PZT Disk Research Articles

Ferroelectric and Piezoelectric Properties of Disk Shape Lead Zirconate Titanate Thick Films

A combination of the preparation techniques for the ferroelectric films and the micro machining of Si is considered to be an effective way to fabricate microelectromechanical systems (MEMS), such as piezoelectric micro-transducer devices for the electrical and medical fields. In this study, disk shape lead zirconate titanate (PZT) thick films were successfully fabricated. 10-mm-thick PZT films were deposited onto Pt/Ti/ SiO2/Si substrate using a chemical solution deposition (CSD) process. Pt top electrode and PZT layer were etched by reactive ion etching (RIE) process, and 100 to 500-mm-diameter PZT thick film disks were fabricated. The relative dielectric constant, dissipation factor, remnant polarization and coercive field were r ¼ 1130, tan � ¼ 0:02, Pr ¼ 0:14 C/m 2 and Ec ¼ 2:5 MV/m, respectively. This means that the ferroelectric and dielectric properties of the PZT thick film disks were comparable with that of the bulk PZT ceramics. Moreover, the prepared PZT thick film disks showed the butterfly-shaped displacement curve, related with piezoelectric response, in the case of bipolar measurement. The PZT thick film disks could be poled with 80 V at room temperature, which is easier than the poling condition of bulk PZT. The piezoelectric constant of the poled PZT thick film disks was estimated to be AFM d33 ¼ 221 pm/V. Therefore, the micro fabricated 10-mm-thick PZT disks is considered to be applicable for piezoelectric micro devices.

Analytical analysis of a circular PZT actuator for valveless micropumps

Abstract Closed form analytical equations are important tools for predicting and optimizing the behavior of a piezoelectric microactuator for micropump applications. However, there is no reliable analytical solution to date to analyze the behavior of a circular piezoelectric microactuator for a valveless micropump. In this paper, a linear strain distribution is assumed across the thickness of the passive plate of the lead zirconate titanate (PZT) actuator given that the mechanical properties such as Young’s modulus and Poisson ratio of the actuator and the passive plate are close. An analytical equation for the passive plate deflection is derived upon this assumption. The analytical result shows excellent agreement with experimental data as well as the results from finite element simulation. Based on this analytical model, the effects of several important parameters and nondimensional variable groups on the actuator performance have been investigated. These parameters and variables include the dimensions and mechanical properties of the PZT disk, the passive plate, and the bonding layer material.

Fabrication of Lead Zirconate Titanate Thick Film Disks for Micro Transducer Devices

ABSTRACTA combination of the preparation techniques for the ferroelectric films and the micro machining of Si is considered to be an effective way to fabricate microelectromechanical systems (MEMS), such as piezoelectric micro-transducer devices for the electrical and medical fields. In this study, 10-μm-thick disk shape lead zirconate titanate (PZT) thick films were successfully fabricated using a chemical solution deposition (CSD) process. Pt top electrode and PZT layer were etched by reactive ion etching (RIE) process, and 100 to 500-μm-diameter PZT micro disks were fabricated on Pt/SiO2/Si substrate. The relative dielectric constant, dissipation factor, remnant polarization and coercive field were εr = 1130, tanδ = 0.02, Pr = 14 μC/cm2 and Ec = 25 kV/cm, respectively. This means that the ferroelectric and dielectric properties of the PZT micro disks were comparable with that of the bulk PZT ceramics. The PZT micro disk showed the butterfly-shaped displacement curve, related with piezoelectric response, in the case of bipolar measurement. The piezoelectric constant of the PZT disks poled at 80Vfor 10 min was estimated to be AFM d33 = 221 pm/V. A resonance frequency of the radial oscillation was evaluated to apply for micro transducer devices.

Effective Piezoelectric Coefficient Calculation of Cymbal Piezocomposite

The "cymbal" metal-ceramic flextensional transducer has been developed for many actuator and sensor applications. In this device the ceramic driving element is sandwiched between two metallic endcaps with shallow cavities. The effective piezoelectric coefficient, d 33 eff , consists of the d 33 of the PZT disc and the contribution of the d 31 which is redirected by the cymbal endcaps. In this work the effective coefficient has been calculated by using a mechanical approach. The calculated values were compared with the experimental ones.

Effect of the Magnetostrictive Layer on Magnetoelectric Properties in Lead Zirconate Titanate/Terfenol‐D Laminate Composites

Magnetoelectric laminate composites of piezoelectric/magnetostrictive materials were prepared by stacking and bonding together a PZT disk and two layers of Terfenol‐D disks with different directions of magnetostriction. These composites were studied to investigate (i) dependence on the magnetostriction direction of the Terfenol‐D disk and (ii) dependence on the direction of the applied ac magnetic field. Three different types of assemblies were prepared by using two types of disks: one with magnetostriction along the radial direction, the other with magnetostriction along the thickness direction. The maximum magnetoelectric voltage coefficient (dE/dH) of 5.90 V/cm·Oe was obtained for a design where the composite was made by two Terfenol‐D layers with a radial magnetostriction direction.

