Static Electric Field Research Articles

High energy storage density in high-temperature capacitor films at low electric fields

High-power applications, particularly in electromagnetic catapults, electric vehicles, and aerospace, necessitate the use of polymer dielectrics that demonstrate reliable performance in high-temperature environments. This study focuses on synthesizing three distinct morphologies of innovative wide-bandgap high-dielectric materials—hydroxyapatite (HAP). By conducting a combination of experiments and Multiphysics finite element simulations, a comprehensive comparison was made regarding the properties exhibited by three polyimide (PI) composites: PI/sea urchin-like HAP, PI/spherical HAP, and PI/rodlike HAP. The incorporation of high-surface-area spherical HAP or high aspect ratio rodlike HAP introduces intricate and convoluted growth paths for electric tree formation within the PI matrix, thereby augmenting the energy storage density (Ue) at elevated temperatures (Uη > 90% = 4.82 J/cm3, Uη > 80% = 6.11 J/cm3, Uη > 70% = 8.73 J/cm3, at 150 ℃). The incorporation of HAP increases the dielectric constant εr to a maximum value of 4.96 in pure PI matrices, enabling the resulting PI/HAP composites to achieve remarkable values for both Ue (4.82 J/cm3) and η (92.4 %) even under low electric field (E) conditions (350 MV/m). The PI/HAP composite film demonstrates high energy storage density under low E, offering an innovative solution for energy storage applications in film capacitors operating in high-temperature environments.

Electric field stimulation on electronic, electro-optical and non-linear optical properties of some fluoro-isothiocyanate and fluorinated alkyl terphenyl liquid crystals: A comparative DFT approach

Employing density functional theory, electronic, electro-optical, and NLO properties of some fluorinated NCS terphenyl and fluorinated terphenyl liquid crystals have been investigated in the presence of static electric field. Two DFT functionals, in this study, includes M06-2X and ωB97XD combined with 6–311 + G(d,p) basis set have been used. All the computations have been performed on Gaussian 16 W program and visualized on GaussView6.0. A comparative analysis of computational outcomes has been done in order to forecast mesogens’ improved electronic characteristics, global descriptors, NLO and UV–vis spectra. All of the chosen LC molecules exhibit properties that make them suitable materials for NLO applications.

Molecular insights into the role of static electric fields in seawater icing

Molecular insights into the role of static electric fields in seawater icing

Optical Second‐ and Third‐Order Nonlinearities in Plasma‐Enhanced Chemical Vapor Deposition‐Grown Silicon Oxides and Silicon Nitrides

Optical second‐ and third‐order nonlinearities ( and ) in nonstoichiometric silicon oxides and silicon nitrides grown by plasma‐enhanced chemical vapor deposition are investigated by second‐harmonic generation (SHG) and electric field‐induced second‐harmonic (EFISH) measurements. The free‐space SHG measurements with a fundamental wavelength of 1030 nm allow us to determine the bulk values of both material platforms for various material compositions. It is demonstrated that the bulk values can be strongly enhanced by increasing the silicon content, reaching maximum values of the main tensor component of for silicon‐rich nitrides and for silicon‐rich oxides. EFISH measurements demonstrate that the values can be pushed even further by adding a static electric field to the materials. Similar to the values, the values are strongly enhanced by increasing the silicon content, leading to a maximum value of m2 V−2 for the silicon‐rich nitrides and m2 V−2 for the silicon‐rich oxides.

Study on the corona aging characteristics of KH570-modified nano-Al(OH)₃ cycloaliphatic epoxy resin in hygrothermal environments

Cycloaliphatic epoxy(CE) resin may experience insulation degradation and pose a threat to the safe operation of equipment when used in high-temperature and high-humidity environment. Therefore, to enhance the corona aging resistance of CE under harsh conditions, this study incorporated γ-methacryloxypropyltrimethoxysilane-modified (KH570) nano-Al(OH)₃ with varying content into the CE. The samples were subjected to corona aging tests under different hygrothermal conditions. The corona aging characteristics of CE in high-temperature and high-humidity environments were analyzed using scanning electron microscopy(SEM), Fourier transform infrared spectroscopy(FTIR), resistivity, and dielectric loss measurements before and after modification. The results indicate that as humidity increases, the unmodified samples develop pores and cracks on the surface, which leads to an increased water absorption rate and internal hydrolysis. However, with the increase in filler content, the water absorption channels on the sample surface decrease, effectively suppressing chemical moisture absorption and maintaining the stability of the internal chemical structure. Among the various filler contents, the effect was most pronounced at 3%wtCE. Under 65 % RH conditions, the volume/surface resistivity increased by 27.28 % and 26.9 %, respectively, the leakage current decreased by 64.85 %, while the dry and wet breakdown voltages increased by 9.3 kV and 6.85 kV, respectively, and the dielectric loss variation with humidity was reduced. Compared to the unmodified material, KH570-modified nano-Al(OH)₃ has significantly improved the insulation and aging resistance properties of the material under hot and humid corona aging conditions. This study provides a reference for improving the performance of epoxy resins under high temperature, high humidity, and strong electric field conditions.

