Piezoelectric Stress Constants Research Articles

Characterization of temperature-dependent full-matrix constants of [001]c-poled Mn-doped 28PIN-43PMN-29PT single crystals using one sample

[001]c-poled Mn-doped xPb(In1/2Nb1/2)O3–(1–x–y)Pb(Mg1/3Nb2/3)O3–yPbTiO3 (PIN–PMN–PT:Mn) single crystals (SCs) in the rhombohedral phase possess not only excellent piezoelectric properties but also a high mechanical quality factor, which make them suitable for fabricating high-performance piezoelectric devices. Characterizing the temperature dependence (TD) of full-matrix constants is indispensable for their use in device design. However, there is a significant lack of relevant data. In this study, the TD of the clamped dielectric properties of [001]c-poled 28PIN-43PMN-29PT:Mn SCs was characterized using a dielectric temperature spectroscopy measurement system from 0 to 60 °C. Their elastic and piezoelectric constants were measured using resonant ultrasound spectroscopy in the same temperature range. With an increase in the temperature, all the elastic stiffness constants decreased, whereas all the clamped dielectric constants and the absolute values of all the piezoelectric stress constants increased. The characterization process required only a single sample, which ensured the consistency of the results. Furthermore, the electrical impedance spectra of the sample at 30 and 50 °C were measured and compared with those simulated using the finite-element method with the characterization results. The close agreement between them confirmed the reliability of the characterization results.

Effect of phase transition on the piezoelectric properties of scandium-alloyed gallium nitride

In this study, the piezoelectric properties of scandium-alloyed gallium nitride (ScGaN), which is expected to be applied to microelectromechanical systems devices, are evaluated by first-principles calculations. The piezoelectric constant (d33) of GaN is found to increase by up to approximately 30 times upon the addition of 62.5 mol. % of Sc. The piezoelectric stress constant (e33) increases and the elastic constant (C33) decreases with increasing Sc content of ScGaN, driving the rise of d33. The improved piezoelectric properties of ScGaN compared with those of GaN are largely attributed to elastic softening, which is thought to be related to the transition from a wurtzite to hexagonal boron nitride (h-BN) structure driven by the change in bonding states between atoms caused by the addition of Sc to GaN. The crystal orbital Hamilton population analysis suggests that addition of Sc to GaN results in the combination of weaker Sc–N and Ga–N bonding, which makes the crystal structure unstable. This weakened bonding is thought to be the main cause of the destabilization of the wurtzite structure and transition to the h-BN structure of ScGaN. The elastic softening associated with this structural transition leads to the dramatic improvement in piezoelectric properties.

Advances in P(VDF-TrFE) Composites: A Methodical Review on Enhanced Properties and Emerging Electronics Applications

Piezoelectric polymers are a class of material that belong to carbon–hydrogen-based organic materials with a long polymer chain. They fill the void where single crystals and ceramics fail to perform. This characteristic of piezoelectric polymers made them unique. Their piezoelectric stress constant is higher than ceramics and the piezoelectric strain is lower compared to ceramics. This study’s goal is to present the most recent information on poly(vinylidene fluoride) with trifluoroethylene P(VDF-TrFE), a major copolymer of poly(vinylidene fluoride) PVDF with piezoelectric, pyroelectric, and ferroelectric characteristics. The fabrication of P(VDF-TrFE) composites and their usage in a variety of applications, including in actuators, transducers, generators, and energy harvesting, are the primary topics of this work. The report provides an analysis of how the addition of fillers improves some of the features of P(VDF-TrFE). Commonly utilized polymer composite preparation techniques, including spinning, Langmuir–Blodgett (LB), solution casting, melt extrusion, and electrospinning are described, along with their effects on the pertinent characteristics of the polymer composite. A brief discussion on the literature related to different applications (such as bio-electronic devices, sensors and high energy-density piezoelectric generators, low mechanical damping, and easy voltage rectifiers of the polymer composite is also presented.

