Piezoelectric and Magnetoelectric Properties of Lead Zirconate Titanate/Ni-Ferrite Particulate Composites

Piezoelectric and magnetoelectric properties of magnetoelectric particulate composites with Lead Zirconate Titanate (PZT) and Ni-ferrite were investigated. The maximum magnetoelectric voltage coefficient, (dE/dH)_max, increased with higher sintering temperature up to 1250°C. Composites sintered at 1300°C, had dissolution of Fe ions into PZT, or interdiffusion between PZT and ferrite. Connectivity of the ferrite particles and sintering temperature were important factors for fabrication of this particulate composite. The composite added with 20 wt.% amount of Ni-ferrite, sintered at 1250°C for 2 hours, had the highest magnetoelectric voltage coefficient of 115 mV/cm · Oe at room temperature. This value is comparable to that of the BaTiO₃-CoFe₂O₄ based composites reported by Philips laboratory, and is 44% higher than other magnetoelectric particulate composites.     

Terfenol-D/PZT/Terfenol-D层状复合磁电传感器磁电效应

采用树脂粘结法制作了L-T型(磁致伸缩层的磁化方向与压电层的极化方向相互垂直)Terfenol-D/PZT/Terfenol-D层状复合磁电传感器。采用等效电路法对磁电系数进行了详细推导,得到磁电系数方程。磁电系数方程显示磁电系数决定于Terfenol-D与PZT的性能参数和磁电传感器中两种材料的体积比。为此从理论和实验上分析了偏置磁场、传感器中两种材料所占的体积比以及驱动磁场频率对磁电系数的影响规律。结果表明偏置磁场、传感器中两种材料所占的体积比和驱动磁场频率对磁电传感器磁电系数的影响都很明显,并且磁电系数的计算结果与实验结果一致,对于所制作的复合磁电传感器,相同条件下磁电系数的计算值与实验值的相对差值小于6%。     

磁致伸缩、压电层状复合磁电传感器非线性动态有限元模型

基于磁致伸缩材料标准平方模型和压电材料线性本构关系,应用Hamilton变分原理建立了磁电传感器的磁-机-电耦合特性的动力学方程。建立的动力学方程考虑了磁致伸缩材料的磁滞现象和E效应的影响。应用所建立的模型求解了LT型磁致伸缩/压电磁电传感器的输出特性,与实验结果进行对比发现模型可较准确地预测磁电传感器在不同偏置磁场和交流驱动磁场激励下其输出电压随时间的变化关系。当偏置磁场为22.1kA/m,正弦交流驱动磁场为7.4kA/m、频率为100Hz时,计算结果和实验结果误差为0.9%。同时,应用该模型还可以确定磁电传感器的最大交流驱动磁场。     

磁致伸缩换能器材料的物理特性

用磁性物理的理论解释了磁致伸缩的产生机制,分析了磁致伸缩材料在磁化过程中的物理特性,指出了使用磁致伸缩换能器的物理条件。文末还介绍了磁致伸缩换能器材料的最新发展动态。     

Theoretical Study on the Tip-Deflection of Multilayer Piezoelectric Cantilever Structures

Tip-deflection is one of the most important characters of the piezoelectric cantilever vibration. In this paper, a new piezoelectric model of multilayer piezoelectric cantilever is obtained, and the analytic expressions for the curvature, displacement and tip-deflection of the multilayer structure are derived. On the base of this solution, the curvature and tip-deflection of five different elementary structures are considered. Compared with others' model, the analytic expressions for the curvature, displacement and tip-deflection are also suitable for more complex structures with more layers based on these elementary structures. Above-mentioned methods and conclusions can be used for optimized design of PZT cantilever structure.     

