Converse Piezoelectric Effect Research Articles

Effect of composition on the structure and piezoelectricity of Na0.5Bi4.5Ti4O15-based flexoelectric-type polar ceramics

Flexoelectric-type polar ceramics might specify a class of heterogeneous ceramics that possess permanent, macroscopic, flexoelectric-type polarization and thus can exhibit both direct and converse piezoelectric effects without undergoing an electrical poling process. Here we show, by studying series of Na0.5Bi4.5Ti4O15-based nominal compositions, that flexoelectric-type polar ceramics can be synthesized by adding an appropriate amount of excess Bi2O3 to Na0.5Bi4.5Ti4O15, whereas the addition of only excess Na2CO3 or excess TiO2 to Na0.5Bi4.5Ti4O15 does not have this effect. The obtained Na0.5Bi4.5Ti4O15+xBi2O3 flexoelectric-type polar ceramics all contain Na0.5Bi4.5Ti4O15 and Bi12TiO20 phases, and their macroscopic polarization might originate from the partial alignment of distorted TiO6 octahedra and BiO5 polyhedra that are located within the grain boundary amorphous phases. Because the sodium-modified Na0.5Bi4.5Ti4O15+2.25Bi2O3 flexoelectric-type polar ceramics were found to have a piezoelectric coefficient, d33, larger than 8pC/N and a depoling temperature higher than 700°C, they are thought to have potential piezoelectric applications in the high-temperature region.

Piezo-strain induced non-volatile resistance states in (011)-La2/3Sr1/3MnO3/0.7Pb(Mg2/3Nb1/3)O3-0.3PbTiO3 epitaxial heterostructures

The non-volatile resistance states induced by converse piezoelectric effect are observed in ferromagnetic/ferroelectric epitaxial heterostructures of (011)-La2/3Sr1/3MnO3/0.7Pb(Mg2/3Nb1/3)O3-0.3PbTiO3 (LSMO/PMN0.7PT0.3). Three stable remnant strain states and the corresponding resistance states are achieved by properly reversing the electric field from the depolarized direction in ferroelectric PMN0.7PT0.3 substrate. The non-volatile resistance states of the LSMO film can be manipulated by applied electric-field pulse sequence as a result of the large coupling between the electronic states of LSMO film and the strain transferred from the ferroelectric substrate. The electrically tunable, non-volatile resistance states observed exhibit potential for applications in low-power-consumption electronic devices.

Piezoelectric enhancement of giant magnetoresistance in spin-valves with different magnetic anisotropies

The phenomenon of giant magnetoresistance (GMR) in spin-valves under applied magnetic field is well established. We present piezoelectric control of the GMR ratio at room temperature for standard multilayered spin-valve structure fabricated on (011)-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) piezoelectric substrate. Four samples namely, S1, S2, S3, and S4 were, respectively, fabricated such that the magnetic easy axis makes an initial angle of 0°, 30°, 45°, and 60° with magnetic field applied during measurement. For S1, the GMR ratio decreases under electric field whereas it increases for the samples making progressively larger initial magnetization angles with the external field. We suggest that for S1, magnetic alignment between the two magnetic layers decreases due to the rotation of bottom free layer magnetization resulting in the decrease of antiparallel resistance as well as the GMR ratio under applied electric field whereas for the other samples, the antiparallel resistance increases due to improvement in antiparallel alignment between the two magnetic layers causing increase in the GMR ratio at room temperature. Our results establish new way to control and even enhance the magnetoresistance via converse piezoelectric effect in spin-valves with different magnetic anisotropies.