Electric-field-induced polarization anisotropy of interband photoluminescence in GaAs

Near-infrared photoluminescence spectra of the n-doped gallium arsenide epilayer under heating lateral electric field conditions are studied. The field dependences of hot electron and hole temperatures are determined from photoluminescence spectra and from solving the power balance equation using current–voltage characteristic. Polarization anisotropy of the photoluminescence radiation arising due to the anisotropy of hot electron distribution function and angular dependence of the interband optical matrix element in the momentum space is observed and investigated. The obtained experimental data are in satisfactory agreement with the theoretical model.

Enhanced Control of Single-Molecule Emission Frequency and Spectral Diffusion.

The Stark effect provides a powerful method to shift the spectra of molecules, atoms, and electronic transitions in general, becoming one of the simplest and most straightforward ways to tune the frequency of quantum emitters by means of a static electric field. At the same time, in order to reduce the emitter sensitivity to charge noise, inversion symmetric systems are typically designed, providing a stable emission frequency with a quadratic-only dependence on the applied field. However, such nonlinear behavior might be reflected in correlations between the tuning ability and unwanted spectral fluctuations. Here, we provide experimental evidence of this trend using molecular quantum emitters in the solid state cooled down to liquid helium temperatures. We finally combine the electric field generated by electrodes, which is parallel to the molecule's induced dipole, with optically excite long-lived charge states acting in the perpendicular direction. Based on the anisotropy of the molecule's polarizability, our two-dimensional control of the local electric field allows us not only to tune the emitter's frequency but also to sensibly suppress the spectral instabilities associated with field fluctuations.

Impact of Static Electric Field on Dielectrophoretic Alignment of Silicon Nanowires

AbstractAmong numerous approaches to assembling nanowires onto electrodes, dielectrophoresis (DEP) is a potential candidate to place the nanowires. However, its yield is still far from perfection, urging fundamental understanding of its dynamics. Here, the impact of a static electric field on dielectrophoretic nanowire assembly on gold electrodes is investigated. Specifically, a 4 peak‐to‐peak alternating voltage with 700 Hz is applied and modulate the offset voltage from 0 to 2V. The highest yield in the alignment of the nanowires at 0.5 V offset voltage is found. With the optical investigation of misaligned nanowires, it is found that rotating wires on top of electrodes, and the analysis of their angular velocity suggest the impact of the induced static charges. The numerical analysis quantifies the length scale of competing two forces, dielectrophoretic force and electric double layer force. This work suggests a quantitative understanding of the interplay between dielectrophoresis and electric double layer, which contributes to the advances in scalable nanowire fabrications.

Performance of a novel annular electric field membrane bioreactor and its membrane fouling control in treating catering wastewater

This study aimed to investigate the effects of different voltage and aeration conditions on catering wastewater treatment and membrane fouling in a novel annular electric field membrane bioreactor (AEMBR). The results indicated that the synergistic effect of annular electric field and aeration promoted the degradation of wastewater and the alleviation of membrane fouling. The treatment effect was optimal under a micro electric field of 0.5 V, with removal rates for COD, NH4+-N, TP, and oil ranging from 96.85% to 99.36%, 80.43%–83.01%, 95.46%–97.79%, and 98.83%–99.15%, respectively. Additionally, the fluorescence intensity of macromolecular proteins and small molecular acids decreased. Simultaneously, the average growth rate of transmembrane pressure (TMP) reduced by approximately 0.4 kPa/d. The species abundance and diversity of activated sludge increased, promoting the growth of dominant bacteria, all while maintaining low energy consumption. The aeration intensity had relatively little impact on system operation, and the force of the annular electric field was greater than the force of aeration. This study verified the optimal benefits under micro electric field conditions and provided a basis for the optimization of future process design to achieve a more efficient and economical wastewater treatment system.

