Preparation and application of silicon-based low-dielectric high-quality-factor microwave dielectric ceramic capable of being sintered at low temperature
阅读说明：本技术 一种硅基可低温烧结的低介高品质因数微波介质陶瓷的制备及应用 (Preparation and application of silicon-based low-dielectric high-quality-factor microwave dielectric ceramic capable of being sintered at low temperature ) 是由 李洁 唐莹 方亮 于 2021-08-11 设计创作，主要内容包括：本发明公开了一种硅基可低温烧结的低介高品质因数微波介质陶瓷的制备及应用。(1)将Li-(2)CO-(3)、SrCO-(3)和SiO-(2)按Li-(2)SrSiO-(4)的组成称量配料；(2)球磨混合6小时,球磨介质为酒精,烘干后预烧；(3)将预烧后粉末与SiTiO-(3)粉末按(1-x)Li-(2)SrSiO-(4)-xSrTiO-(3)进行称量,其中x为体积百分比(0≤x≤0.06),再次球磨后添加聚乙烯醇溶液并造粒,再压制成型,最后在大气气氛中烧结。本发明制备的硅基低介高品质因数微波介质陶瓷,介电常数为7.4～8.2,品质因数高达63,200～100,700GHz,谐振频率温度系数近零,能应用于各种陶瓷基板、介质谐振器与滤波器等微波元器件的制造。(The invention discloses a preparation method and application of a silicon-based low-dielectric high-quality-factor microwave dielectric ceramic capable of being sintered at a low temperature. (1) Mixing Li 2 CO 3 、SrCO 3 And SiO 2 According to Li 2 SrSiO 4 Weighing and proportioning; (2) ball milling and mixing for 6 hours, wherein a ball milling medium is alcohol, and pre-sintering is carried out after drying; (3) mixing the pre-sintered powder with SiTiO 3 Powder is expressed by (1- x )Li 2 SrSiO 4 ‑ x SrTiO 3 Weighing is carried out, wherein x Is calculated by volume percentage (0 ≤ and x ≤0.06），and ball-milling again, adding a polyvinyl alcohol solution, granulating, pressing for forming, and finally sintering in an atmospheric atmosphere. The silicon-based low-dielectric high-quality-factor microwave dielectric ceramic prepared by the invention has the dielectric constant of 7.4-8.2, the quality factor of 63,200-100,700 GHz and the temperature coefficient of resonant frequency close to zero, and can be applied to the manufacture of microwave components such as various ceramic substrates, dielectric resonators, filters and the like.)
1. The preparation and application of the silicon-based low-dielectric high-quality-factor microwave dielectric ceramic capable of being sintered at low temperature are characterized in that the silicon-based low-dielectric high-quality-factor microwave dielectric ceramic has the following general formula: (1-x)Li2SrSiO4-xSrTiO3WhereinxIs in volume percentage of 0 to lessx≤0.06；
The preparation method of the silicon-based low-dielectric high-quality-factor microwave dielectric ceramic comprises the following steps:
(1) 99.9% analytically pure starting powder Li2CO3、SrCO3And SiO2According to Li2SrSiO4Weighing and proportioning;
(2) wet ball-milling and mixing the raw materials in the step (1) for 6 hours, drying the raw materials by using alcohol as a ball-milling medium, and presintering the raw materials for 3 to 5 hours at 600 to 720 ℃ in an atmosphere;
(3) mixing the pre-sintered powder obtained in the step (2) with SiTiO with the purity of 99.9 percent3Powder is expressed by (1-x)Li2SrSiO4-xSrTiO3Weighing is carried out, whereinxIs in volume percentage of 0 to lessxNot more than 0.06 percent, adding a polyvinyl alcohol solution with the mass percentage concentration of 5 percent after ball milling again, and granulating, wherein the dosage of the polyvinyl alcohol solution accounts for 2-4 percent of the total mass of the powder; then pressing and molding, finally sintering for 2-6 hours in an atmosphere of 800-900 ℃ to obtain the silicon-based low-dielectric high-quality-factor microwave dielectric ceramic (1-x)Li2SrSiO4-xSrTiO3。
2. The use of the silicon-based low-temperature sinterable low-k high-q-factor microwave dielectric ceramic of claim 1 wherein the silicon-based low-k high-q-factor microwave dielectric ceramic is used in the fabrication of various ceramic substrates, dielectric resonators and filter microwave devices.
Technical Field
The present invention relates to a dielectric ceramic material, and more particularly to a microwave device such as a ceramic substrate, a resonator, and a filter used in microwave frequencies, and a method for producing and using a dielectric ceramic material for a ceramic capacitor or a temperature compensation capacitor.
