Temperature- and dc bias field- dependent piezoelectric effect of soft and hard lead zirconate titanate ceramics

The dc bias field-dependent piezoelectric coefficient d ₃₃ of lead zirconate titanate ceramics (PZT5, PZT8 and P5H) were determined by a quasi-static method. It was found that piezoelectric coefficient d ₃₃ was almost independent of positive dc bias field for PZT8 and PZT5 ceramics, while for P5H ceramic an obvious decrease of coefficient d ₃₃ was observed under positive dc bias field. On the other hand, the temperature-dependent piezoelectric response for PZT ceramics were investigated by both quasi-static and resonance methods. The piezoelectric coefficient d ₃₃ was found to increase with increasing temperature for both PZT5 and PZT8 ceramics. For P5H ceramics, coefficient d ₃₃ showed a first decreasing and then increasing tendency with respect to temperature. These results were discussed in terms of intrinsic and extrinsic contributions to piezoelectric response.     

Piezoelectric and dielectric aging in pb(zr,ti)o3 thin films and bulk ceramics

Abstract

Piezoelectric and dielectric aging was studied in Pb(Zr,Ti)O₃ (PZT) thin films and bulk ceramics. It was found that piezoelectric aging in thin films obeys the logarithmic time dependence with the relative aging rate much higher than that of the dielectric constant, while comparable aging rates of piezoelectric and dielectric constants were found in PZT ceramics. The origin of piezoelectric aging in PZT films was related to depolarization of the films rather than to suppression of the domain wall motion as was generally accepted for PZT ceramics.     

High throughput experimentation for the development of new piezoelectric ceramics

Piezoelectric ceramics based on the perovskite Pb(Zr,Ti)O₃ (PZT) system are widely used as sensors and actuators. The toxicity of lead has motivated research in the field of alternative environmentally friendly lead-free materials. Lead-free piezoelectric ceramics are numerous and in comparison to PZT poorly investigated. The performance of PZT cannot yet be achieved by any lead-free material. Thus High Throughput Experimentation (HTE) shall be applied to discover new lead-free piezoelectric ceramics. In the present study a parallel solid state synthesis method was established for bulk ceramics. Libraries consisting of chemically diverse oxides are produced via the mixed-oxide route. Subsequently, classical piezoelectric parameters such as ɛ, d₃₃ and Curie temperature are screened. The high throughput route, which allows the synthesis and characterisation of over one hundred samples per week, has to be validated with PZT samples. The morphotropic phase boundary was clearly identified and dielectric measurement shows excellent results. The method may be extended to lead-free materials.     

PZT95/5铁电陶瓷脉冲源用于nF电容器充电

采用简化的物理模型 ,分析了以电容为负载的PZT95 /5铁电陶瓷在冲击波加载下的电响应规律以及极化能的释放和转移特性 ,并运用爆炸平面冲击波垂直加载技术 ,对其在nF电容器下的输出特性进行了试验研究。     

PZT95/5铁电陶瓷击穿的统计分析

采用垂直加载冲击波方式实验研究了 PZT95 / 5铁电陶瓷的电击穿现象。对实验数据的统计分析表明 ,PZT95 /5的击穿可用弱点击穿理论解释 ,符合 weibull分布 ,其几何效应参数≈ 2     

The Effect of Sintering Processes on the Properties of Mn-F Doped PZT Ceramics

Fluoridated PZT ceramics were produced by solid-state and liquid-phase sintering methods, according to the formula Pb(Zr_0.52Ti_0.48)_1-xMn_xO_3-yF_y, where 0 < x < 0.015 and 0 < y < 0.1. The effects of sintering processes on the phase development and microstructure of Mn-F doped PZT ceramics have been investigated using XRD and FEGSEM. In solid-state sintering, the fluoride additive enhanced the densification of PZT ceramics, enabling densification to >95% relative density at a temperature as low as 1000°C. However, fluoride loss at high temperatures was found to be a significant problem. Alternatively, ceramics with a density >92% were prepared by sintering at a temperature of 850°C by incorporating a eutectic mixture of PbO and V₂O₅ as sintering aid. Problems associated with volatilization of fluoride compounds during sintering could be alleviated using this approach. EPMA was employed to analyze the distribution of the additives in the calcined powders and sintered ceramics. The nonlinear dielectric properties were determined by measuring P-E loops, using an AC electric field in the range 0.1 to 2.0 kV mm^?1.     

