Properties Of Piezoelectric Materials Research Articles

Effective Properties of Piezoelectric Fiber-Reinforced Composites with Imperfect Interface

Composites of piezoelectric materials are widely used in practical applications such as medical devices, nondestructive testing devices, and intelligent or smart structures. The study of mechanics and effective properties of piezocomposites is crucial to the design and development of this class of materials. In this paper, a micromechanics model is developed to determine the effective properties of piezoelectric fiber-reinforced composite materials with imperfect fiber-matrix interface bonding conditions. The micromechanics analysis is based on the periodic microfield micromechanics theory and the boundary element method (BEM). The imperfect bonding between the piezoelectric fibers and matrix is taken into account and represented by a spring-factor parameter. Selected numerical results are presented to show the influence of fiber-volume fraction, material properties of fiber and matrix, and interface bonding conditions on the effective properties of piezoelectric fiber-reinforced composites.

層状チタン酸テンプレートを用いた反応性テンプレート粒子成長法によるBa<sub>1−x</sub>Ca<sub>x</sub>TiO<sub>3</sub>配向性セラミックスの作製

Piezoelectric performance can be improved by using crystal-axis oriented materials because piezoelectric properties of the ferroelectric materials are dependent on the crystal-axis direction. In this study, we tried to fabricate Ba1−xCaxTiO3 (BCT) oriented ceramics by reactive template grain growth (RTGG) method using H1.07Ti1.73O4 layered titanate (HTO) plate-like particles as the reactive template. BCT ceramics with [110]-orientation were prepared using HTO-BaCO3-Ca(OH)2 (HBC) and HTO-BaCO3-Ca(OH)2-TiO2 (HBCT) reaction systems. The degree of orientation and the relative density of the BCT ceramics are dependent on the green sheet preparation conditions, such as dispersion condition and added binder amount, calcination temperature and starting material composition. In these reaction systems, firstly oriented BCT particles are formed by a topotactic reaction of HTO template particles with Ba and Ca matrix components, and then, BCT oriented ceramic is formed by the growth of the oriented BCT particles. BCT ceramics with higher density and higher orientation can be fabricated using HBCT reaction system than HBC reaction system, where the orientation degree is dependent strongly on the ratio of HTO template particle to TiO2 matrix particle.

EXPERIMENTAL INVESTIGATIONS ON ENERGY HARVESTING FROM MECHANICAL VIBRATIONS OF BUILDINGS USING MACRO FIBER COMPOSITE

The monitoring of a structure (e.g., a building) enables safe utilization of such a structure. A large number of sensors that measure selected parameters are often required in applied monitoring systems. Cables or batteries are used to power such sensors. This leads to an increase in utilization costs, as the cables have to be spatially located in a monitored building structure, or batteries have to be changed periodically. The use of the natural properties of piezoelectric materials that convert mechanical energy into electrical energy in places where sensors are mounted is a promising field of wireless monitoring system development. This article presents the results of an experimental study for an energy harvesting system using a piezoelectric composite – the Macro Fiber Composite (MFC). The device used for energy harvesting has a beam structure that was achieved by gluing steel and MFC together. In laboratory research, the characteristics of generated currents and electrical power were obtained for several values of vibration amplitude. The most important conclusion was that the resonant frequency of a piezoelectric beam generator should be established (by the selection of proper dimension or/and mass) both for the vibration frequency of the monitored mechanical structure and the vibration amplitude of this structure.

Modified strain gradient Reddy rectangular plate model for biaxial buckling and bending analysis of double-coupled piezoelectric polymeric nanocomposite reinforced by FG-SWNT

