Temperature-stable low-dielectric-constant microwave dielectric ceramic Bi2LaNbTiO9 and preparation method thereof

Abstract

The invention discloses temperature-stable low-dielectric-constant microwave dielectric ceramic Bi2LaNbTiO9 and a preparation method thereof. Firstly, chemical raw materials of Bi2O3, La2O3, Nb2O5 and TiO2 powder are weighed and matched according to the stoichiometric equation of Bi2LaNbTiO9; secondly, the raw materials in the first step are mixed for 12 h in a wet ball mill, ball-milling media are distilled water, and pre-sintering is performed in a 900 DEG C atmosphere for 6 h after drying; thirdly, an adhesion agent is added in the powder prepared in the second step, compression molding is performed after pelletizing, and finally, sintering is performed in a 950-980 DEG C atmosphere for 4 h; the adhesion agent is prepared from a polyvinyl alcohol solution with the mass concentration being 5%, and the adding amount of polyvinyl alcohol accounts for 3% of total mass of the powder. The prepared ceramic is good in sintering performance at the temperature of 1000 DEG C, the dielectric constant reaches 33.2-34.5, the quality factor Qf of the ceramic reaches as high as 51900-66100 GHz, the resonance frequency temperature coefficient is small, and the ceramic has great industrial application value.

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...

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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 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

We are against Bi 2 LaNbTiO 9 、 Bi 2 SmNbTiO 9 and Bi 2 NdNbTiO 9 A series of compounds have been studied on the microwave dielectric properties, and it is found that their sintering temperature is lower than 1000 ° C, where Bi 2 SmNbTiO 9 The loss is too large to find the resonant peak, while Bi 2 NdNbTiO 9 The loss is small but the resonant frequency temperature coefficient is too large (τ ? =69ppm / ℃) and cannot be used as a practical microwave dielectric ceramic

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