Diagnostic Lamb waves in an integrated piezoelectric sensor/actuatorplate: analytical and experimental studies

The objective of this study is to model the diagnostic transient waves in anintegrated piezoelectric sensor/actuator plate with a view to using it as a first steptowards establishing an entire structural health monitoring system and toprovide experimental verification of the proposed models. PZT ceramic disksare surface mounted on an aluminum plate acting as both actuators and sensorsto generate and collect A0 mode Lamb waves. Mindlin plate theory is adopted tomodel the propagating waves by taking both transverse shear and rotary inertiaeffects into account. Actuator and sensor models are both proposed. Theinteraction between an actuator and the host plate is modeled based on classicallamination theory. The converse piezoelectric effect of the actuator istreated as an equivalent bending moment applied to the host plate. The sensoracts as a capacitor that converts the sensed strain change into a voltageresponse. An analytical expression for the sensor output voltage in terms ofthe given input excitation signal is derived, and then experimental work isperformed to verify the accuracy of the analytical model. Experimental resultsshow that single-mode Lamb waves in the plate can be successfully generatedand collected through the integrated PZT disks. The experiment also shows thatthe predicted sensor output for both amplitude and phase agrees well withexperimentally collected data.

Design and simulation of an implantable medical drug delivery system using microelectromechanical systems technology

Abstract A unique design of an implantable micropump for medical drug delivery systems was proposed. The peristaltic pumping principle was selected. Three pump chambers are individually actuated by each bulk PZT (lead zirconate titanate) disk in a peristaltic motion. It is this peristaltic motion that propels the fluid. The design of the micropump includes inlet, three pump chambers, three silicon membranes, three normally closed active valves, three bulk PZT actuators, three actuation reservoirs, flow microchannels, and outlet. To prohibit flow when no power is applied, the micropump was designed to be normally closed. The pump features an integral valve/membrane design such that the pump chambers not only pump the liquid, but also function as the inlet and outlet valves. To determine the dimensions of the proposed micropump, analytical modeling of the micropump chamber was conducted. The design tradeoffs between maximizing the pumped volume and reducing the overall size of the proposed micropump were analyzed. An electromechanical coupled field simulation using the FEA method was employed. Based upon the simulation results, 6 and 12 mm diameter silicon membranes with different thickness of 40 and 80 μm were fabricated using microelectromechanical systems (MEMS) technology. The deflection of these silicon membranes was tested. The PZT actuator was manually glued onto the micropump chamber. The testing data agreed well with the FEA simulation of the deflection. The conductive adhesive layer dramatically reduces the deflection. A 12 mm in diameter and 40 μm thick silicon membrane in each pump chamber is needed to meet the micropump design requirements. The fabrication and experiments of these silicon membranes reported in this paper determine the dimensions and fabrication processes for the complete micropump. A 70 mm ×35 mm ×1.0 mm micropump will be fabricated using MEMS fabrication technology. The complete micropump will be characterized to verify our design.

Design of the Double Ultrasonic Transducer for Nonlinearity Measurement of Acoustic Waves

In this paper, we propose and design a new ultrasonic probe that can effectively measure both the fundamental and the second-harmonic waves simultaneously. The transducer consists of two bonded Pb(Zr, Ti)O3 (PZT) disks with the same properties and the same polarization, and a variable capacitor is connected to the electric terminals of one of the PZT disks for the simulation and experiment. It is shown that the second harmonic as well as the fundamental component can be efficiently received by controlling the capacitance. The result of the nonlinearity parameter B/A for ethanol measured using the double ultrasonic transducer shows good agreement with the reference value, and the B/A value for soybean is obtained.

Preparation of piezoelectric PZT micro-discs by sol-gel method

This paper describes a modified sol-gel method to prepare PZT discs of nearly 1μm thickness without repeating any process. The method is based on the subdivision of the PZT precursor into small areas prior to sintering. The subdivision is realised by pouring the precursor solution into a ZnO mold. Ultrasonic transducers were fabricated using the PZT disc and the piezoelectricity of the PZT disc in GHz ranges were discussed.

