Temperature-stable ultralow dielectric-constant microwave dielectric ceramic Na2ZnMo2O8 and preparation method thereof

Abstract

The invention discloses a temperature-stable ultralow dielectric-constant microwave dielectric ceramic Na2ZnMo2O8 and a preparation method thereof. The preparation method comprises the steps of (1) weighing chemical raw materials including Na2CO3 powder, ZnO powder and MoO3 powder according to the stoichiometric equation Na2ZnMo2O8, and proportioning; (2) carrying out wet-type ball milling on the raw materials in the step (1), mixing for 12 hours, and pre-sintering in the atmosphere with the temperature of 850 DEG C for 6 hours after drying, wherein the ball milling medium is distilled water; and (3) adding an adhesive into the powder prepared in the step (2), granulating, then, carrying out compression molding, and finally, sintering at the atmosphere with the temperature of 900-950 DEG C for 4 hours, wherein the adhesive is a polyvinyl alcohol solution with the concentration of 5%, and the addition dosage of polyvinyl alcohol accounts for 3% of the total mass of the powder. The ceramic disclosed by the invention is good in sintering property at the temperature of lower than 960 DEG C, high in quality factor Qf value up to 67000-83000GHz, small in resonance frequency temperature coefficient and extremely high in application value in industry and has the dielectric constant of 13.4-14.1.

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 to Na 2 ZnM 2 o 8 、Na 2 wxya 2 o 8 、Na 2 Zn 2 Mo 2 o 9 A series of compounds have been studied on the microwave dielectric properties, and it is found that their sintering temperature is lower than 960 ° C, where Na 2 Zn 2 Mo 2 o 9 The loss is too large to find the resonant peak, while Na 2 wxya 2 o 8 The loss is small but the resonant frequency temperature coefficient is too large (τ ? =-61ppm / ℃) and cannot be used as a practical microwave dielectric ceramic

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