Tuning piezoelectric properties of P(VDF-TFE) films for sensor application

With the increasing attention in the biomedical field and intelligent wearable devices, flexible piezoelectric materials show a broad space in the field of sensors. Compared with piezoelectric ceramics, polyvinylidene fluoride (PVDF)-based polymers have been widely studied due to their great flexibility. However, the existing materials are expensive and difficult to process, making it difficult to commercial application. Therefore, some attention has been paid to poly(vinylidene fluoride- tetrafluoroethylene) (P(VDF-TFE), F24) for its low cost and great potential in the piezoelectric field. But few reports, especially for sensing applications, have been reported due to the harsh synthesis process in laboratory in the early stage. In this work, the structure and dielectric properties of P(VDF-TFE) copolymers with different TFE contents are systematically studied, and the effect of thermal annealing on their piezoelectric performances are also explored. The results show that F24–20A130 (obtained by solution casting with TFE content of 20 mol% and annealed at 130 °C) exhibits the best piezoelectric properties, and its piezoelectric stress constant (d33) can reach −20 pC/N. Moreover, this sample exhibits excellent response sensitivity in sensing tests and is expected to be used in flexible sensor fields such as healthcare and wearable devices.

Characterization of the Elastic, Piezoelectric, and Dielectric Properties of Lithium Niobate from 25 °C to 900 °C Using Electrochemical Impedance Spectroscopy Resonance Method.

Lithium niobate (LiNbO) is known for its high Curie temperature, making it an attractive candidate for high-temperature piezoelectric applications (>200 °C); however, the literature suffers from a paucity of reliable material properties data at high temperatures. This paper therefore provides a complete set of elastic and piezoelectric coefficients, as well as complex dielectric constants and the electrical conductivity, for congruent monocrystalline LiNbO from 25 °C to 900 °C at atmospheric pressure. An inverse approach using the electrochemical impedance spectroscopy (EIS) resonance method was used to determine the materials’ coefficients and constants. Single crystal Y-cut and Z-cut samples were used to estimate the twelve coefficients defining the electromechanical coupling of LiNbO. We employed an analytical model inversion to calculate the coefficients based on a linear superposition of nine different bulk acoustic waves (three longitudinal waves and six shear waves), in addition to considering the thermal expansion of the crystal. The results are reported and compared with those of other studies for which the literature has available values. The dominant piezoelectric stress constant was found to be , which remained virtually constant between 25 °C and 600 °C; thereafter, it decreased by approximately 10% between 600 °C and 900 °C. The elastic stiffness coefficients , , and all decreased as the temperature increased. The two dielectric constants and increased exponentially as a function of temperature.

Characterization of the full matrix constants of Bi4Ti3O12 ceramics

Fabricating high-quality, large-size Bi4Ti3O12 (BIT) ceramics is challenging; therefore, the full matrix constants of BIT ceramics have not been characterized, which notably hinders their applications. In this study, the elastic stiffness constants c11E and c33D of the BIT ceramics were determined using the ultrasonic pulse-echo method. In addition, the elastic stiffness constants c12E, c13E, c33E, and c44E were determined using resonant ultrasound spectroscopy. Furthermore, the piezoelectric stress constants e15, e31, and e33 of BIT ceramics were calculated using the formula for the relationship between different material constants.

Geometrically nonlinear isogeometric analysis of smart piezoelectric FG plates considering thermal effects of piezoelectric stress and dielectric constants

In this paper, the isogeometric analysis (IGA) integrated with a simple first-order shear deformation theory (S-FSDT) with only four variables per node is extended to study geometrically nonlinear natural frequency, nonlinear static bending and transient dynamic response of two types of smart piezoelectric functionally graded plates (PFGPs) in thermal environment. The neutral surface is introduced to avoid the stretching-bending coupling effect. The nonlinear strain–displacement relation of the plates is obtained by combining the von Karman strains with the S-FSDT. To investigate the nonlinear mechanical behavior of PFGPs in thermal environment, closer to the real situation, an augmented piezoelectric constitutive equation considering the thermal effects of piezoelectric stress and dielectric constants is used. The accuracy and effectiveness of developed approach are demonstrated through numerical experiment with comparison. We additionally investigate the variation of temperature distribution on geometrically nonlinear response of PFGPs suffering thermo-electro-mechanical load.

