Temprature-stable type microwave dielectric ceramic Li2CuSnO4 with ultralow dielectric constant

Abstract

The invention discloses temprature-stable type microwave dielectric ceramic Li2CuSnO4 with an ultralow dielectric constant and a preparation method thereof. The preparation method comprises: (1) weighing original powder of Li2CO3, CuO and SnO2, with the purity being 99.9 weight percent or above, according to the composition of the Li2CuSnO4; (2) mixing the raw materials of the step (1) for 12 hours by adopting a wet type ball mill, wherein a ball milling medium is distilled water; after drying, pre-sintering in the air atmosphere at 1100 DEG C for 6 hours; (3) adding a binding agent into powder prepared by the step (2) and granulating; pressing and molding; finally, sintering in the air atmosphere at 1150 DEG C to 1200 DEG C for 4 hours, wherein the binding agent is a polyvinyl alcohol solution with the mass concentration of 5 percent and the adding amount of polyvinyl alcohol accounts for 3 percent of the total mass of the powder. The ceramic prepared by the preparation method can be sintered at a temperature lower than 1200 DEG C very well and the dielectric constant reaches 16.2 to 16.9; the quality factor Qf value reaches 62000GHz to 89000GHz; the temperature coefficient of resonance frequency is small and the ceramic has extremely 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 f ) 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

Exploration and development can not only sinter at low temperature but also have near-zero resonance frequency temperature coefficient (-10ppm / ℃≤τ f ≤+10ppm / °C) 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

Our pair group becomes Li 2 CuSnO 4 and Li 2 ZnSnO 4 The sintering and microwave dielectric properties of the ceramics were studied, and it was found that their sintering temperature was lower than 1250 °C, where Li 2 CuSnO 4 With near-zero resonance frequency temperature coefficient and high quality factor; Li 2 ZnSnO 4 Ceramic is a semiconductor, and its dielectric loss is too large in the microwave frequency range, so it cannot be used as a microwave dielectric ceramic

Images