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Origin of enhanced piezoelectric properties revealed through electric field driven studies in 0.94(Na <sub/>0.5</sub> Bi <sub/>0.5</sub> TiO <sub/>3</sub> )a??0.06(Ba <sub/>0.85</sub> Ca <sub/>0.15</sub> Ti <sub/>0.9</sub> Zr <sub/>0.1</sub> O <sub/>3</sub> ) ceramics
摘要： A single phase 0.94(Na0.5Bi0.5TiO3)–0.06(Ba0.85Ca0.15Ti0.9Zr0.1O3) solid solution (i.e., BCZT-0.06) is prepared using a conventional solid-state sintering route with enhanced piezo and ferroelectric properties as compared to Na0.5Bi0.5TiO3 (NBT). In the context of understanding the origin of enhanced piezoelectric properties in a BCZT-0.06 specimen, electric field driven studies on different length scales, viz., global, local, and electronic structure, are carried out using x-ray/neutron diffraction, Raman scattering, and UV–Vis spectroscopic techniques. An analysis on different length scales of the electric field-driven BCZT-0.06 specimen displays minimum rhombohedral lattice distortion (δ r), reduced homogeneous lattice strain (δ), octahedral strain (ζ), and pronounced Ti-cation displacement along the polar [111] direction as compared to parent NBT. The enhanced ferro and piezoelectric responses observed in the BCZT-0.06 specimen have been attributed to the ease of non-180° domain re-orientation, domain switching, and domain wall motion due to reduced strain coupled with a polarization extension mechanism.
关键词： ferroelectric properties,electric field driven studies,solid solution,domain re-orientation,piezoelectric properties
更新于2025-09-19 17:13:59
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Physics of Electrostatic Projection Revealed by High-Speed Video Imaging
摘要： Processes based on electrostatic projection are used extensively in industry, e.g., for mineral separations, electrophotography, or manufacturing of coated abrasives, such as sandpaper. Despite decades of engineering practice, there are still unanswered questions. In this paper, we present a comprehensive experimental study of the projection process of more than 1500 individual spherical alumina particles with a nominal size of 500 μm, captured by high-speed video imaging and digital image analysis. Based on flight trajectories of approximately 1100 projected particles, we determine the acquired charge and dynamics as a function of the relative humidity (RH) and the electric field intensity and compare the results with classical theories. For RH levels of 50% and above, more than 85% of distributed particles are projected, even when the electric field intensity is at its minimum level. This suggests that, beyond a critical value of the electric field intensity, the RH plays a more critical role in the projection process. We also observe that the charging time is reduced dramatically for RH levels of 50% and above, possibly due to the buildup of thin water films around the distributed particles, which can facilitate charge transfer. In contrast, projected particles at the 30% RH level exhibit excessive amounts of electric charge, between 2 and 4 times than that of the saturation value, which might be attributed to triboelectric charging effects. Finally, the physics of electrostatic projection is compared and contrasted with those of induced-charge electrokinetic phenomena, which share similar field-square scaling, as the applied electric field acts on its own induced charge to cause particle motion.
关键词： electric field intensity,high-speed video imaging,alumina particles,charge transfer,electrostatic projection,triboelectric charging,relative humidity
更新于2025-09-19 17:13:59
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Investigation of the incident light intensity effect on the internal electric fields of GaAs single junction solar cell using bright electroreflectance spectroscopy
摘要： The incident light intensity (Iex) effects on a GaAs single junction solar cell (SC) was investigated using bright electroreflectance spectroscopy (BER) and current-voltage (J-V) measurements at room temperature. The p-n junction electric field (Fpn) of the SC was evaluated by analyzing the Franz Keyldesh oscillation (FKO) in the BER spectra. The Iex effect on Fpn was investigated at various incident light intensities from 0.03 to 25 suns. The Fpn decreased gradually with increasing Iex due to the photovoltaic effect. For the forward bias voltage, some part of the electrons and holes drifted to the p and n sides, respectively, and produced the induced electric field in the same direction of the Fpn. Therefore, the Fpn increased up to 2.5 suns. At more than 2.5 suns, most of the electrons and holes moved to the n and p sides and decreased the Fpn due to the photovoltaic effect. In addition, the Fpn was examined under light illumination as a function of different DC bias voltages (-0.2 ~ 0.4 V). The Fpn decreased with increasing bias voltage due to the decrease in potential barrier. The Fpn increased with increasing bias voltage due to the decrease in the photogenerated carrier-induced electric field for high Iex.