Partial Discharge Signal Detection by Piezoelectric Ceramic Sensor and The Signal Processing

Partial discharge (PD) in an insulator or on surface of defective conductor emits acoustic wave transmitting through an air or an insulator. The acoustic wave between 20 kHz and several hundred of kHz can be detected by piezoelectric ceramic sensor that converts the acoustic wave into an electrical signal. Piezoelectric ceramic sensor has either the wide resonant band or the local resonant band depending on the ceramic material or the various combinations of each different component in the manufacturing process. This paper presents the piezoelectric ceramic sensor with 0.95 PZT–0.05 PMNS that yields the piezoelectric properties of high k_p, high Q_m. It has the frequency characteristics of local resonant band, such that it can be applied to PD detection. We have demonstrated the properties of the proposed piezoelectric ceramic sensor by comparing with the conventional electrical PD detector. Quantitative analysis is accomplished by comparing the -q_max from a PD detector and the -v_max from the proposed sensor while -n distributions are the same for both the conventional phase-resolved PD analysis method and the proposed one.     

Dielectric Behavior and Magnetoelectric Effect in Ni0.75Co0.25Fe2O4 + Ba0.8Pb0.2TiO3 ME Composites

Magnetoelectric composites with ferrite + ferroelectric compositions xBa_0.8Pb_0.2TiO₃ + (1 – x) Ni_0.75Co_0.25Fe₂O₄ in which x varies as 0, 0.55, 0.70, 0.85 and 1.0 were prepared by ceramic method. X-ray analysis confirms single-phase formation in x = 0 and x = 1 compositions, whereas the presence of both phases is shown in x = 0.55, 0.70 and 0.85 compositions. Variation of dielectric constant () with temperature and frequency has been studied. All the samples have show linear magnetoelectric conversion in the presence of static magnetic field. Static magnetoelectric conversion factor, (dE/dH), was measured as a function of magnetic field in the samples with x = 0.55, 0.70 and 0.85 compositions. The maximum value of dE/dH was found to be 140 V/cm/Oe for x = 0.85 composition.     

稀土巨磁致伸缩材料及其在低压电器中的应用

稀土巨磁致伸缩材料是在磁场的作用下能产生巨大伸缩形变的一种新型功能材料。本文对此材料作了简要的介绍后，重点介绍了它在低压电器中的应用及其在器件设计中应注意的问题。     

Lead Free Piezoelectric Materials

Lead oxide based ferroelectrics, represented by lead zirconate titanate (Pb(Zr, Ti)O₃) or PZT) are the most widely used materials for piezoelectric actuators, sensors and transducers due to their excellent piezoelectric properties. Considering lead toxicity, there is interest in developing piezoelectric materials that are biocompatible and environmentally friendlier. The low density of non-lead based materials can also be an advantage in transducers for underwater and medical imaging due to expected lower acoustical impedance. Another impetus for seeking alternative to lead based compositions is the need for piezoelectric materials for operation at high temperatures. Several classes of materials are now being reconsidered as potentially attractive alternatives to PZT for special applications. The potassium niobate family, KNbO₃, exhibits low dielectric constants, large thickness coupling coefficient along certain non-polar directions, and low density, all of which have advantages for high frequency transducer applications. Several compositions belonging to bismuth titanate family, Bi₄Ti₃O₁₂, such as SrTi₄Bi₄O₁₅, are promising candidates for high temperature applications. Lead free materials alone (eg. (Na_0.5Bi_0.5)TiO₃) or in solution with PT (BiScO₃ – PbTiO₃) are also potentially interesting as they combine high piezoelectric activity and, in some cases, relatively high T_c. For these families of piezoelectric materials, the processing and piezoelectric response under different conditions of pressure, frequency, and temperature are presently much less understood than for the classical lead containing systems. In this presentation we review and discuss piezoelectric properties of selected lead free compositions (principally for members of the potassium niobate family and bismuth titanate layered compounds) in relation to structural and microstructural features as well as extrinsic contributions (domain walls displacement, conductivity) to their electromechanical properties. It is shown that it is possible to obtain remarkably stable piezoelectric response in some compositions, while others exhibit strong dependence of piezoelectric properties on driving field and frequency. Origins of these different behaviours are discussed.     