Influence of the dynamic lattice strain on the transport behavior of oxide heterojunctions

All-perovskite oxide heterojunctions composed of electron-doped titanate LaxSr1 − xTiO3 (x = 0.1, 0.15) and hole-doped manganite La0.67Ca0.33MnO3 films were fabricated on piezoelectric substrate of (001)-0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT). Taking advantage of the excellent converse piezoelectric effect of PMN-PT, we investigated the influence of the dynamic lattice strain on transport properties of the heterojunctions by applying external bias electric fields on the PMN-PT substrate. Photovoltaic experiments were carried out to characterize the interfacial barrier of the heterojunction. A linear reduction in the barrier height was observed with the increase of the bias field applied on PMN-PT. The value of the barrier height reduces from ∼1.55 (∼1.30) to 1.02 (1.08) eV as the bias field increases from 0 to 12 kV/cm for the junction of La0.10Sr0.9TiO3/La0.67Ca0.33MnO3 (La0.15Sr0.85TiO3/La0.67Ca0.33MnO3). The observed dependency of barrier height on external field can be ascribed to the increasing release of trapped carriers by strain modulation, which results in a suppression of the depletion layer and increases the opportunity for electron tunneling across the depletion area.

Dynamic Characteristic Analysis and Experiment of Piezoelectric Vibration Table of Industrialized Precision Seeding Device

A piezoelectric vibration table was designed for seeding precisely small size of vegetable seed, tree seed, flower seed, etc., it worked under the converse piezoelectric effect of piezoelectric element, piezoelectric vibration driving system produced mechanical micro-displacements with applied electric field, micro-displacements amplified by amplification mechanism driven the seed dish vibrating, producing the boiling movement beneficial to sucking seeds. The mathematical model of piezoelectric vibration was established, static and dynamic state properties of vibration table were analyzed and tested. Experimental results showed that piezoelectric vibration system had a higher drive capacity when 90～110 V electric voltage was loaded, vibration amplitude was above 1.31 mm, vibration frequency was at 13～55Hz and adjustable (resonant frequency about at 25Hz). The piezoelectric vibration table is expected to reach to favorable dynamic characteristics and higher seeding performance, runs smoothly, and meets the agronomic demands for precise tray seeding.

Effect of annealing temperature on the electrostrictive properties of 0.94(Na0.5Bi0.5)TiO3-0.06BaTiO3 thin films

0.94(Na0.5Bi0.5)TiO3-0.06BaTiO3 (NBT-BT6) thin films were fabricated by metal-organic decomposition (MOD) at the different annealing temperatures. Based on the electrostrictive effect and converse piezoelectric effect, the phenomenological approach is provided to characterize the electrostrictive properties of the perovskite relaxor, and it is used to determine the effective electrostriction coefficients $$ Q_{33}^{\mathrm{eff}} $$ and electrostrictive strains $$ {S_3} $$ of NBT-BT6 thin films annealed at the range of 650–800 °C. After the microstructure, ferroelectric, dielectric and piezoelectric properties of the thin films were determined, the maximum values of $$ Q_{33}^{\mathrm{eff}} $$ and $$ {S_3} $$ of NBT-BT6 thin film annealed at 750 °C are respectively determined as 0.0289 m4/C2 and 0.26 % under the bipolar driving field of 391 kV/cm. They are strongly influenced by annealing temperature due to the bismuth evaporation and crystallization of perovskite phase, and the enhanced electrostrictive properties could make NBT-based thin film a promising candidate to the design and application of stacked actuators, microangle-adjusting devices, and oil pressure servo valves.

Free Vibration of Simply Supported Piezolaminated Composite Plates Using Finite Element Method

Piezolaminated smart structures are becoming more popular as they can be used as light weight structures to control structural response in various structural applications. Piezoelectric materials have direct and converse piezoelectric effects which can be adequately employed to control the deflection, shape and vibration of the structure. A finite element methodology based on higher order shear deformation theory is developed for free vibration analysis of smart piezolaminated composite plates subjected to combined action of electrical and mechanical loading. To achieve the accurate prediction of the frequencies, a finite 2D isoparametric element for the mechanical displacement field is combined with an electric potential field. Numerical results are presented for free vibration analysis of simply supported piezolaminated composite plate considering different electric condition with varying thickness to span ratio.

