Volume 2, Issue 3-4 - Special Double Issue: Piezoelectric Materials and Applications with focus on Energy Harvesting, Guest Editor: Ying Yang

In this work, the 1–3 connectivity piezoelectric ceramic–polymer composites have been fabricated by a viscous-polymer processing, where 0.90Pb(Zr 0.52 Ti 0.48 )O 3 –0.05Pb(Mn 1/3 Sb 2/3 )O 3 –0.05Pb(Zn 1/3 Nb 2/3 )O 3 (PZT–PMS–PZN) fibers with 0.5 volume fraction were aligned in epoxy matrix. The sintered PZT fibers, with average diameter of 300 μm and aspect ratio (height/diameter) higher than 3, all showed a pure perovskite phase structure and highly dense morphology. The dielectric, piezoelectric, ferroelectric properties and the vibration modes of the 1–3 composites were measured and demonstrated in comparison with that of the monolithic piezoelectric ceramics. The results confirmed that the 1–3 composites possessed a low acoustic impedance ( Z ) of 13 MRayl and a high thickness coupling coefficient ( k t ) of 0.59, in addition, only single thickness vibration mode with the resonance frequency over 1.5 MHz was observed. With temperature elevation, the properties including dielectric constant ε r , k t , the ratio of k t to k p ( k t / k p ) and the acoustic impedance ( Z ) increase, while the planar electromechanical coupling coefficient ( k p ) show opposite temperature dependence. Under test temperature of 100°C, the 1–3 composites still present excellent temperature stability with increased k t / k p ratio up to 3.6. The researches on temperature-dependent properties of the 1–3 composites are critical for improving its applications in various environments.

Multilayer ceramic actuator composed of piezoelectrically active 0.90Pb(Zr 0.48 Ti 0.52 )O 3 –0.05Pb(Mn 1/3 Sb 2/3 )O 3 –0.05Pb(Zn 1/3 Nb 2/3 )O 3 (PZT–PMS–PZN) layers and electrically conducting silver metal layers were fabricated. Low-temperature sinterable PZT–PMS–PZN ceramics were used as the piezoelectric layers, and silver paste was used as the conductive inner-electrode layers. PZT–PMS–PZN powder, adding 1% CuO as a sintering agent, was prepared by a conventional solid-state reaction process. The green sheet was fabricated by tape-casting method. Silver inner-electrode was printed on the green-tape sheets and the sheets were stacked, warm-pressed, and sintered at 900°C for 4 h after burning out the organic additions. The sintered multilayer ceramics actuator shows distinct layers with few defects in the interfaces. The thicknesses of the piezoelectric and conducting layers are about 40 and 6 μm, respectively. The multilayer PZT–PMS–PZN actuator, composed of 60 active piezoelectric layers, presents a longitudinal displacement of about 2.7 μm at an applied voltage of 80 V, approximately 0.1% of the total thickness of itself.

One of the most attractive sources of raw materials for biofuel production can be algae oil processing into biofuels. In this paper, the authors are proposing a unique ultrasonic piezoelectric system, which would allow the reduction of internal energy losses and concentration of ultrasonic energy into a small closed volume. The current vibrating systems whose ultrasonic energy is concentrated inside of a hollow cylinder where the water–algae mixture is flowing. The ultrasonic energy is concentrated in a local volume to create a high-power bubble implosion process. Two, three or multiple ultrasonic composite systems to concentrate the total energy into a hollow cylinder in order to create a strong algae cell ultrasonication are used. The experiments and the numerical finite element method (FEM) analysis results using the proposed transducers as well as the biological test results on algae cell disruption by ultra-sonication are presented in this paper.

