Multilayer Piezoelectric Actuator Research Articles

Fine grained textured BaTiO3-based piezoelectric ceramics with outstanding strain properties for the lead-free multilayer actuator

Textured BaTiO3-based piezoelectric ceramics show the excellent application potential as their piezoelectric characteristics almost approach the commercial lead-based ceramics. Piezoelectric multilayer actuators (MLAs) with low driving voltages and compact structures are great in line with the equipment trend of miniaturization and functional integration. However, the coarse textured grains result in few grain layers in each thin ceramic layer of MLAs, hardly guaranteeing the electromechanical dependability. In this work, we combined the composition regulation with a modified template grain growth (TGG) to prepare fine-grained textured ceramics. The Zr4+ and Sn4+ co-substituted (Ba0.95Ca0.05)(Ti0.94Zr0.05Sn0.01)O3 (BCZTS) was chosen as the matrix composition. Unreacted BaCO3 (BC, 7.3 % in content) was artificially introduced into matrix to realize the partial reaction template grain growth (RTGG), reducing textured grains from 9.7 μm to 6.9 μm. Textured BCTZS-BC MLAs achieved high texture degree of 92 % and further smaller grain size of 3.4 μm at 1300 °C, due to inhibition on mass transfer and improvement on thermal conductivity of Pt electrodes. The high strain of 0.12 % in textured MLAs is almost 2.3 times enhancement compared to non-textured counterparts, and the ultralow strain hysteresis Hs of 5.6 % at 30 kV/cm is equivalent to that in PZT MLAs. The microscopic coercive voltage is 3.1 V with a maximum displacement of 210 p.m., which is mainly ascribed to the smaller domain sizes and the favorable “4O” domain configuration in textured MLAs.

A modified first-order plate theory of laminated piezoelectric plate actuators

Piezoelectric actuators with large output and high reliability are widely applied in electron device. In this paper, a modified first-order plate theory of laminated piezoelectric plates with upper and lower electrodes is presented. Then, based on the Mindlin first-order shear deformation theory, a quadratic function of electric potential across the thickness is used to describe the inverse piezoelectric effect. The laminated plate governing equations are derived in terms of the resultant force, moment and electric displacement. Further, supplementary equations are introduced through the continuity of electrical potential and the normal electric displacement across interface of each lamina, which are applied to solve the unknown electric functions in each lamina. The numerical results of displacement, deflection and electric potential are consistent with those obtained by the three-dimensional finite element method. Finally, with such a modified plate theory, regulation mechanisms of polarization direction and layer numbers are investigated on actuation properties of laminated piezoelectric actuators. It is shown that the polarization direction can change the driving displacement by an order of magnitude. It is expected that the modified theory can provide a more efficient and accurate approach for analysis of multilayer piezoelectric composite actuators.

Lead-free KNNLT piezoceramic multilayer actuators with Ni electrodes cofired under low oxygen partial pressure

The fabrication of piezoelectric multilayer actuators (MLA) with lead-free piezoceramic materials and excellent performance represents a great challenge in the process of replacing the current family of lead-based actuators. Sintering under low pO2 allows co-firing with base metal electrodes, which is an important step towards competitive multilayer actuator fabrication technologies. We prepared sodium potassium niobate (KNNLT) piezoelectric multilayer actuators with Ni electrodes by sintering at low pO2 of 10−11 atm at 950 °C, followed by reoxidation at 850 °C in 10−6 atm. We demonstrate the impact of the sintering protocol, i.e., sintering temperature Ts and pO2, on the phase composition and continuity of Ni electrodes, and on the actuator performance. We discuss the subtle interplay between sintering conditions, microstructure, reoxidation kinetics and piezoelectric performance. The Ni-MLA exhibits a unipolar strain of 0.74 ‰ at 3 kV/mm, a normalized strain coefficient d33* = 247 p.m./V and a loss of tanδ = 0.041.