面向电力设备检测与诊断的压电材料及器件

随着中国智能电网建设不断推进及电网规模的扩大,以压电材料为核心的传感器和能量采集器在电力系统在线监测、故障检修、无线传感器网络等方面扮演着越来越重要的角色。从电力检测和传感器自取能出发,回顾近年来基于压电效应的电压电场传感器、声检测和环境能量采集装置的研究进展并介绍了压电陶瓷、压电驻极体、压电复合材料等传统和新兴的压电材料。在现有研究基础上,指出在智能电力系统建设中各类压电器件所面临的挑战,包括频率匹配、环境适应性和集成化等,需要新的微纳加工技术、探索压电效应与其他物理效应耦合、设计新型压电材料和能量收集电路来助力新型压电器件的实际应用。     

Synthesis and characterization of PZT: CF magnetoelectric composites

Here, we report the structural, dielectric, ferroelectric, piezoelectric and magnetic properties of ME composites of Lead Zirconate Titanate (PZT) and Cobalt ferrite (CF) with compositional formula (1?x) PbZr_0.55Ti_0.45O₃ + (x) CoFe₂O₄, (x = 0.00, 0.05, 0.10, 0.15 and 1.00 by weight). The samples were synthesized by conventional solid state reaction. The formation of perovskite tetragonal and spinel structure in the composites are confirmed by X-ray diffraction studies. Microstructural study of all samples was done by SEM analysis and average grain size was also calculated. The dielectric properties of samples were studied as a function of frequency and as a function of temperature (30°C – 500°C) respectively. P-E hysteresis loop at room temperature and piezoelectric coefficient were measured to study the ferroelectric and piezoelectric properties. To confirm the ferromagnetic behavior of the composites M-H hysteresis loop measurement was carried out. The Magnetoelectric voltage coefficient (dE/dH) was measured as a function of applied DC magnetic field. The maximum ME output of 389μV/ (cm.Oe) was observed for the composite with x = 0.15.     

超磁致伸缩材料内部磁场特别及材料参数对其影响分析

基于麦克斯韦方程和压磁理论建立了超磁致伸缩材料棒内的磁场分布模型,导出了含有材料磁弹性参数的超磁致伸缩材料棒磁场分布函数,讨论了材料特性参数对材料内部磁场和材料内部涡流损耗的影响。结果表明,材料内部磁场不仅与外激励磁场有关,而且与材料的压磁系数、杨氏模量及相对磁导率有关,同时材料内部磁场与外激励磁场间具有滞回特性;考虑材料特性参数时材料内部的涡流损耗达到最大值所需的材料半径,将大于不考虑材料特性参数时的半径值,同时涡流损耗的变化趋势也将变得和缓,而不论材料参数如何变化,超磁致伸缩棒内磁能损耗的基本规律没有发生变化。     

Fabrication of PZT Thick Films on Silicon Substrates for Piezoelectric Actuator

In recent years, there has been an increased interest in ferroelectric lead zirconate titanate (PZT) films for applications in piezoelectric devices. Many potential applications require a film thickness of about 10 m for higher force, better sensitivity and stability. In this study we fabricate lead zirconate titanate (PZT) thick films by screen printing on silicon substrates with a platinum bottom electrode. Various substrates were studied. The longitudinal piezoelectric coefficient, d₃₃, was measured by the normal load testing method. Breakdown voltage, tan , P-E hysteresis loop and permittivity were measured on the PZT thick films. The results are promising for the use of PZT thick films in various applications, for example, in silicon micromachined micro-pump.     

