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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 thin film and barium strontium titanate, which is applied in ceramics, inorganic insulators and other directions, can solve the problems of high coercive field strength, high dielectric loss, thin film tunable characteristics and reduced quality factors, etc. The effect of temperature stability

Inactive Publication Date: 2006-12-13
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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preparation example Construction

[0019] The preparation process of strontium barium titanate and bismuth zinc niobium precursor solution is the same

[0020] 1. Preparation of barium strontium titanate precursor solution: use analytically pure strontium acetate, barium acetate, and tetrabutyl titanate as raw materials, glacial acetic acid as solvent, and acetylacetone as chelating stabilizer to synthesize strontium barium titanate precursor solution , first according to the chemical composition into Ba 0.5 Sr 0.5 TiO 3 Dissolve barium acetate and strontium acetate satisfying the stoichiometric ratio in glacial acetic acid, fully stir 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 stirred at room temperature for 30 minutes to finally obtain a clear precursor solution of barium strontium titanate with a concentration of 0.4mol / L;

[0021] 2. Preparation of bismuth, zinc and niobium precursor solution: use anal...

Embodiment 1

[0025] On the Pt-coated silicon wafer, a layer of strontium barium titanate thin film was first deposited by spin coating process, and rapidly heat-treated at 650°C for 3 minutes to obtain a strontium barium titanate thin film with cubic perovskite structure. Then deposit a bismuth-zinc-niobium thin film on the barium strontium titanate thin film, and heat rapidly at 700° C. for 3 minutes to obtain a bismuth-zinc-niobium thin film with a cubic pyrochlore structure. By repeating the above process, a six-layer composite film with 3 layers of barium strontium titanate and 3 layers of bismuth, zinc and niobium is finally obtained. The thickness is 0.5μm, and the surface is smooth without cracks. In its crystal phase structure, bismuth-zinc-niobium in the cubic pyrochlore phase and barium strontium titanate in the cubic perovskite phase exist simultaneously. 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-coated silicon wafer, a bismuth-zinc-niobium thin film was first deposited by spin-coating process, and rapidly heat-treated at 700°C for 3 minutes to obtain a bismuth-zinc-niobium thin film with a cubic pyrochlore structure. Then deposit a layer of strontium barium titanate thin film on the bismuth zinc niobium thin film, and rapid heat treatment at 550 DEG C for 3 minutes to obtain the strontium barium titanate thin film with cubic perovskite structure. By repeating the above process, an eight-layer composite thin film with 4 layers of barium strontium titanate and 4 layers of bismuth, zinc and niobium is finally obtained. The thickness is 0.7μm, and the surface is smooth without cracks. In its crystal phase structure, bismuth-zinc-niobium in the cubic pyrochlore phase and barium strontium titanate in the cubic perovskite phase exist simultaneously. 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 thin film in inorganic materials and a preparation method thereof, in particular to a microwave dielectrically adjustable strontium barium titanate / bismuth zinc niobium composite thin film and a preparation method thereof Background technique [0002] With the development of modern communication technology, especially mobile communication technology, the miniaturization of microwave devices and systems is increasingly urgent. Dielectric materials with tunable properties can be used to prepare phase shifters, coplanar waveguides and tunable filters. At present, the research work on tunable dielectric materials is mostly concentrated on ferroelectric strontium barium titanate (Ba 0.5 Sr 0.5 TiO 3 ) and bismuth-zinc-niobium (Bi 1.5 ZnNb 1.5 o 7 ) on the film material. Barium strontium titanate thin film material has a high dielectric constant and large dielectric tunable characteristics, but its dielectric loss ...

Claims

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Application Information

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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