Accelerometer Application of the Modified Moonie (Cymbal) Transducer

The modified Moonie (Cymbal) transducer has been investigated for an accelerometer application. High effective piezoelectric charge coefficients (d33) of the Cymbal transducer was observed around 15000 pC/N, which is much higher than that of the piezoelectric ceramic itself (∼550 pC/N). With this feature the Cymbal trasducer is a good candidate for high sensitive accelerometer applications. The sensitivity of the Cymbal accelerometer was measured as a function of driving frequency and compared with the single plate ceramic disk which was used as driving component in the transducer. Besides, the geometry of the transducer such as endcap thickness, the effect of different Lead Zirconate Titanate (PZT) compositions and metal endcaps on sensitivity was investigated. The sensitivity 50 times higher than the PZT disk was obtained.

Underwater acoustic absorption by collocated smart materials

Abstract Collocated smart structures provide the most effective technique of influencing the stimuli. Such systems can also be used for absorbing underwater acoustic waves. A collocated system is designed by mounting piezoelectric sensor on a multilayer PZT discs stack. Using PZT sensor for narrowband response and modified lead titanate sensor for broadband response, the effectiveness of these smart structures in absorbing acoustic waves is experimentally determined by using an acoustic tube.

PZT/ZnO actuator responding to reducing gases

The bending behaviour of a piezoelectric actuator consisting of a dense PZT (Pb 0.995Nb 0.01(Zr 0.53Ti 0.47) 0.99O 3) plate and a porous ZnO (ZnO + 10 mol% NiO + 0.2 mol% Li 2O) plate in response to reducing-gas (CO, H 2) atmospheres has been investigated. The actuator is prepared by bonding the dense PZT and press-formed ZnO disks using a hot-press technique with glass frits at the interface. The PZT and ZnO plates, cut off from the hot-pressed body, have high resistivities of the same level in air but only the ZnO showed a decrease in resistivity on introduction of reducing gas at 250 °C. An applied d.c. electric field is confirmed to concentrate on the PZT part of the PZT/ZnO actuator on introduction of reducing gases. The shrinkage caused by a d.c. bias at the PZT side of the actuator increases due to the concentration of electric field, and then the actuator shows a change of bending displacement from 3 μm in air to 7 μm in 0.40 vol.% air-balanced CO gas under 250 kV m −1. It is found that the applied voltage is distributed to both plates in air, but concentrates in the PZT part in reducing-gas atmosphere due to a decrease in resistance of the ZnO part.

Mechanical Response to Reducing Gases in PZT/ZnO Actuator

Electrostrictive behavior responding to reducing gas (CO, H2) atmospheres was investigated on a piezoelectric actuator consisting of a dense PZT plate (Pb0.995 Nb0.01(Zr0.53Ti0.47)0.99O3) and a porous ZnO plate (ZnO+0.2mol% Li2O+10mol% NiO). The dense PZT and press-formed ZnO disks were bonded by hot-pressing using glass frits. The PZT side of the actuator showed a shrinkage by a d.c. bias at 250°C, and its value was larger in reducing gas atmosphere than in air. When measured on the separated plates, the PZT and ZnO plates had high resistivities in the same level in air but only the ZnO showed a decrease in resistivity by introduction of reducing gas. It is assumed that the applied voltage is distributed to both plates in air, but concentrated to the PZT part in reducing gas atmospheres due to a decrease in resistance of the ZnO part. The bending displacement of the actuator was also observed in reducing gas atmosphere, although the precise value was not obtained due to the high temperature in measurements.

Design and Characterization for Wide-Band AE Transducer by 1-3 Piezoelectric Composite

This paper reports the experimental results on PZT/polymer 1-3 connectivity composites for solid ultrasonic applications, especially for an AE transducer in nondestructive inspection. A high sensitivity and wideband AE transducer employing the PZT/polymer 1-3 composite has been developed. The 1-3 composite was fabricated based on the “dispersion of resonance” design: A large number of small rods with different heights were carved in a poled solid PZT disk with an ultrasonic cutter and were then back-filled with urethane rubber. Evaluation of piezoelectric characteristics indicated that the composite had g33 value three times larger than that of solid PZT. It was found that the resonance frequency of rods was not intervened each other due to polymer matrix. The AE transducer had higher sensitivity and a wider resonance frequency than a conventional type AE transducer.

Instability of an interface between two fluids in an acoustic field

The interfacial instabilities between two fluids under the action of gravity, interfacial tension, and acoustic radiation pressure is examined, with particular attention given to instabilities at a flat interface. As an example of the instability at a curved surface, the break-up of a liquid drop levitated in air in a standing acoustic field has been studied using the boundary integral method. The nature of the instabilities at a flat interface is a more fundamental question. The theory to predict the threshold of the instability has been derived. Unlike results for static electromagnetic fields, the threshold depends not only on the properties of fluids but also on the frequency of acoustic waves. Experiments on the instabilities at the interface of carbon-tetrachloride and water were performed with a PZT disc transducer with a resonant frequency of 2.11 MHz. At a critical ‘‘threshold’’ level, a disturbance on the interface quickly grows into several sharply pointed peaks, a phenomenon similar to ‘‘Taylor’s cones’’ observed in an electric field. [Work supported by JPL through Contract No. 958722.]