High Power Characterization of Piezoelectric Materials

Three techniques for measuring high voltage/power piezoelectric properties, which have been developed recently, are compared: a voltage-constant piezoelectric resonance method, a current-constant piezoelectric resonance method, and a pulse drive method. The conventional resonance method with a constant voltage circuit exhibits significant distortion (or a hysteresis) in the resonance frequency spectrum under a high vibration level due to large elastic non-linearity, which limits precise determination of the electromechanical coupling parameters. To the contrary, the resonance method with a constant current circuit (i.e., constant velocity) can determine the coupling parameters more precisely from a perfectly-symmetrical resonance spectrum. The general problem in both resonance methods is heat generation in the sample during the measurement. In order to separate the temperature characteristic from the non-linearity, it is recommended that the pulse method be used in parallel, even though the accuracy is not very high.     

Thickness Dependence of Piezoelectric Properties for PZT Thin Films with Regard to MEMS Applications

In this work we report on the investigation of the piezoelectric and ferroelectric properties of Pb(Zr,Ti)O₃ (PZT) thin films with a composition of 45% zirconium and 55% titanium prepared by chemical solution deposition (CSD) regarding the major properties required in MEMS applications. Therefore we have measured the polarization and the piezoelectric coefficient d ₃₃ and strain using a high-resolution double beam laser interferometer. We found that d ₃₃ alike the strain is nearly independent of the sample thickness. To estimate the lifetime of MEMS we stressed the samples by applying switching and non-switching voltage pulses. In the non-switching case, no change of the material properties was observed whereas the use of switching voltage pulses resulted in a strong decrease of the piezoelectric properties and the polarization. Here we found a linear behavior between the material properties in the fatigued state and the sample thickness.     

压电模型参数辨识仿真实验

在对压电材料电气性能参数分析的基础之上,确立了以等效电路的电容、电感等参数作为压电材料性能指标的主要参数,离散化处理得到相应的差分数学模型,并对其进行了模型参数在线识别与最小二乘法MATLAB参数辨识仿真实验。实验结果表明:压电材料电气参数的辨识可以满足综合性能优化0.5%的设计要求。     

Hydrostatic Piezoelectric Coefficient d h of PZT Ceramics and PZN-PT and PYN-PT Single Crystals

The hydrostatic piezoelectric coefficient d_h of Pb(Zr_xTi_{1 – x})O₃ ceramics (PZT), and of Pb(Zn_1/3Nb_{2/ 3})O₃-PbTiO₃ and Pb(Yb_1/2Nb_1/2)O₃-PbTiO₃ (PZN-PT, PYN-PT, respectively) single crystals with compositions near to the morphotropic phase boundary (MPB) have been measured using a dynamic hydrostatic method. The effects of DC electric field and static component of hydrostatic stress on d_h of PZT ceramics, PZN-PT and PYN-PT single crystals were studied. Changes of the piezoelectric hydrostatic coefficients d_h caused by an electric field (DC bias) were observed along with pressure and temperature dependencies. The measurement of the hydrostatic piezoelectric coefficient d_h seems to be promising for investigation of intrinsic (single domain) and extrinsic (domain-walls) contributions to piezoelectric behavior of single crystals and ceramic materials.     

磁电层合大电流传感器的改进和性能分析

对一种现有的磁电层合大电流传感器做了参数优化和改进。通过优化磁路设计、合理设置直流偏磁和扩大磁环气隙等方式,解决了原有传感器的测量波形失真问题,使其可以输出与待测交流电流具有线性幅值关系、波形形状一致的电压信号。试验测试表明,在测量700 A以内的待测电流时,改进后的电流传感器具有4.5 m V/A的电流测量灵敏度,在频率40~1 500 Hz范围内有平坦的输出,并具有一定的抗干扰能力。     

超磁致伸缩谐波电动机的原理与特性

传统超磁致伸缩电动机利用动子与定子间的摩擦力直接驱动，电动机的传动精度和承载能力等受材料摩擦影响较大。将谐波传动技术应用于超磁致伸缩电动机中，研制新型超磁致伸缩谐波电动机将可以有效克服这些缺陷。文章在分析超磁致伸缩电动机的基础上，探讨了新型的超磁致伸缩谐波电动机的原理与特性。