Microwave dielectric ceramic Li3NdWO6 with ultralow dielectric constant and preparation method thereof

Abstract

The invention discloses a temperature stable ultralow dielectric constant microwave dielectric ceramic Li3NdWO6 capable of being sintered at a low temperature and a preparation method thereof. The preparation method comprises the steps of (1) weighing and proportioning original powder of Li2CO3, Nd2O3 and WO3 of which the purities are more than 99.9 weight percent according to the composition of Li3NdWO6; (2) performing wet ball milling and mixing on the raw materials of the step (1) for 12 hours by adopting a ball milling medium which is distilled water, drying, and then pre-sintering in atmosphere of 700 DEG C for 6 hours; and (3) adding an adhesive into the powder prepared in the step (2), granulating, pressing, molding, and finally, sintering in atmosphere of 750-800 DEG C for 4 hours, wherein the adhesive is a polyvinyl alcohol solution of which the mass concentration is 5%, and the adding quantity of the polyvinyl alcohol accounts for 3% of the total mass of the powder. The prepared ceramic is well sintered at 750-800 DEG C, the dielectric constant reaches 14.1-14.9, the quality factor (Qf) value is up to 71,000-92,000GHz, and the temperature coefficient of resonance frequency of the ceramic is small, so the ceramic has 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 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

Explore and develop low-temperature sintering and near-zero resonant frequency temperature coefficient (-10 ppm / ℃≤τ ? ≤+10 ppm / ℃) 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

[0010] We pair Li 3 LaWO 6 , Li 3 wxya 6 , Li 3 wxya 6 , Li 3 EuWO 6 A series of compounds have been studied on the microwave dielectric properties and found that their sintering temperature is lower than 900 ° C, but only Li 3 wxya 6 With near-zero resonant frequency temperature coefficient and high quality factor, Li 3 wxya 6 and Li 3 EuWO 6 Ceramic resonant frequency temperature coefficient τ ? too large (+21 ppm / °C and +39 ppm / °C, respectively), while Li 3 LaWO 6 The loss is too large to be used as a microwave dielectric ceramic

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