Electric Field Energy Density Research Articles

High energy storage properties of NaNbO3-based relaxor antiferroelectric ceramics for capacitor applications

A new generation of environmentally benign NaNbO3 (NN)-based antiferroelectric ceramics have gained great interest in energy storage capacitors. Nevertheless, the low breakdown electric field (Eb) and high energy density loss in pure NN ceramic restrict the improvement of the energy storage property. A combined optimization strategy was implemented in this work, and ceramics of (1-x)NaNbO3-x(Bi1/2Li1/2)HfO3 (abbreviated as NN-xBLH, x = 0.00–0.18) were developed. BLH was initially introduced to stablize the AFE state and achieve the relaxor enhancement effect. Then, a viscous polymer rolling process (VPRP) was empolyed to obtain highly dense and ultra-thin ceramic disks with a thickness of ∼100 μm. Ultimately, at 560 kV/cm, a high Wrec of 7.1 J/cm3 and η of 85.9% were concurrently attained in the NN-0.18BLH ceramic. Meanwhile, the NN-0.18BLH ceramic displays improved thermal stability (25–120 °C). All of these findings show that the NN-0.18BLH ceramic is anticipated to be utilized in future energy storage applications.

Mechanisms responsible for the onset of selective laser flash sintering of 8‐YSZ

AbstractSelective laser flash sintering (SLFS) is a variation of flash sintering where the only external heat source is a scanning laser. The scanning laser locally heats a region of the sample between two electrodes, initiating measured current flow at a threshold electric field and laser energy density. This study focuses on understanding how charge transport occurs during stage I SLFS in 8 mol% yttria stabilized zirconia. Two potential charge transport mechanisms are considered: (1) a continuous current moving along a hot line between electrodes and (2) charge transported in a discrete bundle within a hot spot, localized to the area under the laser beam. Two laser scan patterns are employed to experimentally determine how charge is transported during stage I SLFS. Numerical modeling is used to estimate the temperatures at which SLFS initiates, which allows the calculation of charge carrier densities and mobilities relevant for the onset of SLFS. Results demonstrate that both a discrete bundle of charges and continuous flow of charge carriers contribute to the current at the onset of SLFS.

Time-dependent theory of optical electro- and magnetostriction

Electrostriction, the deformation of dielectric materials under the influence of an electric field, is of continuous interest in optics. The classic experiment by Hakim and Higham [Proc. Phys. Soc. 80, 190 (1962)] for a stationary field supports a different formula of the electrostrictive force density than the recent experiment by Astrath et al. [Light Sci. Appl. 11, 103 (2022)] for an optical field. In this work, we study the origin of this difference by developing a time-dependent covariant theory of optical force densities in photonic materials. When a light pulse propagates in a bulk dielectric, the field-induced force density consists of two parts: (i) The optical wave momentum force density ${\mathbf{f}}_{\mathrm{owm}}$ carries the wave momentum of light and drives forward a mass density wave of the covariant coupled field-material state of light. (ii) The optostrictive force density ${\mathbf{f}}_{\mathrm{ost}}$ arises from the atomic density dependence of the electric and magnetic field energy densities. It represents an optical Lorentz-force-law-based generalization of the electro- and magnetostrictive force densities well known for static electromagnetic fields and derived from the principle of virtual work. Since the work done by ${\mathbf{f}}_{\mathrm{ost}}$ is not equal to the change of the field energy density during the contraction of the material, we have to describe this difference with optostriction-related dissipation terms to fulfill the energy conservation. The detailed physical model of the dissipation is left for further work. The optostrictive force density can be understood in terms of field-induced pair interactions inside the material. Because of the related action and reaction effects, this force density cannot contribute to the net momentum transfer of the optical field. The theory is used to simulate the propagation of a Gaussian light pulse through a dielectric material. We calculate the electric and magnetic fields of the Gaussian light pulse from Maxwell's equations and simultaneously solve Newton's equation of motion of atoms to find how the velocity and displacement fields of atoms develop as a function of time under the influence of the field-induced force density.