The effective electromechanical properties of three-dimensional piezoelectric fiber networks

Cellular piezoelectric fiber networks are highly flexible and ultra-sensitive and are promising for functional devices. However, only a few studies on the correlation between their properties and complex microstructures are available. In this paper, stochastic piezoelectric network models with either uniformly or normally distributed fiber orientations are developed. The interactions between adjacent fibers are modeled by cross-linkers. The effective electromechanical properties of the networks are investigated by a commercially available finite element (FE) software in conjunction with a piezoelectric beam theory based user element. Theoretical analyses are also presented. A linear dependency of the effective elastic constants and piezoelectric stress constants on relative density is obtained, consistent with the stretching dominated deformation mechanism of the networks. The role of fiber orientation in the macroscopic electromechanical properties is elucidated, showing that piezoelectric networks with fiber orientation deviating from uniform distribution can have better elastic and piezoelectric stress coefficients. These findings can provide a design guide for the applications of fiber-based piezoelectric sensors and energy harvesters.

Significant Enhancement of Piezoelectric Response in AlN by Yb Addition.

This study employs first-principles calculations to investigate how introducing Yb into aluminum nitride (AlN) leads to a large enhancement in the material’s piezoelectric response (d33). The maximum d33 is calculated to be over 100 pC/N, which is 20 times higher than that of AlN. One reason for such a significant improvement in d33 is the elastic-softening effect, which is indicated by a decrease in the elastic constant, C33. The strain sensitivity (du/dε) of the internal parameter, u, is also an important factor for improving the piezoelectric stress constant, e33. On the basis of mixing enthalpy calculations, YbxAl1−xN is predicted to be more stable as a wurtzite phase than as a rock salt phase at composition up to x ≈ 0.7. These results suggest that Yb can be doped into AlN at high concentrations. It was also observed that the dielectric constant, , generally increases with increasing Yb concentrations. However, the electromechanical coupling coefficient, , only increases up to x = 0.778, which is likely because of the relatively lower values of within this range.

Large Piezoelectric Response and Ferroelectricity in Li and V/Nb/Ta Co-Doped w-AlN.

Enhancement of piezoelectricity in w-AlN is desired for many devices including resonators for next-generation wireless communication systems, sensors, and vibrational energy harvesters. Based on density functional theory, we show that Li and X (X = V, Nb, and Ta) co-doping in 1Li:1X ratio transforms brittle w-AlN crystal to ductile, along with broadening the compositional freedom for significantly enhanced piezoelectric response, promising them to be good alternatives to expensive Sc. Interestingly, these co-doped w-AlN also show quite large spontaneous electric polarization (e.g., about 1 C/m2 for Li0.125X0.125Al0.75N) with the possibility of ferroelectric polarization switching, opening new possibilities in wurtzite nitrides. An increase in piezoelectric stress constant (e33) with a decrease in elastic constant (C33) results in an enhancement of piezoelectric strain constant (d33), which is desired for improving the performance of bulk acoustic wave (BAW) resonators for high-frequency radio frequency (RF) signals. Also, these co-doped w-AlN are potential lead-free piezoelectric materials for energy harvesting and sensors as they improve the longitudinal electromechanical coupling constant (K332), transverse piezoelectric strain constant (d31), and figure of merit (FOM) for power generation. However, the enhancement in K332 is not as pronounced as that in d33 because co-doping increases dielectric constant. The longitudinal acoustic wave velocity (7.09 km/s) of Li0.1875Ta0.1875Al0.625N is quite comparable to that of commercially used piezoelectric LiNbO3 or LiTaO3 in special cuts (about 5-7 km/s) despite the fact that the acoustic wave velocities, important parameters for designing resonators or sensors, decrease with co-doping or Sc concentration.

Effect of annealing process on hot-electron energy relaxation rates in n-type modulation-doped Ga0.68In0.32N0.017As/GaAs quantum wells via deformation potential and piezoelectric scatterings

Hot electrons relax by interacting with phonons, so information about the electron-phonon interaction mechanisms are obtained by examining the cooling processes of hot electrons. In this study, the effect of annealing time on the electron temperature and energy relaxation rates in as-grown and annealed n-type modulation-doped Ga0.68In0.32N0.017As0.983/GaAs quantum well (QW) samples were investigated by comparing the relative amplitudes of Shubnikov-de Haas oscillations as a function of temperature and electric field. The samples were grown by molecular beam epitaxy (MBE) and annealed at 700 °C for 60 s and 600 s. Experiments were carried out by applying an electric field between 0.165 and 5.276 kV/m at a temperature range between 1.8 and 40 K under magnetic up to 11 T. The energy-relaxation mechanism is found to be a mixing of piezoelectric and deformation potential scatterings of hot electrons in the low-temperature regime up to 40 K electron temperature. The electron power loss by interacting with phonons is characterized with exponential term γ, which is found to be in the range from 3.42 to 4.97. The change of γ showed that the scattering mechanisms are affected by the annealing time. The piezoelectric stress constant (e14) chosen as a fit parameter in the theoretical power loss calculations, which was found between 0.129 and 0.134. The crystal quality at low temperatures has been observed to be effective on energy relaxation times.