Engineering Polarization Rotation in a Ferroelectric Superlattice

A key property that drives research in ferroelectric perovskite oxides is their strong piezoelectric response in which an electric field is induced by an applied strain, and vice versa for the converse piezoelectric effect. We have achieved an experimental enhancement of the piezoelectric response and dielectric tunability in artificially layered epitaxial PbTiO(3)/CaTiO(3) superlattices through an engineered rotation of the polarization direction. As the relative layer thicknesses within the superlattice were changed from sample to sample we found evidence for polarization rotation in multiple x-ray diffraction measurements. Associated changes in functional properties were seen in electrical measurements and piezoforce microscopy. The results demonstrate a new approach to inducing polarization rotation under ambient conditions in an artificially layered thin film.

Influence of multiple piezoelectric effects on sensors and actuators

To reveal the influence of multiple piezoelectric effects (MPE) on piezoelectric sensors/actuators and to improve their performance, the general theoretical models to calculate MPE under a stress and an electric field are established and validated experimentally. A piezostack is used as sensors and actuators for MPE experiments by means of some effective methods. Taking the MPE into consideration, the output voltages of sensors and output displacements of actuators are obtained. Analytical and experimental results show that the piezoelectrics' dielectric, piezoelectric property and even stiffness can be enhanced in view of MPE. Thus, the sensitivity and resolution of the piezoelectric sensors and actuators can be improved through eliminating the influence of MPE. Meanwhile, both theoretical analysis and experiment prove that multiple direct and multiple converse piezoelectric effects have the equal piezoelectric coefficients.

Identicalness between Piezoelectric Loss and Dielectric Loss in Converse Effect of Piezoelectric Ceramic Resonators

The relationship between piezoelectric loss (tan δP) and dielectric loss (tan δE) in the converse piezoelectric effect in piezoelectric ceramics was investigated theoretically and experimentally. The theoretical consideration was based on the assumption that strain should be proportional to polarization without phase delay in both the intrinsic contribution due to lattice deformation and the extrinsic contribution due to domain wall motion. It was expected that the piezoelectric loss in the converse piezoelectric effect should be identical to the dielectric loss. In order to experimentally verify the identicalness between the losses, the immittance curves of the piezoelectric response of various Pb(Zr,Ti)O3-based ceramic resonators were fitted if the piezoelectric loss tan δP (1) is equal to zero, (2) exists as the independent variable, and (3) is the same as the dielectric loss tan δE. The observation result clearly proved that tan δP is identical to tan δE. This identicalness was also demonstrated by analyzing the phase angle of vibration velocity in mechanical response.

Tunable strain effect on the charge/orbital ordering state in electron-doped La0.9Hf0.1MnO3 films

The impact of the lattice strain on the charge/orbital ordering state was studied by using a heterostructure composed with electrondoped La0.9Hf0.1MnO3 (LHMO) and ferro- and piezoelectric 0.67Pb(Mg1/3Nb2/3)O3-0.33PbTiO3. The ferroelectric poling induces a significant reduction in the biaxial tensile strain in the LHMO film, leading to a decrease in the film resistance over the whole temperature range and an increase in the insulator to metal transition temperature T IM. The resistance of LHMO film exhibits different responses to the external electric fields and lattice deformation, which is attributed to the coactions of converse piezoelectric effect and ferroelectric polarity effect. The modification of charge/orbital ordering phase by the electric fields and ferroelectric polarization suggests that the unstable states in the manganites are sensitive to strain effects.

Electric field-induced scatterings in rough quantum wells of AlGaN/GaN high-mobility electronic transistors

The electric field-induced surface and interface roughness scatterings have been investigated by taking both the forward and converse piezoelectric effects into account in AlGaN/GaN high electron mobility transistors. The results show that the converse piezoelectric effect can compensate the polarization fields in the barrier of AlGaN/GaN heterostructure, leading to weaker electric field scatterings. Additionally, the electronic mobilities limited by both surface and interface roughness can be modulated by the gate bias, based on which we can design the devices to obtain higher mobility.