Multipoint Observations of Dispersive Scale Alfvénic Field‐Line Resonances Associated With Substorm Auroral Beads

AbstractWe present a case study of the field‐aligned current (FAC) systems that transpire within the high‐altitude auroral acceleration region of an “auroral bead” initiated double oval substorm observed on 23 February 2001 by the Cluster fleet. Conjunctive Cluster measurements and auroral images from IMAGE reveal that auroral bead current system formation and evolution is a multi‐scale, injection‐mediated process. The FACs at large scales vary on substorm evolution time scales (∼minutes) in response to the injection and evolution of hotter denser magnetospheric plasma. Embedded within the large‐scale FACs are intense short‐scale (≲ few 10s of km) currents comprising dispersive scale Alfvén wave (DAW) fluctuations. The DAWs are a complex mixture of ingoing and reflected components that regularly interfere to form a broad spectrum of kinetic (dispersive) scale Alfvénic field‐line resonances (KFLRs). The Alfvénic currents appear as a nested series of upward and downward FAC densities with amplitudes reaching a few 100 nA/m2. Energized field‐aligned or counterstreaming electrons near keV energies and below are observed with parallel skews that vary in concert with variations in the DAW current sense. Positive correlations between DAW electric field energy densities and the energies of energized H+, He+, and O+ outflow are observed, indicative of ion energization within the DAW fields. Due to their L‐shell location (L ∼5.8–7.0) and associations with injections, the KFLRs are interpreted as the high‐altitude auroral zone analog of KFLRs observed in the equatorial inner magnetosphere.

The interaction between silica flat substrate and functional group-modified nanoparticles.

Inspired by nature, the research of functionalized nanoparticles and nanodevices has been in-depth developed in recent years. In this paper, we theoretically studied the interaction between functional polyelectrolyte brush layer-modified nanoparticles and a silica flat substrate. Based on the Poisson-Nernst-Planck equations, the mathematical model is established. The changes of the volume charge density and electric field energy density when the nanoparticle interacts with the silica flat substrate under multi-ions regulation were investigated. The results show that when there is a strong interaction between the silica flat substrate and nanoparticles, such as the distances between the nanoparticle and silica flat substrate, which are 2 or 5nm, the isoelectric point shift under the influence of silica flat substrate and the total charge density in the brush layer is jointly controlled by the cations in the solution and the volume charge density of the brush layer. With the increase of the distances between the nanoparticle and silica flat substrate, the regulation of the volume charge density of the brush layer dominates. These results will provide guidance for the movement mechanism of functionalized nanoparticles in silica nanochannels.

High efficiency of broadband transmissive metasurface terahertz polarization converter

Terahertz wave is between microwave and infrared bands in the electromagnetic spectrum with the frequency range from 0.1 THz to 10 THz. Controlling and processing of the polarization state in terahertz wave are the focus due to its great influence on the characteristics. In this paper, a transmissive metasurface terahertz polarization converter is designed in 3D structure with an upper surface of ruler-like rectangular, an intermediate dielectric layer and a lower surface of metal grid wires. Numerical simulations of the converter show that the polarization conversion ratio (PCR) is above 99.9% at 0.288 THz–1.6 THz, the polarization rotation angle (PRA) is close to 90° at 0.06 THz–1.4 THz, and the ellipticity angle (EA) is close to 0° at 0.531 THz–1.49 THz. The origin of the efficient polarization conversion is explained by analyzing the electric field intensity, magnetic field intensity, surface current, electric field energy density, and magnetic field energy density distributions of the converter at 1.19 THz and 0.87 THz, which are consistent with the energy transmittance and transmittance coefficient. In addition, the effects of different thickness and material of intermediate layer, thickness of upper surface material, polarized wave incidence angle, and metasurface materials on the performance of the polarization converter are discussed, and how they affect the conversion performance of the polarization converter are also explained. Our results provide a strong theoretical basis and technical support to develop high performance transmission-type terahertz polarization converters, and play an important role to promote the development of terahertz science and technology.

Excellent energy storage and hardness performance of Sr0.7Bi0.2TiO3 ceramics fabricated by solution combustion-synthesized nanopowders

Relaxor ferroelectric Sr0.7Bi0.2TiO3 ceramics were prepared by two types of powders synthesized by solid-state reaction (SSR) and solution combustion synthesis (SCS). The effects of the synthesis techniques of precursor powders on the microstructure, dielectric and energy storage performance of the ceramics were investigated. Compared with the SSR-derived samples, the SCS-derived ceramics show purer phase, more refined grain size, more uniform and denser morphology. Consequently, higher insulating resistivity and activation energy are obtained, thus inhibiting the carrier migration and improving the breakdown field. For the 0.1 mm-thickness ceramics via using SCS nanopowders in place of SSR powders, the critical electric field and recoverable energy density are enhanced from 320 kV/cm and 2.60 J/cm3 to 380 kV/cm and 3.60 J/cm3, respectively. Particularly, a high recoverable energy density of 5.21 J/cm3 with a high efficiency of 91.55% at 543 kV/cm is realized in the 0.04 mm-thickness SCS-derived ceramics. Meanwhile, the Vickers hardness of ceramics is promoted from ∼ 7.15 GPa to ∼ 7.80 GPa by using SSR instead of SCS method. This work suggests that SCS is an effective method to obtain precursor powders for sintering the dielectric ceramics with excellent energy storage and hardness performance.

