成型压力对0-3型锆钛酸铅/水泥压电复合材料的影响

以快硬硫铝酸盐水泥为基体,以锆钛酸铅(PZT)为功能相,用压制成型法制备出0-3型PZT/水泥基压电复合材料。分析成型压力对PZT/水泥基压电复合材料的压电性和介电性的影响,结果表明:不同粒径PZT颗粒作为功能相的水泥基压电复合材料,成型压力对其压电性和介电性有不同的影响。在30~90 MPa压力范围内,成型压力越大,PZT/水泥压电复合材料的压电应变常数d33和相对介电常数εr均显著提高,这是由于气孔率随压力增大而减少,而压电电压常数g33的变化则与功能相的粒径有关。机电耦合系数也有着不同的变化趋势,对于6μm和126μm PZT/水泥压电复合材料,其机电耦合系数Kt和Kp随压力增大缓慢下降,而对于430μm PZT/水泥压电复合材料则呈上升趋势。当压力达到150 MPa时,其压电性和介电性均急剧减小。     

Improvement electrical properties of sol–gel derived lead zirconate titanate thick films for ultrasonic transducer application

In this work, a fabrication process of piezoelectric PZT [Pb(Zr_0.52Ti_0.48)O₃] thick films up to 60 μm deposited on silicon and aluminum substrates is reported. Crystalline spherical modified PZT powder about 300 nm in diameter was used as filler. PZT polymeric precursor produced by Chemat Inc. was used as the matrix material. Spinning films were annealed at 700 °C for one hour in the furnace in air. The thickness of the thick films was measured using a scanning electron microscope (SEM). Compared with previous piezoelectric PZT composite films, the modified piezoelectric thick films exhibit better dielectric properties. The dielectric constant is over 780 and dielectric loss is 0.04 at 1 KHz. Using a PiezoCAD model, the high frequency transducer was designed and fabricated. It showed a bandwidth of 75% at 40 MHz.     

力电多场鼓包法测定PZT铁电薄膜的横向压电系数

为表征Pb(Zr_(0.52)Ti_(0.48))O_3(PZT)薄膜的横向压电性能,以纯力场鼓包测试模型和铁电薄膜材料压电方程为基础,推导了PZT铁电薄膜的力电耦合鼓包本构模型。采用溶胶-凝胶法制备了PZT铁电薄膜,并通过化学腐蚀法获得PZT薄膜鼓包样品。在外加电压为0~14V的条件下进行鼓包测试。结果表明,在纯力场作用下,PZT薄膜的弹性模量和残余应力分别为91.9GPa和36.2MPa;随着电压从2V变化到14V,PZT薄膜的横向压电系数d31从-28.9pm/V变化到-45.8pm/V。本工作所发展的力电耦合鼓包测试技术及力电耦合鼓包本构模型为评价铁电薄膜材料的横向压电性能提供了一种有效的分析方法。     

Surface acoustic wave characteristics and electromechanical coupling coefficient of lead zirconate titanate thin films

Lead zirconate titanate (PZT) thin films were created on ST-X quartz using radio frequency magnetron sputtering deposition. PZT films deposited on quartz are used as a new piezoelectric substrate for surface acoustic wave (SAW) devices. Microelectromechanical technique was used to fabricate interdigital transducers on the surface of the substrate to be used as a SAW delay line device. The results show that the PZT film was successfully deposited on ST-X quartz, and that the PZT film on ST-X quartz can enhance the electromechanical coupling coefficients of SAW.     

Flexible highly-effective energy harvester via crystallographic and computational control of nanointerfacial morphotropic piezoelectric thin film

Controlling the properties of piezoelectric thin films is a key aspect for designing highly effident flexible electromechanical devices.In this stud~ the crystallographic phenomena of PbZr1-xTixO3 (PZT) thin films caused by distinguished interfacial effects are deeply investigated by overlooking views,including not only an experimental demonstration but also ab initio modeling.The polymorphic phase balance and crystallinity,as well as the crystal orientation of PZT thin films at the morphotropic phase boundary (MPB),can be stably modulated using interfacial crystal structures.Here,interactions with MgO stabilize the PZT crystallographic system well and induce the texturing influences,while the PZT film remains quasi-stable on a conventional Al2O3 wafer.On the basis of this fundamental understanding,a high-output flexible energy harvester is developed using the controlled-PZT system,which shows significantly higher performance than the unmodified PZT generator.The voltage,current,and power densities are improved by 556％,503％,and 822％,respectively,in comparison with the previous flexional single-crystalline piezoelectric device.Finally,the improved flexible generator is applied to harvest tiny vibrational energy from a real traffic system,and it is used to operate a commercial electronic unit.These results clearly indicate that atomic-scale designs can produce significant impacts on macroscopic applications.     