Effect of CoFe2O4 content on the dielectric and magnetoelectric properties in Pb(ZrTi)O3/CoFe2O4 composite

Ferroelectric Pb(Zr_0.53Zr_0.47)O₃ (PZT) and ferromagnetic CoFe₂O₄ (CFO) composite ceramics, [(1???x)PZT???xCFO for x?=?10, 20, 30, 40 and 50 wt.%], were prepared by a conventional solid-state reaction method. X-ray diffraction studies revealed that only PZT and CFO phases were present in the composite samples and no other phase was detected. The 0.9PZT-0.1CFO composite ceramic displayed better piezoelectric properties. The piezoelectric resonance frequency increased with the CFO content, but the resonance peak attenuated rapidly and disappeared when the CFO content equaled to 0.5. The permittivity peak temperature was the same as that of pure PZT ceramics. 0.9PZT-0.1CFO composite also had the highest magnetoelectric (ME) coupling coefficient among the studied PZT-CFO composite ceramics. The ME coefficient linearly increased with ac frequency up to 100 kHz.     

Influence of electric field on the ultrasound velocity in PZT ceramics

The paper deals with the influence of the electric bias field on the ultrasound velocity of various samples of Pb(Zr _x Ti_1−x )O₃ (PZT) ceramics. The ultrasonic velocities were measured on commercial types of PZT ceramics as APC 841, APC 850, and APC 856, at room temperature. The comparison of the ultrasound velocities dependence on electric bias field was made for poled/unpoled soft ceramics. The ultrasonic pulse-echo technique was used in our experiment. The ultrasonic system is based on Matec Instruments, Inc. modules. The time domain response was recorded and time of flight between echoes was directly measured by digital oscilloscope, type Agilent 54622D. The high bias field was applied on disk samples by the high voltage amplifier type Trek 610D, using a special setup and sample holder. The sound velocity was found to change drastically near the coercive field for a PZT ceramics, where the velocity of longitudinal waves decreases with an increasing field while the velocity of shear waves increases, which is caused by the change of the elastic anisotropy under influence of the depolarization field. The consequent change of the piezoelectric contribution to effective elastic constant decreases the velocity of longitudinal waves and at the same time increases the velocity of shear waves around the coercive field.     

一种新型三自由度微定位新方法

设计了一种基于压电陶瓷的三维微定位系统,通过12个空间分布的压电陶瓷微驱动器及4个工作平台的配合,实现X、Y、Z向的精密位姿控制.阐述了微定位原理、建立了载物台位姿与压电陶瓷微驱动器伸缩量之间的关系,介绍了系统误差来源以及微定位装置的构造.该研究可望为一些高科技领域的微进给提供实用新技术.     

Resonant frequency temperature coefficients for the piezoelectric resonators working in various vibration modes

Resonant frequency temperature coefficient is dependent on material properties, resonator dimensions and vibration mode. It could be effectively tuned by the resonator dimensions or by the domain structure in ferroelectric crystals. Optimum dimensions for the zero temperature coefficient resonator are calculated for ring radial vibration mode as a function of resonator dimensions (r ₂/r ₁ = 3.8 for hard PZT ceramics, APC841 type). There are similar results of the temperature coefficient calculations for PZT ceramics and crystal resonators. The temperature coefficient is generally smaller for higher overtones of resonant mode.     