关键词： GaAs solar cell,Bright electroreflectance spectroscopy,Electric field
更新于2025-09-19 17:13:59
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High-Efficiency Perovskite Solar Cells Enabled by Anatase TiO2 Nanopyramid Arrays with Oriented Electric Field
摘要： One-dimensional (1D) nanostructured oxides have been proposed as excellent electron transport materials (ETMs) for perovskite solar cells (PSCs), but this has not yet been demonstrated experimentally. Here, we exploit a facile hydrothermal approach to grow highly oriented anatase TiO2 nanopyramid arrays and further demonstrate their advantages for application in PSCs. The oriented TiO2 nanopyramid arrays afford sufficient contact area for electron extraction and increase light transmission. Moreover, the nanopyramid array/perovskite system exhibits an oriented electric field that can increase charge separation and accelerate charge transport, thereby suppressing charge recombination. As a result, the anatase TiO2 nanopyramid arrays-PSCs deliver a champion power conversion efficiency of ~22.5%, which is the highest PCE reported thus far for PSCs consisting of 1D ETMs. This work demonstrates that the rational design of 1D ETMs can achieve PSCs that perform as well as typical mesoscopic and planar PSCs.
关键词： Anatase TiO2,Electric field distribution,Perovskite solar cells,One-dimensional nanostructures,Nanopyramid arrays
更新于2025-09-19 17:13:59
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Mathematical Modelling of Electrically Controlled Filters of Microwave, subTHz and THza??bands on the Base of Grapheneand-Dielectric Multilayer Structure
摘要： Report is devoted to investigations of graphene meta–surfaces for the transmission of radiation induced by plasmons in subTHz and THz ranges, cell of which consists of structures based on graphene ring and graphene nano–tape. It create regimes of radiation transmission – transparency windows induced by electric dipole resonances. Resonant frequency of transparency window can be dynamically tuned in wide band of subTHz and THz bands by changing the chemical potential (Fermi energy) of graphene by applying external electric field (gating) instead of re–fabricating of structures. Questions of possibilities of electronic controlled filters creating of subTHz and THz bands grounded on different configurations of graphene meta–surfaces are discussed; their characteristics and frequency dependencies are investigated. Mathematical modelling and electrodynamic calculation of the filters characteristics of subTHz and THz bands grounded on multilayer structures of “graphene–dielectric” type are carried out. From results of mathematical modelling it follows that periodic layered microstructures “graphene–dielectric” type can be used for creation of subTHz and THz bands broadband filters of planar construction, controlling by electric field and fast tuning at small changes in Fermi energy level of graphene.
关键词： multilayer structures,filters,subTHz,plasmonic,chemical potential,electric field,graphene,meta-surfaces,electric dipole resonances,THz,Fermi energy
更新于2025-09-16 10:30:52
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Time-Domain Detection of the Electric Field and its Conjugate Variable in Ultrabroadband Electro-Optic Sampling
摘要： We demonstrate unambiguous detection of the conjugate variable to the electric field in a time-domain experiment. The polarization change induced by nonlinear mixing of probe and multi-THz fields via the Pockels effect is examined concerning changes in ellipticity and tilting of the polarization ellipsoid. Spectrally resolved measurements yield crucial insights into how sum and difference frequency generation processes shape the electro-optic signal for different detection crystals. This approach enables precise, even simultaneous, measurement of the electric field and its conjugate variable by combinations of different phase biases ((cid:2)/4 and (cid:2)/2) and spectral filtering.