A nonlinear formulation of piezoelectric plates

A nonlinear piezoelectric plate model capable of accurately expressing the direct and converse piezoelectric effects is presented. The developed semi-intrinsic theory is meant to encompass large strains, displacements, and rotations that can occur in the plate as a consequence of a complete coupling between the mechanical and the electrical fields. Based on the assumption that a linear dependence of the electric potential on the plate thickness is not adequate to represent the potential electric energy, a specific structure to the field of admissible displacement is taken into account. A nonlinear regression technique is successively developed to detect the nonlinear dependence of the obtained solutions on the through-the-thickness coordinate. Particular warping functions characterized by the use of an ad hoc polynomial expansion adopted to express their dependence on the plate thickness direction are here considered to describe the shear and the extensional deformability of the plate transverse fibers. Linear constitutive relations for a transversely isotropic continuum are considered. The governing equations of motions for the model are finally obtained.

Simultaneous measurement of electro-optical and converse-piezoelectric coefficients of PMN-PT ceramics

A new scheme is proposed to measure the electro-optical (EO) and converse-piezoelectric (CPE) coefficients of the PMN-PT ceramics simultaneously, in which the PMN-PT ceramics acts as the guiding layer of a symmetrical metal-cladding waveguide. As the applied electric field exerts on the waveguide, the effective refractive index (RI) (or synchronous angle) can be effectively tuned from a selected mode to another adjacent mode owing to the high sensitivity and the small spacing of the ultra-high order modes. Subsequently, a correlation between EO and CPE coefficients is established. With this correlation and the measurement of the effective RI change to the applied voltage, the quadratic EO and CPE coefficients of PMN-PT ceramics are obtained simultaneously. The obtained results are further checked by fitting the variations of effective RI to a quadratic function. Our measurement method can be extended to a wide range of other materials.

Tunable strain effect and ferroelectric field effect on the electronic transport properties of La0.5Sr0.5CoO3 thin films

Tensiled La0.5Sr0.5CoO3 (LSCO) thin films were epitaxially grown on piezoelectric 0.67Pb (Mg1/3Nb2/3)O3-0.33PbTiO3 (PMN-PT) single-crystal substrates. Due to the epitaxial nature of the interface, the lattice strain induced by ferroelectric poling or the converse piezoelectric effect in the PMN-PT substrate is effectively transferred to the LSCO film and thus reduces the tensile strain of the film, giving rise to a decrease in the resistivity of the LSCO film. We discuss these strain effects within the framework of the spin state transition of Co3+ ions and modification of the electronic bandwidth that is relevant to the induced strain. By simultaneously measuring the strain and the resistivity, quantitative relationship between the resistivity and the strain was established for the LSCO film. Both theoretical calculation and experimental results demonstrate that the ferroelectric field effect at room temperature in the LSCO/PMN-PT field-effect transistor is minor and could be neglected. Nevertheless, with decreasing temperature, the ferroelectric field effect competes with the strain effect and plays a more and more important role in influencing the electronic transport properties of the LSCO film, which we interpreted as due to the localization of charge carriers at low temperature.

Theoretical modeling and equivalent electric circuit of a bimorph piezoelectric micromachined ultrasonic transducer

