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A Wide Temperature Insensitive Piezoceramics for High-Temperature Energy Harvesting
摘要： One of the key challenges in the development of high-temperature energy harvesting (HTEH) technology is to clarify the relationship between temperature-dependent material parameters and device power generation capabilities. However, at present, the research on temperature stability of piezoceramics mainly relies on thermal annealing technology, which cannot follow the actual temperature dependence of the piezoelectricity, and it is even more difficult to predict the temperature stability of HTEH. To shed light on this field, here, (1-x)BiScO3-xPbTiO3 system was chosen for building HTEH material, and the temperature dependent electrical parameters, such as d33, εr, and g33, have been measured by multiple in-situ techniques. It was found that the synergistic effect of d33 and εr with temperature helps to obtain a stable g33 value in a wide temperature range. Moreover, in the mode of the cantilever-type energy harvester, a stable output voltage was obtained at x=0.64 harvester with less than 20% change over a broad temperature range of 100-250 oC, and it was verified that the temperature stability of g33 is crucial to the operation stability of HTEH devices.
关键词： in-situ techniques,piezoelectric materials/properties,energy harvesting,thermal properties
更新于2025-11-14 17:28:48
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Dielectric and Piezoelectric Properties of Textured Lead-Free Na0.5Bi0.5TiO3-Based Ceramics
摘要： This work provides a comparative study of the dielectric and piezoelectric properties of randomly oriented and textured 0.88Na0.5Bi0.5TiO3-0.08K0.5Bi0.5TiO3-0.04BaTiO3 (88NBT) ceramics. Textured ceramics were fabricated by template grain growth (TGG) method using NaNbO3 (NN) for templates. For textured ceramics with 4 wt% NN templates, a Lotgering factor of 96% and piezoelectric coe?cient d33 of 185 pC/N were obtained. Compared to the randomly oriented ceramics, textured ceramics show lower strain hysteresis (H = 7.6%), higher unipolar strain of 0.041% with corresponding large signal piezoelectric coe?cient d33* of 200 pm/V at applied ?eld of 2 kV/mm. This enhancement can be explained by the grain orientation along <001> direction by texturing, where an engineered domain con?guration is formed after polarization, leading to decreased hysteresis and increased piezoelectric property.
关键词： electrical conductivity,textured ceramics,template grain growth,piezoelectric materials
更新于2025-11-14 17:28:48
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[SpringerBriefs in Applied Sciences and Technology] Vibration Analysis of Functionally Graded Piezoelectric Actuators ||
摘要： This book has evolved from the passionate desire of the author in using the modern concepts of piezoelectric materials for the design improvement of sensors and actuators. In this connection, the author took up his doctoral studies whose findings have resulted in this book. The initial focus here is on the basic theory, application, and drawbacks of piezoelectric materials. The types of deformation produced in piezoelectric materials due to different piezoelectric effects are reported briefly. Further, the concept of functionally graded material (FGM) used in the design of piezoelectric materials with graded properties is described. The engineering applications of functionally graded piezoelectric materials (FGPMs) are summarized thereafter. In the latter sections, the modal analysis of FGPM actuators is provided. Two types of actuator geometries are taken into consideration—first is beam, and the second is annular plate. The effects of various parameters on the natural frequencies are given in detail. A detailed account of a new numerical technique called the generalized differential quadrature (GDQ), adopted in this book, is also provided. An extension of this technique for the analysis of FGPM structures becomes an important endeavor. The overall focus is on the vibration analysis of FGPM actuators excited under the shear effect using the GDQ method.
关键词： Shear effect,Piezoelectric materials,Functionally graded materials,Vibration analysis,Actuators,Generalized differential quadrature method
更新于2025-09-23 15:23:52
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Micromechanical simulation of ferroelectric domain processes at crack tips
摘要： The electromechanical loading situation at cracks in ferroelectric ceramics is essentially affected by domain switching. Under high electrical and/or mechanical external fields, the state of polarization and remanent strains is substantially changed at the crack tip. These irreversible dissipative processes influence the fracture toughness of the cracked ferroelectric material. In the present paper, the micromechanical domain switching processes at the crack tip are studied by numerical simulation and compared with the in situ experimental results obtained by Jones et al. (Acta Mater 55(16):5538–5548, 2007) using X-ray diffraction analyses in synchrotron. Main attention is payed to the spatial distribution of preferred domain orientation in a mechanically loaded compact tension specimen made of a soft tetragonal lead zirconate titanate ceramics. It is found that the mechanically induced favored domain orientation distribution depends on position within the plane of the CT specimen and correlates with projected deviatoric stresses and strains. Some issues concerning shortcomings in the experimental and simulation results are raised and discussed. The outcome of this type of simulations forms the basis for more realistic fracture mechanical evaluations in future.