Pb(Zr,Ti)O 3 (PZT)-based ternary system thin films, x Pb(Ni,Nb)O 3 –(1– x )PZT (50/50) (PNN–PZT), are grown on Pt/TiO 2 /SiO 2 /Si substrates using radio-frequency magnetron sputtering system. The intrinsic PZT (50/50) thin films are also deposited for comparison. XRD data display a perovskite structure in PNN–PZT thin films, which is similar with that of PZT films. On the other hand, the adding of PNN induces a change in the ratio of (200)/(002) peak intensity in the diffraction patterns, and the tetragonality of PNN–PZT thin films decreases with increasing x . The morphotropic phase boundary (MPB) of PNN–PZT thin film system is confirmed near the composition of 0.05PNN–0.95PZT. PNN–PZT thin films exhibit excellent piezoelectricity and ferroelectricity which are distinctly better than those of PZT thin films. In particular, very high remanent polarization, P r =99 μC/cm 2 , small coercive field of 55 kV/cm, large relative dielectric constants, ε r =2,030 and distinct piezoelectric response are observed from sample 0.05PNN–0.95PZT.

Ultrasonic non-destructive testing is presented as a method to determine differences in material distribution at elevated temperatures in hybrid workpieces made of different metals. Varying material distribution causes differences in transit time and can be detected by ultrasonic transit time measurements. Therefore, custom transducers are manufactured to perform transit time measurements on hybrid workpieces. Results of these measurements are shown.

The design, fabrication and characterization of a distinctive electro-thermal MEMS safety-and-arming device are presented in this paper. The device is comprised of a V-shape actuator and a micro lever. The V-shape actuator can generate a large output force but small displacement; thus, it is necessary to design a micro lever to amplify the insufficient displacement, which can broaden the device applications in different fields. The temperature distribution, the maximum displacement and the step response time of the actuator are analyzed and validated by the finite element analysis software ANSYS. The whole device is fabricated on SOI (Silicon-on-Insulator) wafer, and MUMPs process is introduced. The characterized performance of the device shows output displacement at more than 150 µm within 17 V driving voltage, and the consuming power is about 1.53 W. The chip size is about 5 × 5 × 0.5 mm 3 , which can be easily integrated with other micro devices.

Lead-free (K, Na)NbO 3 (KNN) ferroelectric films were fabricated on Ti substrates by sol–gel non-alkoxide process. Nb 2 O 5 was used to prepare the soluble niobium source by citrate method. KNN thin films with perovskite phase were obtained by pyrolyzing at 500°C and annealing at 700°C. The influence of A-site ion excess on the phase, microstructure and electric properties of the films was investigated. X-ray diffraction and energy-dispersive spectroscopy (EDS) data indicate that the volatilization of K was severer than Na during the thermal treatment, and K excess is assisted to get pure perovskite phase. Meanwhile, the P – E loops and the dielectric curves manifest that K excess plays a role to improve the ferroelectric performance, while Na excess contributes to good dielectric property.

As a new type of motor, the traveling wave type rotary ultrasonic motors (TRUM) have a wide range of applications. However, the friction between stator and rotor leads to its poor start reliability, which retards the progress of application of ultrasonic motors. Sometimes TRUMs which are widely used cannot start after storage. Height of tooth of the ultrasonic motor’s stator is one of the factors affecting TRUM’s start stabilizing. In this paper, combined with the ultrasonic motor running mechanism, the factors that affect TRUM’s start reliability are studied. Model of ultrasonic motor stator tooth height is analyzed by finite element analysis (FEA). Five TRUMs with different tooth heights are fabricated and measured. A TRUM with 1.85 mm tooth height can start properly in humidity 90%, but ultrasonic motors with 1.8–1.9 mm tooth height cannot start properly under the same conditions.

