microwave devices capable of maintaining ultra-low loss over a wide temperature range are critical, as their performance directly impacts the safety and operational stability of the equipment.

[0003] However, existing microwave dielectric ceramic materials still face several challenges in applications. First, to obtain high Q×f values, many material systems often require ion substitution, oxide addition, or multiphase composite methods for control. These methods not only increase the complexity of the fabrication process and hinder large-scale production, but may also introduce structural defects or phase instabilities, making it difficult to effectively adjust the temperature coefficient (τf). Second, under complex conditions such as the high and low temperature cycling involved in vehicle-mounted radar and the extreme thermal environments faced by satellite communication equipment, existing materials struggle to simultaneously meet the requirements of high Q×f and wide-temperature-range dielectric stability. This leads to increased frequency drift, signal distortion, and significant performance degradation in microwave devices during practical applications. As the core foundation of microwave devices, the performance of microwave dielectric materials directly determines the device's operational quality. Therefore, developing materials with low dielectric constants, high quality factors, and excellent temperature stability has become a critical issue that urgently needs to be addressed in this field. Summary of the Invention

[0004] This invention provides a microwave dielectric material Mg3TiO5 that combines high Q×f, suitable dielectric constant, excellent temperature stability, and high density. This material can be sintered at 1320-1440℃ to form a pure spinel structure with space group Fd-3m, exhibiting good crystal phase stability. Its microwave dielectric properties are excellent: εr ~ 15.3, Q×f ~ 198000 GHz, τ fWith a dielectric strength of ~−45ppm / ℃ and a relatively low sintering temperature (ST 1350-1380℃), this material exhibits high feasibility and economic efficiency in its preparation. More importantly, its dielectric properties fluctuate by only about 5% over a wide temperature range of −50℃ to 200℃, significantly outperforming conventional microwave dielectric ceramics. This demonstrates excellent high and low temperature stability, meeting the stringent requirements for stable operation in high-reliability, high-frequency communication equipment. Therefore, the Mg3TiO5 microwave dielectric ceramic material developed in this invention effectively addresses the shortcomings of existing materials in terms of temperature stability and dielectric loss, providing a material solution with significant application advantages for next-generation high-frequency, high-reliability microwave devices.

[0005] The purpose of this invention is to provide a Mg3TiO5 microwave dielectric material and its preparation method. The microwave dielectric ceramic involved in this invention has the chemical formula Mg3TiO5 and is prepared by a solid-state method. The Mg3TiO5 ceramics prepared by sintering at 1320-1440 °C are all pure phases with a spinel structure and space group Fd-3m. Its optimal microwave dielectric property is ε0. r ~15.3, Q×f ~198000 GHz, τ f ~−45 ppm / ℃, ST=1350-1380 ℃.

[0006] The above-mentioned Mg3TiO5 microwave dielectric material with high and low temperature resistance and ultra-low loss is prepared according to the following steps:

[0007] (1) MgO or basic magnesium carbonate (Mg(OH)2・4MgCO3・5H2O) and TiO2 with a purity of 99% or higher and a particle size of 400-600 nm are mixed according to the chemical formula to obtain the initial powder.

[0008] (2) The initial powder obtained in step (1) is placed in a nylon ball mill jar for ball milling, drying, sieving, and pre-burning in an atmospheric atmosphere at 1000℃ for 3 hours, and then ball milled, dried, and sieved again.

[0009] (3) The powder obtained in step (2) is granulated by adding a 5% polyvinyl alcohol solution, and then pressed into shape. The resulting green body is sintered in an atmospheric atmosphere at 1320-1440℃ for 4 hours to finally obtain a Mg3TiO5 microwave dielectric material that is resistant to high and low temperatures and has ultra-low loss.

[0010] (4) The raw materials prepared in step 1 need to undergo a pretreatment process. First, MgO or basic magnesium carbonate (Mg(OH)2・4MgCO3・5H2O) and TiO2 are dried in a drying oven at 110℃ for 24 hours to remove moisture.

[0011] (5) The ball milling process described in step 2 involves placing the obtained initial powder into a nylon ball mill jar and mixing it according to a ratio of powder:deionized water:zirconia balls of 1:3~4:5~10. The zirconia balls used have diameters of 3mm, 5mm, and 10mm, and their ratio is 3:3:4. The powder in the nylon ball mill jar is then ball milled in a planetary ball mill for 12-24 hours at a speed of 220rpm.

[0012] (6) The sieving process described in step 2 mainly involves sieving through a 60-mesh sieve after the first drying and through an 80-mesh sieve after the second drying.

[0013] (7) The granulation process described in step 3 involves adding a 5% polyvinyl alcohol solution to the obtained powder, wherein the amount of polyvinyl alcohol added accounts for 3-5% of the total mass of the powder for granulation. A total of 20g of powder is continuously stirred for about 2 hours, and then sieved through a 100-mesh sieve.