In this paper, the modified strain gradient (MSG) Reddy rectangular plate theory is extended for biaxial buckling and bending analysis of double-coupled polymeric nanocomposite plates reinforced by functionally graded single-walled boron nitride nanotubes (FG-SWBNNTs) and functionally graded single-walled carbon nanotubes (FG-SWCNTs). Different distribution patterns of BNNTs and SWCNTs including uniform distribution (UD), FG-V, FG-X and FG-O are used. The micromechanical approach is employed to determine the elastic and piezoelectric material properties of the double-coupled nanocomposite rectangular plates. The equilibrium equations are obtained by Hamilton's principle. Then, the critical biaxial buckling load and deflection of the double-coupled nanocomposite plates are derived by Navier's method with simply supported boundary conditions for all edges. A good agreement is observed between the obtained and literature results. Inclusive parametric study is conducted to investigate the effects of material length scale parameters, applied voltage, elastic foundation coefficients, aspect ratio and van der Waals interaction on the dimensionless critical biaxial buckling load and deflection of the double-coupled nanocomposite rectangular plates. The results reveal that the elastic foundation and van der Waals interaction in contrast to applied voltage increase the dimensionless critical biaxial buckling load and vice versa decrease the dimensionless deflection of the double-coupled nanocomposite plates. Influence of the material length scale parameters on the dimensionless critical biaxial buckling load and deflection of the double-coupled nanocomposite plates are insignificant at h/l ≥ 10 for modified couple stress theory (MCST) and MSGT. Also, the effects of volume fraction and various distributions of SWNTs on the shear stress of polymeric nanocomposite Reddy rectangular plates are studied. The obtained results can be useful for micro-electro-mechanical (MEMS) and nano-electro-mechanical (NEMS) systems.

Thermal Buckling of Piezolaminated Plates Subjected to Different Loading Conditions

A thermal buckling analysis is presented for simply supported rectangular laminated composite plates that are covered with top and bottom piezoelectric actuators, and subjected to the combined action of thermal load and constant applied actuator voltage. The thermomechanical properties of composite and piezoelectric materials are assumed to be linear functions of the temperature. The formulations of the equations are based on the higher-order laminated plate theory of Reddy and using the Sanders nonlinear kinematic relations. The closed-form solutions for the buckling temperature are obtained through the Galerkin procedure and solving the resultant eigenvalue problem, which are convenient to be used in engineering design applications. Numerical examples are presented to verify the proposed method. The effects of the plate geometry, fiber orientation in composite layers, lay-up configuration, different utilized piezoelectric materials, temperature dependency of material properties, thermal conductivity, and energy generation on the buckling load are investigated.

Parametric design-based modal damped vibrational piezoelectric energy harvesters with arbitrary proof mass offset: Numerical and analytical validations

This paper focuses on the primary development of novel numerical and analytical techniques of the modal damped vibration energy harvesters with arbitrary proof mass offset. The key equations of electromechanical finite element discretisation using the extended Lagrangian principle are revealed and simplified to give matrix and scalar forms of the coupled system equations, indicating the most relevant numerical technique for the power harvester research. To evaluate the performance of the numerical study, the analytical closed-form boundary value equations have been developed using the extended Hamiltonian principle. The results from the electromechanical frequency response functions (EFRFs) derived from two theoretical studies show excellent agreement with experimental studies. The benefit of the numerical technique is in providing effective and quick predictions for analysing parametric designs and physical properties of piezoelectric materials. Although analytical technique provides a challenging process for analysing the complex smart structure, it shows complementary study for validating the numerical technique.

Performance enhancement of PZT material for circular diaphragm energy harvester

The property of piezoelectric material was one of the keys to optimize energy harvester based on piezoelectric effect. In this paper, the relation between the parameters of piezoelectric material and the performance of circular diaphragm energy harvester was studied. Theoretical analysis and idiographic experiment were combined to estimate the dependence of output power on the material parameters: piezoelectric coefficient d33 and dielectric constant e. The results show piezoelectric material with high-d33 and low-e was good for increasing the output power of energy harvester, and the influence of piezoelectric coefficient is more obvious than that of dielectric constant. Among soft PZT, material PZT-51 could best fit energy harvesting. By optimizing PZT material, the energy harvester using single piezoelectric circular diaphragm could generate a maximum power of 9.08 mW for a matching load about 45 kΩ and a tip mass of 30 gat its resonant frequency of 178 Hz.