关键词： Domain switching,Crack tip,Ferroelectric/piezoelectric materials,Fracture,Process zone
更新于2025-09-23 15:23:52
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Determination of the appropriate piezoelectric materials for various types of piezoelectric energy harvesters with high output power
摘要： For a type-1 piezoelectric energy harvester (PEH), in which stress develops in the supporting system of the piezoelectric materials, the electromechanical coupling factor (kij) of the piezoelectric materials is important for the output power at the resonance frequency. Therefore, soft-piezoelectric materials are good candidates for these PEHs. For type-2 PEHs, in which stress develops in the piezoelectric material and supporting system, the figure of merit (FOM) of the output power at the resonance frequency is (kij2×Qm)/s11E, where Qm and s11E are the mechanical quality factor and the elastic compliance of piezoelectric materials, respectively. In particular, the effect of Qm is very large for these PEHs, indicating that hard-piezoelectric materials are good candidates for type-2 PEHs operating at the resonance frequency. For both type-1 and type-2 PEHs operating at off-resonance frequency, the kij2×dij×gij is the FOM of the output power of the PEHs, where gij is a piezoelectric voltage constant. Therefore, soft-piezoelectric materials are also good candidates for both type-1 and type-2 PEHs operating at the off-resonance frequency.
关键词： PEH,Piezoelectric materials,FOM,kij,Qm
更新于2025-09-23 15:23:52
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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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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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[IEEE 2019 IEEE 2nd International Conference on Power and Energy Applications (ICPEA) - Singapore, Singapore (2019.4.27-2019.4.30)] 2019 IEEE 2nd International Conference on Power and Energy Applications (ICPEA) - Characteristics of Disturbance in Frequency 9 -150 kHz of Photovoltaic System under Fluctuated Solar Irradiance
摘要： Gallium nitride (GaN) is a wide bandgap semiconductor material and is the most popular material after silicon in the semiconductor industry. The prime movers behind this trend are LEDs, microwave, and more recently, power electronics. New areas of research also include spintronics and nanoribbon transistors, which leverage some of the unique properties of GaN. GaN has electron mobility comparable with silicon, but with a bandgap that is three times larger, making it an excellent candidate for high-power applications and high-temperature operation. The ability to form thin-AlGaN/GaN heterostructures, which exhibit the 2-D electron gas phenomenon leads to high-electron mobility transistors, which exhibit high Johnson’s figure of merit. Another interesting direction for GaN research, which is largely unexplored, is GaN-based micromechanical devices or GaN microelectromechanical systems (MEMS). To fully unlock the potential of GaN and realize new advanced all-GaN integrated circuits, it is essential to cointegrate passive devices (such as resonators and filters), sensors (such as temperature and gas sensors), and other more than Moore functional devices with GaN active electronics. Therefore, there is a growing interest in the use of GaN as a mechanical material. This paper reviews the electromechanical, thermal, acoustic, and piezoelectric properties of GaN, and describes the working principle of some of the reported high-performance GaN-based microelectromechanical components. It also provides an outlook for possible research directions in GaN MEMS.
关键词： HEMT,piezoelectric materials,micromachining,microelectromechanical systems,III-V,wide bandgap,resonators
更新于2025-09-19 17:13:59
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Revisiting the electroelastic solution for an FGPM thick-walled cylinder subjected to mechanical and electric loadings
摘要： Theoretical analysis for an empty thick-walled FGPM cylinder exposed to electric and mechanical loadings are investigated. The cylinder is a composite material composed of PZT4 and PVDF and the volume fraction of PZT4 is given by the power law with three controllable parameters which can cover more complex circumstances. The hypergeometric equation of the radial displacement is acquired by utilizing the Voigt method, and the solutions of the stresses and the electric potential are obtained after solving the radial displacement. The method in this paper is appropriate for real functionally graded piezoelectric materials and can avoid assumptions about unknown overall material parameters appeared in previous references. Finally, the impacts of the parameter n in volume fraction of FGPM cylinder on mechanical and electric behaviors are examined. Furthermore, the distinction between the hoop stress and radial stress is discussed to decrease the pressure concentration in FGPM cylinder.
关键词： thick-walled cylinder,functionally graded piezoelectric materials,electric potential,electroelastic solution
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Device model for intermediate band materials
摘要： Gallium nitride (GaN) is a wide bandgap semiconductor material and is the most popular material after silicon in the semiconductor industry. The prime movers behind this trend are LEDs, microwave, and more recently, power electronics. New areas of research also include spintronics and nanoribbon transistors, which leverage some of the unique properties of GaN. GaN has electron mobility comparable with silicon, but with a bandgap that is three times larger, making it an excellent candidate for high-power applications and high-temperature operation. The ability to form thin-AlGaN/GaN heterostructures, which exhibit the 2-D electron gas phenomenon leads to high-electron mobility transistors, which exhibit high Johnson’s figure of merit. Another interesting direction for GaN research, which is largely unexplored, is GaN-based micromechanical devices or GaN microelectromechanical systems (MEMS). To fully unlock the potential of GaN and realize new advanced all-GaN integrated circuits, it is essential to cointegrate passive devices (such as resonators and filters), sensors (such as temperature and gas sensors), and other more than Moore functional devices with GaN active electronics. Therefore, there is a growing interest in the use of GaN as a mechanical material. This paper reviews the electromechanical, thermal, acoustic, and piezoelectric properties of GaN, and describes the working principle of some of the reported high-performance GaN-based microelectromechanical components. It also provides an outlook for possible research directions in GaN MEMS.
关键词： wide bandgap,resonators,HEMT,micromachining,III-V,microelectromechanical systems,piezoelectric materials
更新于2025-09-16 10:30:52