Low-loss temperature-stable microwave dielectric ceramic LiBSi3O8

Abstract

The invention discloses low-loss temperature-stable ultralow-dielectric-constant microwave dielectric ceramic LiBSi3O8 and a preparation method thereof. The preparation method includes: (1), weighing and blending original powder of Li2CO3, B2O3 and SiO2 higher than 99.9% (weight percent) in purity according to composition of LiBSi3O8; (2), subjecting raw materials of the step (1) to wet ball-milling and mixing for 12h, drying, and pre-sintering in an atmosphere of 1100 DEG C for 6h, wherein a ball-milling medium is distilled water; (3), adding a binder into powder obtained in the step (2), granulating, pressing for forming, and sintering in an atmosphere of 1150-1200 DEG C for 4h, wherein polyvinyl alcohol solution of 5% in mass concentration is adopted as the binder, and adding amount of polyvinyl alcohol accounts for 3% of total weight of the powder. The ceramic prepared by the method is good in sintering performance at temperature below 1200 DEG C, dielectric constant reaches 6.1-6.6, quality factor Qf of the ceramic is up to 74000-107000GHz, resonant frequency temperature coefficient is low, and the ceramic has huge application value in 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 LiBSi 3 o 8 , LiAlSi 3 o 8 with LiInSi 3 o 8 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 which LiBSi 3 o 8 With near-zero resonant frequency temperature coefficient and high quality factor, LiAlSi 3 o 8 with LiInSi 3 o 8 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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