Comprehensive Numerical Analysis of a Four-Way Two-Position (4/2) High-Frequency Switching Digital Hydraulic Valve Driven by a Ring Stack Actuator

This paper presents a feasibility study using a commercially available ring stack actuator to develop a four way-two position (4/2) high frequency switching digital hydraulic valve. The excellent characteristics of multilayer piezoelectric actuators, such as a simple design, reduced moving parts, high reliability, and fast response, make them ideal for constructing this type of digital hydraulic valve. High frequency switching digital hydraulic valves (HFSVs), indeed, must be able to switch from fully open to fully closed positions in less than 5 ms, while maintaining minimal pressure losses and delivering large flows. The proposed valve architecture is assessed using well-established equations implemented in a Simulink model, allowing the hydraulic, mechanical, and electrical parts of the valve to be accurately simulated. The paper first provides a detailed description of the numerical model. Next, the hysteresis model of the ring stack actuator is validated against the data provided by the manufacturers on their website. Finally, the numerical results obtained with both open-loop and closed-loop control systems are presented. The simulations show that at a switching frequency of 200 Hz with maximum amplitude and duty cycle of the input pulse digital signal, the valve exhibits high average flow rates (~60 L/min), low average power consumption (~1500 W), and maintains a pressure drop of only 15 bar. Moreover, the simulations reveal that the control system is very effective since the valve switching time is within 1 ms.

Excellent strain properties in (K,Na)NbO3-based piezoceramics induced by lamination composite strategy

To reconcile the contradiction between piezoelectric property and its temperature stability, the preparation of composite piezoceramics using multiple components has become an emerging direction. Herein, (K,Na)NbO3-based piezoceramics are adopted to prepare high-performance laminated composite ceramics inspired by the lamination composite strategy, and sintered in the reducing atmosphere to meet the development of multilayer piezoelectric actuators with base metal internal electrodes. By adjusting the composition ratio, a high inverse piezoelectric coefficient d33* of 1065 pm/V (@ 2 kV/mm) is obtained in the two-component composite ceramics, which fluctuated less than ± 6% in the range of 25–160 °C. In the three-component composite ceramics, a higher d33* value of 1326 pm/V (@ 2 kV/mm) is achieved and maintained > 90% until 150 °C. The electric-field-induced strain performances of laminated composite ceramics significantly exceed those of their basic components, which is related to the piezoresponse gain provided by the internal interfaces. The excellent temperature stabilities come from the more diffused phase transition temperature range formed by the complementation of multiple components. The combination of ultrahigh strain performance, high temperature stability, and good fatigue resistance, together with sintering in the reducing atmosphere, constitutes an important step to promote the application of (K,Na)NbO3-based multilayer piezoelectric actuators.

High-performance (K,Na)NbO 3-based multilayer piezoelectric ceramic actuators with nickel inner electrodes

High-performance (K,Na)NbO ₃-based multilayer piezoelectric ceramic actuators with nickel inner electrodes

Superior Large-Signal Piezoelectric Coefficient in Textured NBT-Based Piezoceramics by Template-Induced Structure and Composition Modulation.

The field-induced-phase transition in (Na1/2Bi1/2)TiO3-based lead-free piezoceramics can be facilitated in the ⟨001⟩-crystallographic orientation, and the templated grain growth is an effective method to align polycrystalline ceramics along with specific directions. However, due to the low texturing degree and undesirable composite effect of the added templates, the textured ceramics using the templated grain growth (TGG) method usually require a higher driving field to trigger the phase transition instead. Here, ⟨001⟩-textured (Na0.5Bi0.5)0.935Ba0.065Ti0.978(Fe0.5Nb0.5)0.022O3 ceramics are prepared through a liquid-phase-assisted TGG process at a low sintering temperature (1000 °C), in which the NaNbO3 (NN) templates induce a strong crystallographic anisotropic structure (a high Lotgering factor of 95%) while dissolving into oriented grains. The dissolution of templates acts as a composition doping and contributes to reducing the driving electric field as proven by the phase-field simulation analysis. Furthermore, electrical and structural characterizations reveal that an increased ionic disorder occurs in the textured ceramic, causing highly dynamic polar nanoregions and a larger reversible phase transition. Thanks to the appropriate structure/composition control, the textured ceramic achieves a large d33* value of 907 pm/V at 40 kV/cm. The high-performance lead-free ceramic under low driving electric field benefits the development of multilayer piezoelectric actuators.

Wireless Piezoelectric Motor Drive

Nanopositioners with embedded piezoelectric motors are used in a variety of industries, from microscopy to laser processing or measurement systems. A concrete example would be fine-tuning of multiple mirror or lens units in a system. After fine adjustment of a mirror or lens, its position is expected to be maintained when the system is not energized. Features such as small size, direct drive, and maintaining position with high rigidity at power off make inertia-type piezoelectric motors suitable for such “set and go”-type applications. However, wiring with dedicated control electronics for each positioner can increase system complexity. In this study, a wireless driving method for piezoelectric inertia-type motors is introduced for the first time, to the best of our knowledge. In our approach, sawtooth signals for driving a two-phase piezoelectric inertia motor are converted into two complementary pulse-width-modulated (PWM) signals at 1.0 MHz and amplified by class-D amplifier topology, in which GaN transistors are implemented. The amplified complementary PWM signals are applied to a transmitter coil. A receiver coil, which forms an LC network with the capacitances of the piezoelectric multilayer actuators, picks up the driving signals. The filtered voltage waveform by the receiver coil is converted into a modified sawtooth signal, which can operate the piezoelectric inertia-type motor wirelessly. Initial measurements revealed that even a single driving pulse can be transmitted to the receiver coil and precise movements of the slider can be obtained. Mean step sizes for single pulse drive are 140 nm in one direction and 125 nm in the reverse direction.