Piezoelectric properties of rhombohedral ferroelectric materials with phase transition

The temporal evolution of domain structure and its piezoelectric behavior of ferroelectric material BaTiO 3 during the transition process from rhombohedral to tetragonal phase under an applied electric field have been studied by employing Landau–Ginzburg theory and the phase-field method. The results obtained show that, during the transformation process, the intermediate phase was monoclinic MA phase, and several peak values of piezoelectric coefficient appeared at the stage where obvious change of domain pattern occurred. In addition, by comparing the cases of applied electric field with different frequencies, it was found that the maximum piezoelectric coefficient obtained decreased with increasing frequency value. These results are of great significance in tuning the properties of engineering domains in ferroelectrics, and could provide more fundamentals to the design of ferroelectric devices.

Effect of pores and grain size on the elastic and piezoelectric properties of quartz-based materials

The role of grain size and porosity in the piezoelectric and elastic properties of SiO 2 -based materials was investigated using resonant piezoelectric spectroscopy (RPS) and resonant ultrasound spectroscopy (RUS). RPS performed on agate revealed a piezoelectric effect comparable in magnitude to that in single-crystal quartz. The observed strong piezoelectricity in agate requires preferential orientation of SiO 2 during crystal growth. Similarly, in novaculite and sandstone finite (but weak) RPS signals were evident, suggesting that the expected randomization of the piezoelectric quartz grains is incomplete. On the other hand, Vycor, a silica glass with a porosity of 40, showed no evidence of the piezoelectric effect. According to temperature-dependent RPS and RUS measurements, the α-β transition temperature in quartz does not change in polycrystalline samples. Finally, the temperature dependence under heating of the elastic constants is reversible in quartz and agate and irreversible in sandstone and Vycor.

Temperature stability of sodium-doped BiFeO3–BaTiO3 piezoelectric ceramics

An enhancement in piezoelectric properties of lead-free ceramic materials by compositional engineering is often accompanied by a sacrifice in the temperature-stability of properties. Here we demonstrate that high piezoelectric properties and excellent high-temperature stability are obtained simultaneously in 0.72BiFeO3–0.28Ba1−x Na x TiO3 (BF–BTNx, x = 0–0.035) ceramics. Our results show that the high temperature-stable piezoelectric properties from 26 to 470 °C, combined with room temperature high piezoelectric constant d 33 = 165pC/N and electromechanical coupling factor k p = 0.35 are achieved for x = 0.015 BF–BTNx ceramics. The results suggest Na-doped BF–BT system ceramic is a potential candidate for high temperature harsh environments actuators and sensors applications.

Mechanical Noise Limit of a Strain-Coupled Magneto(Elasto)electric Sensor Operating Under a Magnetic or an Electric Field Modulation

The mechanical noise limit of a strain-coupled magneto(elasto)electric composite has been investigated when a magnetic or an electric field modulation is applied to sense a low-frequency magnetic field and access dc field measurement capabilities. The sensitivity and noise of such a composite sensor were derived from constitutive equations based on the piezoelectric and ferromagnetic material properties. The analysis was used to evaluate the equivalent noise floor of the composite sensor and to explain the origin of noise by constituting a mechanically coupled electromagnetic model. Experimental measurements revealed a good fit with the proposed model. For example, an equivalent magnetic noise level of ~60 pT/Hz at 1 Hz with dc capability was achieved using an appropriate field modulation.

High performance AlScN thin film based surface acoustic wave devices with large electromechanical coupling coefficient

AlN and AlScN thin films with 27% scandium (Sc) were synthesized by DC magnetron sputtering deposition and used to fabricate surface acoustic wave (SAW) devices. Compared with AlN-based devices, the AlScN SAW devices exhibit much better transmission properties. Scandium doping results in electromechanical coupling coefficient, K2, in the range of 2.0% ∼ 2.2% for a wide normalized thickness range, more than a 300% increase compared to that of AlN-based SAW devices, thus demonstrating the potential applications of AlScN in high frequency resonators, sensors, and high efficiency energy harvesting devices. The coupling coefficients of the present AlScN based SAW devices are much higher than that of the theoretical calculation based on some assumptions for AlScN piezoelectric material properties, implying there is a need for in-depth investigations on the material properties of AlScN.

