Microwave dielectric ceramic K2SnW4O15 with ultralow dielectric constant

Abstract

The invention discloses a microwave dielectric ceramic K2SnW4O15 with an ultralow dielectric constant and a near-zero resonance frequency temperature coefficient and a preparation method of the microwave dielectric ceramic. The preparation method comprises the following steps: (1) weighing and burdening original powder of K2CO3, SnO2 and WO3 with the purity more than 99.9% (in percentage by weight) according to constituents of K2SnW4O15; (2) using a wet ball mill to mix the raw materials in the step (1) for 12 hours, adding distilled water as a ball milling medium in the ball mill, after drying, preburning the dried substance in the atmosphere at 750 DEG C for 6 hous; (3) adding a binding agent to the powder prepared in the step (2), pelletizing, carrying out compression molding on the pellets, and finally sintering the molded product for 4 hours in the atmosphere at 820-840 DEG C, wherein the binding agent is a polyvinyl alcohol solution with a mass concentration of 5%; the addition amount of the polyvinyl alcohol is 3% of the total mass of the powder. The ceramic prepared by the invention is well sintered at 820-840 DEG C; the dielectric constant of the ceramic is up to 7.4-8.2, the Qf (quality factor) is highly up to 57100-59600 GHz; the resonance frequency temperature coefficient is close to zero; the ceramic has the great application value in the industry.

Description

technical field [0001] The invention relates to a dielectric ceramic material, in particular to a dielectric ceramic material used for manufacturing microwave components such as ceramic dielectric substrates, resonators and filters, and a preparation method thereof. Background technique [0002] Microwave dielectric ceramics refer to ceramics that are used as dielectric materials in circuits in the microwave frequency band (mainly UHF and SHF bands) and perform one or more functions. They are widely used as resonators, filters, and dielectric substrates in modern communications. Components such as chips and dielectric waveguide circuits are the key basic materials of modern communication technology. They have been used in portable mobile phones, car phones, cordless phones, TV satellite receivers and military radars. They are used in modern communication tools. It is playing an increasingly important role in the process of miniaturization and integration. [0003] Dielectri...

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Problems solved by technology

[0009] In the process of exploring and developing new low-firing microwave dielectric ceramic materials, material systems such as Li-based compounds, Bi-based compounds, tungstate compounds and tellurate-based compounds with inherently low sintering temperatures have received extensive attention and research. However, due to the three performance indicators of microwave dielectric ceramics (ε r with Q f and τ ? ) is a mutually restrictive relationship (see literature: The restrictive relationship between the dielectric properties of microwave dielectric ceramic materials, Zhu Jianhua, Liang Fei, Wang Xiaohong, Lu Wenzhong, Electronic Components and Materials, Issue 3, March 2005), satisfying three There are very few single-phase microwave dielectric ceramics that require high performance and can be sintered at low temperature, mainly because their resonant frequency temperature coefficient is usually too large or the quality factor is too low to be practically produced and applied.

At present, most of the research on microwave dielectric ceramics is a summary of experience obtained through a large number of experiments, but there is no complete theory to explain the relationship between microstructure and dielectric properties. Predict the microwave dielectric properties such as its resonant frequency temperature coefficient and quality factor, which largely limits the development of low temperature co-firing technology and microwave multilayer devices

For example, the low-temperature sinterable ultra-low dielectric constant microwave dielectric ceramics recorded in the current prior art are usually unable to be practical because the temperature coefficient of resonance frequency is too large in the negative direction (the temperature coefficient of resonance frequency of such microwave dielectric ceramics Usually in the range τ ? ≤-30ppm / ℃)

Explore and develop low-temperature sintering and near-zero resonant frequency temperature coefficient (-10 ppm / ℃≤τ ? ≤+10 ppm / ℃) and high quality factor (Q×f≥50000GHz) ultra-low dielectric constant microwave dielectric ceramics is a problem that those skilled in the art have been eager to solve but have always been difficult to succeed

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