High enhancement of near-field radiative heat transfer between nanoparticles via the surface modes of the dielectric thin film

We study the radiative heat transfer between two nanoparticles placed above the thin film under the framework of the dipole approximation and reflection Green's function. We show a high enhancement of heat transfer between particles, owing to the antisymmetric and symmetric surface modes excited at a wide band. The presence of the SiC thin film produces four orders of magnitude of amplification for the case of SiC particles which support the localized surface phonon polaritons (SPhPs). Enhancement is caused by the intense surface modes excited at the particle resonance and further proved through spectral analysis. The thin film can also provide an enhancement at a considerable distance, different from the huge inhibitory effect exhibited in the semi-infinite slab case. We address the role of the interparticle distance in the enhancement of heat flux by analyzing the SPhPs propagation length above the thin film. Finally, we show the thin film can intensify the coupling between SiC and doped Si particles, bringing out a high enhancement of radiative heat transfer between two particles with dissimilar materials. This enhancement is also attributed to the strong antisymmetric modes that amplify the emitted electric field energy density in the half-space from the SiC particle. This type of strong amplification can play an essential role in thermal tuning in the nanoparticle system.

Rotation-induced significant modulation of near-field radiative heat transfer between hyperbolic nanoparticles

Modulation of near-field radiative heat transfer (NFRHT) with rotated anisotropic hBN and α-MoO3 nanoparticles (NPs) are investigated. The spectral heat power, total heat power and electric field energy density are calculated at different particle orientations. Numerical results show that the modulation factor of the α-MoO3 NPs could be up to ∼12,000 with particle radius of 40 nm at a gap distance of 200 nm, which is ∼ 10-fold larger than the state of the art. Excitation of localized hyperbolic phonon polaritons (LHPPs) in different particle orientations allow for the excellent modulation. The modulation factor of the hBN NPs is 5.9 due to the insensitivity of the LHPPs in the type II hyperbolic band to the particle orientations. This work might be helpful in designing a high performance near-field radiative modulator in particle systems.

Photonic crystals with split ring unit cells for subwavelength light confinement.

Here we report a photonic crystal with a split ring unit cell shape that demonstrates an order of magnitude larger peak electric field energy density compared with that of a traditional photonic crystal. Split ring photonic crystals possess several subwavelength tuning parameters, including split ring rotation angle and split width, which can be leveraged to modify light confinement for specific applications. Modifying the split ring's parameters allows for tuning of the peak electric field energy density in the split by over one order of magnitude and tuning of the air band edge wavelength by nearly 10 nm in the near infrared region. Designed to have highly focused optical energy in an accessible subwavelength gap, the split ring photonic crystal is well suited for applications including optical biosensing, optical trapping, and enhanced emission from a quantum dot or other nanoscale emitter that could be incorporated in the split.

Density of electric field energy around two surface-charged spheres surrounded by electrolyte II. The smaller sphere is inside the larger one

<abstract> <p>Based on the generalized version of Newton's Shell Theorem <xref ref-type="bibr" rid="b7">[7]</xref> the electric field energy density, <italic>u<sub>F</sub></italic> around two surface-charged spheres surrounded by electrolyte where the smaller sphere is inside the larger one is analytically calculated. According to the calculations when the surfaces of the spheres are farther from each other than four times of the Debye length the field energy density around and inside the smaller sphere is basically independent from the presence of the larger sphere. The electric field energy density is maximal when the smaller sphere touches the inner surface of the larger sphere and the maximum of <italic>u<sub>F</sub></italic> is located at the touching point on the outer surface of the larger sphere.</p> </abstract>

Density of electric field energy around two surface-charged spheres surrounded by electrolyte I. The spheres are separated from each other