Background
The microwave dielectric ceramic is applied to the micro-structureMaterials which are used as media in a wave band (300 Mz-300 Hz) circuit and complete one or more functions of microwave waveguide, shielding, resonance and the like become key basic materials of modern mobile communication technology. Three important indexes for measuring the performance of microwave dielectric materials are dielectric constant epsilonrQuality factor Qxf and resonant frequency temperature coefficient tauf. The dielectric constant is inversely proportional to the size of the device, and the size of the component is determined; the high quality factor is beneficial to improving the signal strength and the resonant frequency resolution; as close to zero (± 10ppm/° c) as possible to ensure good thermal stability of the device.
Recently, the application markets of a wireless communication system based on 5G, an internet of things, an intelligent transportation system, intelligent driving and the like are rapidly developed, and microwave dielectric components tend to be developed with high frequency, small size, light weight, thin type and high performance. When the communication frequency is increased to the millimeter wave band (>30GHz), low εrNot only can reduce the cross coupling loss between the material and the electrode, but also can reduce the delay in the signal transmission process to meet the requirements of high frequency and high speed, and has high quality factor (Qxf)>90000GHz) is advantageous for improving the frequency selective characteristics of the element and reducing the amount of heat generated during operation, and therefore, the dielectric constant (. epsilon.) is ultra-lowr<10) And high quality factor (Q f)>90,000GHz) microwave dielectric ceramics are increasingly being researched and developed.
Existing low epsilonrWith the material system of high Q x f value being mainly Al2O3Series, spinel MgAl2O4And ZnAl2O4System, MgTiO3Silicate M2SiO4(M＝Mg、Zn)、Li2TiO3System, K2NiF4Form SrRAlO4(R is Sm, Nd, La) or the like[1-4]Wherein silicate ceramics such as Mg2SiO4、Zn2SiO4Low epsilon of isogenicrAnd high Q × f, low density, and low cost.
The sintering temperature of the material systems is generally higher than 1300 ℃, and the materials can not be directly co-sintered with low-melting-point metals such as Ag, Cu and the like to form a multilayer ceramic capacitor. In recent years, with the development of Low Temperature Co-fired ceramic technology (LTCC) and the requirements of microwave multilayer device development, researchers at home and abroad have conducted extensive exploration and research on some Low-Temperature Co-fired system materials, mainly by adopting a glass-ceramic or glass-ceramic composite material system, because a Low-melting-point glass phase has relatively high dielectric loss, the dielectric loss of the material is greatly improved due to the existence of the glass phase. Therefore, the development of the microwave dielectric ceramic material with low intrinsic sintering temperature without glass phase is the focus of the current research.
In the process of exploring and developing a novel low-sintering microwave dielectric ceramic material, material systems such as a Li-based compound, a Bi-based compound, vanadate, molybdate, tungstate system compound, tellurate system compound and the like with low inherent sintering temperature are widely concerned and researched. However, because three performance indexes of the microwave dielectric ceramic are restricted, the single-phase microwave dielectric ceramic which meets the three performance requirements and can be sintered at low temperature is very few. At present, most of the research on microwave dielectric ceramics is summarized empirically through a large number of experiments, but no complete theory is provided to illustrate the relationship between the microstructure and the dielectric property, which limits the development of low-temperature co-firing technology and microwave multilayer devices to a great extent. The search and development of microwave dielectric ceramics capable of being sintered at low temperature and having ultra-low dielectric constant and higher quality factor is a problem that those skilled in the art are eagerly to solve but are always difficult to achieve successfully.
Through research and summary, the inventor finds that a certain proportion of Li is introduced into orthosilicate and orthogermanate, so that the sintering temperature of the orthosilicate and the orthogermanate can be effectively reduced, for example, Li2ZnSiO4、Li2MgSiO4、Li2CaSiO4And Li2ZnGeO4、Li2MgGeO4The sintering temperature is reduced by 200-450 ℃ compared with that of the corresponding orthosilicate and orthogermanate, but is still higher than the melting point (961 ℃) of the silver electrode. Replacement of Sr by only 2mol of Li ions2SiO4Preparation of Li from medium 1mol Sr ion2SrSiO4The sintering temperature of the ceramic is reduced to 880 ℃, and the ceramic has ultra-low dielectric constant and high quality factor. By complex chemical bondsTheoretical analysis shows that the weaker covalency (18%) of Si-O bonds is the key to the low sintering temperature. And by introducing into Li2SrSiO4Adding 0.06 volume ratio of SrTiO3Introduction of Li2SrSiO4Greater τ of the ceramicfAdjust to near zero.
Disclosure of Invention
The invention aims to provide preparation and application of a silicon-based low-dielectric high-quality-factor microwave dielectric ceramic capable of being sintered at low temperature.
The chemical composition of the silicon-based low-dielectric high-quality-factor microwave dielectric ceramic comprises the following components: (1-x) Li2SrSiO4-xSrTiO3Wherein: x is volume percentage (x is more than or equal to 0 and less than or equal to 0.06).
