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Lead-free high-voltage active crystal material and preparation method thereof

A technology of active crystals and crystal materials, applied in the field of electronic functional materials and piezoelectric crystals, can solve problems such as spontaneous steering limited by two dimensions, dielectric properties, changes in piezoelectric elastic properties, large electromechanical coupling coefficients, etc., to achieve performance and application expansion, piezoelectric performance enhancement, performance and application enhancement effects

Inactive Publication Date: 2014-01-29
SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] BaTiO 3 The base piezoelectric ceramic research is relatively mature, and it is the earliest practical piezoelectric ceramic, which belongs to ABO 3 type perovskite structure, at room temperature, it has a high dielectric constant, a large electromechanical coupling coefficient, and a relatively high piezoelectric constant (d 33 Up to 190pC / N) and small loss, but due to the low Curie point (120°C) and the ferroelectric tetragonal to orthogonal phase transition point around 5°C, the applicable temperature range is very narrow, and the temperature near room temperature Poor stability
Therefore, it cannot replace the wide application of lead zirconate titanate piezoelectric ceramics (PZT) in the field of piezoelectric ferroelectricity, mainly because of the following deficiencies: the Curie point is not high (Tc=120°C), and the time and temperature stability of performance are also low. Poor; there is a phase transition near room temperature, the dielectric, piezoelectric, and elastic properties change significantly, and the working temperature range is narrow; there is still a certain gap between the piezoelectric properties and the lead-containing series ceramics, and it is difficult to modify by doping Greatly improve its performance; high temperature sintering (1300-1350°C) is required, and sintering is difficult; it is difficult to change the performance through doping to meet different needs
This type of ceramic material also has the following disadvantages: the crystal structure determines that its spontaneous turning is limited by two dimensions, resulting in low piezoelectric activity; too high a coercive field (Ec) is not conducive to polarization
Therefore, if piezoelectric BCZT crystals can be grown, it will greatly promote the development and application of environmentally friendly lead-free ferroelectric crystal materials, but so far there is no report on the growth of BCZT crystals.

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  • Lead-free high-voltage active crystal material and preparation method thereof
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  • Lead-free high-voltage active crystal material and preparation method thereof

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preparation example Construction

[0049] figure 1 A schematic flow chart showing the growth of BCZT crystals in the present invention by the pulling method. refer to figure 1 , the preparation method of BCZT crystal material of the present invention comprises: with BaCO 3 , CaCO 3 、TiO 2 and ZrO 2 The powder is the raw material according to the stoichiometric ratio, adding TiO 2 and / or ZrO 2 The powder is used as a flux, and the polycrystalline material is prepared by ball milling, briquetting and sintering; the polycrystalline material is placed in a crucible, heated and melted by intermediate frequency or resistance heating, and then the crystal is grown by the pulling method; and the growth is completed After the crystals were lifted from the melt and cooled to room temperature.

[0050] In order to maintain the ratio of Zr and Ti elements in the melt and the resulting crystal, in an exemplary embodiment, TiO 2 with ZrO 2 Binary mixed oxides with a molar ratio of (5-30):1 are used as flux.

[0051...

Embodiment 1

[0061] Use high-purity BaCO with a purity of not less than 99.99% 3 , CaCO 3 、TiO 2 and ZrO 2 powder as the starting material, these four powders were prepared according to the Ba 0.85 Ca 0.15 Ti 0.9 Zr 0.1 o 3 Make a ratio. At the same time, choose the proportion of TiO 2 :ZrO 2 =9 binary mixed oxides as flux, the amount of binary mixed flux added according to the above ratio of raw materials 25wt%. After the preparation of the raw materials is completed, they are fully ball milled and mixed, then pressed into blocks, and sintered at 1250°C for 20 hours in an air atmosphere to fully decompose the carbonate and react to synthesize polycrystalline materials for crystal growth.

[0062] The synthesized polycrystalline material is placed in a platinum crucible, and the polycrystalline material is heated in an air atmosphere in a resistance heating crystal growth furnace until it melts. The seed crystal used for crystal growth is BaTiO in the direction 3 Seed crystal,...

Embodiment 2

[0064] Use high-purity BaCO with a purity of not less than 99.99% 3 , CaCO 3 、TiO 2 and ZrO 2 powder as the starting material, these four powders were prepared according to the Ba 0.75 Ca 0.25 Ti 0.9 Zr 0.1 o 3 Make a ratio. At the same time, choose the proportion of TiO 2 :ZrO 2 =18 binary mixed oxides as flux, the amount of binary mixed flux added according to the above ratio of raw materials 30wt%. After the preparation of the raw materials is completed, they are fully ball milled and mixed, then pressed into blocks, and sintered at 1250°C for 30 hours in an air atmosphere to fully decompose the carbonate and react to synthesize polycrystalline materials for crystal growth.

[0065] The synthesized polycrystalline material is placed in a platinum crucible, and the polycrystalline material is heated in an air atmosphere in a resistance heating crystal growth furnace until it melts. The seed crystal used for crystal growth is BaTiO in the direction 3 For the seed...

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Abstract

The invention relates to a lead-free high-voltage active crystal material and a preparation method thereof. The chemical formula of the crystal material is Ba(1-x)CaxTi(1-y)ZryO3, wherein x=0.005-0.5, y=0.005-0.5, and space group is 99. The BCZT crystal material provided by the invention, compared with a ceramic material thereof, has greatly improved piezoelectric property, wherein a piezoelectric constant is that d33=300-5000pC / N. The invention provides the method and a patch for converting lead-free piezoelectric ceramic Ba(1-x)CaxTi(1-y)ZryO3 (BCZT) into lead-free piezoelectric crystal. For a first time, a pluralistic complicated ceramic material is converted into a complicated monocrystalline material, such that material performance and application are greatly improved and expanded.

Description

technical field [0001] The invention relates to a novel lead-free piezoelectric crystal with high-voltage electrical activity, which belongs to the technical field of electronic functional materials, and further belongs to the field of piezoelectric crystals. Background technique [0002] Since the discovery of the piezoelectric effect by the Curie brothers in 1880, until the specific application of the piezoelectric effect in material engineering in the mid-1940s, piezoelectric materials have been more and more widely used in the fields of modern electronics and information. Various civilian and military industries such as laser, ultrasound, and navigation have been widely used, and have become an extremely important class of materials among various functional materials. After decades of development and application, piezoelectric ceramics or piezoelectric crystals with large piezoelectric activity are all materials containing lead, and the lead content is quite large. At p...

Claims

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Application Information

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IPC IPC(8): C30B29/32C30B15/00
CPCC30B15/00C30B29/32
Inventor 陈建军郑燕青涂小牛孔海宽涂一帆杨建华施尔畏
Owner SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI