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Grain boundary effects on piezoelectric properties of the core–shell-structured BaTiO <sub/>3</sub> @TiO <sub/>2</sub> ceramics
摘要： Grain boundary effect on BaTiO3 has been widely investigated for several decades. However, all of them tailored the grain boundary by grain size of BaTiO3. In this case, a direct way was introduced to modify the grain boundary by coating technique to investigate the role of grain boundary in ferroelectric materials. Nonferroelectric phase TiO2 was employed to investigate grain boundary effects on the electrical properties of BaTiO3 piezoelectric ceramics. TiO2 coating can result in the reduction of piezoelectric and ferroelectric properties and the annealing process in oxygen can increase piezoelectric behavior of pure BaTiO3 due to valence state of Ti ions while that remains for Ti-modified composition possibly due to the increased grain boundary effect by impedance analysis. Compared with ferroelectric grain, grain boundary plays a critical role to impact the electrical properties of perovskite-type ferroelectric materials.
关键词： defects.,Piezoelectric properties,ferroelectric properties,BaTiO3 and titanates
更新于2025-09-19 17:15:36
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Ferroelectric mesocrystalline BaTiO <sub/>3</sub> /BaBi <sub/>4</sub> Ti <sub/>4</sub> O <sub/>15</sub> nanocomposite: formation mechanism, nanostructure, and anomalous ferroelectric response
摘要： Ferroelectric mesocrystalline nanocomposites are promising materials for the enhancement of ferroelectricity via lattice strain engineering due to their high density of heteroepitaxial interfaces. In the present study, a ferroelectric mesocrystalline BaTiO3/BaBi4Ti4O15 (BT/BBT) nanocomposite was synthesized using the layered titanate H1.07Ti1.73O4 via a facile two-step topochemical process. The BT/BBT nanocomposite is constructed from well-aligned BT and BBT nanocrystals oriented along the [110] and [11?1] crystal-axis directions, respectively. Lattice strain is introduced into the nanocomposite through the formation of a BT/BBT heteroepitaxial interface, which results in a greatly elevated Curie temperature for BBT in the range of 400 °C to 700 °C and an improved piezoelectric response with d*33 = 130 pm V?1. In addition, the BT/BBT nanocomposite is stable up to a high temperature of 1100 °C; therefore, mesocrystalline ceramics can be fabricated as high-performance ferroelectric materials.
关键词： piezoelectric response,nanocomposite,ferroelectric,mesocrystalline,BaBi4Ti4O15,BaTiO3,Curie temperature,lattice strain
更新于2025-09-19 17:15:36
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Electromechanical Properties of Ferroelectric (NaKLi)(NbTa)O <sub/>3</sub> –CaZrO <sub/>3</sub> Ceramics
摘要： Electromechanical Properties of Ferroelectric (NaKLi)(NbTa)O3–CaZrO3 Ceramics. The effect of CaZrO3 to electric and mechanical properties of (Na0.47K0.51Li0.02)(Nb0.8Ta0.2)O3 was investigated. With increment of CaZrO3, the crystal structure of (Na0.47K0.51Li0.02)(Nb0.8Ta0.2)O3 changed from the mixture of ferroelectric orthorhombic and rhombohedral phases to paraelectric pseudo-cubic phase. On the way of transition from ferroelectric to paraelectric phases, the composition range showing the mixture of ferroelectric/paraelectric phases with a structure of core/shell was revealed with an advent of relatively large strain behavior. The shell phase formed via solid-state diffusion of Nb, Ta, Na, K ions between (Na0.47K0.51Li0.02)(Nb0.8Ta0.2)O3 and CaZrO3 particles, followed by its subsequent solution process with mixing a Ta-rich perovskite with Ca and Zr ions. In contrast, the core phase formed via a solution-precipitation process, resulting in a Ta-depleted ferroelectric perovskite. Energy-dispersive X-ray analysis showed that core was a Nb-rich ferroelectric phase and the shell was a Ta-rich paraelectric phase with Ca and Zr ions at room temperature. This structure implies an interaction between straining behaviors in the core and shell phases under an electric field, leading large deformation in macro-scale.
关键词： Piezoelectric Properties,Electrostrain,(NaKLi)(NbTa)O3,CaZrO3,Ferroelectric Material
更新于2025-09-19 17:15:36
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Emergence of high piezoelectricity along with robust electron mobility in Janus structures in semiconducting Group IVB dichalcogenide monolayers
摘要： Piezoelectric harvesting emerging nanoelectromechanical energy. Pristine, semiconducting 1T-MX2 (M = Zr and Hf; X = S, Se, and Te) monolayers are intrinsically centrosymmetric, and hence non-piezoelectric. This inversion symmetry is broken in their Janus monolayer (non-centrosymmetric) structures, leading to the emergence of a high degree of piezoelectricity in them. This brings along a new dimension in nanoscale piezoelectricity, as the origin of this piezoelectricity is predominantly ionic in nature, in contrast to the 1H-MoS2 monolayer, where it is of electronic character. DFT calculations reveal the piezoelectric coefficient (d22 = 4.68–14.58 pm V?1) in these Janus monolayers to be much higher than that in single layer 1H-MoS2 (d11 = 2.99 pm V?1). 9% uniaxial tensile strain applied along the arm-chair direction is found to raise d22 in HfSSe Janus monolayers to 123.04 pm V?1, which reaches the level of piezoelectric coefficients in the state-of-the-art perovskites. The major contribution of the ionic component to the piezoelectric coefficient is attributable to the predominance of ionic character in the interatomic bonds in these monolayers, which arises from the decoupled band edges, i.e., no hybridization between the band edge states (chalcogen-p and metal-d). Contrarily, 1H-MX2 (M = Mo and W; X = S, Se, and Te) monolayers with coupled band edges are held together mainly by covalent bonds, resulting in the dominance of electronic contribution to piezoelectricity. The nature of band edges causes a lower deformation potential for electrons in 1T Hf and Zr based dichalcogenide monolayers and their Janus structures with respect to 1H-MX2 (M = Mo and W; X = S, Se, and Te) monolayers. This induces a much higher electron mobility in the former than in 1H-MX2 (M = Mo and W; X = S, Se, and Te) monolayers. The carrier mobility calculated using Lang et al.'s formalism [Phys. Rev. B, 2016, 94, 235306] agrees well with the experimentally measured electron mobility. Our predictive findings underscore the imminent need to synthesize these 1T-MX2 semiconducting Janus structures to induce a high level of piezoelectricity together with robust electron mobility.
关键词： nanomaterials,Piezoelectric,nanoelectromechanical energy,harvesting,emerging
更新于2025-09-19 17:15:36
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An Easily Fabricated Linear Piezoelectric Actuator Using Sandwich Longitudinal Vibrators With Four Driving Feet
摘要： A piezoelectric actuator using three sandwich longitudinal vibrators is proposed and tested. The two horizontal vibrators are parallel to each other and orthogonal to the vertical vibrator. The ends of the two horizontal vibrators serve as the four driving feet. The actuator has a simple fabricating process, which will shorten the period of fabrication. Two modes of the actuator are used to get the elliptical trajectories on the driving feet. The frequencies of the two modes are tuned to be about 21.60 kHz with modal analysis by the finite element method (FEM). The operating principle is also examined with transient analysis by FEM. A prototype is fabricated and its vibration characteristics are verified by using a scanning laser Doppler vibrometer. The prototype shows the best mechanical performance with the optimum working frequency and phase difference of 18.50 kHz and 60°, respectively. The typical output of the prototype is a no-load speed of 439.41 mm/s, a maximum thrust of 40 N, and a maximum power of 5.01 W at the voltage of 200 VP?P. The mechanical characteristics of the prototype show that the exciting voltages can be used for the speed control due to the approximately linear relationship between them.
关键词： resonant state,vibration test.,Linear piezoelectric actuator,sandwich longitudinal vibrators
更新于2025-09-19 17:15:36
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Nonlocal analytical solution of functionally graded multilayered one-dimensional hexagonal piezoelectric quasicrystal nanoplates
摘要： Based on the nonlocal elasticity theory, the static bending deformation of a functionally graded multilayered one-dimensional (1D) hexagonal piezoelectric quasicrystal (PQC) simply supported nanoplate is investigated under surface mechanical loadings. The functionally graded material is assumed to be exponential along the thickness direction. By utilizing the pseudo-Stroh formalism and propagator matrix method, exact closed-form solutions of functionally graded multilayered 1D hexagonal PQC nanoplates are then obtained by assuming that the layer interfaces are perfectly contacted. Numerical examples for six kinds of sandwich functionally graded nanoplates made up of piezoelectric crystals, quasicrystal and PQC are presented to illustrate the influence of the exponential factor, nonlocal parameter and stacking sequence on the phonon, phason and electric fields, which play an important role in designing new composite structures in engineering.