[0014] (8) The sintering method described in step 3 is to first heat the sample at 650°C for 2 hours at a heating rate of 2°C / min to remove polyvinyl alcohol, then heat it at 1320-1440°C in an atmospheric atmosphere for 4 hours at a heating rate of 3°C / min, then heat it down to 1000°C at a rate of 1°C / min and hold it for 1 hour, and finally cool it down naturally to obtain the final sample.

[0015] The Mg3TiO5 microwave dielectric material and its preparation process of the present invention successfully solve the technical problems of insufficient temperature stability, high loss, complex process and difficulty in mass production of microwave dielectric ceramics in the prior art. It provides a key basic material with excellent performance, stability and reliability and industrialization potential for next-generation high-frequency communication devices, antenna systems, aerospace electronic equipment and microwave components in extreme environments. It has important scientific significance and broad application prospects.

[0016] Furthermore, the preparation method proposed in this invention employs a solid-state process route, which utilizes readily available and inexpensive raw materials, has clearly defined steps, and high repeatability. The relatively low sintering temperature also helps reduce energy consumption, making it suitable for industrial-scale production. This method overcomes the reliance on complex control methods such as ion substitution and multiphase composites found in traditional materials, avoiding the introduction of structural instability. Simultaneously, it achieves performance comparable to or even surpasses that of similar foreign materials, enhancing my country's independent innovation capabilities and technological competitiveness in the field of high-performance microwave dielectric ceramics.

[0017] Compared with the prior art, the present invention has the following characteristics:

[0018] 1. The overall microwave dielectric properties are significantly superior to existing materials: The microwave dielectric properties of Mg3TiO5 are: ε r ~15.3, Q×f ~198000 GHz, τ fWith a dielectric constant of ~−45 ppm / ℃, this material's ultra-high Q×f has significant advantages in low dielectric constant material systems, and its overall performance is at the leading level among similar materials.

[0019] 2. Excellent dielectric stability over a wide temperature range, meeting the requirements of extreme environments: The dielectric properties of the material of this invention fluctuate by less than 5% over a wide temperature range of −50℃ to 200℃, which is significantly better than the problems of large frequency drift and increased loss of traditional microwave ceramics in high and low temperature environments. It can be widely used in high reliability fields such as aerospace, military electronics, and polar equipment.

[0020] 3. Low sintering temperature and wide process window, which is conducive to industrial-scale production: The material can achieve high density at 1350-1380℃, which significantly reduces the sintering temperature compared to most high Q×f ceramics (>1500℃). At the same time, spinel pure phase can be formed in the range of 1320-1440℃, with high process tolerance, making it suitable for large-scale production.

[0021] 4. The preparation adopts a conventional solid-state method, which has a mature process and low cost: The preparation process includes conventional steps such as pretreatment, ball milling, pre-calcination, secondary ball milling, granulation, pressing, and sintering. The raw materials are readily available and inexpensive, the process is stable, and no expensive equipment or special atmosphere is required, which makes it highly valuable for industrial promotion.

[0022] This invention can significantly improve the reliability and performance of existing microwave devices: the material can effectively reduce problems such as frequency drift, signal loss, temperature sensitivity, and long-term stability degradation. It supports the miniaturization and high-frequency operation of microwave devices, and is particularly suitable for next-generation high-frequency fields such as 5G / 6G, radar, and satellite communications. Attached Figure Description

[0023] Figure 1 The XRD diffraction pattern of Mg3TiO5 ceramic;

[0024] Figure 2 The graph shows the dielectric constant of Mg3TiO5 ceramic as a function of temperature.

[0025] Figure 3 The graph shows the Q×f of Mg3TiO5 ceramic as a function of temperature.

[0026] Figure 4 The image shows the microstructure of Mg3TiO5 ceramic. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings.

[0028] The preparation method of Mg3TiO5 in this application is as follows:

[0029] MgO and TiO2 with a purity of over 99% and a particle size of 400-600 nm were mixed according to their chemical formulas to obtain initial powder. The MgO and TiO2 were then dried in a 110℃ drying oven for 24 hours to remove moisture.

[0030] The initial powder was placed in a nylon ball mill jar and mixed with deionized water in a ratio of 1:3:6. The zirconia balls used were 3mm, 5mm, and 10mm in diameter, in a ratio of 3:3:4. The powder in the nylon ball mill jar was ball-milled in a planetary ball mill for 12 hours at a speed of 220 rpm. After ball milling, the powder was dried and then sieved through a 60-mesh sieve. It was then pre-calcined at 1000℃ in an atmospheric atmosphere for 3 hours, followed by a second ball milling and drying, and finally sieved through an 80-mesh sieve.

