PZT 95/5铁电陶瓷的冲击压缩Hugoniot特性研究

 采用一级气体炮加载装置,利用加窗VISAR技术,对极化和未极化两种状态的PZT 95/5铁电陶瓷进行了逆向冲击实验,在0.52~3.8 GPa冲击压力范围内,得到了PZT 95/5铁电陶瓷两种状态的σ-u关系。对比文献已有实验数据显示,PZT 95/5铁电陶瓷的Hugoniot曲线与初始密度值密切相关,高密度的PZT 95/5铁电陶瓷在0~3.0 GPa压力范围内的σ-u关系接近线弹性,较低压力下不同极化状态的Hugoniot数据表明,PZT 95/5铁电陶瓷发生了冲击相变。     

Pyroelectric and photoelectric responses of capacitors based on thin PZT films

The influence of 0.63-μm laser radiation and an external electric field on the photo-and pyroelectric response of thin ferroelectric Pb(Zr_0.54Ti_0.46)O₃ (PZT) films is studied at various temperatures. The films are grown by RF magnetron sputtering of a PZT ceramic target on platinum-coated substrates. It is found that the photosensitivity of PZT films increases after switching of the applied static electric field, as well as after an increase in temperature.     

Study of 1-3 PZT fibre/epoxy composite force sensor

Lead zirconate titanate (PZT) fibres were prepared by a powder-based extrusion method. Pre-sintered PZT powder mixed with poly(acrylic acid) was spun in a spinnerette to produce fibres. The fibre of ∼400 μm diameter was used to fabricate 1-3 PZT fibre/epoxy composite discs with different volume fractions (ϕ) of PZT. Since the ceramic fibres are rather brittle, their elastic properties cannot be measured directly. In order to determine the properties of the ceramic fibres, effective properties of the fibres/epoxy 1-3 composite were measured. By using a modified series and parallel model, the properties of 1-3 composites can be calculated. Then, the elastic coefficient s_33,fibre^E, relative permittivity ε_33,fibre^T and piezoelectric strain coefficient d_33,fibre of the ceramic fibre could be found. Ring-shaped PZT fibre/epoxy materials composites with different ϕ were fabricated to be used as the sensing material in force sensor applications. The ring-shape composite with ϕ=0.5 was installed into a housing and the sensor was calibrated by different methods and its sensitivity was found to be 144 pC/N within the frequency range of 0.5–6.4 kHz which is much higher than that of a quartz force sensor with a similar structure. PACS 07.07.Df; 72.80.Tm; 77.84.Dy     

Finite element modelling of dense and porous piezoceramic disc hydrophones

The acoustic characteristics of dense and porous piezoceramic disc hydrophones have been studied by finite element modelling (FEM). The FEM results are validated initially by an analytical model for a simple disc of dense piezoceramic material and then it is extended to a porous piezoceramic disc replicating a foam-reticulated sample. Axisymmetric model was used for dense piezoceramic hydrophone due its regular geometric shape. 3-dimensional model was used for the porous piezoceramics, since the unit cell model is inadequate to fully represent transducers of finite lateral dimensions. The porous PZT discs have been synthesised by foam-reticulation technique. The electrical impedance and the receiving sensitivity of the hydrophones in water are evaluated in the frequency range 10-100 kHz. The model results are compared with the experimental data. The receiving sensitivity of piezocomposite hydrophones is found to be reasonably constant over the frequency range studied. The sharp resonance peaks observed for the dense piezoceramic hydrophone has broadened to a large extent for porous piezoceramic hydrophones, indicating higher losses. The flat frequency response suggests that the 3-3 piezocomposites are useful for wide-band hydrophone applications.     

