High-dielectric-constant microwave dielectric ceramic material and preparation method thereof

Abstract

The invention discloses a high-dielectric-constant microwave dielectric ceramic material and a preparation method thereof. A composition expression of the high-dielectric-constant microwave dielectric ceramic material is aBaCO3-bSm2O3-cNd2O3-dTiO2-eAl2O3, and a, b, c, d and e are molar percentages and meet the following conditions: 15% < = a < = 16%, 5% < = b < = 15%, 3% < = c < = 15%, 65% < = d < = 67%, and 0.5% < = e < = 1.5%. The microwave dielectric ceramic material can maintain the temperature coefficient of resonance frequency in a near-zero range while maintaining a relatively high dielectric constant and a relatively high quality factor, so that the high-performance requirement of a microwave element is met.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave dielectric ceramic materials, and in particular, relates to a high dielectric constant microwave dielectric ceramic material and a preparation method thereof. Background Art

[0002] With the continuous construction and optimization of 5G networks, base stations will have higher and higher performance requirements for components, and the requirements for microwave dielectric materials that meet their needs will also be further improved. At this stage, high-frequency communications have the advantages of high capacity, large bandwidth, and low latency, but they still cannot meet the rapidly developing needs of 5G communication technology. In particular, components and materials that make up components in the microwave frequency band need to develop in the direction of smaller size, higher dielectric constant, lower loss, and better temperature stability to ensure that the components maintain good working conditions in harsh environments. Therefore, it is of great significance to develop a microwave dielectric ceramic material with a high dielectric constant and a resonant frequency temperature coefficient of near zero.

[0003] At present, microwave dielectric ceramic materials with tungsten bronze structure have been widely studied. Studies have shown that microwave dielectric ceramics with this structure have a high dielectric constant (about 80) and quality factor (about 10,000). However, in order to meet the needs of communication applications, its temperature stability still needs to be improved. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a high dielectric constant microwave dielectric ceramic material and a preparation method; the microwave dielectric ceramic material is a tungsten bronze structure, which can maintain a high dielectric constant and quality factor while maintaining the resonant frequency temperature coefficient in a near-zero range, thereby meeting the high performance requirements of microwave components.

[0005] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0006] On the one hand, the present invention provides a high dielectric constant microwave dielectric ceramic material, whose composition expression is aBaCO3-bSm2O3-cNd2O3-dTiO2-eAl2O3, wherein a, b, c, d, and e are all molar percentages and meet the following conditions: 15%≤a≤16%, 5%≤b≤15%, 3%≤c≤15%, 65%≤d≤67%, and 0.5%≤e≤1.5%.

[0007] Furthermore, the dielectric constant of the microwave dielectric ceramic material is 75-77, the quality factor Qf value is not less than 12000 GHz, and the resonant frequency temperature coefficient is adjustable and the absolute value is ≤8 ppm / °C.

[0008] Another aspect of the present invention provides a method for preparing a high dielectric constant microwave dielectric ceramic material, comprising the following steps:

[0009] 1) BaCO3, Sm2O3, Nd2O3, TiO2, and Al2O3 are weighed respectively according to the molar percentage of each composition in the composition expression aBaCO3-bSm2O3-cNd2O3-dTiO2-eAl2O3, the weighed materials are fully mixed and then ball-milled, and after ball-milling, they are dried, sieved, put into a corundum crucible, and then pre-calcined at a temperature to obtain a powder substrate;

[0010] 2) fully ball-milling the powder substrate obtained in step 1), drying, granulating and sieving after ball-milling;

[0011] 3) The granular material screened in step 2) is pressed into a shape, and finally subjected to debinding and sintering to obtain the microwave dielectric ceramic material.

[0012] Furthermore, the pre-burning temperature in step 1) is 800-1000° C., and the pre-burning time is 2-5 hours.

[0013] Furthermore, in step 2), the particle size D50 of the powder after ball milling is less than 2.5 μm.

[0014] Furthermore, the granulation in step 2) is to mix the dried powder with a binder and then prepare micron-sized spherical particles.