The preparation method of the silicon-based low-dielectric high-quality-factor microwave dielectric ceramic comprises the following steps:
(1) 99.9% analytically pure starting powder Li2CO3、SrCO3And SiO2According to Li2SrSiO4Weighing and proportioning;
(2) wet ball-milling and mixing the raw materials in the step (1) for 6 hours, drying the raw materials by using alcohol as a ball-milling medium, and presintering the raw materials for 3 to 5 hours at 600 to 720 ℃ in an atmosphere;
(3) mixing the pre-sintered powder obtained in the step (2) with SiTiO with the purity of 99.9 percent3Powder of (1-x) Li2SrSiO4-xSrTiO3Weighing, wherein x is the volume percentage (x is more than or equal to 0 and less than or equal to 0.06), adding a polyvinyl alcohol solution with the mass percentage concentration of 5% after ball milling again, and granulating, wherein the dosage of the polyvinyl alcohol solution accounts for 2-4% of the total mass of the powder; pressing and molding, and finally sintering for 2-6 hours in an atmosphere at 800-900 ℃ to obtain the silicon-based low-dielectric high-quality-factor microwave dielectric ceramic (1-x) Li2SrSiO4-xSrTiO3。
The silicon-based low-dielectric high-quality-factor microwave dielectric ceramic (1-x) Li prepared by the invention2SrSiO4-xSrTiO3The densification temperature is lower than 880 ℃, the dielectric constant is lower than 7.4-8.2, the quality factor is as high as 63,200-100, 700GHz, the temperature coefficient of the resonant frequency is nearly zero, and the ceramic material can be widely used for various ceramic substrates and resonant frequencyThe manufacture of microwave components such as devices, filters and the like meets the technical requirements of low-temperature co-firing technology and microwave multilayer devices, and the synthesis raw materials are low in cost and have great application value in industry.
Detailed Description
Example 1:
(1) 99.9% analytically pure starting powder Li2CO3、SrCO3And SiO2According to Li2SrSiO4Weighing and proportioning;
(2) wet ball-milling and mixing the raw materials in the step (1) for 6 hours, drying the raw materials and pre-burning the raw materials for 4 hours in the atmosphere at 700 ℃ after the ball-milling medium is alcohol;
(3) ball-milling the pre-sintered powder obtained in the step (2) again, adding a polyvinyl alcohol solution with the mass percentage concentration of 5%, and granulating, wherein the dosage of the polyvinyl alcohol solution accounts for 2% of the total mass of the powder; then pressing and molding, finally sintering for 4 hours in an atmosphere at 880 ℃ to obtain the silicon-based low-dielectric high-quality-factor microwave dielectric ceramic Li2SrSiO4。
Example 2:
(1) 99.9% analytically pure starting powder Li2CO3、SrCO3And SiO2According to Li2SrSiO4Weighing and proportioning;
(2) wet ball-milling and mixing the raw materials in the step (1) for 6 hours, drying the raw materials and pre-burning the raw materials for 4 hours in the atmosphere at 700 ℃ after the ball-milling medium is alcohol;
(3) mixing the pre-sintered powder obtained in the step (2) with SiTiO with the purity of 99.9 percent3Powder of 0.96Li2SrSiO4-0.04SrTiO3Weighing, ball-milling again, adding 5% polyvinyl alcohol solution by mass percentage, and granulating, wherein the dosage of the polyvinyl alcohol solution accounts for 3% of the total mass of the powder; then pressing and molding, finally sintering for 4 hours in an atmosphere at 880 ℃ to obtain the silicon-based low-dielectric high-quality-factor microwave dielectric ceramic 0.96Li2SrSiO4-0.04SrTiO3。
Example 3:
(1) 99.9% analytically pure starting powder Li2CO3、SrCO3And SiO2According to Li2SrSiO4Weighing and proportioning;
(2) wet ball-milling and mixing the raw materials in the step (1) for 6 hours, drying the raw materials and pre-burning the raw materials for 4 hours in the atmosphere at 700 ℃ after the ball-milling medium is alcohol;
(3) mixing the pre-sintered powder obtained in the step (2) with SiTiO with the purity of 99.9 percent3Powder of 0.94Li2SrSiO4-0.06SrTiO3Weighing, ball-milling again, adding 5% polyvinyl alcohol solution by mass percentage, and granulating, wherein the dosage of the polyvinyl alcohol solution accounts for 4% of the total mass of the powder; then pressing and molding, finally sintering for 4 hours in an atmosphere at 880 ℃ to obtain the silicon-based low-dielectric high-quality-factor microwave dielectric ceramic 0.94Li2SrSiO4-0.06SrTiO3。
The ceramic can be widely used for manufacturing microwave components such as various ceramic substrates, dielectric resonators, filters and the like, and can meet the technical requirements of systems such as mobile communication, satellite communication and the like.
Table 1 shows the contents of the components and the microwave dielectric properties of the examples, and the microwave dielectric properties were evaluated by the cylindrical dielectric resonator method.
Table 1: ingredient content and microwave dielectric Properties of the examples
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