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Orientation factor and piezoelectric property in textured (K,Na)NbO <sub/>3</sub> system ceramics with minimal templates
摘要： To lower the sintering temperature and decrease the weight ratio of templates required for fabricating textured (K,Na)NbO3 (KNN) system ceramics, the method of preparing platelike NaNbO3 (NN) single-crystal particles for the templates was improved. The NN crystal particles synthesized by the single-step molten salt method using a mixed salt were treated by ultrasonic vibration and subsequently screened. Using these improved templates, we developed the fabrication method for the textured KNN system ceramics by which the weight ratio of the templates required for the orientation control can be reduced to 1/10 of the conventional weight ratio. The effects of decreasing the weight ratio of templates on sintering temperature, orientation factor, and piezoelectric properties were investigated. In addition, the effects of adding Bi2O3 to KNN calcined powder were also studied to suppress abnormal grain growth, which appears in the textured samples fabricated using smaller amounts of the templates.
关键词： reactive template grain growth,molten salt synthesis,Bi2O3 addition,lead-free piezoelectric materials,ultrasonic treatment,textured ceramics
更新于2025-09-23 15:21:01
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Hierarchically decomposed finite element method for a triply coupled piezoelectric, structure, and fluid fields of a thin piezoelectric bimorph in fluid
摘要： This paper proposes a numerical method for analyzing a thin piezoelectric bimorph in fluid. A hierarchically decomposed finite element method (FEM) is proposed for modeling the triply coupled piezoelectric-structure–fluid interaction. The electromechanical coupling (piezoelectric-structure interaction) behavior in a thin piezoelectric bimorph is described by the classical constitutive equation, the incompressible fluid flows by the Navier–Stokes equation and the structure by the Cauchy equation of motion. The piezoelectric-structure–fluid interaction system is decomposed into subsystems of fluid–structure interaction (FSI) and piezoelectric field, then the piezoelectric field and the FSI are coupled using the block Gauss–Seidel method, the fluid–structure interaction is split into the fluid–structure velocity field and the pressure field using an algebraic splitting and the fluid–structure velocity field is partitioned into fluid velocity field and structure velocity field. Using the proposed method, the resonance characteristics of a piezoelectric bimorph cantilever made of PVDF and PZT-5H material in fluid are investigated for actuation and sensor configurations.
关键词： Thin piezoelectric bimorph,Hierarchical decomposition,Finite element method (FEM),Fluid–structure interaction (FSI),Piezoelectricity,Piezoelectric-structure interaction
更新于2025-09-23 15:19:57
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3D Printed Instrumentation for Point-of-Use Leaky Waveguide (LW) Biochemical Sensor
摘要： High sensitivity force sensing is a desirable function of capacitance touch screen panels. In this paper, we report on a dynamic force detection technique by utilizing piezoelectric materials. The force-voltage responsivities are investigated for four widely used stack-ups, with various panel thicknesses and touch locations. Based on the theoretical analysis and simulation results, the maximum responsivity and the signal-to-noise ratio are achieved at 0.42 V/N and 59.1 dB, respectively. The proposed technique implements force sensing successfully, enhancing the human–machine interactivity experience.
关键词： Force sensing,sensitivity,capacitive touchscreen panel,piezoelectric film
更新于2025-09-23 15:19:57
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Ferroelectric properties and phase transitions of high performance vertically aligned KNN nanowire-arrays grown by pulsed laser deposition
摘要： Pulsed laser deposition (PLD) was used to synthesize piezoelectric nanowire-arrays of K0.5Na0.5NbO3 (KNN) on Pt/TiO2/SiO2/Si substrates. These arrays were successfully prepared by using two different deposition conditions than the previously reported for KNN. KNN with orthorhombic structure and minority secondary phases were identified by XRD. Ferroelectric and Piezoelectric properties were confirmed by piezoresponse force microscopy, and showed that nanowire-arrays have an improvement in their effective piezoelectric coefficient of d33eff = 94.6 pm/V and 133.6 pm/V, higher than previously reported coefficients. Pulsed laser photoacoustic technique was used to analyze the phase transition temperatures and they showed a phase transition (O-T) at ～170 ?C and a phase transition (T-C) at ～360 ?C, lower temperatures than those found for bulk ceramics. Furthermore, it was identified the presence of minor amount of secondary ferroelectric phase (K4Nb6O17).