In this paper, high-quality multiferroic (1- x )BiFeO 3 - x YMnO 3 ( x =0.05, 0.10, 0.15) thin films were successfully epitaxially grown on (001)SrTiO 3 substrates with La 0.67 Sr 0.33 MnO 3 buffered layers by pulsed laser deposition (PLD). X-ray diffraction shows the thin films are all single-phase perovskite with preferential orientation along the (001) direction. The (002) diffraction angles of thin films (from 0 to 0.15) shift to right, indicating the decrease of lattice parameters. All YMnO 3 -doped thin films exhibit strong upward self-poling via piezoelectric force microscope (PFM) measurement. Saturated ferroelectric hysteresis loops of thin films cannot be obtained even at the frequency of 50 kHz because of large leakage currents. It is noted that BFO-YMO thin films exhibit ferroelectricity considering the PFM and ferroelectric test. The magnetization measurements show that all BiFeO 3 -based films exhibit weak ferromagnetic behaviors with saturated magnetization at room temperature. The enhancement of magnetization was observed because of YMO doping, with the maximum saturation magnetization ( M s ) of 17.07 emu/cm 3 in x =0.10 thin film.

An analysis method allowing investigations of load influences on ultrasonic transducer oscillations is developed and presented. The focus here is on transducers utilized in ultrasonic-assisted machining due to the high process loads occurring. These loads can affect the operational vibration by exciting bending or torsion modes. However, the explicit impact on the process has yet to be determined. Hereby, conclusions about each oscillation mode effecting the operational vibration separately would be desirable. To achieve this, the eigenmodes being excited in dependence of the load have to be determined. Though the question remains of how big the respective influence on the operational vibration is. In the contribution at hand both questions will be answered by means of a modal transformation-based analysis that is illustrated by an explicit example. It is shown that a defined modal force permits determining the excited modes and the explicit share of the applied load coupling into the particular mode, respectively. In addition, the qualitative impact of each eigenmode on the resulting vibration can be evaluated by means of the magnitude of the modal equation’s particular solution. The developed analysis is applied on process and mounting loads. Therefore, different load setups are investigated in dependence of the force direction and the application point, thus leading to the conclusion that the presented analysis method is versatile usable, trustable and efficient.

The optimal design of a piezoelectric linear actuator using parametric optimum method-based finite element method (FEM) was presented. First, the FEM model of the cymbal stack transducer was generated with its initial configuration. The structural parameters were chosen as the design variables and the displacement on the top surface of the transducer taken as the objective function. Second, the zero-order optimization method was chosen as the basic tool of the structural updating. The structural optimization scheme of the cymbal stack transducer was carried out based on ANSYS parametric design language (APDL). Finally, an example of dynamic response analysis was performed on the cymbal stack transducer to verify the structural optimization scheme. The results show that the displacement on the top surface is increased by 32.9% compared with the case of initial configuration.

The excitation of mechanoreceptors in the finger with different frequencies and intensities generates a tactile impression. For the experience of a complete surface many distributed sources are needed in the tactile display. For these local stimulations of the finger several piezoelectric bending actuators will be arranged in an array perpendicular to the skin. The challenge in the system design is to transfer high dynamic shear forces to the skin at required frequencies together with a compact display design. In order to estimate the dynamic behavior of the bending actuators a transfer matrix method model based on the Timoshenko beam theory is derived. Beside the outer geometric values, the layered structure of the actuator is included in the model. In addition the influence of the load on the actuator’s tip in lateral and in normal direction as well as on the rotational degree of freedom is taken into account. Using the analytical approach, a parametric study is carried out to find an optimized actuator design for the display. For the validation, the modeled beam is compared with experimental data.

It is well known that green algae cells are used for bio-fuel production. There are a few known ways of how to process algae cells for oil extraction – chemical and mechanical. Ultrasonic cavitation is one example of mechanical processing that is in use. Longitudinal ultrasonic systems are used for this purpose. In a proposed system the flow of an algae–liquid mixture is created by means of the ultrasonic capillary effect, thus the transducer is the only energy consumer which now acts as a homogenizer (disruptor) and a pump at the same time. What is important is that the capillary is located nearby the strong cavitation field which decreases the chance of unprocessed algae cells flowing into the secondary reservoir. Numerical and comparative tests are done and presented in this paper. The main results are presented in figures and tables, all advantages of the system are outlined in the conclusion section.