<abstract> <p>Based on the generalized version of Newton's Shell Theorem the electric field energy density, <italic>u<sub>F</sub></italic> around two separated surface-charged spheres surrounded by electrolyte is calculated. According to the calculations when the surfaces of the charged spheres are farther from each other than four times of the Debye length the field energy density around one of the charged sphere is basically independent from the presence of the other sphere. In this case at low electrolyte ion concentration <italic>u<sub>F</sub></italic> = 0 within the spheres and outside the sphere <italic>u<sub>F</sub></italic> decreases with increasing distance from the surface of the sphere, while at high electrolyte ion concentration <italic>u<sub>F</sub></italic> fast decreases with increasing inner and outer distance from the surface of the sphere. When the charged sheres are close to each other their electric interaction affects the field energy density especially where the surfaces of the spheres are close to each other. Also to model electrophoresis analytical equations are derived for the interaction energy between and the density of electric field energy around a charged flat surface and a charged sphere surrounded by neutral electrolyte.</p> </abstract>

New physical parameterizations of monopole solutions in five-dimensional general relativity and the role of negative scalar field energy in vacuum solutions

Novel parameterizations are presented for monopole solutions to the static, spherically-symmetric vacuum field equations of five-dimensional general relativity. First proposed by Kaluza, 5D general relativity unites gravity and classical electromagnetism with a scalar field. These monopoles correspond to bodies carrying mass, electric charge, and scalar charge. The new parameterizations provide physical insight into the nature of electric charge and scalar field energy. The Reissner-Nordström limit is compared with alternate physical interpretations of the solution parameters. The new parameterizations explore the role of scalar field energy and the relation of electric charge to scalar charge. The Kaluza vacuum equations imply the scalar field energy density is the negative of the electric field energy density for all known solutions, so the total electric and scalar field energy of the monopole is zero. The vanishing of the total electric and scalar field energy density for vacuum solutions seems to imply the scalar field can be understood as a negative-energy foundation on which the electric field is built.

Excellent energy storage performance in La and Ta co-doped AgNbO3 antiferroelectric ceramics

Lead-free dielectric materials with high breakdown electric field strength and energy density are required for pulsed power devices with high level of integration. This work describes: (Ag0.94La0.02)(Nb1-xTax)O3 lead-free antiferroelectric ceramics, which were prepared by rolling process. Following composition engineering, an outstanding energy density of 6.9 J cm-3 at electric field of 490 kV cm-1 was achieved, coupled with remarkable frequency stability (<1% over 1-100 Hz under E = 420 kV cm-1) for (Ag0.94La0.02)(Nb0.80Ta0.20)O3 ceramics. Moreover, it also shows excellent charge-discharge properties (discharge density = 1429 A cm-2, power density = 144 MW cm-3). The addition of La3+ and Ta5+ induced a disordered local structure, which gradually decreased the phase transition temperature of M2-M3 to room temperature, reflecting the enhanced antiferroelectricity. All advantageous properties observed for the La and Ta co-doped AgNbO3 ceramics highlight their significant potential for energy storage applications.

Electric-field-based Poisson-Boltzmann theory: Treating mobile charge as polarization.

Mobile charge in an electrolytic solution can in principle be represented as the divergence of ionic polarization. After adding explicit solvent polarization a finite volume of an electrolyte can then be treated as a composite nonuniform dielectric body. Writing the electrostatic interactions as an integral over electric-field energy density we show that the Poisson-Boltzmann functional in this formulation is convex and can be used to derive the equilibrium equations for electric potential and ion concentration by a variational procedure developed by Ericksen for dielectric continua [J.L. Ericksen, Arch. Rational Mech. Anal. 183, 299 (2007)AVRMAW0003-952710.1007/s00205-006-0042-4]. The Maxwell field equations are enforced by extending the set of variational parameters by a vector potential representing the dielectric displacement which is fully transverse in a dielectric system without embedded external charge. The electric-field energy density in this representation is a function of the vector potential and the sum of ionic and solvent polarization making the mutual screening explicit. Transverse polarization is accounted for by construction, lifting the restriction to longitudinal polarization inherent in the electrostatic potential based formulation of Poisson-Boltzmann mean field theory.