关键词： Phase transitions,KNN nanowire-arrays,Ferroelectric properties,Pulsed laser deposition,Piezoelectric coefficient
更新于2025-09-23 15:19:57
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Piezoelectric Transduction of a Wavelength-Scale Mechanical Waveguide
摘要： We present a piezoelectric transducer in thin-film lithium niobate that converts a 1.7-GHz microwave signal to a mechanical wave in a single mode of a 1-μm-wide waveguide. We measure a ?12-dB conversion efficiency that is limited by material loss. The design method we employ is widely applicable to transduction in wavelength-scale structures in emerging phononic circuits such as those needed for efficient piezo-optomechanical converters and spin-phonon transducers.
关键词： phononic circuits,lithium niobate,piezoelectric transduction,piezo-optomechanical converters,mechanical waveguide,spin-phonon transducers
更新于2025-09-23 15:19:57
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Changing the critical snap-through loads of post-buckled beams using piezoelectric actuation
摘要： Post-buckled and curved structures experience snap-through instabilities when external loads from mechanical, ?uid, or thermal environments result in a loss of local stability and a dramatic jump to a remote stable equilibrium. Fatigue caused by snap-through is a concern in many engineered systems because of the large stress reversals involved. This paper studies the extent to which the strategic placement and actuation of piezoelectric materials bonded to clamped-clamped post-buckled beams can in?uence the loads at which snap-through occurs. The electromechanical system is modeled using elastica theory with extensions to account for the in?uence of piezoelectric actuation on the structure. Static equilibrium positions and their stability are computed across a large con?guration space using numerical integration and a shooting method. The results indicate that the effect of piezoelectric actuation on critical snap-through load depends on the degree to which the beam is buckled, the location of the external load, the placement of the piezoelectric material, and the applied actuation voltage. Experiments are performed to validate the numerical results and provide a physical demonstration of changing snap-through loads with piezoelectric actuation. Experimental results demonstrate that critical snap-through loads can be altered by factors ranging from 0.4 to 2.0, and numerical results indicate that even larger changes to snap-through loads are physically realizable.
关键词： piezoelectric actuation,elastica theory,snap-through,post-buckled beams
更新于2025-09-23 15:19:57
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One-Structure-Based Multi-Effects Coupled Nanogenerators for Flexible and Self-Powered Multi-Functional Coupled Sensor Systems
摘要： The simultaneous monitoring of multi-physical signals is essential for future sensor systems, but is currently only realized by integrating a variety of sensor types into a single device. However, the ability to use a single sensor structure that shares common electrodes can provide a route to multi-functional sensing while also decreasing device size and increasing spatial resolution. Here we report a ferroelectric barium titanate film-based multi-effect coupled nanogenerator for scavenging light, mechanical, and thermal energies to realize a self-powered multi-functional coupled sensor system without using any external power source. The coupled nanogenerator exhibits a strong coupling enhancement with detection sensitivities of 0.42 nA/(mW/cm2) during illumination by 405 nm light, 1.43 nA/kPa for pressure detection, and -8.85 nA/K for temperature sensing, where both the light and pressure sensing performances have the highest sensitivities during a cooling temperature variation of ~19.5 K and the largest temperature detection sensitivity can be achieved during strong light illumination of 83.2 mW/cm2. Moreover, the coupled nanogenerator array can be integrated into flexible forms for tactile pressure, temperature, and light sensors, and enabling coupled sensing for the development of electronic skins.
