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 共查询到10条相似文献,搜索用时 78 毫秒
1.
This study examines the fabrication process and mechanical properties of piezoelectric films with the substrate, which is made from silicon carbide. After depositing the PZT thick film on silicon carbide substrate and silicon substrate respectively, it was shown that silicon carbide substrate formed a stable interface with PZT thick film up to 950?°C, compared with silicon substrate. In addition, the dielectric constant of the PZT thick film sintered at 950?°C on a silicon carbide substrate was 843, and this value was about over 25 % improved value compared with that on a silicon substrate. A thick film piezoelectric micro transducer of a micro cantilever type was fabricated by using a multifunctional 3C–SiC substrate. The fabricated micro cantilever was a micro cantilever with multiple thin films on either silicon or silicon carbide substrate. The piezoelectric thick-film micro cantilever that was fabricated by using a SiC substrate showed excellent mechanical and thermal properties. The piezoelectric micro cantilever on the SiC substrate shows an excellent sensitivity towards the change of mass compared with the piezoelectric micro cantilever on the Si substrate.  相似文献   

2.
We propose theoretically two optical sensor structures based on Fabry–Perot resonator and fringes of equal thickness structure. Different from the conventional slab waveguide sensors in which the sample interacts with the evanescent field in the cladding layer, the proposed sensors contain the sample in the core layer. The first proposed sensor comprises a piezoelectric material as a substrate with the driving potential difference as the sensing probe for refractive index changes of the sample. The second sensor comprises fringes of equal thickness structure with the number of fringes per unit length is the probe for changes in the index of the sample. The calculations reveal that the proposed sensors have high sensitivity to changes in the refractive index of the sample.  相似文献   

3.
吴金根  高翔宇  陈建国  王春明  张树君  董蜀湘 《物理学报》2018,67(20):207701-207701
作为重要的功能材料,压电材料已经在国民经济的多个领域里有着重要应用.随着现代工业的快速发展,特别是新能源、交通和国防工业的高速发展,功能材料的应用已经从常规使用转向极端环境下的服役.本文综述了具有高居里点的压电材料,包括钙钛矿型压电陶瓷、铋层状结构氧化物压电陶瓷、钨青铜结构压电陶瓷以及非铁电压电单晶等;介绍了其晶体结构特征和高温压电性能、最新研究进展,并列举了一系列的高温压电器件和应用,包括高温压电探测器、传感器、换能器和驱动器等.另外,本文总结了高温压电材料的热点研究问题,并展望了今后的发展方向.  相似文献   

4.
高次谐波体声波谐振器(High-overtone Bulk Acoustic Resonator,HBAR)是由基底、压电薄膜及上下电极所组成的器件,它具有高的品质因数Q和多模谐振频谱特性.从给出HBAR的谐振谱出发,以各层的结构(厚度)和材料特性(特性阻抗和机械衰减因子)为参数,系统研究了机械品质因数QM的谐振谱特性。QM随基底或压电薄膜的厚度变化表现为一系列对应不同阶数的曲线。在给定频率下,QM随基底厚度的增加振荡上升,且最终趋于基底材料的机械品质因数,而其随压电薄膜厚度的增加呈波浪式下降。对于给定结构的HBAR,QM随频率(阶数)的增加呈波浪式下降。此外,考虑电极的厚度对QM的变化规律影响不大。为了获得较大的QM,应选择Al/AlN/Al/Sapphire或YAG结构的HBAR,且基底要较厚,压电薄膜和电极厚度要适中。   相似文献   

5.
Phononic band structure with periodic elliptic inclusions for the square lattice is investigated based on the plane wave expansion method. The numerical results show the systems composed of tungsten (W) elliptic rods embedded in a silicon (Si) matrix can exhibit a larger complete band gap than the conventional circular phononic crystal (PC) slabs. The phononic band structure of the plate-mode waves and the width of the first complete band gap can be tuned by varying the ratio of the minor axis and the major axis, the orientation angle of the elliptic rods and the thickness of the PC slabs. We also study the band structure of plate-mode waves propagating in two-dimensional (2D) slabs with periodic elliptic inclusions coated on uniform substrate.  相似文献   

