High-quality-factor stable-temperature microwave dielectric ceramic LiFeGe2O6

Abstract

The invention discloses high-quality-factor stable-temperature ultralow dielectric constant microwave dielectric ceramic LiFeGe2O6 and a preparation method thereof. The preparation method comprises the following steps: (1) weighing and proportioning original powder (with the purity of 99.9% or above by weight) of Li2CO3, Fe2O3 and GeO2 according to composition of LiFeGe2O6; (2) performing wet-type ball-milling and mixing on the raw materials obtained in the step (1) for 12 h, drying and then pre-burning for 6 h in the atmosphere of 1100 DEG C, wherein the ball-milling medium is distilled water; (3) adding a binder into the powder prepared in the step (2), pelletizing, then pressing for shaping, and finally, sintering for 4 h in the atmosphere of 1,150-1,200 DEG C, wherein the binder is a polyvinyl alcohol solution with the mass concentration of 5%, and polyvinyl alcohol accounts for 3% of the total mass of the powder. The prepared high-quality-factor stable-temperature microwave dielectric ceramic LiFeGe2O6 has excellent sintering performance below 1,200 DEG C, has the dielectric constant of 6.5-6.9 and the quality factor Qf of 80,000-101,000 GHz, is small in temperature coefficient of resonance frequency and has an extremely high application value in the industry.

Description

technical field [0001] The invention relates to a dielectric ceramic material, in particular to a dielectric ceramic material for manufacturing microwave components such as ceramic substrates, resonators and filters used in microwave frequencies 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. [00...

AI Technical Summary

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 f ) is a mutual 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 meet the practical application requirements.

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

Exploration and development can not only sinter at low temperature but also have near-zero resonance frequency temperature coefficient (-10ppm / ℃≤τ f ≤+10ppm / °C) and high quality factor microwave dielectric ceramics are difficult problems that those skilled in the art have been eager to solve but have always been difficult to achieve

Our pair composition is LiFeGe 2 o 6 、LiAlGe 2 o 6 and LiBGe 2 o 6 The sintering and microwave dielectric properties of the ceramics were studied, and it was found that their sintering temperature was lower than 1200 ° C. Among them, LiFeGe 2 o 6 With near-zero resonant frequency temperature coefficient and high quality factor, LiAlGe 2 o 6 and LiBGe 2 o 6 Ceramics are semiconductors with large dielectric loss and no resonance peak, so they cannot be used as practical microwave dielectric ceramics

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