关键词： photovoltaic effect,pyroelectric effect,piezoelectric effect,electronic skin
更新于2025-09-23 15:19:57
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Improved output voltage of 0–3 cementitious piezoelectric composites with basalt fibers
摘要： In this paper, basalt fibers (BF) was employed as high modulus component with good interface bonding with cement matrix to enhance local stress applied on piezoelectric ceramic particles in 0–3 cementitious piezoelectric composites (0–3 CPCs). The effect of content of BF varying from 0.00 vol% to 0.23 vol% on the mechanical, piezoelectric and dielectric properties of 0–3 CPCs and the output voltage of 0–3 CPCs sensor was evaluated. The results showed that amplitude of output voltage of the 0–3 CPCs sensor with 0.12 vol% BF maximized at 4.98 V, which was 60.0% higher than that of the 0–3 CPCs sensor without fibers for the compact structure of the 0–3 CPCs and good interface bonding between BF and cement matrix as a reason of good stress transfer in the composites. While the split tensile strength, piezoelectric voltage constant (g33), piezoelectric strain constant (d33), relative dielectric constant (εr) and dissipation factor (tanδ) was 13.1 MPa, 11.36 × 10?3 V m/N, 43 pC/N, 430.0 and 0.43, respectively. It provided a novel method to improve the mechanical-electrical response of piezoelectric sensor by enhancing local stress applied on piezoelectric ceramic particles in the piezoelectric composites.
关键词： 0–3 cementitious piezoelectric composites,Stress transfer,Basalt fibers,Output voltage
更新于2025-09-23 15:19:57
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3-3 Piezoelectric Metamaterial with Negative and Zero Poisson’s Ratio for Hydrophones Applications
摘要： This study presents the electromechanical properties of the 3-3 piezoelectric metamaterial based on variants of honeycomb (HC) structure. Three kinds of three-dimensional (3D) elastically anisotropic and piezoelectrically active HC structures were introduced, namely, conventional HC (3D-CHC), a re-entrant HC (3D-RE) and a semi-re-entrant HC (3D-SRE). Highly porous 3D finite element models of the mentioned three kinds of metamaterials were developed and the role of ligament orientation on their effective elastic, piezoelectric and dielectric properties was completely characterized. The intrinsic symmetry of HC structure was utilized and simplified mixed boundary conditions equivalent to periodic boundary conditions were recognized. In comparison to their bulk constituent, all the 3-3 type piezoelectric HC networks exhibited an enhanced response, especially for the longitudinal poling. The normalized figures of merit show a mild dependence on the angle θ and the underlying deformation mechanisms associated with the zero, positive and negative Poisson’s ratios. Figures of merit such as hydrostatic strain coefficient (hd), the hydrostatic figure of merit (ghhd) and the acoustic impedance (Z) reached their best values at small angles, i.e., θ=30°. Longitudinally poled networks exhibited four order of magnitude increase in their hydrostatic figure of merit (foam to solid ratio >10,000) and one order of magnitude decrease in the acoustic impedance indicating their applicability for the design of hydrophones.
关键词： piezoelectric materials,auxetic smart structures,metamaterials,electromechanical properties,cellular materials,honey comb structures,unit cell method
更新于2025-09-23 15:19:57
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Defect-relevant piezoelectric and ferroelectric properties in LiCuTa3O9-doped K0.5Na0.5NbO3 lead-free piezoceramics
摘要： Lead-free K0.5Na0.5NbO3 + x mol LiCuTa3O9 (abbreviated to KNN-xLCT) piezoceramics are synthesized via a conventional sintering technique. All ceramics exhibit perovskite structure and their densification is improved after the addition of LCT. The doping of small quantities of LCT (x ≤ 0.015) results in the generation of two sorts of defect complexes [i.e., ?? V??(Cu???o ) ], inducing greatly hardening electrical behaviors with high mechanical quality factor Qm of ~ 780 at x = 0.015. However, excess LCT (x ≥ 0.015) contributes to the substantial reduction of defect complexes, and thus the ceramics are softened, presenting a relatively low Qm of ~ 480 at x = 0.03. It is noted that the ceramics with x = 0.03 remain comparatively great piezoelectric performances: d33 = 96 pC/N and kp = 37%. Our study indicates that the electrical properties of KNN-based ceramics doped with LCT are closely related with microscopic defect structure in the materials.
关键词： Lead-free piezoceramics,K0.5Na0.5NbO3,Piezoelectric properties,Defect complexes,LiCuTa3O9
更新于2025-09-23 15:19:57