6.
Mechanical quality factor Qm is a key characteristic parameter of High-overtone bulk acoustic resonator(HBAR). The effects of structure parameter(thickness) and perfor?mance parameters(characteristic impedance and mechanical attenuation factor) of substrate,piezoelectric film and electrode constituting HBAR on Qm are carried out. The relationships between Qm and these parameters are obtained by a lumped parameter equivalent circuit instead of distributed parameter equivalent circuit near the resonance frequency, and the an?alytical expressions oi Qm are given. The results show that Qm increases non-monotonically with the continuous increase of the substrate thickness for HBAR with certain piezoelectric film thickness, and it approaches to the substrate material mechanical quality factor as the substrate thickness is large. Qm decreases wavily with the continuous increase of the piezoelectric film thickness for HBAR with certain substrate thickness. Sapphire and YAG with low mechanical loss are appropriate as the substrate to get a larger Qm- The electrode loss must be considered since it can reduce Qm- Compared with Au electrode, A1 electrode with lower loss can obtain higher Qm when the appropriate electrode thickness is selected. In addition, Qm decreases with the increase of frequency. These results provide the theoretical basis for optimizing the parameters of HBAR and show that trade-oflFs between Qm and must be considered in the design because their changes are often inconsistent.  相似文献   

7.
The averaged dielectric, piezoelectric, and elastic constants of thin polycrystalline barium titanate and lead titanate films are calculated within a modified effective-medium approximation, which takes fully into account piezoelectric interactions between crystallites. Films with c-or a-type crystal texture resulting from mechanical interaction with the substrate are considered when the film becomes ferroelectric under cooling of the heterostructure. The dependences of the effective material constants of textured films on the residual macroscopic polarization of a film are described. An analysis is made of the effect of two-dimensional clamping of a film on a thick substrate on measurements of dielectric and piezoelectric constants. Fiz. Tverd. Tela (St. Petersburg) 40, 2206–2212 (December 1998)  相似文献   

8.
The results of sensor and electron-microscopic studies of the initial stages of cadmium telluride film formation through vapor deposition on a substrate at room temperature and on a substrate cooled by liquid nitrogen (highly nonequilibrium conditions) are reported. A piezoelectric quartz resonator is used as a sensor. The kinetic curves of the sensor analytical signal and photomicrographs are presented. A jumplike character of the nucleation process and a quasi-periodical growth mechanism for island films are disclosed. A sequence of new-phase island ensembles is formed in an analogous way. These islands increase the substrate surface coverage in a quasi-discrete manner. The experimental results are shown to agree with current theory of the first-order phase transitions and models of layer formation in highly nonequilibrium conditions.  相似文献   

9.
A high-overtone bulk acoustic resonator(HEAR) is composed of a substrate,a piezoelectric film and upper and lower electrodes,the influences of their structure parameter(thickness) and performance parameter(characteristic impedance) on effective electromechanical coupling coefficient K_(eff)~2 are investigated systematically.The relationship between K_(eff)~2 and these parameters is obtained by a lumped parameter equivalent circuit instead of distributed parameter equivalent circuit near the resonant frequency,and K_(eff)~2 at the resonance frequency closest to the given frequency is analyzed.The results show that K_(eff)~2 declines rapidly and oscillatorily with the continuous increase of the substrate thickness when the piezoelectric film thickness is fixed,and decreases inversely proportion to the thickness when the substrate thickness is greater than a certain value.With the ratio of the characteristic impedance of the substrate to the piezoelectric layer increasing,the maximum of K_(eff)~2 obtained from the variation curve of K_(eff)~2 with the continuous increase of the piezoelectric film thickness decreases rapidly before reaching the minimum value,and later increases slowly.Fused silica with low impedance is appropriate as the substrate of HBAR to get a larger K_(eff)~2.Compared with Al electrode,Au electrode can obtain larger K_(eff)~2 when the appropriate electrode thickness is selected.The revealed laws above mentioned provide the theoretical basis for optimizing parameters of HBAR.  相似文献   

10.
The theory for designing distributed piezoelectric modal sensors is well established for beam structures. However, the current modal sensor theory is limited in scope in that it can only be applied in the case of classical boundary conditions (i.e., either clamped, free, simply supported or sliding). In this paper a solution to the problem of finding the shape of piezoelectric modal sensors for a beam with arbitrary boundary conditions is proposed, using the Adomian decomposition method (ADM). A general expression for designing the shape of a piezoelectric modal sensor is presented, in which the output signal of the designed sensor is proportional to the response of the target mode. Other modes are filtered out. The modal sensor shape is expressed as a function of the second spatial derivative of the structural mode shape function. Based on the ADM and employing some simple mathematical operations, the closed-form series solution of the second spatial derivative of the mode shapes can be determined. Then the shapes of the designed modal sensors are obtained. Finally, some numerical examples are given to demonstrate the feasibility of the proposed modal sensors. It is shown that, for classical boundary conditions, the shapes of the modal sensors based on the ADM agree well with analytical and numerical results given in the literature. For general boundary conditions it is found that the shape of the modal sensors is influenced by the number of modes of interest because the second spatial derivatives of the mode shapes are not orthogonal to one another. The modal sensors for general boundary conditions can be considered as modal filters within a limited frequency band.  相似文献   

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