High-quality factor ultralow-dielectric constant microwave dielectric ceramic Li2Mg2V8O23

Abstract

The invention discloses a high-quality factor temperature-stabilizing ultralow-dielectric constant microwave dielectric ceramic Li2Mg2V8O23 capable of being sintered at low temperatures as well as a preparation method thereof. The preparation method comprises the following steps: (1) weighing and proportioning original powder of Li2CO3, MgO and V2O5 with the purity over 99.9wt% according to composition of Li2Mg2V8O23; (2) wet-bal-milling and mixing the raw materials in the step (1) for 12 hours, wherein a ball-milling medium is distilled water, and drying and pre-sintering for 6 hours in an air atmosphere of 750 DEG C; (3) adding an adhesive into the powder prepared in the step (2) and granulating, then pressing and moulding, an finally sintering for 4 hours in an air atmosphere at 800-850 DEG C, wherein the adhesive is a 5% (mass concentration) polyvinyl alcohol solution and the additive amount of polyvinyl alcohol accounts for 3% of the total mass of the powder. The ceramic disclosed by the invention is well sintered at 850 DEG C, the dielectric constant reaches 17.4-17.9, the quality factor Of value reaches up to 110000-141000 GHz, and the temperature coefficient of resonance frequency is small. 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 in microwave frequency (mainly UHF and SHF frequency bands) circuits as dielectric materials and complete one or more functions. They are widely used in modern communications as resonators, filters, dielectric bases Components such as chips and dielectric guided wave loops are the key basic materials of modern communication technology. They have been widely used in portable mobile phones, car phones, cordless phones, TV satellite receivers and military radars. They are widely used in modern communication tools. It is playing an increasingly important role in the process of miniaturization and integration....

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 Mg 2 V 8 o 23 , Li 2 Cu 2 V 8 o 23 , Li 2 Ni 2 V 8 o 23 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 2 Mg 2 V 8 o 23 With near-zero resonant frequency temperature coefficient and high quality factor, Li 2 Ni 2 V 8 o 23 Ceramic resonant frequency temperature coefficient τ ? It is too large (-71 ppm / ℃) and the dielectric loss is also high, so it cannot be used as a practical microwave dielectric ceramic