Temperature-stable middle-dielectric-constant microwave dielectric ceramic CaTiNbBiO7 and preparation method thereof

Abstract

The invention discloses low-loss temperature-stable middle-dielectric-constant microwave dielectric ceramic CaTiNbBiO7 and a preparation method thereof. The method comprises the steps that 1, the chemical raw materials of CaCO3, TiO2, Nb2O5 and Bi2O3 powder are weighed and matched according to a stoichiometric formula CaTiNbBiO7; 2, wet ball milling and mixing are conducted on the raw materials obtained in the first step for 12 h, a ball milling medium adopts distilled water, and after drying is conducted, presintering is conducted for 6 h in the air atmosphere of 950 DEG C; 3, a binding agent is added to powder obtained in the second step, granulation is conducted, pressing forming is conducted, and sintering is conducted for 4 h in the air atmosphere of 1,025-1,075 DEG C. The binding agent adopts a polyvinyl alcohol solution with the mass concentration of 5%, and the addition amount of polyvinyl alcohol accounts for 3% of the total mass of the powder. According to the low-loss temperature-stable middle-dielectric-constant microwave dielectric ceramic CaTiVBiO7 and the preparation method thereof, the prepared ceramic is sintered well at 1,100 DEG C or below, the dielectric constant reaches 35.2-36.5, the value of the quality factor Qf reaches up to 48,900-56,100 GHz, the temperature coefficient of the resonant frequency is small, and the microwave dielectric ceramic has 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 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

Our analysis of CaTiNbBiO 7 、CaTiTaBiO 7 and SrTiNbBiO 7 A series of compounds have been studied on the microwave dielectric properties, and their sintering temperature is found to be lower than 1100 °C, among which SrTiNbBiO 7 The loss is too large to find the resonance peak, while CaTiTaBiO 7 The loss is small but the resonant frequency temperature coefficient is too large (τ ? =46ppm / ℃) and cannot be used as a practical microwave dielectric ceramic

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