Impact of overvoltage on the mode transition of the spark gap switch: from edge breakdown to stochastic breakdown

Abstract Spark gap switch (SGS) is a fundamental but critical component for large-scale pulsed power devices, whose reliable operation is significantly affected by the breakdown characteristics of SGS. It is observed experimentally that, with the increase of overvoltage, the bridging position of the spark channel transits from edge to stochastic center. In this work, the influence of overvoltage on the breakdown process of a parallel-plate SGS with low geometric distortion of static electric field (<13%) between an atmospheric-pressure air gap of 5 mm is investigated by particle-in-cell/Monte Carlo collision simulation. It is found that, under a low overvoltage (ratio of applied voltage U a to static breakdown voltage U 0, U a/U 0 = 1.5), the streamers at the edge first bridge the gap before that in the central region, due to the field enhancement induced by the electrode curvature. Under higher overvoltage (U a/U 0 = 3), the synchronicity between streamers initiating from the center and those from the edge is greatly improved during the inception stage. After the streamers pass the middle of the gap, the field enhancement at the streamer front is more intensified and promotes the generation of fast electrons. These fast electrons rapidly magnify the difference among the propagating streamers by providing abundant seed electrons ahead of the discharge channel, which leads to the randomness of the bridging position. The results in this work demonstrate the relationship between overvoltage and streamer dynamics, which is beneficial for the performance improvement of SGS.

3D electric field coupling with Cu foam hydrogel: Achieving efficient and high-speed solar interfacial evaporation

Solar interfacial evaporation is a clean and sustainable steam production method. Existing studies coupled electric field with 2D evaporator have acquired significant enhancement but the evaporation rate is relatively low. To obtain higher evaporation rates, this work has designed a novel Cu foam hydrogel interface evaporator, which could construct 3D electric field to improve the performance of 3D evaporator. The effects of electric field conditions and evaporator structure types on evaporation have been studied experimentally. Results reveal that the 3D electric field with low energy consumption has obvious improvement effect on the evaporation performance of the 3D evaporator and could reduce its surface temperature. Under electric field, the Cu foam hydrogel evaporator has achieved 159 % enhancement of evaporation performance and higher evaporation rate up to 3.053 kg·m−2·h−1 at the solar radiation intensity of only 1 sun. The enhancement mechanism is that the electric field can enhance the transport and evaporation of water in hydrogel. Besides, the evaporation of Cu foam hydrogel evaporators involves a larger surface area. Meanwhile, the 3D electric field has a stronger influence on the evaporator surface, and the above factors work together to improve the evaporator performance.

Floquet engineering of interparticle correlations in electron-hole few-body system for strong radial confinement

We investigate the effects of off-resonant THz-frequency laser light coupling to bound few-body electron-hole system, i.e. the exciton and negatively charged trion confined in quantum wire. To solve this problem, we first conduct a unitary Hennerberger-Kramers transformation of the Hamiltonian and diagonalize its perturbative approximation to obtain the exciton and trion Floquet states. Within this framework, the light-matter coupling renormalizes an attractiveehinteraction, leaving the repulsiveeeunchanged, thus modifying corresponding two-particle correlation energies. Generally, the correlation energy ofehwould exceed theeeone for a semiconductor material with strongly localized heavy holes. However, as the former is weakened by increasing laser intensity, this relation can be reversed. Consequently, the trion may dissociate unconventionally, the hole gradually decouples from still strongly interacting electrons, and adequate energy and optical spectra changes accompany this process. The energy levels of the exciton and trion Floquet states are raised, while their optical brightness smoothly decreases for stronger laser intensities. We also show this process can be further modified by breaking the mirror symmetry of wire with a static electric field, and then the occurrence of the avoided crossings between the lowest energy levels of the trion depends on the laser intensity. These anticrossings shall be observed experimentally, confirming thus the usefulness of Floquet engineering for fast manipulations of the few-particle states in electron-hole systems on a subpicosecond time scale.

Velocity Scanning Tomography for Room-Temperature Quantum Simulation.

