Ultralow-loss yttrium aluminum garnet microwave dielectric ceramic material and preparation method thereof

Abstract

The invention provides an ultralow-loss yttrium aluminum garnet microwave dielectric ceramic material, the chemical general formula of the material is Y3-xAl5-yRzO12, and R is one or more selected from Mg < 2 + >, Ga < 3 + >, Si < 4 + >, Ti < 4 + > and Nb < 5 + > heterovalent ions; 0 < = x < = 0.15, 0 < = y < = 0.8 and 0.03 < = z < = 1.5; the invention also provides a preparation method of the ultralow-loss yttrium aluminum garnet microwave dielectric ceramic material. The preparation method comprises the following steps: burdening, ball milling, drying and sieving, presintering, dry pressing,isostatic cool pressing, vacuum sintering and atmosphere control annealing. The prepared material is typical ultralow-loss garnet type aluminum-based microwave dielectric ceramic, Q * f ranges from 180000 GHz to 220000 GHz, the relative dielectric constant epsilonr ranges from 8 to 12, and the frequency temperature coefficient tauf ranges from -33 ppm / DEG C to -22 ppm / DEG C. The formula does notcontain volatile toxic metals such as Pb, Cd and the like, the performance is stable, and the raw materials are sufficiently supplied in China, so that the low cost of the high-performance microwave ceramic becomes possible.

Description

technical field [0001] The invention belongs to the technical field of preparation of electronic information functional materials, and relates to a microwave dielectric ceramic material with ultra-high Q value obtained by regulating the non-stoichiometric ratio of yttrium-aluminum garnet and the content of additives and a preparation method thereof. Background technique [0002] Microwave dielectric ceramics refer to ceramics that are used as dielectric materials in microwave (300MHz~300GHz) frequency band circuits and perform one or more functions. They are key basic materials in modern communication technology and are widely used in dielectric resonators and filters. , dielectric substrate, dielectric waveguide circuit, microwave capacitor, duplexer, antenna and other microwave components. In high-frequency microwave circuits, many microwave devices need to use dielectric ceramic materials as substrates, making microwave ceramic dielectric substrate materials increasingly ...

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Problems solved by technology

And by doping 1wt% Nb2O5, the microwave dielectric properties of yttrium aluminum garnet microwave are partially improved: εr= 11.2, Q×f=120000GHz, τf=-48ppm / ℃, the value of Q×f has been significantly improved, but the value of Q×f is still low, because the relative density of this sample is too high The low is only 96%, there are a lot of pores inside, resulting in serious dielectric loss

Later, "Journal of the European Ceramic Society" (Journal of the European Ceramic Society) 2015 article "SPS sintering parameters, LiF additives and Nd doping on the microwave dielectric and optical properties of transparent YAG ceramics" (Effect of the spark plasma sintering parameters, LiF additive, and Nd dopant on the microwavedielectric and optical properties of transparent YAG ceramics) reported that nano-YAG powder was prepared by thermal decomposition, and then co-doped with TEOS and TiO2, in 1520 Sintered at ℃ for 5 hours to obtain yttrium aluminum garnet microwave dielectric ceramics, the relative density is 97.6%, and the microwave dielectric properties are: εr=9.9, Q×f=71700GHz, τf=-30ppm / ℃, the relative density and performance have not been significantly improved

[0005] It can be seen from this that in the above-mentioned research on YAG microwave dielectric ceramics, whether the traditional solid-state reaction method is used or the micron-submicron ceramic powder is obtained by ball milling It is still difficult to prepare high-quality YAG ceramics with high relative density (≥99.5%), no porosity, and few impurities, or the preparation of nano-powder by wet chemical method, resulting in low Q×f value (≤120000GHz)

, Not only that, because YAG is a stoichiometric crystal, its ratio is very precise, Y / Al=3 / 5, so it is very difficult to prepare YAG ceramics, which will lead to non-stoichiometric materials during the preparation process

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