The application of high permittivity piezoelectric ceramics to 2D array transducers for medical imaging

Two-dimensional (2D) array transducers have become of great interest in the last few years, in view of real-time volumetric ultrasonic imaging. The electrical matching between the high electrical impedance of elements and the standard cables and electronics is one of the key issues in 2D array design. The use of high-permittivity ceramics such as PNNZT either in bulk configuration or in 1-3 piezocomposites decreases the electrical impedance. In this paper, bulk samples of PNNZT and PZT ceramics are characterised, and results are compared. 2D array elements are then manufactured and their electrical impedances measured. Theoretical predictions of homogenisation models for 1-3 piezocomposites allow the simulation of the electroacoustic behaviour of 2D array elements. Results for both piezocomposite and bulk materials can be obtained. Calculations of the input impedance, the sensitivity and the bandwidth of the different configurations are compared and discussed. These results demonstrate the advantages of the PNNZT compositions over standard PZT.     

Lamb wave dispersion in a PZT/metal/PZT sandwich plate with imperfect interface

Abstract

The Lamb wave dispersion in a PZT/Metal/PZT sandwich plate is investigated by employing the exact linear equations of electro-elastic waves in piezoelectric materials within the scope of the plane-strain state. It is assumed that at the interfaces between the piezoelectric face layers and metal core layer, shear-spring and normal-spring type imperfect conditions are satisfied. The degree of this imperfectness is estimated through the corresponding shear-spring and normal-spring type parameters which appear in the contact condition characterizing the transverse and normal displacements’ discontinuity. The corresponding dispersion equation is derived, and as a result of the numerical solution to this equation, the dispersion curves are constructed for the first and second lowest modes in the cases where the material of the face layers is PZT and the material of the middle layer is Steel (St). Consequently, for the PZT/St/PZT sandwich plate, the study of the influence of the problem parameters such as the piezoelectric and dielectric constants, layer thickness ratios, non-dimensional shear-spring, and normal-spring type parameters, is carried out. In particular, it is established that the imperfectness of the contact between the layers of the plate causes a decrease in the values of the wave propagation velocity.     

采用PZT动态调制的光纤光栅应变力测量技术

提出了一种新型PZT的动态调制光纤光栅应变力测量技术。把光谱仪对峰值波长移动的测量改变为示波器对峰值光功率时间间隔的测量 ,并对这种技术进行了理论分析和实验研究。用交变电压调制固定在光纤光栅上的PZT ,同时对施加在光栅上的应力进行测量。实践证明 ,测光脉冲时间间隔法与光谱峰值移动法的测量结果相同 ,而且两者与理论计算结果相符     

冲击波加载下PZT 95/5铁电陶瓷的电阻率研究

利用炸药爆炸产生的平面冲击波,研究了垂直模式冲击波加载下PbZr_0.95Ti_0.05O₃ (PZT 95/5)铁电陶瓷冲击波压缩区域的电阻率变化.在建立的模型中考虑了冲击波压缩区域的有限电阻率,计算结果表明：在压力约2.0GPa,负载短路的条件下,PZT 95/5铁电陶瓷冲击波压缩区域的电阻率从初始10⁷—10¹¹Ωcm迅速降到最小值约40Ωcm,然后基本保持在120—140Ωcm之间. 关键词： PZT 95/5铁电陶瓷 冲击波 电阻率     

Mechanical Reinforcement and Piezoelectric Properties of PZT Ceramics Embedded with Nano-Crystalline

The double-scale lead zirconate titanate （PZT） piezoelectric ceramics were prepared by the solid state processing with PZT nano-crystalline and micro-powder. The microstructures, electrical and mechanical properties of the double-scale PZT are investigated. All the sintered ceramics exhibit a single perovskite structure and the grain size of the dou ble-scale PZT reduces due to the incorporation of PZT nano-crystalline. Compared to normal PZT, the mechanical properties increase significantly and the piezoelectric properties decrease slightly. Mechanisms responsible for the reinforcement of the double-scale PZT are discussed.     

Electro-optic study of PZT ferroelectric ceramics using modulation of reflected light

Electro-optic coefficients of variations in the refractive index of PZT and PLZT ceramic materials induced by ac electric field are estimated using modulation of reflected light. The electro-optic coefficients of PLZT ceramics measured with the aid of conventional birefringence using the phase shift of transmitted radiation and the proposed method of birefringence using the modulation of reflected light are compared.     