Quantum simulation offers an analog approach for exploring exotic quantum phenomena using controllable platforms, typically necessitating ultracold temperatures to maintain the quantum coherence. Superradiance lattices (SLs) have been harnessed to simulate coherent topological physics at room temperature, but the thermal motion of atoms remains a notable challenge in accurately measuring the physical quantities. To overcome this obstacle, we implement a velocity scanning tomography technique to discern the responses of atoms with different velocities, allowing cold-atom spectroscopic resolution within room-temperature SLs. By comparing absorption spectra with and without atoms moving at specific velocities, we can derive the Wannier-Stark ladders of the SL across various effective static electric fields, their strengths being proportional to the atomic velocities. We extract the Zak phase of the SL by monitoring the ladder frequency shift as a function of the atomic velocity, effectively demonstrating the topological winding of the energy bands. Our research signifies the feasibility of room-temperature quantum simulation and facilitates their applications in quantum information processing.

SU(N) magnetism with ultracold molecules

Abstract Quantum systems with SU(N) symmetry are paradigmatic settings for quantum many-body physics. They have been studied for the insights they provide into complex materials and their ability to stabilize exotic ground states. Ultracold alkaline-earth atoms were predicted to exhibit SU(N) symmetry for N = 2I +1 = 1, 2, . . . , 10, where I is the nuclear spin. Subsequent experiments have revealed rich many-body physics. However, alkaline-earth atoms realize this symmetry only for fermions with repulsive interactions. In this paper, we predict that ultracold molecules shielded from destructive collisions with static electric fields or microwaves exhibit SU(N) symmetry, which holds because deviations of the s-wave scattering length from the spin-free values are only about 3% for CaF with static-field shielding and are estimated to be even smaller for bialkali molecules. They open the door to N as large as 32 for bosons and 36 for fermions. They offer important features unachievable with atoms, including bosonic systems and attractive interactions.

Optimizing dielectric constants of epoxy composites infused with Palmyra palm and nano fillers using response surface methodology

The study focuses on Palm fruit Fibers (PF) extracted from the palmyra palm tree (Borassus flabellifer) treated with 5 % alkali solution (NaOH). This treatment eliminates impurities from the fiber surface and enhances bonding with the epoxy matrix. Epoxy composites, reinforced with PF/nanofillers (h-BN, Al2O3 and MWCNT), are developed by using the box Behnken method (BBD) and dielectric constant is investigated under high-frequency and electrical field conditions. Dielectric constants (K) of the nanocomposites are determined using various capacitor terminal setups. The electrical properties of the Epoxy/PF nanocomposite, based on fiber content (Wt. %), fiber mesh size (μm) and nanofillers are evaluated using response surface methodology (RSM). Models, predicting nanocomposite dielectric constants, are established, fitting experimental values closely with R2 nearing 1 and residuals adhering to a normal probability plot. The optimized dielectric constant of 1.05 is achieved at 3 wt% palm fiber content, 150 μm fiber mesh size and 1 wt% nano h-BN.

Mechanism of β-MnO2 particle for the peroxymonosulfate activation under electric field: the promoting effect of carbamazepine on Mn(III) and reactive oxygen species production

In this study, β-MnO2 was introduced into electro-peroxymonosulfate process as particle electrodes (E/PMS/β-MnO2) to reveal the pathway of reactive manganese species (RMnS) and its promoting effect on reactive oxygen species (ROS) production. A significant synergistic was observed in the E/PMS/β-MnO2 process, the reaction constant was 3 times higher than that in the E/PMS process. The mechanism experiments revealed the generation pathway of Mn(III)aq during the E/PMS/β-MnO2 process. The pyrophosphate complex experiments and electrochemical analysis demonstrated that Mn(III)aq was dominantly generated through the electron transfer between carbamazepine (CBZ) and Mn(IV) under electric field conditions, rather than the reduction process in the cathode area. Furthermore, quenching experiments and competition kinetics method demonstrated the production of Mn(III)aq has the potential to enhance the formation of reactive oxygen species (ROS), especially •OH and SO4•−. In addition, Mn(V)aq and Mn(VI)aq was proved unable to be produced during the E/PMS/β-MnO2 process. Different from other similar electrochemical studies, 1O2 was mainly generated by the reaction betweenO2•− and •OH in this research. It was observed that the inclusion of Cl— facilitated the removal of CBZ, whereas the addition of humic acid (HA) had negligible impact on CBZ removal during the E/PMS/β-MnO2 process. At last, the results of various water matrices effects and toxicology analysis showed that the E/PMS/β-MnO2 process has satisfactory performance in practical application. This study could provide new insights for electro-persulfate treatment processes.

