Ultra-low dielectric constant temperature-stable type microwave dielectric ceramic Li2TiSi6O15

Abstract

The invention discloses an ultra-low dielectric constant temperature-stable type microwave dielectric ceramic Li2TiSi6O15 and a preparation method thereof. The preparation method comprises the following steps: (1) weighing and preparing Li2CO3, TiO2 and SiO2 raw powder with the purity of more than or equal to 99.9wt% according to the composition of the Li2TiSi6O15; (2) performing wet type ball milling and mixing on raw materials in the step (1) for 12 hours through a ball milling medium of distilled water, drying and preburning for 6 hours in the air atmosphere at a temperature of 990 DEG C; and (3) adding a binder into the powder obtained in the step (2), granulating, performing pressure forming, and finally sintering for 4 hours in the air atmosphere at a temperature of 1040-1090 DEG C, wherein a 5wt% polyvinyl alcohol solution is adopted as the binder, and the addition amount of the polyvinyl alcohol accounts for 3% of total mass of the powder. The prepared ceramic is well sintered at 1100 DEG C below, the dielectric constant is up to 9.1-9.6, the quality factor Qf value is up to 160000-197000 GHz, the resonance frequency temperature coefficient is small, and the ultra-low dielectric constant temperature-stable type microwave dielectric ceramic Li2TiSi6O15 has great application values industrially.

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 2 TiSi 6 o 15 , Li 2 ZrSi 6 o 15 , Li 2 GeSi 6 o 15 A series of compounds have been studied on the microwave dielectric properties and found that their sintering temperature is lower than 1100 °C, but only Li 2 TiSi 6 o 15 With near-zero resonant frequency temperature coefficient and high quality factor, Li 2 ZrSi 6 o 15 and Li 2 GeSi 6 o 15 Ceramic resonant frequency temperature coefficient τ ? Too large (- 29 ppm / °C and + 48 ppm / °C, respectively) to be used as a practical microwave dielectric ceramic

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