[0015] Furthermore, the binder used in granulation is selected from at least one of polyvinyl alcohol solution, polyvinyl butyral solution, acrylic acid solution or methyl cellulose.

[0016] Furthermore, in step 3), the granular material is pressed into a cylinder with a diameter of 10 mm and a height of 6 mm.

[0017] Furthermore, the debinding process in step 3) is carried out at 600° C. for 2 hours.

[0018] Furthermore, the sintering process in step 3) is performed at 1250-1350° C. for 3-7 hours.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention dopes rare earth elements Nd and Sm, adds a certain amount of Al2O3, and sinters with BaCO3 and TiO2. While ensuring a high dielectric constant and quality factor of the material, the temperature stability of the microwave dielectric ceramic is improved, the resonant frequency temperature coefficient reaches the requirement of near-zero adjustable, and the overall dielectric properties of the microwave dielectric ceramic are optimized. The microwave dielectric ceramic material of the present invention has a dielectric constant of 75±1, a quality factor of not less than 12000GHz, a resonant frequency temperature coefficient of -8 to +8ppm / °C, and has good dielectric properties.

[0021] The present invention also controls the particle size of the ceramic powder so that the grains of the prepared microwave dielectric ceramic material are small and uniform, which helps to reduce dielectric loss and thus increase the service life of the ceramic material. DETAILED DESCRIPTION

[0022] The technical solutions in the present invention will be described clearly and completely below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] The present invention provides a high dielectric constant microwave dielectric ceramic material, whose composition expression is aBaCO3-bSm2O3-cNd2O3-dTiO2-eAl2O3, wherein a, b, c, d, and e are all molar percentages and meet the following conditions: 15%≤a≤16%, 5%≤b≤15%, 3%≤c≤15%, 65%≤d≤67%, and 0.5%≤e≤1.5%.

[0024] The microwave dielectric ceramic material has a dielectric constant of 75 to 77, a quality factor Qf value of not less than 12000 GHz, an adjustable resonant frequency temperature coefficient and an absolute value of ≤8 ppm / °C.

[0025] The method for preparing the high dielectric constant microwave dielectric ceramic material comprises the following steps:

[0026] 1) BaCO3, Sm2O3, Nd2O3, TiO2 and Al2O3 are weighed respectively according to the molar percentage of each composition in the composition expression aBaCO3-bSm2O3-cNd2O3-dTiO2-eAl2O3, the weighed materials are fully mixed and then ball-milled, and after ball-milling, they are dried, sieved and put into a corundum crucible, and then heat-insulated and pre-fired to obtain a powder substrate; wherein the heat-insulated pre-fired temperature is 800-1000° C., and the heat-insulated pre-fired time is 2-5 h;

[0027] 2) ball-milling the powder substrate obtained in step 1) to obtain a powder particle size D50 less than 2.5 μm, drying, granulating, and sieving after ball-milling; wherein the granulation is to mix the dried powder with a binder and then prepare micron-sized spherical particles; the binder used in the granulation is selected from at least one of polyvinyl alcohol solution, polyvinyl butyral solution, acrylic acid solution, or methyl cellulose;

[0028] 3) The sieved granular material in step 2) is pressed into a cylinder with a diameter of 10 mm and a height of 6 mm, and finally the microwave dielectric ceramic material is obtained by debinding and sintering; wherein the debinding process is to keep the temperature at 600°C for 2 hours; and the sintering process is to sinter at 1250-1350°C for 3-7 hours.

[0029] The high dielectric constant microwave dielectric ceramic material with a resonance frequency temperature coefficient close to zero can be applied to microwave components.

[0030] Example 1

[0031] The composition expression of the microwave dielectric ceramic material of this embodiment 1 is aBaCO3-bSm2O3-cNd2O3-dTiO2-eAl2O3, wherein a=15.3%, b=5.3%, c=12.5%, d=65.7%, and e=1.2%.

