Low-loss temperature stabilized microwave dielectric ceramic LiMg3NbWO9

Abstract

The invention discloses low-temperature sinterable temperature-stabilized microwave dielectric ceramic LiMg3NbWo9 with ultralow dielectric constant and a preparation method thereof. The preparation method comprises the following steps: (1) weighing and preparing the original powder of Li2CO3, MgO, WO3 and Nb2O5 with the purity of more than 99.9% by weight according to the constitution of LiMg3NbWO9; (2) carrying out wet-type ball milling and mixing on the raw materials of step (1) for 12 hours, and baking and pre-sintering for 6 hours at 900 DEG C under an air atmosphere, wherein the ball milling medium is distilling water (3) adding a bonder into the powder prepared from step (2) and granulating, carrying out compression moulding and sintering for 4 hours at 950-990 DEG C under an air atmosphere, wherein the bonder is 5wt% of the polyvinyl alcohol solution and the adding amount of the polyvinyl alcohol is 3% of the total weight of the powder. The ceramic prepared by the invention is well sintered below 1000 DEG C, the dielectric constant is 9.0-9.7, the quality factor Qf value reaches up to 110000-147000 GHz, the temperature coefficient of resonance frequency is small and the ceramic has a huge industrial application value.

Description

Technical field [0001] The invention relates to a dielectric ceramic material, in particular to a dielectric ceramic material used 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 and perform one or more functions in circuits in the microwave frequency band (mainly UHF and SHF frequency bands). They are widely used as resonators, filters, and dielectric substrates in modern communications. Chips and dielectric guided wave 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. The process of miniaturization and integration is playing an increasingly important role. [0003] The diele...

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] Our composition of LiMg 3 wxya 9 、LiZn 3 wxya 9 、LiCu 3 wxya 9 A series of compounds have been studied on the microwave dielectric properties and found that their sintering temperature is lower than 1000 ° C, but only LiMg 3 wxya 9 With near-zero resonant frequency temperature coefficient and high quality factor, LiZn 3 wxya 9 Ceramic resonant frequency temperature coefficient τ ? Too large (-49 ppm / ℃ respectively) and the dielectric loss is too high to be used as a practical microwave dielectric ceramic

Images