Ca3NbGa3Si2O14晶体的介电和压电特性

利用Y切和(yxl)30°切两种样品测量了Ca3NbGa3Si2O14晶体的介电、压 电和部分弹性参数.计算了(yxl)θ切型相关压电常数随切角的变化.与La3Ga5SiO14晶体相比，Ca3NbGa3Si2O14晶体具有更优良的压电性能，其压电常数 d11=7.93×10-12C/N，d14=-5.88×10-12C/N. 关键词： Ca3NbGa3Si2O14晶体 介电常数 压电常数     

干涉法测量压电材料的复压电常数

介绍了采用迈克尔逊干涉仪测量压电材料复压电常数的新方法。干涉仪中一个平反射镜与被测试样粘为一体，另一外与控制压电陶瓷粘为一体。利用光电二极管和两个锁相放大器对干涉图像进行转换和放大测量。     

一种测量切向压电常数d15的新方法

本文提出了测量压电材料切向压电常数d₁₅的一种新方法—准静态法。有限元仿真分析表明了测量原理的正确性。方法利用设计产生切向力的专用夹具,在普通的准静态d₃₃仪上,就可方便,快捷,准确地测量大多数压电材料的切向压电常数d₁₅。     

Ca_3NbGa_3Si_2O_(14)晶体的介电和压电特性

利用Y切和 (yxl) 30°切两种样品测量了Ca3NbGa3Si2 O1 4晶体的介电、压电和部分弹性参数 .计算了 (yxl)θ切型相关压电常数随切角的变化 .与La3Ga5SiO1 4晶体相比 ,Ca3NbGa3Si2 O1 4晶体具有更优良的压电性能 ,其压电常数d1 1=7 93× 10 - 1 2 C N ,d1 4=- 5 88× 10 - 1 2 C N .     

用声波速度确定骨组织弹性参数

本文用超声方法确定密质骨的弹性特征,其基本原理是基于弹性波理论中的Christoffel方程。本文应用液浸、声波穿透技术,对牛胫骨样品中一些特殊入射方向的声波速度进行了测试,利用固体中沿任意方向的弹性波传播速度与材料的弹性系数间的关系,通过计算机编程反演出具有六方晶体对称结构的密质骨组织的5个独立弹性常数。结果与相关文献中其它方法所得结果一致。     

1-3型压电复合材料

1－3型压电复合材料是目前研究和应用得比较广泛的一种压电材料．本文简述了这种压电复合材料的理论模型、制作方法和实验结果；指出除了圆形PZT压电材料所具有的径向模和厚度模以外，1－3型压电复合材料还具有横向结构模．本文介绍了这种压电复合材料的特点，如低声阻抗、低介电常数、高静水压压电常数以及PZT相分布的可控制性等．这些特点有利于改善压电复合材料换能器的时间响应和空间响应．     

扬声器用压电陶瓷

扬声器用的压电陶瓷具有阻抗低、电声转换效率高,Q_m值低的特点。它是在PZT中加入镧(La)等添加物,虽然居里温度被降到180℃左右,但是获得了介电常数5000、压电常数(d_(31))310×10~(-12)m/V、Q_m50左右的软性压电陶瓷。 最近,随着流延法技术的成熟,采用流延法批量生     

激光干涉法测压电陶瓷的压电常数d31

介绍迈克尔逊干涉仪原理在测微小位移中的应用。确定一种锆钛酸铅镧压电陶瓷的压电常数ｄ３１，得到了一种测ｄ３１的可行可靠的新方法。     

单向纤维增强复合板弹性常数的反演方法研究

利用小波变换和人工神经网络技术,对激光激发单向纤维增强复合板产生的兰姆波信号进行分析,进而反演出单向纤维增强复合板的弹性常数。对小波变换和神经网络算法加以优化以提高反演结果的准确性,并分别对纤维方向和垂直于纤维方向的实验波形进行弹性常数的反演,两个方向的反演结果十分吻合。研究表明,利用该方法可直接从激光激发兰姆波的瞬态实验波形中反演出复合板的弹性常数,既不用事先知道兰姆波各模式传播的群速度,也不必采用传统的最小二乘法拟合色散曲线来反演弹性常数。     

轴对称功能梯度压电材料圆柱壳弯曲问题的幂级数解

从压电材料基本方程出发，针对沿径向极化且材料常数沿极化方向梯度变化的轴对称压电圆柱壳，导出了其在两端简支、接地条件下弯曲问题的幂级数解，并通过算例考察了壳厚度对其电弹性场分布的影响。     

压电管堆式宽带换能器*

研究了一种具有管状叠堆结构的圆管换能器,其敏感元件是由纵向极化压电陶瓷单元组成的薄壁管状压电叠堆,探讨利用管状叠堆纵向和径向振动耦合实现宽带发射。利用压电柱壳振动理论推导了管堆的频率方程,分析了换能器的纵向和径向模态的振动耦合特性。在理论分析的基础上利用有限元方法对换能器的带宽和发射电压响应进行优化并研制换能器样机。测试结果表明,纵向极化的管状压电叠堆结构具有良好的发射电压响应和宽带特性,与理论及仿真结果相符。     

Nonlinearity in inverse and transverse piezoelectric properties of Pb(Zr0.52Ti0.48)O3 film actuators under AC and DC applied voltages