An electric circuit model for a circular bimorph piezoelectric micromachined ultrasonic transducer (PMUT) was developed for the first time. The model was made up of an electric mesh, which was coupled to a mechanical mesh via a transformer element. The bimorph PMUT consisted of two piezoelectric layers of the same material, having equal thicknesses, and sandwiched between three thin electrodes. The piezoelectric layers, having the same poling axis, were biased with electric potentials of the same magnitude but opposite polarity. The strain mismatches between the two layers created by the converse piezoelectric effect caused the membrane to vibrate and, hence, transmit a pressure wave. Upon receiving the echo of the acoustic wave, the membrane deformation led to the generation of electric charges as a result of the direct piezoelectric phenomenon. The membrane angular velocity and electric current were related to the applied electric field, the impinging acoustic pressure, and the moment at the edge of the membrane using two canonical equations. The transduction coefficients from the electrical to the mechanical domain and vice-versa were shown to be bilateral and the system was shown to be reversible. The circuit parameters of the derived model were extracted, including the transformer ratio, the clamped electric impedance, the spring-softening impedance, and the open-circuit mechanical impedance. The theoretical model was fully examined by generating the electrical input impedance and average plate displacement curves versus frequency under both air and water loading conditions. A PMUT composed of piezoelectric material with a lossy dielectric was also investigated and the maximum possible electroacoustical conversion efficiency was calculated.

Active control of delaminated composite shells with piezoelectric sensor/actuator patches

Present study deals with the development of finite element based solution methodology to investigate active control of dynamic response of delaminated composite shells with piezoelectric sensors and actuators. The formulation is based on first order shear deformation theory and an eight-noded isoparametric element is used. A coupled piezoelectric-mechanical formulation is used in the development of the constitutive equations. For modeling the delamination, multipoint constraint algorithm is incorporated in the finite element code. A simple negative feedback control algorithm coupling the direct and converse piezoelectric effects is used to actively control the dynamic response of delaminated composite shells in a closed loop employing Newmark's time integration scheme. The validity of the numerical model is demonstrated by comparing the present results with those available in the literature. A number of parametric studies such as the locations of sensor/actuator patches, delamination size and its location, radius of curvature to width ratio, shell types and loading conditions are carried out to understand their effect on the transient response of piezoceramic delaminated composite shells.

Phase competition induced nonlinear elastoresistance effect in thin films of Pr0.7Sr0.3MnO3

Thin films of Pr0.7Sr0.3MnO3 grown on 0.7PbMg1/3Nb2/3O3-0.3PbTiO3 substrates were reversibly strained via the converse piezoelectric effect. The transport properties of Pr0.7Sr0.3MnO3 were effectively modulated by the electric fields across the substrate. The roles of strain were explored by measuring resistance as a function of electric field and temperature. For all samples, deviations from a linear resistance-voltage relation were found. Two quantities, area difference and standard deviation, were used to characterize the nonlinearity. Both the nonlinearity and magnitude of resistance modulation peak at temperatures close to those of metal-insulator transition, indicating that the competing phases significantly changes the behaviors of strain responses.

Multifunctional behaviors of an indium tin oxide/PbLa(ZrTi)O3/indium tin oxide wafer illuminated by ultraviolet light

This article presents multifunctional behaviors of a Pb0.97La0.03(Zr0.52Ti0.48)O3 (3/52/48) wafer subjected to ultraviolet light illumination with a focus on its photoresistive effects. When this PLZT wafer that is spurted with indium tin oxide electrodes and then polarized through thickness is illuminated by ultraviolet light, its resistance increases rather than decreases as observed in conventional photoresistors made of semiconductors. Giant negative voltage and resistance are detected when light is switched off. The bending deformation caused by the photovoltaic and converse piezoelectric effects is examined and the photoinduced electrical field strength is further investigated. The electrical fields in light on–off states are studied. Hysteresis and memristive features of the indium tin oxide/PbLa(ZrTi)O3/indium tin oxide (ITO/PLZT/ITO) sample under repetitive light on–off operations are investigated.

Piezo‐Phototronic Effect‐Induced Dual‐Mode Light and Ultrasound Emissions from ZnS:Mn/PMN–PT Thin‐Film Structures

Electric-field-controllable luminescence of a ZnS:Mn/PMN-PT system is demonstrated. The light-emission of ZnS:Mn is caused by the piezoelectric potential, resulting from the converse piezoelectric effect of the PMN-PT substrate. Simultaneous generation of light and ultrasound waves is observed in this single system, which offers great potential to develop a dual-modal source combing light and ultrasonic waves for various applications.