Impact Force Analysis in Inertia-Type Piezoelectric Motors

In an inertia-type motor, a piezoelectric multilayer actuator is espoused to a transient vibration velocity as high as 1.0 m/s during slip time. This vibration velocity makes the inertia-type motors dynamic but not quasi-static. We propose a kinetic model to describe the condition under which slippage can occur between a slider and a stator. The transient current absorbed by the multilayer actuators in a stator during slip time defines the slippage behavior of the slider. A new thickness-mode force factor expression (A33), which is a relation between the transient current and the transient vibration velocity, is described in electrical domain. Impact force acting on a friction coupler produced by the actuators in the stator is proportional to the rate of change in the transient current during the sliding time. Additionally, we present the structure and characteristics of a two-phase inertia-drive-type piezoelectric motor, on which the proposed model was evaluated. Driving the multilayer actuators with truncated and mirrored sawtooth signals enhances the system dynamics. As one actuator expands and the other shrinks, their respective hysteretic nonlinearities are canceled. The motor operating frequency can be as great as 30 kHz and typically load characteristics are unloaded velocity greater than 16.0 mm/s and generated force higher than 3.0 N.

Design and development of outstanding strain properties in NBT-based lead-free piezoelectric multilayer actuators by grain-orientation engineering

(Na1/2Bi1/2)TiO3-based (NBT-based) piezoelectric multilayer actuators (MLAs) have attracted massive attention to replacing conventional lead-based piezoelectric devices recently in the fields of micro-actuation and micro-manipulation due to serious concerns of the lead element to the environment and human beings. To simultaneously achieve a high-strain output and effective co-firing with 70Ag/30Pd internal electrodes, we applied a grain orientation engineering approach to prepare a (001)c-textured NBT-based ((Na1/2Bi1/2)0.935Ba0.065Ti0.978(Fe1/2Nb1/2)0.022O3) MLA by low-temperature sintering. Notably, the textured MLA achieved a high texturing degree (F00l = 94%) at a low sintering temperature (1000 °C) and an excellent strain level of 0.46% (at 60 kV/cm) which is about 2.6 times as high as that of the non-textured counterpart. The outstanding strain performance can be explained by the optimized composition/phase selection, the lattice distortion, and the strong crystallographic anisotropy induced by the introduced NaNbO3 templates. The analysis of mechanical properties and fracture micromorphology reveals the effects of grain orientation engineering on the fracture strength and Young's modulus of bulk ceramics and MLAs. To explore potential practical applications, the temperature stability and electric fatigue of the MLAs were investigated. With the design and fabrication of the textured NBT-based MLA, this work provides a new paradigm for the applications of lead-free piezoceramics by appropriate phase controlling and grain-orientation engineering.

Review of the State and Prospects of Development and Application of Domestic Multilayer Piezoactuator for Rocket and Space Technology and Ground space Infrastructure

The article gives an overview of the state of development and applications of actuators in the world. A method and technology for manufacturing domestic multilayer piezoelectric elements by the method of slip casting from the piezomaterial of the PZT system and multilayer piezoelectric actuators based on them is described. It is noted that in terms of their technical level, multilayer domestic piezo products correspond to the best foreign samples. Preliminary studies of multilayer piezoelectric products in Russia and abroad have confirmed their unique capabilities when they work in space instrumentation and ground structures for monitoring and controlling space objects. The results of studies on the use of multilayer piezo products of JSC "NII "Elpa" and their foreign analogues in systems are given. The results of the study of various design options for piezoelectric platforms of angular and linear displacements with nanometric accuracy are presented. The optimal design options are selected based on the use of special multilayer piezoactuator APM-1 and APM-2 for their use in rocket and space technology instruments and ground-based space infrastructure. The technology developed at JSC Research Institute Elpa makes it possible to create promising multilayer piezo products of various classes and purposes for rocket and space equipment and ground-based space infrastructure.

