High-quality factor low-dielectric constant microwave dielectric ceramic SrLiLaW2O9

Abstract

The invention discloses temperature-stable low-dielectric constant microwave dielectric ceramic SrLiLaW2O9 and a preparation method thereof, wherein the microwave dielectric ceramic can be sintered at a low temperature. The preparation method comprises the following steps: (1) weighing original powder of SrCO3, Li2CO3, La2O3 and WO3 according to the composition of SrLiLaW2O9 for compounding, wherein the purities are 99.9 percent or higher by weight percent; (2) conducting wet ball mill mixing on the raw materials obtained in the step (1) for 12 hours, carrying out drying, and pre-burning the dried mixture in a 800 DEG C air atmosphere for 6 hours, wherein distilled water is taken as a ball mill medium; (3) adding a binder into the powder obtained in the step (2), carrying out pelleting and pressure molding, and sintering in a 850 to 900 DEG C air atmosphere for 4 hours, wherein the binder adopts a polyvinyl alcohol solution of which the mass concentration is 5 percent, and the add amount of the polyvinyl alcohol solution is 3 percent of the total weight of the powder. The microwave dielectric ceramic prepared according to the preparation method can be well sintered at 900 DEG C or a lower temperature, reaches 23.1 to 23.7 in dielectric constant and 89000 to 126000 GHz in quality factor Qf, is low in temperature coefficient of resonance frequency, and has a very high 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...

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 pair composition SrLiLaW 2 o 9 、SrLiNdW 2 o 9 、BaLiLaW 2 o 9 、SrLiBiW 2 o 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 SrLiLaW 2 o 9 With near-zero resonant frequency temperature coefficient and high quality factor, SrLiNdW 2 o 9 Ceramic resonant frequency temperature coefficient τ ? It is too large (-29 ppm / ℃) and the dielectric loss is also high, so it cannot be used as a practical microwave dielectric ceramic

BaLiLaW 2 o 9 and SrLiBiW 2 o 9 As an ionic conductor, the loss in the microwave frequency band is too large to find the resonance peak

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