[0032] The method for preparing the microwave dielectric ceramic material comprises the following steps:

[0033] 1) BaCO3, Sm2O3, Nd2O3, TiO2, and Al2O3 are weighed respectively according to the molar percentage of each composition; the weighed materials are mixed thoroughly and then ball-milled, and after ball-milling, they are dried, sieved, and placed in a corundum crucible, and then pre-calcined at a temperature of 800° C. for 5 hours to obtain a powder substrate;

[0034] 2) The powder substrate obtained in step 1) is fully ball-milled and tested for particle size, and its D50 is 1.335 μm, followed by drying, granulation, and sieving;

[0035] 3) The sieved granules in step 2) are pressed into cylinders with a diameter of 10 mm and a height of 6 mm, and are first sintered at 600° C. for 2 h to remove binder, and then sintered at 1260° C. for 5 h to obtain the microwave dielectric ceramic material.

[0036] Example 2

[0037] The composition expression of the microwave dielectric ceramic material of this embodiment 2 is aBaCO3-bSm2O3-cNd2O3-dTiO2-eAl2O3, wherein a=15.3%, b=7.1%, c=10.7%, d=65.7%, and e=1.2%.

[0038] The method for preparing the microwave dielectric ceramic material comprises the following steps:

[0039] 1) BaCO3, Sm2O3, Nd2O3, TiO2, and Al2O3 are weighed respectively according to the molar percentage of each composition; the weighed materials are mixed thoroughly and then ball-milled, and after ball-milling, they are dried, sieved, and placed in a corundum crucible, and then pre-calcined at a temperature of 850° C. for 4 hours to obtain a powder substrate;

[0040] 2) The powder substrate obtained in step 1) is fully ball-milled and tested for particle size, and its D50 is 1.164 μm, followed by drying, granulation, and sieving;

[0041] 3) The sieved granules in step 2) are pressed into cylinders with a diameter of 10 mm and a height of 6 mm, and are first sintered at 600° C. for 2 h to remove binder, and then sintered at 1280° C. for 5 h to obtain the microwave dielectric ceramic material.

[0042] Example 3

[0043] The composition expression of the microwave dielectric ceramic material of this embodiment 3 is aBaCO3-bSm2O3-cNd2O3-dTiO2-eAl2O3, wherein a=15.3%, b=8.9%, c=8.9%, d=65.7%, and e=1.2%.

[0044] The method for preparing the microwave dielectric ceramic material comprises the following steps:

[0045] 1) BaCO3, Sm2O3, Nd2O3, TiO2, and Al2O3 are weighed respectively according to the molar percentage of each composition; the weighed materials are mixed thoroughly and then ball-milled, and after ball-milling, they are dried, sieved, and placed in a corundum crucible, and then pre-calcined at 850° C. for 3 hours to obtain a powder substrate;

[0046] 2) The powder substrate obtained in step 1) is fully ball-milled and tested for particle size, and its D50 is 0.858 μm, followed by drying, granulation, and sieving;

[0047] 3) The sieved granules in step 2) are pressed into cylinders with a diameter of 10 mm and a height of 6 mm, and are first sintered at 600° C. for 2 h to remove binder, and then sintered at 1300° C. for 5 h to obtain the microwave dielectric ceramic material.

[0048] Example 4

[0049] The composition expression of the microwave dielectric ceramic material of Example 4 is aBaCO3-bSm2O3-cNd2O3-dTiO2-eAl2O3, wherein a=15.1%, b=14.0%, c=3.5%, d=66.9%, and e=0.5%.

[0050] The method for preparing the microwave dielectric ceramic material comprises the following steps:

[0051] 1) BaCO3, Sm2O3, Nd2O3, TiO2, and Al2O3 are weighed respectively according to the molar percentage of each composition; the weighed materials are mixed thoroughly and then ball-milled, and after ball-milling, they are dried, sieved, and placed in a corundum crucible, and then pre-calcined at 850° C. for 2 h to obtain a powder substrate;

[0052] 2) The powder substrate obtained in step 1) is fully ball-milled and tested for particle size, and its D50 is 1.029 μm, followed by drying, granulation, and sieving;

[0053] 3) The sieved granules in step 2) are pressed into cylinders with a diameter of 10 mm and a height of 6 mm, and are first sintered at 600° C. for 2 h to remove binder, and then sintered at 1315° C. for 4 h to obtain the microwave dielectric ceramic material.