Tiny Piezoelectric Multi-Layered Actuators with Application in a Compact Camera Module-Design, Fabrication, Assembling and Testing Issues.

Piezoelectric actuators with multi-layer structures have largely gained attention from academic and industry experts. This is due to its distinctive advantages of fast response time, huge generative force and the inherent good planar electromechanical coupling factor, as well as other mechanical qualities. Typically, lead zirconate titanate (PZT) is one of the most represented piezoelectric ceramic materials that have been used for multi-layer piezoelectric actuators. Piezoelectric multi-layered actuators (PMLAs) were developed vigorously in the past decades due to the emergence of portable devices, such as smartphones with a highly compact camera module (CCM) and an image stabilizer (IS). This study reviewed the progress made in the field of PMLA applications, with a particular focus on the miniaturized dimensions and associated generated output force, speed and maximum output power requirement for various loads. Several commercial attempts, such as Helimorph, Lobster and the two-degrees-of-freedom ultrasonic motor (USM), were investigated. The proposed simple bimorph and multi-layer bimorph USMs experimentally showed thrust as high as 3.08 N and 2.57 N with good free speed and structural thicknesses of 0.7 and 0.6 mm, respectively. When compared with the other 14 reported linear USMs, they ranked as the top 1 and 2 in terms of the thrust-to-volume ratio. The proposed design shows great potential for cellphone camera module application, especially in moving sensor image stabilization. This study also provided outlooks for future developments for piezoelectric materials, configurations, fabrication and applications.

Effect of Li2CO3 addition on structural and electrical properties of 0.7 BiFeO3–0.3BaTiO3 piezoelectric ceramic

In this work, Li2CO3 was added into 0.7[Formula: see text]0.3[Formula: see text][Formula: see text][Formula: see text]0.01molMnO2 (70BFBTMn) piezoelectric ceramics to reduce their sintering temperatures. 70BFBTMn ceramics were sintered by a conventional solid reaction method, and their structural, dielectric, piezoelectric and ferroelectric properties were studied. These results indicate that 0.5% (mole) Li2CO3 is the optimized content and it can reduce the sintering temperature by 100[Formula: see text]C, making the possibility of the piezoelectric ceramics cofiring with Ag electrodes at low temperatures to manufacture multilayer piezoelectric actuators.

A low-cost multilayer piezoelectric actuator for ultrasonic motor stator driving fabricated by a low-temperature co-fired ceramic process

Multilayer piezoelectric ceramics have wide application prospects in the fields of precision driving and intelligent sensing owing to their low driving voltages and large strains. However, high sintering temperatures and expensive noble metal electrodes limit their application as multilayer piezoelectric ceramic actuators (MLAs) in conventional devices. In this study, a modified piezoelectric ceramic powder and Ag inner electrode were used to prepare a low-cost MLA with a low sintering temperature of 900 °C. The MLA showed superior piezoelectric properties with d33 = 3015 pC/N and a large electric-field-induced strain of 0.13% at 22.2 kV/cm. Moreover, the stator of the ultrasonic motor composed of this MLA produced the ideal vibration mode, and the maximum rotation speed of the ultrasonic motor was 192 r/min under a 50 g load, which verifies the applicability of this component in practical minimised devices. These results demonstrate a strategy for fabricating low-cost and high-precision micro-actuators for precision driving.

Ultrahigh electric‐field‐induced strain in KNN‐based piezoelectric ceramics sintered in reducing atmosphere

AbstractWith the goals of sustainable development adopted by more and more nations, the lead‐free trend of multilayer ceramic actuators has become a widely recognized consensus. Sintering in a reducing atmosphere is a necessary approach for preparing lead‐free ceramics co‐fired with low‐cost nickel internal electrodes. Herein, (1 − x)K0.48Na0.52Nb0.96Ta0.04O3–xSr(Zr0.5Ti0.5)O3 + 0.03ZrO2 + 0.08MnO2 (KNNT‐SZT) ceramics were sintered in a reducing atmosphere using a solid‐state reaction. The Sr(Zr0.5Ti0.5)O3 (SZT) dopant decreased the Curie temperature TC and the O–T phase transition temperature. The enhanced diffuseness of the ferroelectric phase transition of KNNT‐SZT ceramics is attributed to the element doping and the locally inhomogeneous microstructure. High inverse piezoelectric coefficients d33* of 883 and 787 pm/V were obtained for the 8‐ and 9‐mol% SZT‐doped samples, respectively. These results were attributed to the synergistic effect of ferroelectric domains with different sizes. The diffused O–T phase transition significantly improved the piezoelectric temperature stability of the 9‐mol% SZT‐doped sample, whose electric‐field‐induced strain decreased by <10% from room temperature (25°C) to 115°C. The cyclic fatigue test showed that >98% of the initial d33* was retained after 106 cycles of unipolar electrical loading. The KNNT‐SZT ceramics sintered in a reducing atmosphere possessed excellent inverse piezoelectric properties and are expected to be applied in the field of multilayer ceramic piezoelectric actuators with base metal internal electrodes.