The quantitative measurement method for the radiation energy of the acoustoelectric converted wave field of building electricity

In order to provide the basis for the quantitative measurement of wave field radiation energy formed by building electricity and promote the development of construction industry, the quantitative measurement method for the radiation energy of the acoustoelectric converted wave field of building electricity is studied. Based on the multipole sound field of any azimuth order, the displacement potential of the sound field generated by the sound source is obtained, and the sound source model of the building electricity is established. According to the Pride theory, the acoustoelectric coupling equations are derived by using the established sound source model, and the acoustoelectric conversion of the building electricity is carried out. In this paper, the energy of Stoneley wave induced electric field in uniform medium is obtained according to the first coupling relation of acoustoelectric. The concept of electric energy density of low-frequency acoustoelectric polarization electric field is put forward, and the quantitative measurement of radiation energy of wave field is realized by deducing the specific expression. In the process of low-frequency acoustically induced polarization, the relationship between the density of electric energy and the frequency of sound wave and the permeability is obtained by simulation experiment. The results show that the energy distribution characteristics of buildings are similar when the distance between buildings is small, and the permeability and the density of electric energy are increasing.

Modelling the effect of nanofiller’s shape and alignment on the dielectric strength and permittivity of polyethylene nanocomposite insulation

Solid insulation defects are a major cause of power failures. Incorporation of micro and nanoparticles in the solid insulation materials has proven its advantage. It has been reported that nanocomposites are far superior in terms of insulation to microcomposites because of larger interphase area between nanofillers and polymer in nanocomposites. In addition to that nature, size, shape, concentration and alignment of nanofillers affect the properties of resulting nanocomposite insulation. A lot of work has reported the effect of nanofiller’s nature, size and concentration but very little is reported on the effect of filler’s shape and alignment on the insulation and dielectric properties. In this paper nanocomposite dielectrics with nanofillers of various shapes and alignment are modelled by varying their permittivity using finite element method. To characterize the effect of various shapes and orientation electric field intensity and energy density models are computed. Simulations are performed using AC/DC module of COMSOL Multiphysics. The results revealed that shape and alignment of nanofillers are the two key factors in tuning the breakdown strength and permittivity of nanocomposite dielectrics for their applications in insulation as well as high voltage capacitors.

Charge Properties and Electric Field Energy Density of Functional Group-Modified Nanoparticle Interacting with a Flat Substrate.

Functionalized nanofluidics devices have recently emerged as a powerful platform for applications of energy conversion. Inspired by biological cells, we theoretically studied the effect of the interaction between the nanoparticle and the plate which formed the brush layer modified by functional zwitterionic polyelectrolyte (PE) on the bulk charge density of the nanoparticle brush layer, and the charge/discharge effect when the distance between the particle and the plate was changed. In this paper, The Poisson–Nernst–Planck equation system is used to build the theoretical model to study the interaction between the nanoparticle and the plate modified by the PE brush layer, considering brush layer charge regulation in the presence of multiple ionic species. The results show that the bulk charge density of the brush layer decreases with the decrease of the distance between the nanoparticle and the flat substrate when the interaction occurs between the nanoparticle and the plate. When the distance between the particle and the plate is about 2 nm, the charge density of the brush layer at the bottom of the particle is about 69% of that at the top, and the electric field energy density reaches the maximum value when the concentration of the background salt solution is 10 mm.

Revisiting magnetogenesis during inflation

We revisit the mechanism of primordial magnetogenesis during inflation by taking into account the dynamics of the stochastic noises of the electromagnetic perturbations. We obtain the associated Langevin and Fokker-Planck equations for the electromagnetic fields and solve them analytically. It is shown that while the backreactions of the electric field energy density may spoil inflation too early, but there are regions of parameter space where the usual decaying behavior of the magnetic fields are replaced by a mean-reverting process of stochastic dynamics. As a result, the magnetic fields settle down into an equilibrium state with the amplitude significantly larger than what is obtained in the absence of the stochastic noises. We show that magnetic fields with present time amplitude $\sim 10^{-13}$ Gauss and coherent length ${\rm Mpc}$ can be generated while the backreactions of the electric field perturbations are under control.

Phase Transition Photodetection in Charge Density Wave Tantalum Disulfide.

The charge density wave (CDW) phase is a macroscopic quantum state with periodic charge density modulation accompanied by periodic lattice distortion in low-dimensional metals. External fields, such as an electric field and optical excitation, can trigger the transitions among different CDW states, leaving an under-explored mechanism and attracting great interest toward optoelectronic applications. Here, we explore a photoinduced phase transition in 1T-TaS2 under an electrical field. By analyzing the phase transition probability, we obtained a linear dependence of the phase transition barrier on the electric field and laser energy density. Additionally, the threshold laser energy for the phase transition decreases linearly with an increasing applied electrical field. Finally, picojoule photodetection was realized in the visible and near-infrared ranges near the CDW transition edge. Our work will promote the understanding of the CDW phase transition mechanism as well as open pathways for optoelectronic applications.