PZT components derived from polysulphone spinning process

The present paper deals with the development of lead zirconate titanate (PZT) fibres, pearls and fibre fragments, for their use as active phase in piezocomposites. As new a approach, the green ceramic components are shaped by polysulphone spinning, allowing for effective and flexible forming over a wide range of different geometries and sizes. The correlation between processing parameters, e.g. the slurry composition, nozzle size and operation velocity, and the resultant shape of ceramic components is analysed. Sintered piezoceramic parts show a dense microstructure. Performance data are evaluated on PZT/epoxy composites. Measurement results of strain, polarisation and piezoelectric coupling are given and discussed. The developed PZT components are seen as key for the creation of smart and lightweight structural components. Further, free formed PZT components open new design approaches for sensing and actuating devices and ultrasound transducers.     

New synthesis route for lead zirconate titanate powder

Phase pure lead zirconate titanate (PZT) powder was produced via a new aqueous coprecipitation method. A suite of characterization techniques, including FTIR, Raman, X-ray diffraction, SEM as well as nitrogen sorption were employed to investigate the structural evolution of the synthesized and calcined powder. The dried precipitate formed in aqueous phase yielded approximately 80 wt% final product after calcination. The PZT perovskite structure was obtained after calcination at 550 °C for 3 h. Milling of the calcined powder reduced the mean particle size from approximately 10 µm to 2 µm. With increasing calcination temperature from 550 °C to 700 °C, both surface area and pore volume decreased while pore size increased from 3.4 nm to 9.8 nm. The bulk density of pelletized samples increased from 4.83 to 7.57 g/cm³ with increasing sintering temperature from 800 °C to 1200 °C. Powder processing using this aqueous route is simple and reproducible leading to a method that is readily scalable for industrial applications.     

Influence of ferroelectric domain texture on the performance of multilayer piezoelectric actuators

Lead zirconate titanate (PZT)-based multilayer piezoelectric actuators (MAs) present a maximum in their piezoelectric properties when pre-stressed with a low mechanical load (ca. 50 MPa) along the longitudinal axis of the actuator. In this work, we investigate this phenomenon by combining polarised Raman spectroscopy with a Reverse Monte Carlo (RMC) method in order to quantify the domain orientation distribution of PZT-based MAs, both in-situ and at the remanent state, under combined applied electric field and mechanical load. Our study shows that the performance maximum of MAs is the result of two competing effects: (i) an increasing reservoir for non-180° domain switching for increasing applied compressive pre-stress and (ii) a large activation energy for domain switching at high pre-stresses. Hence, our study uncovers structure-property relationships in piezoceramic components that could be used to finely tune the electromechanical response of actuators.     

Thermodynamic cycle optimization for pyroelectric energy conversion in the thin film regime

Pyroelectric energy conversion is both simulated and realized on thin film lead zirconate titanate capacitors. The thermodynamics of the energy conversion cycle were explored, and the performance of the Brayton cycle was compared with the conventional Ericsson pyroelectric cycle. Cycle performance was examined using coefficients extracted from measured isothermal polarization hysteresis loops. It was found that the Brayton cycle is slightly more efficient than the Ericsson cycle over the range of temperatures tested and has significant efficiency improvements with increasing pyroelectric coefficients. The results from actual energy conversion cycles differed slightly from simulated performance, confirming the known challenges with synchronizing pyroelectric cycles with realistic thermal excitation. Finally, a one‐dimensional thermal transient model is used to explore the power conversion potential of thin film pyroelectrics. It is shown that the Brayton cycle has a significant performance advantage over the Ericsson cycle at higher operating frequencies. A power density of 8 mW/cm³ was obtained using the Brayton cycle for a thin film system at about 60 °C with an applied field of 5 V and stimulation frequency of 0.2 Hz. Copyright © 2017 John Wiley & Sons, Ltd.     