Microscopic view on the polarization-resolved S-SHG intensity of the vapor/liquid interface of pure water.

Second harmonic generation (SHG) is a nonlinear optical phenomenon where two photons at the frequency ω combine to form a single photon at the second-harmonic frequency 2ω. Since that second-order process is very weak in bulk isotropic media, optical SHG responses of interfaces provide a powerful and versatile technique to probe the molecular structure and dynamics of liquid interfaces. Both local dipole contributions and non-local quadrupole contributions can be interesting to investigate different properties of the interface, such as the molecular orientation or the charge density. However, a major difficulty is to comprehend the link between the S-SHG intensity and molecular details. This article reports a numerical approach to model the polarization-resolved SHG intensities of a model vapor/liquid interface of pure water. The influence of the interfacial local environment on the hyperpolarizability is taken into account using quantum mechanical/molecular mechanics calculations. The numerical predictions are in very good agreement with experiments. We detail the hypotheses made during the modeling steps and discuss the impact of various factors on the modeled SHG intensities, including the description of the exciting field in the interfacial layer, the effect of neighboring molecules on the second-harmonic polarization, and the presence of an additional static electric field at the interface.

Influence of constant and alternating electric fields on the deformation and destruction of a liquid droplet

Examining the impact of electromagnetic field, which provides thrust in contemporary rocket engines, is turning into a significant issue. Its resolution is required to guarantee the safety of space flight by enhancing engine performance and lowering fuel consumption. Spacecraft propulsion is achieved by low-thrust rocket engines. The principle of operation for ion colloid engines is the electrostatic acceleration of charged droplets. A static electric field accelerates charged liquid droplets created by electrospraying them in a low-thrust colloid engine. A promising technology in many industries is the active control of droplet motion and deformation with electric field. An electromagnetic field impact on droplet deformation and destruction in a viscous liquid is examined. The effect of electromagnetic field on individual droplets and emulsions is examined in terms of their physical mechanisms. Constant and alternating electric field effects on liquid droplet are represented numerically. The effects of droplet electric capillary number and viscosity ratio on droplet unsteady deformations is explored. The parameters that correspond to the droplet destruction are found. The results obtained have potential applications in enhancing the efficiency of current industrial electric dehydrators and in advancing the development of new electromagnetic field-based demulsification technologies.

Static and dynamic open loop control of selective laser flash sintering conducted with direct current electric fields

AbstractSelective laser flash sintering utilizes a scanning laser as a heat source to locally initiate flash sintering in the regions scanned by the laser. A key challenge towards utilizing this process for additive manufacturing (AM) is the induced electrical current that arises during flash sintering. With traditional scan patterns conducted with static electric fields, electrical and thermal runaway and associated thermal shock cracking occur. In this study, several open‐loop control strategies with static and dynamic applied electric fields were utilized to control peak currents. These strategies were shown to be effective in reducing peak currents to below 1.0 µA and reducing the severity of, but not completely eliminating cracking. Alternative strategies are suggested that could lead to complete elimination of cracks.

Widely tunable reflection by a hybrid ion-doped positive-negative chiral nematic liquid crystal under an electric field.

In this study, a new methodology, in which the cation and chiral agent are doped in positive and negative nematic liquid crystal mixture to form cation-doped positive-negative chiral nematic liquid crystals (PN-CNLCs), is proposed. These PN-CNLCs are capable of achieving a wide wavelength tuning range close to 90 nm under the action of a high-frequency electric field. The dielectric interaction between these two liquid crystals with different dielectric anisotropies in the electric field allows for the effective change of the pitch of the CLCs. We discovered the tilting of the pitch in the PN-CNLCs by a series of well-designed validation experiments. The experimental results prove the symmetrical helix is formed along the alignment direction in PN-CNLCs. Furthermore, the experiments demonstrated that an increase in voltage does not directly affect the pitch, but it increases the tilt angle of the helix axis with respect to the normal of the LC cell. This study offers, to our knowledge, a novel perspective on the tuning performance of CLCs under electric field conditions, by integrating the properties of positive and negative liquid crystals. This finding not only contributes to the understanding of the electric field response mechanism of CLCs but also provides new avenues for the application of CLCs in fields such as wavelength tuning.