Domain configuration and piezoelectric properties of (K0.50Na0.50)1−Li (Nb0.80Ta0.20)O3 ceramics

Abstract Domain structure plays an important role in determining piezoelectric properties of ferroelectric materials. However, limited studies have been carried out on the domains of (K,Na)NbO 3 -based lead free ceramics. The domain configuration, domain reversal behavior and piezoelectric properties of (K 0.50 Na 0.50 ) 1− x Li x (Nb 0.80 Ta 0.20 )O 3 (KNN-Li x ) ceramics with x = 0.02, 0.035 and 0.05, were studied in this research. It was observed that ceramics with different phases show distinctly different domain configurations and domain reversal behaviors. When compared to other two compositions, x = 0.035 with coexistent orthorhombic-tetragonal phases at room temperature was found to possess curved domain stripes and larger average domain width, leading to optimal piezoelectric properties with d 33 * = 260 pm/V and k p = 48%. Based on the microstructures, polarization hysteresis loops and unipolar strain curves under high electric field, it was concluded that the larger domain size and easier domain switching are due to the coexistence of orthorhombic and tetragonal phases, account for the improved properties in KNNT-Li 0.035 ceramics.

Mechanical and Electrical Control of Charged Domain Walls in Ferroelectric Materials

Charged domain walls (CDWs) in ferroelectrics, as a result of “head-to-head” or “tail-to-tail” polarization configurations, are of significant scientific and technological importance, as they have been shown to play a critical role in affecting the atomic structures and controlling the electric, photoelectric and piezoelectric properties of ferroelectric materials. An understanding of the local response and underlying dynamic mechanism of CDWs under external excitations is necessary to engineer reliable ferroelectric devices. In this work, we present the nanoscale behavior of individual CDWs under applied mechanical stress and electric fields in a BiFeO3 thin film using in situ transmission electron microscopy (TEM).

Fabrication of textured alumina by magnetic alignment via gelcasting based on low-toxic system

The controlled development of texture in ceramics allows to improve some electrical, piezoelectric and mechanical properties of advanced ceramics materials by tailoring the microstructure. A highly textured microstructure of undoped dense alumina was attained by applying a novel combination of gelcasting techniques with magnetic alignment followed by sintering. A newly synthesized low-toxic acrylic monomer based on galactose was introduced to the gelcasting procedure. Thermal analysis of the gelcast has been performed to examine decomposition process of the new binder and match appropriate sintering rate. The effectiveness of the proposed procedure has been related to rheological properties of the suspension by clarifying the influence of the powder and the dispersant content. It has been also related to the idle time of polymerization by clarifying the influence of the initiator content. The new method is compared to slip casting in high magnetic field that has been used widely so far.

Shear Horizontal Waves in Orthotropic Layer/Piezoelectric Cylinder Structures

This paper investigates the dispersion characteristics of shear horizontal waves propagating in a piezoelectric cylinder covered by orthotropic layer. The surface of the orthotropic layer is assumed to be mechanically free; The stress and displacement at the interface is continuous. The solution of the equation is expressed by Bessel function, and the dispersion equation is derived by using the boundary conditions and the interface conditions, the numerical examples are provided to show the influences of the orthotropic degree and the properties of piezoelectric materials on the dispersion characteristics of SH waves.

Influences of Preparation Process on the Orientation and Properties of PZT Piezoelectric Thick Film Generation Materials