Effects of Strain Node on the Actuation Performance of Multilayer Cantilevered Piezoactuator with Segmented Electrodes

A model of a segmented electrode multilayer cantilever piezoelectric actuator was established to predict its actuation performance, and then, theoretical and numerical analyses of the strain nodes were performed based on normalized deflection and strain distributions. The segmented electrodes instead of the continuous electrodes are applied in a multilayer cantilever piezoelectric actuator which can avoid the modal displacement offsets at the high vibration modes, thereby enhancing the tip deflection. The theoretical analysis and simulation results show that the tip deflection of the segmented electrode at the second mode was almost 100% larger than that of the continuous electrode. At the second mode, the maximum error between the theoretical calculation value of the tip deflection and the simulation result is 6.8%. It is because the segmented electrode is optimally designed at the strain node, which avoids the modal displacement offsets of a multilayer cantilever piezoelectric actuator at the high vibration modes; meanwhile, the theoretical results are closer to the FEM simulation results. It reveals that the tip deflection of a multilayer cantilever piezoelectric actuator can be precisely estimated by the proposed model. This research can provide some useful guidance improving the actuation performance and optimizing the design of a multilayer cantilever piezoelectric actuator.

FEM implementation of the nonlinear damage evolution model for piezoelectric material under bipolar electrical fatigue load

The service life of piezoelectric actuator is significantly affected by the high electric fatigue load. Predicting damage evolution in piezoelectric materials under high electric load is essential for the reliability and life prediction of piezoelectric structures and devices. In this paper, a nonlinear damage evolution FE model and its acceleration program are proposed which are capable of modeling nonlinear damage evolution of piezoelectric material and structure under high electric fatigue load. The simulation results of degraded piezoelectric constant varying with the number of cycles are compared with the experimental results, and a well agreement verifies the validity of the nonlinear damage evolution FE model. Moreover, the damage distribution evolution of piezoelectric multi-layer actuator with standard double comb electrode is studied by the proposed nonlinear damage evolution model. The driving performance of piezoelectric multi-layer actuator decreases rapidly under the high electric fatigue load, where the damage area starts from the tip of the electrode and gradually spreads to the area between the electrodes. Based on the nonlinear damage evolution and its FEM implementation, the damage distribution and evolution for piezoelectric structures with variable amplitude bipolar electrical fatigue load can be obtained. This provides a reliable reference for the life prediction and application of the piezoelectric actuator.

Study on Multidegree-of-Freedom Ultrasonic Motor Using Vibration Mode Rotation of Metal Spherical Stator

Most of the multidegree-of-freedom ultrasonic motors (MDOF-USMs) use a spherical rotor, and the design of the stator is restricted due to the use of the resonance mode. (1) Therefore, there is almost impossible to freely design the overall shape, resulting in a complicated structure. (2) To solve such an inconvenience, an MDOF-USM using a metal spherical stator was proposed. The vibration mode rotation on the stator was designed by theoretical analysis of spherical vibration and finite element method analysis. Multilayer piezoelectric actuators (MPAs) were embedded in the sphere to excite the vibration mode. Cylindrical projections were attached to the surface of the stator to magnify the vibration displacement and worked as the driving part. Their effects were evaluated using an electronic circuit simulator method of performance analysis. (3) As a result, two types of vibration mode rotation methods for the 3-DOF rotation were confirmed. It was also confirmed that the rotor covering the outside stator rotates around three axes. However, tiny torque, low power factor, and slow speed were obtained. (4) An MDOF-USM using a spherical stator was realized according to the operating principle. However, since the cause of such a low performance is the excitation method of the sphere and the rotor structure, research for improvement is required in the future.

Design and Development of Outstanding Strain Properties in NBT-Based Lead-Free Piezoelectric Multilayer Actuators by Grain-Orientation Engineering

Design and Development of Outstanding Strain Properties in NBT-Based Lead-Free Piezoelectric Multilayer Actuators by Grain-Orientation Engineering

Application of Multilayer Piezoelectric Actuator in Lithography Scanners

Application of Multilayer Piezoelectric Actuator in Lithography Scanners