Microwave dielectric ceramic Li4La3Nb3O14 with medium dielectric coefficient and preparation method of microwave dielectric ceramic Li4La3Nb3O14

Abstract

The invention discloses low-temperature sintered temperature-stable type microwave dielectric ceramic Li4La3Nb3O14 with a medium dielectric coefficient and a preparation method of the microwave dielectric ceramic Li4La3Nb3O14. The preparation method comprises steps as follows: (1), original powder of Li2CO3, La2O3 and Nb2O5 with the purity higher than 99.9% in percentage by weight is weighed in the composition proportion of Li4La3Nb3O14 and mixed; (2), the raw material in the step (1) is subjected to wet type ball milling and mixing in distilled water serving as a ball milling medium for 12 hours and pre-sintered for 6 hours in an air atmosphere with the temperature of 850 DEG C after being dried; (3), a binder is added to powder prepared in the step (2), the mixture is granulated, pressed to be shaped and sintered for 4 hours in the air atmosphere with the temperature ranging from 900 DEG C to 950 DEG C, the binder adopts a polyvinyl alcohol solution with the mass concentration being 5%, and the adding quantity of the polyvinyl alcohol solution accounts for 3% of the total mass of the powder. The prepared ceramic is well sintered under 960 DEG C, the dielectric coefficient reaches 36.1-37.2, the Qf (quality factor) of the ceramic is as high as 55,000-73,000 GHz, the temperature coefficient of resonance frequency is low, and the ceramic has 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 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. [0003] Dielectr...

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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 mutually 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

Exploring and developing microwave dielectric ceramics that can be sintered at low temperature and have near-zero resonant frequency temperature coefficient (-10ppm / ℃≤τ?≤+10ppm / ℃) and high quality factor is the technology in this field A difficult problem that people have always wanted to solve but have never been able to succeed in

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