Application of compound oxide NaAl3Ca2Sb2O12 in serving as temperature-stable type microwave dielectric ceramic

Abstract

The invention discloses application of compound oxide NaAl3Ca2Sb2O12 in serving as temperature-stable type microwave dielectric ceramic and a preparation method of the compound oxide. The preparation method comprises the following steps: (1) weighing and proportioning chemical raw materials, i.e. Na2CO3, Al2O3, CaCO3 and Sb2O5 powder, according to the chemical formula NaAl3Ca2Sb2O12; (2) performing wet type ball grinding on the raw materials in the step (1) for mixing for 12 hours through distilled water serving as a ball grinding medium, drying the materials, and pre-sintering in the air atmosphere at the temperature of 1,100 DEG C for 6 h; (3) adding an adhesive into the powder obtained in the step (2), performing granulation and pressing molding in sequence, and finally sintering in the air atmosphere at the temperature of 1,150 to 1,200 DEG C for 4 hours, wherein the adhesive is a polyvinyl alcohol solution with the mass concentration of 5 percent, and the adding amount of polyvinyl alcohol is 3 percent of the total mass of the powder. The ceramic prepared by the method disclosed by the invention can be well sintered at the temperature of 1,200 DEG C or below; the dielectric constant is 8.4 to 8.9, and the quality factor Qf is 77,100 to 88,400 GHz; the resonant frequency and the temperature coefficient are small; the compound oxide NaAl3Ca2Sb2O12 has extremely high 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...

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Problems solved by technology

[0008] 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 requirements of practical applications.

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

We have a non-garnet structure with a composition of NaAl 3 Ca 2 Sb 2 o 12 、NaAl 3 Ca 2 V 2 o 12 with NaAl 3 Ca 2 Nb 2 o 12 The ceramics were sintered and microwave dielectric properties were studied, and it was found that their sintering temperature was lower than 1200 ° C, but only NaAl 3 Ca 2 Sb 2 o 12 With near-zero resonant frequency temperature coefficient and high quality factor, NaAl 3 Ca 2 Nb 2 o 12 As a semiconductor, the dielectric loss in the microwave frequency band is too large to be used as a practical microwave dielectric ceramic, NaAl 3 Ca 2 V 2 o 12 The resonant frequency temperature coefficient is -64ppm / ℃, and it cannot be used as a practical microwave dielectric ceramic

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