Near tip stress intensity factor for an edge-crack in a Pb(ZrxTi1−x)O3 thin film with 90° domain switching under a continuous laser irradiation

The near tip stress intensity factor K_Itip for an edge-crack in a Pb(Zr_xTi_1−x)O₃ thin film was investigated by superposition of the applied stress intensity factor K_Iapp under a continuous laser irradiation and the shielding stress intensity factor ΔK_I for 90° domain switching. Both K_Iapp and ΔK_I were solved by the weight function method, and switching toughening was analyzed based on the small scale domain switching theory. Results show that K_Itip of the edge-crack in the thin film is significantly affected by the initial poling angle, and the edge-crack tip is toughened by the domain switching area with the increase of the initial poling angle. The methodology can predict the fracture toughening of Pb(Zr_xTi_1−x)O₃ thin films quantitatively.     

Mechanical and electric fatigue of PZT(53/47) films on metallic substrates

Abstract

We have investigated the fatigue of electromechanical and dielectric properties of sol-gel derived PZT(53/47) thin films deposited on metallic substrates by means of electric and mechanical cycling. For the mechanical cycling a two point bending method was used to apply transversal stress to the samples. During mechanical cycling the piezoelectric coefficient d₃₁ remained constant up to about 10⁵ cycles, for a higher number of cycles a strong decrease was observed. During electric cycling no significant changes in the ferroelectric and electromechanical hysteresis loops could be found up to about 3×10⁵ cycles. Above this number the coercive field increases, the maximum strain and the remanent polarization decrease.

Obviously each electric cycling of the investigated films is accompanied by a mechanical cycling. It is assumed, that microcracks induced by mechanical stress are the main reason for the deterioration of the physical properties films during electric and mechanical cycling both.     

MPB Phase Transition and Microstructure of (1 – x)PMN–xPZT Activated by 0.05BZN Ceramics

The relaxor ferroelectric materials can be found in morphotropic phase boundary (MPB) existing between tetragonal and cubic phase. Since the MPB shifts to other phases by adding ceramics composition. [(1 – x)Pb(Mg_1/3 Nb_2/3)O₃–x Pb(Zr_0.52Ti_0.48)O₃] were doped by 0.05Ba(Zn_1/3 Nb_2/3)O₃ when x = 0.4, 0.3, and 0.2 ceramics, which prepared by using a two–step sintering process. The MPB transitions were studied by the use of XRD. The samples, at x = 0.4, were in MPB and then gradually shifted to cubic phase at x = 0.2. The microstructure of samples fracture found that the largest grain size of 4.51 μm for x = 0.2. This study using TEM technique which demonstrated a crystalline morphology with the largest crystal size about 1.293 μm at x = 0.3. These results also revealed that not only the ferroelectric phase shifted to relaxor behavior with decreasing PZT contents in PMN–PZT system but also activated by BZN, which led to the presence of the relaxor behavior.     

基于PZT传感器的管道扭转模态激励效果研究

导波激励模态单一性与衰减特性是导波激励效果的重要指标。采用PZT传感器,在建立基于PZT-5材料传感器并置于管道一端均匀对称分布的导波激励系统的基础上,以模态单一性与降低衰减特性为目标,研究了在低频段内模态特性以及传感器对T(0,1)模态的影响,得出了激励T(0,1)模态的最优激励方案。     

压电陶瓷精密控制系统的自适应模糊控制器研究

针对压电陶瓷等非线性系统,建立压电陶瓷微精密位移系统模型,并将模糊控制器替换传统的比例、积分和微分(PID)控制器,实现对PID参数的在线自整定。对模糊控制器的控制变量及论域等级等进行了研究及制定,并对其进行MATLAB仿真。实验结果表明,模糊逻辑控制器比传统PID控制器的响应速度快,超调量小,且控制策略简单易行。     

基于嵌入压电技术的钢管核心混凝土缺陷检测

钢管混凝土构件核心混凝土缺陷影响到其延性和承载力。利用自制的嵌入式压电功能元,该文提出了基于压电陶瓷应力波测量与分析的核心混凝土缺陷监测方法。通过对比在不同状态的简谐激励下测量信号幅值和扫频激励下小波包能量的差异,定义了基于测量信号幅值和小波包能量的损伤指标。结果表明,利用提出的嵌入式压电技术和定义的损伤指标,有效地识别了钢管混凝土构件的核心混凝土损伤,损伤指标对损伤程度敏感。