[0054] Comparative Example 1

[0055] The microwave dielectric ceramic material of the comparative example 1 has a composition expression of aBaCO3-bSm2O3-cNd2O3-dTiO2-eAl2O3, wherein a=15.3%, b=2.7%, c=15.2%, d=65.7%, and e=1.1%.

[0056] The method for preparing the microwave dielectric ceramic material comprises the following steps:

[0057] 1) BaCO3, Sm2O3, Nd2O3, TiO2, and Al2O3 are weighed respectively according to the molar percentage of each composition; the weighed materials are mixed thoroughly and then ball-milled, and after ball-milling, they are dried, sieved, and placed in a corundum crucible, and then pre-calcined at 850° C. for 5 hours to obtain a powder substrate;

[0058] 2) The powder substrate obtained in step 1) is fully ball-milled and tested for particle size, and its D50 is 1.359 μm, followed by drying, granulation, and sieving;

[0059] 3) The sieved granules in step 2) are pressed into cylinders with a diameter of 10 mm and a height of 6 mm, and are first sintered at 600° C. for 2 h to remove binder, and then sintered at 1280° C. for 6 h to obtain the microwave dielectric ceramic material.

[0060] Comparative Example 2

[0061] The composition expression of the microwave dielectric ceramic material of Comparative Example 2 is aBaCO3-bSm2O3-cNd2O3-dTiO2-eAl2O3, wherein a=15.1%, b=17.6%, c=0%, d=66.9%, and e=0.4%.

[0062] The method for preparing the microwave dielectric ceramic material comprises the following steps:

[0063] 1) BaCO3, Sm2O3, TiO2, and Al2O3 are weighed respectively according to the molar percentage of each composition; the weighed materials are mixed thoroughly and then ball-milled, and after ball-milling, they are dried, sieved, and placed in a corundum crucible, and then pre-calcined at 850° C. for 4 hours to obtain a powder substrate;

[0064] 2) The powder substrate obtained in step 1) is fully ball-milled and tested for particle size, and its D50 is 0.932 μm, followed by drying, granulation, and sieving;

[0065] 3) The sieved granules in step 2) are pressed into cylinders with a diameter of 10 mm and a height of 6 mm, and are first sintered at 600° C. for 2 h to remove binder, and then sintered at 1280° C. for 6 h to obtain the microwave dielectric ceramic material.

[0066] Comparative Example 3

[0067] The composition expression of the microwave dielectric ceramic material of Comparative Example 3 is aBaCO3-bSm2O3-cNd2O3-dTiO2-eAl2O3, wherein a=15.1%, b=15.0%, c=2.6%, d=66.9%, and e=0.4%.

[0068] The method for preparing the microwave dielectric ceramic material comprises the following steps:

[0069] 1) BaCO3, Sm2O3, Nd2O3, TiO2, and Al2O3 are weighed respectively according to the molar percentage of each composition; the weighed materials are mixed thoroughly and then ball-milled, and after ball-milling, they are dried, sieved, and placed in a corundum crucible, and then pre-calcined at a temperature of 900° C. for 2 hours to obtain a powder substrate;

[0070] 2) The powder substrate obtained in step 1) is fully ball-milled and tested for particle size, and its D50 is 0.956 μm, followed by drying, granulation, and sieving;

[0071] 3) The sieved granules in step 2) are pressed into cylinders with a diameter of 10 mm and a height of 6 mm, and are first sintered at 600° C. for 2 h to remove binder, and then sintered at 1300° C. for 6 h to obtain the microwave dielectric ceramic material.

[0072] Performance Testing

[0073] The microwave dielectric properties of the microwave dielectric ceramic materials of the embodiment and the comparative example were tested using a microwave network analyzer and are shown in Table 1.