Collective effects and optical characteristics of CdSexTe1-x

Collective effects and some response characteristics such as piezoelectric stress and strain constants, Fröhlich coupling parameter, optical electronegativity and exciton properties of CdSexTe1-x common-cation ternary alloys have been investigated. The calculations are carried out using a pseudopotential approach under a modified virtual crystal approximation that takes into account the alloy disorder effect, combined with the Adachi model. Generally, a good accord is obtained between our results and those available in the literature. The composition dependence of the features of interest shows that the Fröhlich coupling parameter remains almost constant, the piezoelectric properties vary almost linearly and the optical properties exhibit a non-linear behavior.

First-Principles Study of Piezoelectric Properties and Bonding Analysis in (Mg, X, Al)N Solid Solutions (X = Nb, Ti, Zr, Hf).

The enhancement mechanism of piezoelectric properties by codoping Mg + X (X = Nb, Ti, Zr, Hf) into aluminum nitride (AlN) was investigated by first-principles calculations. Theoretically, the piezoelectric constant (d33) can be increased when the elastic constant (C33) is decreased and the piezoelectric stress constant (e33) is increased. All components of e33, which consists of the clamped e33, the Born effective charge (Z33), and the strain sensitivity (du/dε) of the internal parameter, were improved by the addition of Mg + X into AlN. The decrease in C33 and the increase in du/dε that were observed in Mg + X-codoped AlN indicate the occurrence of elastic softening which was considered to be influenced by changes in the interatomic bond in the wurtzite structure. The bonding analysis of metal–nitrogen (Me–N) pairs in the Mg + X-codoped AlN system which was carried out by crystal orbital Hamilton populations showed that the covalent bonding (Me–N) was weaker than in pure AlN. Therefore, this weaker covalent bond is considered to be one of the origins of the elastic softening. Similar phenomena were also found for Sc-doped AlN which has higher piezoelectric response than that of pure AlN.

Piezoelectric and electromechanical coupling constants for GaxIn1-xSb semiconducting alloys

ABSTRACTThe compositional dependence of piezoelectric stress and strain constants and electromechanical coupling coefficient of GaxIn1-xSb have been investigated. The calculations were performed using a pseudopotential approach combined with the Adachi model where different concepts of ionicity are considered. Our results are compared with the available data and found to be in good accord with each other. Our findings show that as the Ga content varies, the piezoelectric and related constants and transport properties of the alloy system of interest are significantly affected.

First-principles study of crystal structure, elastic stiffness constants, piezoelectric constants, and spontaneous polarization of orthorhombic Pna21-M2O3 (M = Al, Ga, In, Sc, Y)

We perform first-principles calculations to investigate the crystal structure, elastic and piezoelectric properties, and spontaneous polarization of orthorhombic M2O3 (M = Al, Ga, In, Sc, Y) with Pna21 space group based on density functional theory. The lattice parameters, full elastic stiffness constants, piezoelectric stress and strain constants, and spontaneous polarization are successfully predicted. Comparison with available experimental and computational results indicates the validity of our computational results. Detailed analysis of the results clarifies the difference in the bonding character and the origin of the strong piezoelectric response and large spontaneous polarization.

