Low dielectric constant microwave dielectric ceramic NaBi2Sb3O11 capable of being sintered at low temperatures

Abstract

The invention discloses a low dielectric constant microwave dielectric ceramic NaBi2Sb3O11 capable of being sintered at low temperatures and a preparation method of the ceramic. The preparation method comprises the following steps: (1) weighing and dosing original powder of Na2CO3, Bi2O3 and Sb2O5 with the purities which are over (99.9wt%) based on composition of NaBi2Sb3O11; (2) carrying out wet type ball-mill mixing on the raw material for 12 hours, wherein the ball-milling medium is distilled water, and pre-sintering for 6 hours in atmosphere at 850 DEG C after being dried; and (3) adding an adhesive into the power prepared by the step (2) and granulating, then compression-moulding, and finally sintering for 4 hours in atmosphere at 900-930 DEG C, wherein the adhesive is a 5% polyvinyl alcohol solution, the addition of polyvinyl alcohol accounts for 3% of total weight of the powder. The ceramic disclosed by the invention is well sintered at 900-930 DEG C, and the dielectric constant reaches 28.4-29.3, the quality factor Qf value reaches 59600-64200GHz, and the temperature coefficient of resonance frequency is small, so that the ceramic has extremely huge 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 be practically produced and applied.

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

For example, the low-permittivity microwave dielectric ceramics that can be sintered at low temperature in the current prior art are usually unable to be applied to LTCC technology due to their large temperature coefficient of resonance frequency and high sintering temperature.

Explore and develop low-temperature sintering (sintering temperature lower than 1000°C) and near-zero resonant frequency temperature coefficient (τ ? ≈0) and high quality factor (Q×f≥50000GHz) microwave dielectric ceramics with low dielectric constant is a difficult problem that those skilled in the art have been eager to solve but have always been difficult to achieve

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