Effects of a PbTiO3 insertion layer on the morphological and electromechanical characteristics of sol-gel-driven 0.2PZN-0.8PZT piezoelectric films for energy harvesters

This study investigated the morphological and electromechanical characteristics of 0.2PZN-0.8PZT films fabricated using a PbTiO3 layer. Crack-free 1-microm-thick films with a pure perovskite phase were obtained on Pt/Ti/SiO2/Si substrates using a modified sol-gel deposition method. A highly dense and smooth morphology and a high piezoelectric coefficient (d33) of 230 pC/N were observed in a 0.2PZN-0.8PZT film with a PbTiO3 insertion layer after annealing at 750 degrees C. The as-produced sol-gel-driven 0.2PZN-0.8PZT thin films are attractive for application to piezoelectrically operated microelectronic actuators, sensors, or energy harvesters due to their low facility cost, smooth surface, and excellent electromechanical characteristics.     

Piezoelectric properties of PZT films prepared by the sol-gel method and their application in MEMS

Pb(Zr_0.52Ti_0.48)O₃ (PZT) piezoelectric thin films with thickness of 0.7-2.2 μm were prepared on Pt/Ti-coated SiO₂/Si (0.5 μm/300 μm) substrates by the sol-gel method. The piezoelectric coefficient e₃₁ of the PZT thin film was − 12.5 ± 0.3 C/m², which is evaluated by measuring the tip displacement of PZT-coated cantilevers of the dimensions 50 mm long, 4 mm wide, and 0.3 mm thick. The prepared PZT films demonstrated excellent piezoelectric properties and have large potential applications in MEMS devices. Micro-machined ultrasonic sensors, in which PZT-coated membrane functioned as sensing element, were fabricated and their properties were also characterized.     

High frequency piezoelectric MEMS ultrasound transducers

High-frequency ultrasound array transducers using piezoelectric thin films on larger structures are being developed for high-resolution imaging systems. The increase in resolution is achieved by a simultaneous increase in operating frequency (30 MHz to about 1 GHz) and close coupling of the electronic circuitry. Two different processing methods were explored to fabricate array transducers. In one implementation, a xylophone bar transducer was prototyped, using thin film PbZr(0.52)Ti(0.48)O(3) (PZT) as the active piezoelectric layer. In the other, the piezoelectric transducer was prepared by mist deposition of PZT films over electroplated Ni posts. Because the PZT films are excited through the film thickness, the drive voltages of these transducers are low, and close coupling of the electronic circuitry is possible. A complementary metal-oxidesemiconductor (CMOS) transceiver chip for a 16-element array was fabricated in 0.35-microm process technology. The ultrasound front-end chip contains beam-forming electronics, receiver circuitry, and analog-to-digital converters with 3-Kbyte on-chip buffer memory.     

0-3型压电陶瓷-硫铝酸盐水泥复合材料的压电性能

采用压制成型法,以快硬硫铝酸盐水泥为基体制备了水泥基压电复合材料。分析讨论了极化工艺条件和PZT含量对水泥基压电复合材料压电性的影响。结果表明,较高的极化电场强度和较长的极化时间均有利于压电性能的提高,但当极化电场强度和极化时间达到4.0 kV/mm和45 min后,压电应变常数d₃₃趋于稳定; 随着PZT含量的增加,硫铝酸盐水泥基压电复合材料的压电应变常数d₃₃、压电电压常数g₃₃和机电耦合系数K_P、K_t均显著增大。当PZT质量分数达到85%时,K_P和K_t可达28.54%和28.19%。      

Piezoelectric films for high frequency ultrasonic transducers in biomedical applications

Piezoelectric films have recently attracted considerable attention in the development of various sensor and actuator devices such as nonvolatile memories, tunable microwave circuits and ultrasound transducers. In this paper, an overview of the state of art in piezoelectric films for high frequency transducer applications is presented. Firstly, the basic principles of piezoelectric materials and design considerations for ultrasound transducers will be introduced. Following the review, the current status of the piezoelectric films and recent progress in the development of high frequency ultrasonic transducers will be discussed. Then details for preparation and structure of the materials derived from piezoelectric thick film technologies will be described. Both chemical and physical methods are included in the discussion, namely, the sol-gel approach, aerosol technology and hydrothermal method. The electric and piezoelectric properties of the piezoelectric films, which are very important for transducer applications, such as permittivity and electromechanical coupling factor, are also addressed. Finally, the recent developments in the high frequency transducers and arrays with piezoelectric ZnO and PZT thick film using MEMS technology are presented. In addition, current problems and further direction of the piezoelectric films for very high frequency ultrasound application (up to GHz) are also discussed.     