Constitutive modeling of the densification of PZT ceramics

In the present work, sintering constitutive models were employed to investigate the high-temperature densification behavior of undoped stoichiometric lead zirconate titanate (PZT) ceramics with perovskite structure. The constitutive models used were based on classical grain-boundary diffusion and interface reaction, and also the coupled mechanism of the two processes. PZT ceramics were fabricated and the calcination and sintering of the materials were discussed. Using the constitutive models employed and the experimental results obtained, the activation energy for densification of the PZT ceramics investigated was determined as 390±30 KJ/mol. It was noted that the coupled mechanism of grain-boundary diffusion and interface reaction was the controlling process during the densification of the materials investigated.     

Modified PZT ceramics as a material that can be used in micromechatronics

Results on investigations of the PZT type ceramics with the following chemical composition: Pb_0.94Sr_0.06(Zr_0.50 Ti_0.50)_0.99 Cr_0.01O₃ (PSZTC) which belongs to a group of multicomponent ceramic materials obtained on basis of the PZT type solid solution, are presented in this work. Ceramics PSZTC was obtained by a free sintering method under the following conditions: T _sint = 1250 °C and t _sint = 2 h. Ceramic compacts of specimens for the sintering process were made from the ceramic mass consisting of a mixture of the synthesized PSZTC powder and 3% polyvinyl alcohol while wet. The PSZTC ceramic specimens were subjected to poling by two methods: low temperature and high temperature. On the basis of the examinations made it has been found that the ceramics obtained belongs to ferroelectric-hard materials and that is why it may be used to build resonators, filters and ultrasonic transducers.     

Selecting passive and active materials for 1.3 composite power transducers

1.3 PZT-polymer composites were fabricated using the dice and fill method with various PZT types and volume fractions. These composites were evaluated for power underwater transducer applications with an air backed and no matching layer configuration. Electrical input and acoustical output powers were monitored as a function of the drive level. Total acoustic power densities of 30 W/cm2 were obtained with a P189/epoxy piezocomposite vibrating at 350 kHz with a low duty cycle (1-5%) and with a 90% efficiency. Power densities up to 20 W/cm2 were measured with a 50% duty cycle. Evolution and destruction of the transducers were monitored versus increasing averaged power. It was observed that better efficiencies were obtained with low volume fraction configurations allowing natural acoustic impedance matching to water. It was found that hard PZT type (Navy III) are optimal compositions even for piezocomposite transducers. It is shown that, unlike a common belief, the polymer mechanical losses are comparable to those of the active ceramic justifying that 1.3 piezocomposites are suited for low-cost power applications. In fact, the main limitation induced by the polymer phase is a strong thermal breakdown when the temperature of the transducer approaches the glass transition region of the polymer. Measurements of the polymer losses as a function of the temperature were obtained confirming this point and offering interesting new alternatives for future composite power transducers.     

Dielectric and piezoelectric properties of PZT–cement composites

Lead zirconate titanate (PZT) and cement composites of 0–3 connectivity were produced using PZT of 30–90% by volume. The effects of PZT on dielectric and piezoelectric properties of the composites were then investigated. The dielectric constant (ε_r) of the composites was found to increase with increasing PZT content. The ε_r value of 90% PZT composite obtained was 291 which is noticeably higher than that of PC sample (ε_r = 79). The dielectric loss (tan δ) was found to decrease with PZT content and the tan δ value was lowest at 0.63 for 90% PZT composite. Piezoelectric coefficient (d₃₃) was found to increase with PZT content as expected. However, the effects were most significant at two stages, first at 30% PZT volume content (14 pC/N) and then at very high PZT content (90% by volume) where d₃₃ value reached 43 pC/N.     

Study of elemental and phase composition of PZT thin films by auger depth profiling

The composition of PZT thin films deposited by diode HF sputtering of a ceramic target on Pt/Ti/SiO₂/Si substrates was studied. The remanent polarization of grown films was to 22 μC/cm². A technique for verifying the adequacy of elemental and phase composition of thin films to the ferroelectric phase composition was proposed. The problems of reliable contact of Pt electrodes with the PZT layer were considered.     

