Ultra-low dielectric constant microwave dielectric ceramic li2zn2si2o7 and its preparation method

Abstract

The invention discloses temperature-stable type ultralow-dielectric-constant dielectric ceramic Li2Zn2Si2O7 and a preparation method thereof. The preparation method comprises: (1) weighing original powders of Li2CO3, ZnO and SiO2 with the purity of 99.9 wt% or more according to the formula of Li2Zn2Si2O7 and proportioning; (2) performing wet-type ball milling mixing on the raw materials of the step (1) for 12 h by selecting distilled water as a ball milling medium, baking and pre-burning at 850 DEG C in atmosphere for 6 h; and (3) adding a binder into the powder prepared in the step (2) and granulating, then performing compression molding, and finally sintering at 900-930 DEG C in atmosphere for 4 h, wherein the binder employs a polyvinyl alcohol solution with the mass concentration of 5% and the addition amount of polyvinyl alcohol is 3% by mass of the total powder. The prepared ceramic has good sintering at 900-930 DEG C, has the dielectric constant up to 11.1-11.9, has the quality factor Qf up to 110000-132000 GHz, has a small resonant-frequency temperature coefficient, and has extremely great 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 ? ) 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 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

Exploring and developing microwave dielectric ceramics that can be sintered at low temperature and have near-zero resonant frequency temperature coefficient (-10ppm / ℃≤τ?≤+10ppm / ℃) and high quality factor is the technology in this field A difficult problem that people have always wanted to solve but have never been able to succeed in

[0010] We pair Li 2 Zn 2 Si 2 o 7 , Li 2 Zn 2 Ti 2 o 7 , Li 2 Mg 2 Si 2 o 7 , Li 2 Mg 2 Ti 2 o 7 A series of compounds have been studied on the microwave dielectric properties and found that their sintering temperature is lower than 950 °C, but only Li 2 Zn 2 Si 2 o 7 With near-zero resonant frequency temperature coefficient and high quality factor, Li 2 Zn 2 Ti 2 o 7 , Li 2 Mg 2 Si 2 o 7 and Li 2 Mg 2 Ti 2 o 7 Ceramic resonant frequency temperature coefficient τ ? Too large (+78ppm / °C, +29ppm / °C and +56ppm / °C, respectively) and cannot be used as a practical microwave dielectric ceramic

Images