关键词： propagator matrix method,nanoplates,functionally graded materials,piezoelectric quasicrystals,pseudo-Stroh formalism,nonlocal elasticity theory,exact solutions
更新于2025-09-19 17:15:36
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Generalized Rayleigh surface waves in a piezoelectric semiconductor half space
摘要： In this paper, plane strain surface waves, also named generalized Rayleigh surface waves, in a transversely isotropic piezoelectric semiconductor half space are investigated. The governing equations of generalized Rayleigh surface waves include the equations of motion, Gauss’ law of electrostatics and the conservation of charge. Based on the basic theory of elastic-dynamic equations, the governing equations are deduced as equations related to the displacement, the electric potential and the perturbation of the carrier density and are solved analytically. We discuss dispersion curves and the attenuation tendency of generalized Rayleigh waves for real wave number cases. The results reveal that the semiconductor should lead to phase velocity decreasing, and the anomalous dispersion and damping of generalized Rayleigh waves. However, enough in-plane biasing electric field along the wave propagation should lead to the amplification of the waves. The influence of the out-plane biasing electric field is so slight that it can be omitted. These properties should be reproduced in the case of real frequencies. The results obtained may provide theoretical guidance for the design of high-performance surface acoustic wave devices made of piezoelectric semiconductors.
关键词： Damping,Piezoelectric semiconductor,Generalized Rayleigh surface,Biasing electric field
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE SENSORS - New Delhi, India (2018.10.28-2018.10.31)] 2018 IEEE SENSORS - Design and Fabrication of a Piezoelectric Micromachined Ultrasonic Transducer Array Based on Ceramic PZT
摘要： This paper presents a piezoelectric micromachined ultrasonic transducer (pMUT) array fabricated using high-piezoelectric-coefficient ceramic PZT wafers. A new process for polishing ceramic PZT layers down to 5 μm has been developed and applied for manufacturing high-sensitivity pMUTs. A 2 MHz working pMUT array (8×8 elements) based on ceramic PZT has been designed, modeled, fabricated and characterized.
关键词： pMUT,piezoelectric transducers,ultrasonic,micromachined transducers,ceramic PZT
更新于2025-09-19 17:15:36
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D controller for precise nanopositioning in the presence of hardware-induced constant time delay
摘要： The fast and accurate tracking of periodic and arbitrary reference trajectories is the principal goal in many nanopositioning applications. Flexure-based piezoelectric stack driven nanopositioners are widely employed in applications where accurate mechanical displacements at these nanometer scales are required. The performance of these nanopositioners is limited by the presence of lightly damped resonances in their dynamic response and actuator nonlinearities. Closed-loop control techniques incorporating both damping and tracking are typically used to address these limitations. However, most tracking schemes employed use a first-order integrator whereas a triangular trajectory commonly used in nanopositioning applications necessitates a double integral for zero-error tracking. The phase margin of the damped system combined with the hardware-induced delay deem the implementation of a double-integrator unstable. To overcome this limitation, this paper presents the design, analysis and application of a new control scheme based on the structure of the traditional Two-Degrees-of-Freedom PID controller (2DOF-PID). The proposed controller replaces the integral action of the traditional 2DOF-PID with a double integral action (2DOF-PI2D). Despite its simplicity, the proposed controller delivers superior tracking performance compared to traditional combined damping and tracking control schemes based on well-reported designs such as positive position feedback (PPF), Integral resonant control (IRC), and Positive Velocity and Position Feedback (PVPF). The stability of the control system is analyzed in the presence of a time delay in the system. Experimental results validating the efficacy of the proposed chattering-free control of a piezo-driven nanopositioning system are included.
关键词： Vibration,Piezoelectric actuators (PEAs),Precision Motion control
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE International Ultrasonics Symposium (IUS) - Kobe, Japan (2018.10.22-2018.10.25)] 2018 IEEE International Ultrasonics Symposium (IUS) - High-Volume Production and Non-Destructive Piezo-Property Mapping of 33% SC Doped Aluminium Nitride Thin Films
摘要： Scandium-doped aluminum nitride (ScAlN) thin films with 22% scandium content (Sc0.22Al0.78N) were deposited on a 100-mm sapphire substrate using a sputtering tool. The films exhibit enhanced piezoelectric properties compared to pure AlN, making them promising for microelectromechanical systems (MEMS) applications. The dielectric constant and loss tangent were measured at 100-mm and 20-mm wavelengths, showing values of εr ≈ 11.7 ± 0.2 and tanδ ≈ 0.002 ± 0.001, respectively. These results indicate high potential for voltage manufacturing and sensing devices.
关键词： dielectric properties,piezoelectric,sputtering,ScAlN,thin films,MEMS
更新于2025-09-19 17:15:36