Fabrication and characterization of micromachined high-frequency tonpilz transducers derived by PZT thick films

Miniaturized tonpilz transducers are potentially useful for ultrasonic imaging in the 10 to 100 MHz frequency range due to their higher efficiency and output capabilities. In this work, 4 to 10-microm thick piezoelectric thin films were used as the active element in the construction of miniaturized tonpilz structures. The tonpilz stack consisted of silver/lead zirconate titanate (PZT)/lanthanum nickelate (LaNiO3)/silicon on insulator (SOI) substrates. First, conductive LaNiO3 thin films, approximately 300 nm in thickness, were grown on SOI substrates by a metalorganic decomposition (MOD) method. The room temperature resistivity of the LaNiO3 was 6.5 x 10(-6) omega x m. Randomly oriented PZT (52/48) films up to 7-microm thick were then deposited using a sol-gel process on the LaNiO3-coated SOI substrates. The PZT films with LaNiO3 bottom electrodes showed good dielectric and ferroelectric properties. The relative dielectric permittivity (at 1 kHz) was about 1030. The remanent polarization of PZT films was larger than 26 microC/cm2. The effective transverse piezoelectric e31,f coefficient of PZT thick films was about -6.5 C/m2 when poled at -75 kV/cm for 15 minutes at room temperature. Enhanced piezoelectric properties were obtained on poling the PZT films at higher temperatures. A silver layer about 40-microm thick was prepared by silver powder dispersed in epoxy and deposited onto the PZT film to form the tail mass of the tonpilz structure. The top layers of this wafer were subsequently diced with a saw, and the structure was bonded to a second wafer. The original silicon carrier wafer was polished and etched using a Xenon difluoride (XeF2) etching system. The resulting structures showed good piezoelectric activity. This process flow should enable integration of the piezoelectric elements with drive/receive electronics.     

Effect of microwave annealing temperatures on lead zirconate titanate thin films

Lead zirconate titanate (Pb(1.1)(Zr(0.52)Ti(0.48))O(3)) thin films of thickness 260?nm on Pt/Ti/SiO(2)/Si substrates were densified by 2.45?GHz microwave annealing. The PZT thin films were annealed at various annealing temperatures from 400 to 700?°C for 30?min. X-ray diffraction showed that the pyrochlore phase was transformed to the perovskite phase at 450?°C and the film was fully crystallized. The secondary (again pyrochlore) phase was observed in the PZT thin films, which were annealed above 550?°C. The surface morphologies were changed above 550?°C of the PZT thin films due to the secondary phase. Higher dielectric constant (ε(r)) and lower dielectric loss coercive field (E(c)) were achieved for the 450?°C film than for the other annealed films.     

Fabrication and modeling of high-frequency PZT composite thick film membrane resonators

High-frequency, thickness mode resonators were fabricated using a 7 microm piezoelectric transducer (PZT) thick film that was produced using a modified composite ceramic sol-gel process. Initial studies dealt with the integration of the PZT thick film onto the substrate. Zirconium oxide (ZrO2) was selected as a diffusion barrier layer and gave good results when used in conjunction with silicon oxide (SiO2) as an etch stop layer. Using these conditions, devices were produced and the acoustic properties measured and modeled. The resonators showed a resonant frequency of about 200 MHz, an effective electromechanical coupling coefficient of 0.34, and a Q factor of 22. Modeling was based on a Mason-type model that gave good agreement between the experimental data and the simulations. The latter showed, for the PZT thick film, an electromechanical coupling coefficient of 0.35, a stiffness of 8.65 x 10(10) N x m(-2) and an e33,f piezoelectric coefficient of 9 C x m(-2).     

改性PZT/PVDF体系压电复合材料的介电和压电性能

采用复合材料模压工艺,制备了体积分数不同的改性PZT(含铌的钛锆酸铅)/PVDF(聚偏二氟乙烯)压电复合材料。采用扫描电镜对材料的形貌进行了分析,并利用HP4294A,Z-3A型准静态测试仪等系统地研究了改性PZT体积分数对材料介电、压电性能的影响。结果显示,在改性PZT体积分数为70%时,获得了性能优良的压电复合材料。在压电陶瓷高含量区(>0.5),部分压电陶瓷颗粒相互联接,形成了类似0-3(3-3)型复合连通形式,是复合材料获得优良压电、介电性能的主要原因。     

Preparation of (001)-oriented Pb(Zr,Ti)O3 thin films and their piezoelectric applications