Elasto-optically induced modulation of in-fiber grating

Strong effects due to uniaxial stress applied to an in-fiber grating reflection peak splits because of the elastooptically induced birefringence. The separation between the two peaks increases with the stress, and they broaden and shift. By modulating the pressure using a PZT disk at frequencies up to 1 MHz, modulation of the reflectivity, which varies with the wavelength within the grating reflection band, was obtained. >

Partially stabilized zirconia-polymer composites fabricated with an ultrasonic cutter

Piezoelectric transducers have been made of partially stabilized zirconia (PZT) ceramics with composition close to PbZr0.sTi0.50 3. Compared with other piezoelectrics, however, the piezoelectric voltage c o n s t a n t g33( = d33/g33 , where d33 and 633 are the piezoelectric charge constant and dielectric constant, respectively) of PZT is small. This problem can be solved by combining PZT and polymer in a composite with 1-3 connectivity [1,2]. This type of composite consists of PZT rods embedded in a polymer matrix, in which the rods are oriented perpendicular to the transducer electrodes. Several different techniques to make the composites have been reported in the literature [3]. A practical and simplified method for the fabrication (diamond saw dicing) of 1-3 composites was developed by Savakus et aI. [4] and Takeuchi et al. [5], but their process to cut the ceramics with a diamond saw is rather delicate and time-consuming. Safari et al. [6] fabricated composites by drilling holes in sintered PZT blocks using an ultrasonic cutter. Ceramics can be carved into various shapes and patterns using various kinds of tools by this method. This letter describes an alternative processing method, in which narrow grooves are carved in poled solid PZT discs with an ultrasonic cutter and are then back-filled with epoxy resin, urethane rubber or silicone rubber. The piezoelectric properties of the composites thus obtained are presented. Ceramic discs of poled PZT (Honda Electronics Co., Japan) were prepared by a conventional powder processing method and sintered to a density of 7.58gcm -3. The basic characteristics of the studied material are shown in Table I. The PZT disc was mounted on an ultrasonic cutter (UM5000-DA; Nihon Densi Kogyo Co., Japan). Ultrasonic cutting is a machining method which is designed to cut materials a little at a time using a combination of ultrasonic vibration generated from the tool with

Preparation of chemically etched piezoelectric resonators for density meters and viscometers

Photolithography and chemical etching were investigated as a potential means of fabricating miniature piezoelectric devices. Among the acids studied, concentrated HCl demonstrated the fastest etching of PZT disks over a wide temperature range. HCl also proved to be compatible with some commercially available photoresists and so could be incorporated into a simple processing procedure for delineating and etching patterns in the ceramic. Using this technique, flexural mode resonators similar to tuning forks were generated with fundamental resonances between 10 and 115 kHz. These devices were then used to provide simultaneous measurements of the density and viscosity of liquids by monitoring the position of the resonance frequency and the width of the resonant peak, respectively.

Direct measurement of electrostriction in perovskite type ferroelectrics

Abstract A simplified AC capacitance dilatometer based on the design of Uchino and Cross1 has been constructed to measure directly the temperature dependence of electrostrictive strain in perovskite type ferroelectric crystals and ceramics. A mechanical bridge circuit is used to compensate for thermal expansion of the mechanical components, eliminating the need for DC servo stabilization. The instrument has been used in the temperature range from 20°C to 200°C. In the AC method, the electrostrictive strain under AC driving field is compared to the known strain induced in a quartz reference crystal under phase locked conditions. The method has been checked with the known piezoelectric behavior of quartz and of selected PZT disk samples. Measurements of Q constants will be reported for lead magnesium niobate (PMN), lead magnesium niobate:lead titanate solid solutions (PMN:PT), and lead iron niobate:lead iron tungstate (PFN:PFW).

Photoacoustic probe for spectroscopic measurements in condensed matter: convenient and corrosion-resistant

A simple effective photoacoutic probe employing the acoustic waveguide effect in quartz substrate is described. The photoacoustic probe consists of a quartz rod to the upper end of which a PZT-5A piezoelectric ceramic disk is attached. The probe was used in the acquisition of a dye-laser-excited photoacoustic spectrum of 10-microg/ml 9,10-dimethylanthracene in ethanol at room temperature. With the probe system, the spectrum was found to be essentially identical with the corresponding spectra obtained with a standard cuvette cell/attached PZT disk and a cylindrical cell/attached PZT tube detection systems; the observed relative sensitivities were 1.6:1.0:4.4, respectively.