关键词： sum and difference frequency generation,ultrabroadband electro-optic sampling,Pockels effect,electric field,conjugate variable
更新于2025-09-16 10:30:52
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Effects of the film thickness and poling electric field on photovoltaic performances of (Pb,La)(Zr,Ti)O3 ferroelectric thin film-based devices
摘要： The ferroelectric photovoltaic (FPV) effect obtained in inorganic perovskite ferroelectric materials has received much attention because of its large potential in preparing FPV devices with superior stability, high open-circuit voltage (Voc) and large short-circuit current density (Jsc). In order to obtain suitable thickness for the ferroelectric thin film as light absorption layer, in which, the sunlight can be fully absorbed and the photo-generated electrons and holes are recombined as few as possible, we prepare Pb0.93La0.07(Zr0.6Ti0.4)0.9825O3 (PLZT) ferroelectric thin films with different layer numbers by the sol-gel method and based on these thin films, obtain FPV devices with FTO/PLZT/Au structure. By measuring photovoltaic properties, it is found that the device with 4 layer-PLZT thin film (~300 nm thickness) exhibits the largest Voc and Jsc and the photovoltaic effect obviously depends on the value and direction of the poling electric field. When the device is applied a negative poling electric field, both the Voc and Jsc are significantly higher than those of the device applied the positive poling electric field, due to the depolarization field resulting from the remnant polarization in the same direction with the built-in electric field induced by the Schottky barrier, and the higher the negative poling electric field, the larger the Voc and Jsc. At a -333 kV/cm poling electric field, the FPV device exhibits the most superior photovoltaic properties with a Voc of as high as 0.73 V and Jsc of as large as 2.11 μA/cm2. This work opens a new way for developing ferroelectric photovoltaic devices with good properties.
关键词： Film thickness,Ferroelectric thin film,Ferroelectric photovoltaic devices,Depolarized electric field,Inorganic perovskite
更新于2025-09-16 10:30:52
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The effects of close packing and electric fields on the optical properties of three-dimensionally stacked quantum dots
摘要： An algorithm to evaluate the position of spherical quantum dots in a closely packed state inside a cube is presented and its accuracy confirmed numerically. A finite-difference method to solve the corresponding three-dimensional Schr?dinger equation in the presence of an external electric field is then described. The Arnoldi factorization method is used to diagonalize the resulting huge sparse matrix. The results reveal that both the intensity and direction of the electric field can significantly change the height of the absorption peak and are thus both important. Two different semiconducting structures, viz. GaAs/AlxGa1?xAs and InSb/GaSb, are investigated, revealing that the latter exhibits a more tunable absorption coefficient. The effect of the composition parameter x on the mentioned optical properties is also studied. The combination of this and earlier work indicates that photodetection in the wide range of 1.2–8.4 THz is possible. The proposed structure can thus be regarded as a possible candidate for use in photodetection devices in different fields of industries such as imaging, medicine, and materials characterization.
关键词： Close packing effect,Electric field,Finite difference method,Absorption coefficient,Three-dimensionally stacked quantum dots
更新于2025-09-16 10:30:52
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Graphene Photonics || Electronic Properties
摘要： The ?ow of free charge carriers, i.e., electrons in the conduction band or holes in the valence band, in a semiconductor that is subject to an electric ?eld is accelerated by the electric field but is hindered by scattering events. In a semiconductor, free carriers accelerate in the presence of an electric field. The randomly distributed scattering centers, such as impurities and defects, act as a counter force that decelerates and de?ects the carriers. When the steady state is eventually reached under a constant electric field, a constant ?ow of carriers is achieved. In graphene, by contrast, charge carriers on the Dirac cone have a constant speed and do not accelerate or decelerate in response to the electric field or the scattering centers; instead, the effect of the electric field is rather to align the motion of carriers to the direction of the electric field, and the scattering centers act as a source to disturb this alignment process. This process is well captured by the Boltzmann transport equation, which has successfully described many statistical behaviors of carriers in metals and semiconductors. The purpose of this chapter is to describe the electronic properties of graphene, starting from the Boltzmann transport equation.
关键词： Boltzmann transport equation,charge carriers,electric field,electronic properties,conductivity,scattering events,graphene,two-dimensional material
更新于2025-09-16 10:30:52
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[IEEE 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - Berlin, Germany (2019.6.23-2019.6.27)] 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - A Microassembled Triangular-Prism-Shape Three-Dimensional Electric Field Sensor
摘要： This paper, for the first time, presents a microassembled three-dimensional (3D) electric field sensor (EFS), which is a chip-level compact triangular-prism-shape sensor consisting of X-, Y- and Z-axis electric field (EF) sensing chips. The proposed 3D EFS is fabricated on a silicon-on-insulator (SOI) die, introducing photosensitive polyimide (PSPI) into its micromachining process to produce flexible micro-hinges and make separate components into a foldable integrative structure. Interlocking latches are employed to ensure the orthogonality of the three sensing axes. Structures of each EF sensing chip are symmetrically designed for reducing cross-axis coupling interference, and good performances have been demonstrated by experiments.
关键词： microassembly,Electric field sensor,triangular-prism-shape,three-dimensional,photosensitive polyimide
更新于2025-09-16 10:30:52