Effects of complex doping on microstructural and electrical properties of PZT ceramics

The influence of complex dopants including donor and acceptor ions on microstructure and electrical properties of PZT (Zr/Ti = 53/47) ceramics was investigated. The prepared PZT ceramics modified with complex soft dopants, La⁺³ and Nb⁺⁵, showed that the piezoelectric properties were enhanced and stable with the compositional variations, which made it possible to establish the higher reliability and reproducibility of the piezoelectric performances. For 1.0 mol% La and 1.2 mol% Nb doped composition, the maximum value, k _P = 0.66, was obtained. Unlike single element doping, the complex doping of both the donor and acceptor ions caused various compensation effects for the piezoelectric properties of the PZT ceramics. The improved piezoelectric properties, i.e., enhanced Q _m with remaining higher k _p , were obtained in the PZT composition complexly doped with La⁺³ and Fe⁺³. For 1.0 mol% La and 2.0 mol% Fe doped PZT composition, relatively high Q _m and k _p values of 580 and 0.53, respectively, were obtained. It was also shown that the PZT composition had the rather lowered dielectric constant, ε _r = 800, and considerably low loss, tanδ = 0.003. By changing the dopants compositions, the properties can also be tailored over wider range.     

Preparation of Functionally Graded PZT Ceramics Using Tape Casting

Functionally graded ferroelectric ceramics (FGM) have been fabricated for pyroelectric applications by an aqueous tape casting technology. The FGM produced in this study consisted of a porous Lead Zirconate Titanate (PZT) tape-cast ceramic, which was made by starch inclusions; sandwiched between two dense PZT layers by stacking and lamination. This paper investigates the effect of porosity on the microstructure and electrical properties of the PZT FGM samples produced. The microstructure of the porous and laminated sintered structures was studied using Scanning Electron Microscopy (SEM). The grain size of the porous layer tended to decrease with increasing corn-starch content. The dielectric constant and pyroelectric coefficient of the FGM both showed decreasing behaviour with increasing porosity.     

Thick piezoelectric coatings via modified sol-gel technique

Abstract

A hybrid sol-gel approach is reported for the deposition of high-quality composite PZT films of the thickness  1 μm. In this approach, the metallo-organic sol-gel precursor solution is mixed with fine piezoelectric powders and dip-coated onto Pt/Ti/SiO₂/Si substrates. Different organic viscous additives and deposition strategies were tried in order to deposit dense films with the properties approaching to those of bulk PZT. Using commercial PZT powder (TRS600FG) and ultrasonic mixing during deposition process, composite films having dielectric permittivity of ～2500 and saturation polarization ～35 μC/cm² were obtained. These values are intermediate between bulk ceramics and conventional sol-gel PZT films and therefore are indicative of good piezoelectric properties.     

Reactive Calcination Derived PZT Ceramics

Perovskite PZT ceramics are synthesized from stoichiometric oxide ratios of Pb, Zr, and Ti. The oxide powders are mixed mechanically and calcinated, and then sintered to form the desired perovskite phase using conventional solid-state reaction and reactive calcination routes. Highly reactive powders are produced by reacting the materials near the temperature of maximum volumetric expansion. At this point, an almost single phase with relatively high homogeneous structure is obtained. Also, the highly reactive powders allow densification to occur at temperatures as low as 950C without the need to the additions of excess lead oxides. The dielectric properties of the PZT ceramics prepared by reactive calcination route are measured and compared with the conventional route.     

Active beam vibration control using PZT actuators

Abstract

Smart materials of lead-zirconate-titanate (PZT) piezoelectric ceramics have attracted attention in recent years for active vibration control, acoustic noise suppression, health monitoring and damage assessment. We at McDonnell Douglas Aerospace have been studying these ceramics for use as sensors and actuators in various space and aircraft structures. In this paper, we will report results of a recent study on active vibration control using monomorph PZT actuators. The experiments were performed on thin aluminum cantilever beams. Collocated and non-collocated sensors and actuators were employed. Two control techniques: the classical velocity feedback and adaptive feedback controls, were investigated. We have obtained significant damping and broadband vibration attenuation of greater than 30 dB using the classical control with the single-input single-output feedback approach. A 24 dB reduction has also been achieved using the adaptive control with the multiple-input single-output approach. Detailed experimental methods and results will be described.     

Effect of Buffer Layer on the Properties of Laser Ablated PZT Thin Films

Lead zirconate titanate (PbZr _x Ti_1?x O₃) or PZT ceramics are a class of piezoelectric materials that are currently experiencing widespread use in industry as electromechanical devices. PtSi/ZnO/PZT thin films were deposited by pulsed laser deposition at relatively low substrate temperature. The PZT thin films on PtSi substrates and on ZnO buffer layer were deposited at substrate temperature 300°C. The composition analysis shows that the film deposited at low temperature is stoichiometric. The films exhibit ferroelectric nature with coercive field of 19.6 kV/cm for 800 nm thick film. The leakage current density of the films shows a good insulating behavior.     