Langevin-type piezoelectric transducers are widely used for different industrial applications such as high-accuracy positioning, ultrasonic welding, bonding, drilling, etc. Usually Langevin-type transducers operate at longitudinal mode by employing d 33 vibrations of piezoceramic elements. A novel design of piezoelectric actuator based on two bending-type Langevin transducers is introduced. Two half-wavelength transducers are connected by a special aluminum plate. Piezoceramic rings with two-directional polarizations are used for bending oscillation excitation. An input voltage with phase shifted by π /2 on different transducers is applied. The forward and backward elliptical motion of the contact tip is controlled by changing phases of electric signals on different transducers. A numerical simulation was carried out to investigate the trajectories of contact point motion and to validate the operating principle of the actuator. Experimental prototype of the piezoelectric actuator was fabricated, and the measurements of driven tip movements and mechanical output were performed. The results of numerical and experimental analysis are discussed.

Ultrasonic actuators are used for a wide field of applications. The vibration energy can be used to realize many processes like ultrasonic welding or bonding. Furthermore there are many processes which run more efficient and faster combined with ultrasonic vibration like ultrasonic-assisted turning or drilling. Piezoelectric transducers are the main part of those applications. Most of the applications have a time-variant load behavior and need an amplitude feedback control to guarantee a stable process. To ensure correct function tests of the feedback control systems have to be done. In this case the processes have to be executed in association with a high number of cycles. To emulate the behavior of the environment the automotive and aerospace industries use hardware in the loop systems since a long time but there is no such a method for ultrasonic systems. This paper presents a method to realize high dynamic load emulation for different ultrasonic applications. Using a piezoelectric transformer it is possible to reproduce load curves by active damping on the secondary side of the transformer using a current proportional digital feedback circuit. A theoretical and experimental study of hardware in the loop system for ultrasonic applications is given by this paper. The present system allows testing a wide field of feedback control algorithms with high flexibility and a high number of cycles by utilization of low-cost components. This proceeding decreases design periods in association with feedback control.

The structure, dielectric and piezoelectric properties of 0.96(Bi 0.5 Na 0.5 )TiO 3 -(0.04- x )BaTiO 3 - x LiNbO 3 ( x = 0, 0.01, 0.02, 0.03, 0.04) ceramics were investigated by a conventional solid-state reaction method. All compositions show a single perovskite structure without any second phases. It was ascertained that the morphotropic phase boundary (MPB) of ferroelectric rhombohedral and relaxor tetragonal lies in the range of 0.02 ≤ x ≤ 0.04 at room temperature. As a result, the MPB compositions show improved properties; the saturated polarization, remnant polarization and coercive field are 43.7 μC/cm 2 , 38.7 μC/cm 2 and 48.7 kV/cm for x = 0.02 and 43 μC/cm 2 , 37.9 μC/cm 2 and 47 kV/cm for x = 0.03, respectively. The maximum of piezoelectric constant d 33 (124pC/N) was obtained for the ceramic with x = 0.03, which was located at the MPB region. Our results do not only supplement for BNT-based lead-free piezoelectric ceramics but also provide a way to develop new high-performance Pb-free piezoceramics.

In this article the modeling of a broadband energy harvester utilizing piezoelectric and electromagnetic effects for rotational applications is presented. The hybrid energy harvester consists of a one-side-clamped piezoelectric bimorph with a solenoid on the free end and is excited periodically but non-harmonically by magnets that are fixed on a rotating object. To estimate and describe the performance of the energy harvester concept a linear semi-analytical model for the bimorph and the solenoid is developed and then enhanced for non-harmonic system oscillations by decomposing them into their harmonic components. A comparison between the calculated and measurement signals of a prototype device shows great conformity. According to model-based and experimental analysis, the hybrid system has good broadband behavior regarding electric power output. That aspect makes the device a perfect energy-harvesting system for application with highly fluctuating revolution speeds like miniature wind turbines.