The motion of domain walls is a crucial factor in piezoelectric properties and is usually related to the irreversible and hysteretic behaviors. Herein, we report on the investigation of inverse and transverse piezoelectric coefficients of capacitor-based and microcantilever-based Pb(Zr_0.52Ti_0.48)O₃ films with a change in the DC bias and the AC applied voltage. A large inverse piezoelectric strain coefficient of about 350 p.m./V, and a low strain hysteresis of about 7.1%, are achieved in the film capacitors under a low applied voltage of 2 V (20 kV/cm) which can benefit the actuators for motion control in high-precision systems. The field-dependences of the transverse piezoelectric coefficients, obtained from four-point bending and microcantilever displacement, are in good agreement with each other. The results also reveal that the irreversible domain-wall motion is attributed to the nonlinearity in the field-dependent piezoelectric strain and cantilever displacement.     

Analysis of force-frequency effect of piezoelectric circular resonators strained by edge angular-sector stresses

Summary A theoretical analysis of force-frequency effect of two opposite loads distributed over an angular part of the crystal edge is performed in the case of a piezoelectric resonator or sensor. Stresses are determined at the centre of the crystal and the subsequent frequency shift is calculated. Applying the obtained results, the location and angular width of holders are determined for an AT-cut. To speed up publication, the authors of this paper have agreed to not receive the proofs for correction.     

大角度低温光学扫描器

本文介绍了低温大角度扫描器的理论特性和制作技术。我们进行了利用压电陶瓷“逆压电效应”原理在常温条件下进行大角度、可控光扫描的探索性工作,并取得了可喜的成功,并在此基础上研究出了能在液氮环境下进行大角度扫描的低温扫描器。     

Fabrication and characteristics of thin disc piezoelectric transformers based on piezoelectric buzzers with gap circles

This paper investigates design, fabrication and test of thin disc piezoelectric transformers (PTs) based on piezoelectric buzzers with gap circles at different diameters of the gap circles. The performance test is focused on characteristics of voltage gains, including maximum voltage gains and maximum-gain frequencies, for each piezoelectric transformer under different load conditions. Both a piezoelectric buzzer and a gap circle on a silver electrode of the buzzer are needed to build any type of the PTs. Here, the gap circle is used to form a ring-shaped input electrode and a circle-shaped output electrode for each piezoelectric transformer. To do so, both structure and connection of a PT are first expressed. Then, operating principle of a PT and its related vibration mode observed by a carbon-power imaging technique are described. Moreover, an experimental setup for characterizing each piezoelectric transformer is constructed. Finally, effects of diameters of the gap circles on characteristics of voltage gains at different load resistances are discussed.     

On the propagation of long thickness-stretch waves in piezoelectric plates

We study the propagation of thickness-stretch waves in a piezoelectric plate of polarized ceramics with thickness poling or crystals of class 6 mm whose sixfold axis is along the plate thickness. For device applications we consider long waves with wavelengths much longer than the plate thickness. A system of two-dimensional equations in the literature governing thickness-stretch, extensional, and symmetric thickness-shear motions of the plate is further simplified. The equations obtained can be used to analyze piezoelectric plate acoustic wave devices operating with thickness-stretch modes.     

Analytical model of piezoelectric cantilever as rheological sensor

Cantilever sensors have attracted much attention due to their potential as a platform for the development of many physics, chemical, and biological sensors. An analytical model based on analyzing the equivalent circuit of a piezoelectric cantilever as a rheological sensor has been derived and applied in real test. This model can be used to significantly improve the resolution and detection range of the devices. Based on this model, piezoelectric cantilevers have been used for characterizing Newtonian oils with viscosity between 1 and 10⁴ mPa s, and good agreements between experimental and modeled results have been obtained.     

Novel application of Ag/PbBiO2I nanocomposite in piezocatalytic degradation of rhodamine B via harvesting ultrasonic vibration energy

Ag/PbBiO₂I nanocomposite was synthesized and firstly applied in piezocatalytic degradation of rhodamine B (RhB) under ultrasonic vibration. The two-dimensional structure endows PbBiO₂I nanosheets piezoelectric property, so that it can drive the piezocatalytic reaction under ultrasonic vibration. The loading of Ag nanoparticles forms Schottky barriers between the Ag-PbBiO₂I contact region, which improves the separation of charge carriers and subsequently increases the piezocatalytic efficiency. The RhB degradation rate of the optimal Ag/PbBiO₂I sample is 0.0165 min⁻¹, which reaches 6.8 times that of pure PbBiO₂I. This work indicates that the PbBiO₂I nanosheet shows promising potential in utilizing ultrasonic vibration energy.     

压电MEMS超声换能器研究进展

MEMS(micro-electromechanical systems)超声换能器(MEMS ultrasonic transducer,简称MUT)是采用微电子和微机械加工技术制作的新型超声换能器。与传统超声换能器相比,MUT具有体积小、重量轻、成本低、功耗低、可靠性高、频率控制灵活、频带宽、灵敏度高以及易于与电路集成和实现智能化等特点。是超声换能器的重要的研究方向之一。MUT的研究主要包括压电MUT(piezoelectric MUT,简称PMUT)和电容MUT(capacitiveMUT,简称CMUT)两个方面。本文概述了PMUT研究的发展进程和研究成果,展望了PMUT的研究和应用前景。