Abstract: As it's excellent mechanical and electrical conversion characteristics, Piezoelectric material has become an important material for capturing environmental mechanical energy to get electrical energy. In this paper, (100) oriented PZT piezoelectric thick film has been prepared on Pt/Cr/SiO2/Si substrate by sol-gel used PT as transition layer. The influences of preparation process on the (100) oriented degree, ferroelectric properties, dielectric properties and piezoelectric properties of PZT piezoelectric thick film were investigated. Experiment results show that, the increasing of annealing temperature and shortening annealing time can promote PZT piezoelectric thick film growing along (100) orientation. The increasing of annealing temperature results in the decreasing of remnant polarization intensity and increasing of coercive field. Under the frequency of 1 KHz, (100) oriented PZT piezoelectric thick film with thickness of 1.5 m has the dielectric constant ˰̶̿˰́̃̅̆˼˰̈̃́˰̴̱̾˰̇̈̀˰̱̈́˰̵̷̱̱̼̹̾̾̾˰̵̹̈́̽˰̶̿˰̹̅̽̾˼˰̹́̀̽̾˰̴̱̾˰̹́̅̽̾˼˰̴̱̾˰̴̵̵̹̼̳̹̳̈́͂˰̴̹̹̱̹̓̓̀̈́̿̾˰̱̈́̾ڄ˰̹̓˰̀˾̃́£¬0.20 and 0.22, respectively. (100) orientation of PZT piezoelectric thick film can effectively improve the piezoelectric properties of PZT piezoelectric thick film, PZT piezoelectric thick film with thickness of 1.5 m and annealing time of 5min has the better (100) orientation degree, has the piezoelectric constant d33 of 102.5 pC/N. Keywords: (100) orientation; PZT generation material; ferroelectric properties; dielectric properties; piezoelectric properties

Extensive domain wall motion and deaging resistance in morphotropic 0.55Bi(Ni1/2Ti1/2)O3–0.45PbTiO3 polycrystalline ferroelectrics

Domain wall motion is known as a major source of extrinsic contributions to the dielectric and piezoelectric properties of ferroelectric materials. In the present work, we report the extent of non-180° domain wall motion during strong and weak electric field amplitudes in situ using time-resolved, high-energy X-ray diffraction in the ferroelectric morphotropic phase boundary composition 0.55Bi(Ni1/2Ti1/2)O3–0.45PbTiO3 (BNT-45PT). After application of strong electric fields, two phases are shown to coexist. In the tetragonal phase of this material, the extent of 90° domain wall motion is significant and the domain alignment is nearly saturated. Weak (subswitching) cyclic electric fields are then also shown to induce domain wall motion. Deaging, or the progressive loss of preferred domain orientation during sequentially increasing field amplitudes, is notably low in these materials, showing that the initial domain alignment is strongly stabilized. Overall, the in situ measurements reveal that domain wall motion significantly impacts the structure and properties of BNT-45PT and reinforces the importance of understanding domain wall motion contributions to the physical properties of ferroelectrics.

Tailoring of unipolar strain in lead-free piezoelectrics using the ceramic/ceramic composite approach

The electric-field-induced strain response mechanism in a polycrystalline ceramic/ceramic composite of relaxor and ferroelectric materials has been studied using in situ high-energy x-ray diffraction. The addition of ferroelectric phase material in the relaxor matrix has produced a system where a small volume fraction behaves independently of the bulk under an applied electric field. Inter- and intra-grain models of the strain mechanism in the composite material consistent with the diffraction data have been proposed. The results show that such ceramic/ceramic composite microstructure has the potential for tailoring properties of future piezoelectric materials over a wider range than is possible in uniform compositions.

Gas/Liquid Phase Change Actuator for Use in Extreme Temperature Environments

Manipulating materials exposed to extreme temperature environments presents numerous significant challenges. For example, steel industries require new methods for the direct handling of materials at temperatures greater than 1000°C, and material scientists require new methods for handling specimens at the helium temperature, where high-quality analysis must be performed with very low levels of thermal noise. However, conventional actuators do not work in such environments because of their low thermostability and, more importantly, the loss of the magnetic and piezoelectric properties of the actuator materials. For example, it is well known that magnetism and piezoelectricity completely disappear at temperatures exceeding the Curie point. This paper proposes a new working principle for actuators based on the gas/liquid phase change of working fluids. We show possibilities for the actuator design, including selections for temperature-resistant materials and working fluids at various temperatures. In addition, we discuss the design of the first prototype actuator, which worked successfully at 180°C by utilizing the gas/liquid phase change of water. The basic experimental results show significant potential for the actuator.