Au/PZT/BIT/p-Si异质结的制备与性能研究

采用脉冲激光沉积(PLD)工艺,制备了以Bi₄Ti₃O₁₂(BIT)为过渡阻挡层的Au/PZT/BIT/p-Si异质结.研究了BIT铁电层对Pb(Zr_0.52Ti_0.48)O₃(PZT)薄膜晶相结构、铁电及介电性能的影响,对Au/PZT/BIT/p-Si异质结的导电机制进行了讨论.氧气氛530℃淀积的PZT为多晶铁电薄膜,与直接淀积在Si基片上相比,加入BIT铁电层后PZT铁 关键词： 铁电薄膜 异质结构 脉冲激光沉积(PLD)     

冲击加载下PZT 95/5铁电陶瓷的脉冲大电流输出特性

极化了的PZT 95/5铁电陶瓷在冲击波作用下发生铁电相到反铁电相的结构相变，释放出被束缚的电荷，流经外电路，形成脉冲电流.基于这一原理，针对低感、低阻负载的要求，对PZT 95/5铁电陶瓷 LRC电路响应进行了理论分析，并开展了实验研究.实验采用多组PZT 95/5铁电陶瓷并联，获得了前沿小于500ns，峰值大于5kA的大电流. 关键词： PZT 95/5铁电陶瓷 冲击波 爆电电源     

Effect of PZT particle size on dielectric and piezoelectric properties of PZT–cement composites

In this work, the effect of PZT particle size on the properties of PZT–PC composites was investigated. PZT of various median particle sizes (3.8–620 μm) were used at 50% by volume to produce the composites. The results showed that the dielectric properties of the composites increased marginally with PZT particle size where ε_r = 176 and 167 for composites with 620 μm and 3.8 μm PZT particle size, respectively. A noticeable increase in d₃₃ values was also found when the particle size was increased where the composite with 620 μm PZT particles size was found to have d₃₃ value of 26 pC/N compared to 17 pC/N for the composite with 3.8 μm PZT particle size. The enhancement in the dielectric and piezoelectric properties was contributed to lesser contacting surfaces between the cement matrix and the PZT particles.     

0.5PZN-0.5PZT压电陶瓷拉曼散射研究

PZT基多元系压电陶瓷在三方相含量与四方相含量相等的准同型相界处(MPB)具有极为优异的压电性能。文章采用拉曼散射方法研究了0.5PZN-0.5PZT陶瓷体系中三方-四方相共存与弥散相变现象。研究发现,与纯PZT相比,0.5PZN-0.5PZT体系拉曼谱呈明显宽化特征,表明体系弛豫性较强,依据介温谱计算出弥散因子γ高达1.71。通过对拉曼谱峰进行Gauss函数拟合,定量计算三方相R₁模式与四方相E(3TO)和A₁(3TO)模式相对强度,以及四方相E(4LO)和A₁(3LO)模式与三方相R_h模式相对强度,结果表明0.5PZN-0.5PZT体系三方相与四方相含量相等,组成位于准同型相界,该结果得到XRD相分析验证。电学测量表明0.5PZN-0.5PZT陶瓷压电性能优异：k_p=0.66, d₃₃=425 pC/N,适宜作为压电致动器材料使用。     

FeCuNbSiB对FeNi/PZT复合结构磁电效应的影响

构造了FeCuNbSiB/FeNi/PZT磁电复合结构并与FeNi/PZT复合结构进行了对比研究.分析了高磁导率材料FeCuNbSiB对FeNi磁场的影响机理,研究了FeCuNbSiB/FeNi/PZT三相复合结构的磁电效应.实验表明,在FeNi/PZT两相层合结构中黏接FeCuNbSiB层后:1)最优偏置磁场从200 Oe降低到55 Oe,最大谐振磁电电压系数从1.59 V/Oe增大到2.77 V/Oe;2)在低偏置磁场中,层合结构磁电电压转换系数提高了1.7—7.8倍;3)层合结构的磁电电压对静态磁场 关键词： 层合结构 最优偏置磁场 高磁导率 磁电电压转换系数