Piezoelectric and dielectric characteristics of low-temperature-sintering Pb(Mg1/2W1/2)O3–Pb(Ni1/3Nb2/3)O3–Pb(Zr,Ti)O3 ceramics according to the amount of PNN substitution

In this study, in order to develop low-temperature-sintering ceramics for multilayer piezoelectric actuator, Pb(Mg_1/2W_1/2)O₃–Pb(Ni_1/3Nb_2/3)O₃–Pb(Zr,Ti)O₃ (abbreviated as PMW–PNN–PZT) ceramics were fabricated using Li₂CO₃ and CaCO₃ as sintering aids and their dielectric and piezoelectric properties were investigated with the amount of Pb(Ni_1/3Nb_2/3)O₃ (abbreviated as PNN) substitution. PMW–PNN–PZT composition ceramics could be sintered up to 870°C by adding sintering aids. At the sintering temperature of 900°C, electromechanical coupling factor (k _p), piezoelectric constant (d ₃₃) and Curie temperature (Tc) in the composition ceramics with 9 ;mol% PNN substitution showed the optimal value of 0.64 517 ;pC/N and 317°C, respectively for multilayer actuator application.     

Dielectric and pyroelectric properties of (1 − x)PST-xPZT ferroelectric ceramics

Pb(Sc_1/2Ta_1/2)O₃ (PST) ceramics were investigated greatly in the world for their unique pyroelectric, ferroelectric and dielectric properties and comprehensive applications on uncooled focal plane arrays, infrared detectors and other electronic devices. However, the PST ceramics doped with other perovskite ferroelectrics showed more excellent electrical and electronic properties. In this paper, (1???x)PST-xPZT(PSTZT) ferroelectric ceramics were prepared by conventional solid state process. The experiment results demonstrated that the PSTZT ceramics had pure perovskite phase. The temperature dependence of permittivity of PSTZT ceramics was investigated in detail, which indicated that PSTZT was not a complete diffusive phase transition ferroelectric ceramics. At room temperature, the pyroelectric coefficient of PSTZT (x?=?0.1) ceramics was about 15*10^?8C/(cm² K).     

Device effects of various Zr/Ti ratios of PZT thin-films prepared by sol-gel method

Abstract

PZT, PbZr_xTI_1?xO₃, thin-films with various Zr/Ti ratios, 100/0 (lead zirconate) to 0/100 (lead titanate), were prepared by the sol-gel method. Basic electric properties, dielectric constant, tan σ, P-E hysteresis curve, switching properties were measured respectively as a function of composition. Dielectric constant indicated a specific peak value (～1100) around the morphotropic phase boundary between tetragonal and rhombohedral phase. Satisfactory low-voltage saturated hysteresis curves were observed for the compositions of PZT(90/10) through PZT(20/80). The remanent polarization and the coercive field increased as the titanium content decreased. The result of X-ray measurement showed that the lattice constants of thin-Film PZT are different from bulk ceramics for compatible compositionsS. The boundary, on which the c/a ratio must be 1 (rhombohedral phase), was slightly shifted to PbTiO₃ side. This distortion in crystal structure is considered to be due to the thin-film effect, which the lattice mismatch between the platinum substrate and the PZT layer, restricted the ions to position into proper cites.     

Preparation of Bulk Pb(Zr, Ti)O3 with Crystallographic Texture by Templated Grain Growth Method

Polycrystalline Pb(Zr, Ti)O₃ (PZT) ceramics with 111-texture were prepared by the templated grain growth (TGG) method using the platelike Ba₆Ti₁₇O₄₀ (B6T17) particles as templates. Textured PZT was obtained by sintering of green compacts containing matrix PZT, aligned B6T17, and excess PbO. Excess PbO formed a liquid phase and promoted the dissolution of PZT grains and the precipitation on B6T17 grains. A similarity of the arrangement of ions on (001) of B6T17 and (111) of PZT gave 111-texture to matrix PZT.