[0074] Table 1 Parameter values ​​of the embodiments and comparative examples and microwave dielectric properties of microwave dielectric ceramic materials

[0075] Group D50(μm) Sintering temperature(℃) <![CDATA[ε r ]]> Qf(GHz) <![CDATA[τ f (ppm / ℃)]]> Example 1 1.335 1260 76.45 12703 6.5 Example 2 1.164 1280 76.22 12917 7.2 Example 3 0.858 1300 75.58 13041 0 Example 4 1.029 1315 76.96 12039 -2.5 Comparative Example 1 1.359 1280 77.26 11570 36.2 Comparative Example 2 0.932 1280 75.91 11223 -32.1 Comparative Example 3 0.956 1300 76.04 11641 -22.6

[0076] It can be seen from Table 1 that, compared with Comparative Examples 1-3, the microwave dielectric ceramic materials prepared in Examples 1-4 of the present invention can maintain the following microwave properties under the sintering conditions of 1260-1340°C: ε r =76±1, Qf>12000GHz, resonant frequency temperature coefficient τ f The absolute value is less than 8ppm / ℃; moreover, the present invention reduces the dielectric loss of the ceramic material and prolongs the service life of the microwave components by controlling the grain size of the powder. In Example 3, the microwave dielectric ceramic material prepared by doping Sm2O3 and Nd2O3 in equal molar proportions has the smallest D50 particle size, and the material has the highest quality factor and a resonant frequency temperature coefficient of zero. Its excellent dielectric properties meet the development requirements of 5G communication technology and are conducive to the preparation of more efficient microwave components.

[0077] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any modifications or equivalent transformations made using the contents of the present invention specification, or direct or indirect applications in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A high dielectric constant microwave dielectric ceramic material, characterized in that: Its composition expression is aBaCO3-bSm2O3-cNd2O3-dTiO2-eAl2O3, where a, b, c, d, and e are all molar percentages and meet the following conditions: 15%≤a≤16%, 5%≤b≤15%, 3%≤c≤15%, 65%≤d≤67%, and 0.5%≤e≤1.5%.

2. The high dielectric constant microwave dielectric ceramic material according to claim 1, characterized in that: The microwave dielectric ceramic material has a dielectric constant of 75 to 77, a quality factor Qf value of not less than 12000 GHz, an adjustable resonant frequency temperature coefficient and an absolute value of ≤8 ppm / °C.

3. A method for preparing the high dielectric constant microwave dielectric ceramic material according to claim 1 or 2, characterized in that: The steps include: 1) BaCO3, Sm2O3, Nd2O3, TiO2, and Al2O3 are weighed respectively according to the molar percentage of each composition in the composition expression aBaCO3-bSm2O3-cNd2O3-dTiO2-eAl2O3, the weighed materials are fully mixed and then ball-milled, and after ball-milling, they are dried, sieved, put into a corundum crucible, and then pre-calcined at a temperature to obtain a powder substrate; 2) fully ball-milling the powder substrate obtained in step 1), drying, granulating and sieving after ball-milling; 3) The sieved granular material in step 2) is pressed into a shape, and finally subjected to debinding and sintering to obtain the microwave dielectric ceramic material.

4. The method for preparing a high dielectric constant microwave dielectric ceramic material according to claim 3, characterized in that: The pre-burning temperature in step 1) is 800-1000° C., and the pre-burning time is 2-5 hours.

5. The method for preparing a high dielectric constant microwave dielectric ceramic material according to claim 3, characterized in that: In step 2), the particle size D50 of the powder after ball milling is less than 2.5 μm.

6. The method for preparing a high dielectric constant microwave dielectric ceramic material according to claim 3, characterized in that: The granulation in step 2) is to mix the dried powder with a binder and then make micron-sized spherical particles.

7. The method for preparing a high dielectric constant microwave dielectric ceramic material according to claim 6, characterized in that: The binder used for granulation is selected from at least one of polyvinyl alcohol solution, polyvinyl butyral solution, acrylic acid solution or methyl cellulose.

8. The method for preparing a high dielectric constant microwave dielectric ceramic material according to claim 3, characterized in that: In step 3), the granules are pressed into cylinders with a diameter of 10 mm and a height of 6 mm.

9. The method for preparing a high dielectric constant microwave dielectric ceramic material according to claim 3, characterized in that: The debinding process in step 3) is carried out at 600°C for 2 hours.

10. The method for preparing a high dielectric constant microwave dielectric ceramic material according to claim 3, characterized in that: The sintering process in step 3) is sintering at 1250-1350° C. for 3-7 hours.