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Microwave adjustable dielectric barium strontium titanate/bismuth zinc niobate composite film and its preparation method

A technology of barium strontium titanate film and barium strontium titanate, which is applied in ceramics, inorganic insulators, etc., can solve the problems of high coercive field strength, low electrical quality factor, unfavorable device application, etc., and achieves good temperature stability. Effect

Inactive Publication Date: 2008-05-07
XI AN JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Barium strontium titanate thin film material has a high dielectric constant and large dielectric tunable characteristics, but its dielectric loss (tanδ) is relatively high, resulting in a low electrical quality factor Q (=1 / tanδ), which affects Focusing on the application of barium strontium titanate film in tunable microwave devices, researchers from various countries are currently trying to solve these problems by doping and replacing barium strontium titanate, for example, by doping oxides such as magnesium oxide (MgO) It can reduce the dielectric loss of barium strontium titanate very well, but at the cost of sacrificing the tunable characteristics of the material, which reduces the tunable characteristics and quality factor of the film
Bismuth-zinc-niobium thin film material is a newly discovered material with tunable properties in recent years. It has very low dielectric loss, relatively moderate dielectric constant, and good microwave dielectric tunable properties, but its coercive field strength is relatively high. , is not conducive to device application

Method used

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Examples

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Effect test

preparation example Construction

[0019] The preparation process of barium strontium titanate and bismuth-zinc-niobium precursor solutions are the same

[0020] 1. Preparation of barium strontium titanate precursor solution: using analytically pure strontium acetate, barium acetate, and tetrabutyl titanate as raw materials, glacial acetic acid as solvent, and acetylacetone as chelating stabilizer to synthesize barium strontium titanate precursor solution , First according to the chemical composition as Ba 0.5 Sr 0.5 TiO 3 Dissolve barium acetate and strontium acetate that meet the stoichiometric ratio in glacial acetic acid, stir well at 80°C for 30 minutes, mix tetrabutyl titanate and acetylacetone at a molar ratio of 2:1, and then add the mixed solution of barium acetate And stir at room temperature for 30 minutes to finally obtain a clear barium strontium titanate precursor solution with a concentration of 0.4 mol / L;

[0021] 2. Preparation of bismuth-zinc-niobium precursor solution: using analytically pure nio...

Embodiment 1

[0025] On the Pt-plated silicon wafer, a layer of barium strontium titanate film is first deposited by a spin coating process, and fast heat-treated at 650° C. for 3 minutes to obtain a barium strontium titanate film with a cubic perovskite structure. Then, a layer of bismuth-zinc-niobium film is deposited on the barium strontium titanate film, and the bismuth-zinc-niobium film with cubic pyrochlore structure is obtained by rapid heat treatment at 700°C for 3 minutes. Repeat the above process to finally obtain a six-layer composite film with three layers of barium strontium titanate and three layers of bismuth zinc niobium. The thickness is 0.5μm, and the surface is smooth without cracks. The crystalline phase structure also contains cubic pyrochlore phase bismuth zinc niobium and cubic perovskite phase strontium barium titanate. The dielectric constant is 150, the dielectric loss is 1.5%, and the coercive field strength is 200KV / cm.

Embodiment 2

[0027] On the Pt-plated silicon wafer, a layer of bismuth-zinc-niobium film is deposited by a spin-coating process, and then quickly heat-treated at 700°C for 3 minutes to obtain a bismuth-zinc-niobium film with a cubic pyrochlore structure. Then, a layer of barium strontium titanate film is deposited on the bismuth-zinc-niobium thin film, and rapid heat treatment is performed at 550° C. for 3 minutes to obtain a barium strontium titanate film with cubic perovskite structure. By repeating the above process, an eight-layer composite film with 4 layers of barium strontium titanate and 4 layers of bismuth zinc niobium is finally obtained. The thickness is 0.7μm, and the surface is smooth without cracks. The crystalline phase structure also contains cubic pyrochlore phase bismuth zinc niobium and cubic perovskite phase strontium barium titanate. The dielectric constant is 180, the dielectric loss is 2%, and the coercive field strength is 150KV / cm.

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Abstract

The invention relates the microwave dielectric adjustable barium strontium titanate / bismuth zinc niobium coextruded film and preparing method, comprising barium strontium titanate and bismuth zinc niobium film. The invention chooses two kinds of microwave adjustable dielectric film which have different structures and action mechanisms, the bismuth zinc niobium film material possessing cubic structure and barium strontium titanate film possessing cubic perovskite structure are made by sol-gal process to get coextruded film possessing multilayer film structure, and the invention uses the good temperature stability, dielectric constant and low deterioration of bismuth zinc niobium film to compensate for high dielectric constant and dielectric loss of barium strontium titanate, improving character factor of film and getting new pattern practical coextruded film material.

Description

Technical field [0001] The invention relates to a dielectric film in an inorganic material and a preparation method thereof, in particular to a microwave dielectric adjustable strontium barium titanate / bismuth zinc niobium composite film and a preparation method thereof Background technique [0002] With the development of modern communication technology, especially mobile communication technology, the requirements for miniaturization of microwave devices and systems are becoming more and more urgent. Dielectric materials with tunable characteristics can be used to prepare phase shifters, coplanar waveguides and tunable filters. Tunable microwave devices, such as tunable microwave devices. At present, most of the research work on tunable dielectric materials focuses on ferroelectric barium strontium titanate (Ba 0.5 Sr 0.5 TiO 3 ) And cubic pyrochlore structure of bismuth zinc niobium (Bi 1.5 ZnNb 1.5 O 7 ) On the film material. Barium strontium titanate film material has high di...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B35/465C04B35/495C04B35/624H01B3/12
Inventor 任巍史鹏吴小清阎鑫林鹏姚熹
Owner XI AN JIAOTONG UNIV