Preparation of (001)-oriented Pb(Zr,Ti)O(3) (PZT) thin films and their applications to a sensor and actuators were investigated. These thin films, which have a composition close to the morphotropic phase boundary, were epitaxially grown on (100)MgO single-crystal substrates by RF magnetron sputtering. These (001)-oriented PZT thin films could be obtained on various kinds of substrates, such as glass and Si, by introducing (100)-oriented MgO buffer layers. In addition, the (001) oriented PZT thin films could be obtained on Si substrates without buffer layers by optimizing the sputtering conditions. All of these thin films showed excellent piezoelectric properties without the need for poling treatment. The PZT thin films on the MgO substrates had a high piezoelectric coefficient, d(31), of -100 pm/V, and an extremely low relative dielectric constant, epsilon(r), of 240. The PZT thin films on Si substrate had a very high d(31) of -150 pm/V and an epsilon(r) = 700. These PZT thin films were applied to an angular rate sensor with a tuning fork in a car navigation system, to a dual-stage actuator for positioning the magnetic head of a high-density hard disk drive, and to an actuator for an inkjet printer head for industrial on-demand printers.     

Surface Electric Gibbs Free Energy and Its Effect on the Electromechanical Behavior of Nano-Dielectrics

This paper considers the surface effect through the surface and bulk electric Gibbs free energy. The analytical expressions are derived for the effective elastic, dielectric and piezoelectric modulus for nano-structural elements in electromechanical coupling problems. Numerical examples for PZT are given to illustrate the size effects on the electromechanical properties of nano-particles, nano-wires and nano-films quantitatively. The solution shows that the electromechanical properties of piezoelectric nano-material are size-dependent but the size effects on the elastic property and dielectric property are different.     

Extruded PZT/polymer composites for electromechanical transducer applications

PZT/polymer composites having a 1–3 parallel connectivity were fabricated by impregnating a sintered, extruded honeycomb configuration of PZT with various polymers. The resultant composites were found to have densities less than 2900 kg/m³, a dielectric constant of ～500 and a piezoelectric d₃₃ of ～300×10^?12 C/N. The 1–3 connectivity increases the piezoelectric voltage coefficient (g₃₃) from 22×10^?3 Vm/N (solid PZT) to ～70×10^?3 Vm/N.The composites have thickness mode electromechanical coupling coefficients (k_t) which are ～25% greater than that of homogeneous PZT, and are readily adaptable for broad bandwidth operation. This combination of electromechanical properties makes these composites ideal for low voltage displacement and pulse echo applications.     

锆钛酸铅(PZT)薄膜的制备及其改性研究

文章综述了锆钛酸铅(PZT)薄膜的主要制备方法,其中包括射频磁控溅射法、脉冲激光沉积法、溶胶-凝胶法和金属有机化学气相沉积法。讨论了不同工艺参数对于PZT薄膜的结构和性能的影响,并针对PZT薄膜出现的疲劳现象进行掺杂改性,探讨提高其抗疲劳性能的途径。     

Hydrothermal temperature effect on magnetoelectric coupling of Ni/Pb(Zr0.52Ti0.48)O3 bilayers

Magnetoelectric (ME) Ni/Pb(Zr_0.52Ti_0.48)O₃ bilayers have been prepared by hydrothermal method. The structure and ferroelectric properties of the Pb(Zr_0.52Ti_0.48)O₃ (PZT) thin films prepared at various hydrothermal temperatures are characterized by X-ray diffraction and ferroelectric testing. With the hydrothermal temperature increasing the grain size of the PZT thin films gradually decreases leading to a gradual increase of the coercive field and a decrease of the remnant polarization of the Ni/PZT bilayers. The ME voltage coefficient of the Ni/PZT bilayers gradually decreases as hydrothermal temperature increases. The large ME coefficient makes these Ni/PZT bilayers possible for applications in multifunctional devices such as electromagnetic sensor, transducers and microwave devices.     

Preparation and characterization of preferred oriented PZT films on amorphous substrates

The (001) preferred orientation of Nb-doped Pb(Zr_0.52Ti_0.48) O₃ (PZT) thin films was successfully realized on amorphous glass substrate with LaNiO₃(LNO) as electrode by rf-sputtering method. It was found that the LNO film greatly promotes formation of the PZT film with pervoskite phase on amorphous substrate and the preferred orientation of the PZT film depends strongly on the process of preparation. The experimental results show that the dielectric constant and loss of the PZT films with the (001) preferred orientation are 1308 and 0.042, respectively, at 1 kHz, 0.05 V. The remanent polarization (P_r), saturation polarization (P_s) and coercive field (E_c) are 34.5, 43 C/cm² and 105 kV/cm, respectively. The PZT films also show a 33 kV/cm internal bias field due to its (001) preferred orientation. The piezoelectric coefficient d₃₃ of the PZT film without the poled treatment is about 15 pC/N due to its (001) preferred orientation. The effect of the foreign stress on the piezoelectric voltage response of the PZT/LNO/glass was investigated. The results make us consider using the PZT film as an artificial skin to realize the self-diagnosis of amorphous materials under the action of stress.