[0031] The obtained powder was granulated by adding a 5% polyvinyl alcohol solution, with the polyvinyl alcohol accounting for 4% of the total powder mass, and stirred continuously for 2 hours. The granulated powder was then sieved through a 100-mesh sieve. The powder was pressed into shape, and the sample was heated to 650℃ for 2 hours at a heating rate of 2℃ / min to remove the polyvinyl alcohol. Then, it was sintered in an atmospheric atmosphere at the temperatures shown in Table 1 for 4 hours at a heating rate of 3℃ / min, followed by a decrease to 1000℃ at a heating rate of 1℃ / min and holding for 1 hour. Finally, it was allowed to cool naturally to obtain the final material.

[0032] The performance tests conducted on the obtained materials are shown in Table 1:

[0033] Table 1

[0034]

[0035] Figure 1 The XRD pattern of Example 3 is shown. This XRD pattern is a perfect match with the standard PDF card PDF#74-2258, indicating that Mg3TiO5 crystallizes into a spinel phase with space group Fd-3m.

[0036] Figure 2 The dielectric constant of Example 3 varies with temperature. In the temperature range of -50 to 200 degrees, the fluctuation of the dielectric constant is within 5%.

[0037] Figure 3 The graph of Q×f versus temperature for Example 3 shows that the fluctuation of Q×f is within 5% in the temperature range of -50 to 200 degrees.

[0038] Figure 4 The image shows the microstructure of Example 3, which reveals a dense microstructure.

Claims

1. A Mg3TiO5 microwave dielectric material, characterized in that, The chemical formula is Mg3TiO5, its Q×f is at least 198000 GHz, and the fluctuation of its microwave dielectric properties in the range of -50℃ to 200℃ is less than or equal to 5%; the preparation method of the Mg3TiO5 microwave dielectric material is as follows: (1) MgO or basic magnesium carbonate and TiO2 with a purity of 99% or higher and a particle size of 400-600nm are mixed according to the elemental composition of the product to obtain the initial powder. (2) The initial powder obtained in step (1) is ball-milled, dried, sieved and pre-calcined, then ball-milled, dried and sieved again; (3) The powder obtained in step (2) is granulated by adding polyvinyl alcohol solution, then pressed into shape, and the obtained green embryo is sintered in an atmospheric atmosphere at 1320-1440℃ to obtain Mg3TiO5 microwave dielectric material.

2. The method for preparing the Mg3TiO5 microwave dielectric material according to claim 1, characterized in that, The steps are as follows: (1) Take MgO or basic magnesium carbonate and TiO2 with a purity of 99% or higher and a particle size of 400-600nm, and then mix them according to the elemental composition of the product to obtain the initial powder. (2) The initial powder obtained in step (1) is ball-milled, dried, sieved and pre-calcined, then ball-milled, dried and sieved again; (3) The powder obtained in step (2) is granulated by adding polyvinyl alcohol solution, then pressed into shape, and the obtained green embryo is sintered in an atmospheric atmosphere at 1320-1440℃ to obtain Mg3TiO5 microwave dielectric material.

3. The method for preparing Mg3TiO5 microwave dielectric material according to claim 2, characterized in that, The raw materials prepared in step (1) are pretreated as follows: MgO or basic magnesium carbonate and TiO2 are dried in a drying oven to remove moisture.

4. The method for preparing Mg3TiO5 microwave dielectric material according to claim 2, characterized in that, The ball milling method in step (2) is as follows: the obtained initial powder is placed in a nylon ball milling jar and mixed in a ratio of powder:deionized water:zirconia balls of 1:3~4:5~10.

5. The method for preparing Mg3TiO5 microwave dielectric material according to claim 4, characterized in that, Zirconia balls with diameters of 2.5-3.5mm, 4.5-5.5mm, and 9.5-10.5mm were used; the powder in the nylon ball mill jar was ball-milled in a planetary ball mill for 12-24 hours.

6. The method for preparing Mg3TiO5 microwave dielectric material according to claim 2, characterized in that, The sieving process described in step 2 is as follows: after the first drying, the material is sieved through a screen, and after the second drying, the material is sieved through a screen again; the mesh size of the screen used after the second drying is greater than the mesh size used after the first drying.

7. The method for preparing Mg3TiO5 microwave dielectric material according to claim 2, characterized in that, The granulation method described in step 3 is as follows: add a polyvinyl alcohol solution, wherein the amount of polyvinyl alcohol added accounts for 3-5% of the total mass of the powder, granulate, stir evenly, and then sieve.

8. The method for preparing Mg3TiO5 microwave dielectric material according to claim 2, characterized in that, The sintering process described in step 3 is as follows: The sample is heated at 600℃~700℃ for 1h-3h at a heating rate of 1.5℃~5℃ / min to remove polyvinyl alcohol. Then, it is sintered in an atmospheric atmosphere at 1320-1440℃ for 3-6 hours at a heating rate of 1.5℃~5℃ / min. Then, it is cooled down to below 1000℃ at a rate of 0.5℃~2℃ / min and held for 0.5-3 hours. Finally, it is allowed to cool naturally to obtain the material described above.

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