Modeling a new energy harvesting pavement system with experimental verification

A novel design of an energy harvesting pavement system (EHPS) is introduced in this paper. The basic concept behind this design is to transform asphalt layers into a piezoelectric energy harvester to collect dissipated vehicle kinetic energy in a large-scale system. This EHPS design consists of two conductive asphalt layers and one piezoelectric material layer. To verify the feasibility of the design, this ongoing study theoretically analyzed the EHPS via a three-degree-of-freedom electromechanical model and practically tested a prototype in the laboratory. Asa result, voltage outputs measured in the laboratory from the prototype design matched those estimated from the electromechanical model. Through testing the effects of several components in the EHPS on electricity generation, this study confirms that using more flexible conductive asphalt mixtures and arranging more piezoelectric elements with a higher piezoelectric stress constant can increase electrical outputs from the EHPS. Regarding specific external vibration conditions, a high frequency of external vibration can lead to a dramatic effect of each piezoelectric element’s capacitance on increasing electrical outputs, but also can reduce the benefit from adding more piezoelectric elements to produce higher electrical outputs. After optimizing this EHPS prototype by adding more piezoelectric elements with higher piezoelectric stress constant and improving the flexibility of conductive asphalt mixtures, the maximum electric power from the proposed EHPS can be increased from approximately 1.2mW to 300mW under a high frequency (30Hz) external vibration. The levelized cost of electricity of this EHPS can be $19.15/kWh on a high-volume roadway within a 15-year service life.

Multiscale numerical investigation on effective physical properties of multiferroic BaTiO3/CoFe2O4 composites

In this paper, the effective physical properties were numerically investigated for polycrystalline multiferroic com- posite materials consisting of ferroelectric BaTiO3 and ferromagnetic CoFe2O4 phases. An asymptotic homogenization theory was employed for scale-bridging between macrostructures and microstructures. The microstructural crystal orientations of both phases were assumed to be perfectly poled and the volume fraction of ferroelectric phase was changed from 0% to 100%. And then the homogenized physical properties of macrostructure, such as elastic stiffness, electric permittivity, magnetic permeabil- ity, piezoelectric and piezomagnetic stress constants, magnetoelectric constants, were estimated through the multiscale finite element analysis. Especially the local piezoelectric or piezomagnetic constants of each phase were virtually varied and their influence on the global magnetoelectric constant was discussed to understand ideal material combination.

A conceptual study on the dynamics of a piezoelectric MEMS (Micro Electro Mechanical System) energy harvester

The mechanical behavior of a bimorph piezoelectric micro cantilever exposed to harmonic base excitation is investigated. The governing motion equation coupled with the equation of the output electrical circuit is discretized using Galerkin method and numerically integrated over the time. Two different types of output circuits including parallel and series connections are examined and the most effective output circuit from the power delivery point of view on the domain of the governing parameters is introduced. The energy conservation is examined by comparing the input and harvested energies. It is concluded that the energy harvesting in the absence of mechanical damping resembles the behavior of a damped mechanical oscillator due to the exponential attenuation of the motion amplitude. It is shown that the output power in terms of the load resistance of the output circuit, exhibits Lorenzian behavior revealing the multi factorial dependency of the power on the governing parameters. The effect of load resistance and the effective piezoelectric stress constant on the equivalent damping ratio is investigated. Subjected to harmonic base excitation, the steady state voltage, current and power responses are presented. The results are presented for various piezoelectric materials and on the plane of load resistance and effective piezoelectric stress constant, the output power delivery as well as the equivalent non-dimensional damping coefficient is determined.

Ab initio calculations of polarization, piezoelectric constants, and elastic constants of InAs and InP in the wurtzite phase

We report first-principle density functional calculations of the spontaneous polarization, piezoelectric stress constants, and elastic constants for the III–V wurtzite structure semiconductors InAs and InP. Using the density functional theory implemented in the VASP code, we obtain polarization values–0.011 and–0.013 C/m2, and piezoelectric constants e33 (e31) equal to 0.091 (–0.026) and 0.012 (–0.081) C/m2 for structurally relaxed InP and InAs respectively. These values are consistently smaller than those of nitrides. Therefore, we predict a smaller built-in electric field in such structures.

Inverse piezoelectricity of single-stranded DNA film on microcantilever

The paper aims to reveal the relation between the inverse piezoelectricity of singlestranded DNA (ssDNA) film and the origin and sign of the deflection of microcantilever produced by the DNA immobilization. By using Zhang’s two-variable method for strain field of laminated beam and the linearized Poisson-Boltzmann equation for bioelectric potential of polyelectrolyte brush, an approximate model is presented to confirm the previous conjecture that the sign of the piezoelectric constant of ssDNA film might decide the sign of the surface stress. There is only one fitting parameter (piezoelectric stress constant) needed in the simplified model, which greatly reduces the difficulty of identifying the nanoscale electrical/mechanical properties of DNA film. Numerical fitting curves based-on the analytical models agree well with the pertinent experimental dada. The difference between the previous four-layered model and the present two-layered approximate model is also compared.