Role Of Electric Field Research Articles

The role of electric field in enhancing separation of gas molecules (H2S, CO2, H2O) on VIB modified g-C3N4 (0 0 1)

In this study, the first-principles calculations were performed to investigate the adsorption behaviors of gas molecules H2S, CO2 and H2O on Cr, Mo and W modified g-C3N4 (0 0 1) surface. The results show that H2S, CO2 and H2O are physically adsorbed on the pristine g-C3N4, while the adsorption becomes chemisorbed due to the introduction of transition metals which significantly improve the interfacial electron transfer and narrow the band gap of g-C3N4 (0 0 1). Furthermore, it is found that the adsorption behaviors can be greatly influenced by the applied electric field. The adsorption energy is generally arranged in the order of Eads(H2S) > Eads(H2O) > Eads(CO2), and W/g-C3N4 (0 0 1) exhibits the best separation capability. The study could provide a versatile approach to selectively capture and separate the mixed gases in the catalytic reactions by controlling the applied intensity of electric field.

Partial electron localization in a finite-size superlattice placed in an electric field

AbstractPartial electron localization in a finite-size superlattice placed in an electric field is considered. The role of electric field in forming of quasilocalized states is investigated. A quantitative criterion for the degree of partial localization is suggested based on analysis of maximal probability density of finding an electron at a given point. It is found that with increase in the electric field the degree of localization does not increase monotonically. Furthermore, the localization is affected stronger by the amplitude of superlattice potential than by the electric field.

Role of electric fields in the MHD evolution of the kink instability

The discovery (Bonfiglio et al 2005 Phys. Rev. Lett. 94 145001) of electrostatic fields playing a crucial role in establishing plasma motion in the flux conversion and dynamo processes in reversed field pinches is revisited. In order to further elucidate the role of the electrostatic fields, a flux rope configuration susceptible to the kink instability is numerically studied with an MHD code. Simulated nonlinear evolution of the kink instability is found to confirm the crucial role of the electrostatic fields. A new insight is gained on the special function of the electrostatic fields: they lead the plasma towards the reconnection site at the mode resonant surface. Without this step the plasma column could not relax to its nonlinear state, since no other agent is present to perform this role. While the inductive field generated directly by the kink instability is the dominant flow driver, the electrostatic field is found to allow the motion in the vicinity of the reconnection region.

Numerical Investigations of Electro-Thermal Convection in Dielectric Nanofluid Layer

The numerical investigations of a dielectric nanofluid under the simultaneous action of an Alternating Current electric field and a uniform adverse temperature gradient has been studied using the linear theory and normal mode analysis. The eigen-value problem is solved analytically and numerically using the Galerkin technique. Effect of various non-dimensional parameters on thermal Rayleigh number Ra for the stationary convection has been determined. The boundaries are considered to be stress-free. Thermal Rayleigh number has been computed for various values of electric Rayleigh number for the onset of instability using the software-MATHEMATICA Version 5.2. Numerical results are presented graphically. The thermal Rayleigh number decreases linearly as the concentration Rayleigh number Rn increases. Moreover for stability motion, the value of thermal Rayleigh number Ra occurs only for negative values of Rea and it is positive. The value of critical thermal Rayleigh number Ra decreases with decreasing the value of Rea. It is observed that the role of electric field is not of much sinificance the convection in the fluid layer in case of stability motions. In case of stability, the thermal Rayleigh number is independent of Prandtl number and hence Prandtl number has no role to play.

Electric Field-Controlled Crystallizing CaCO3 Nanostructures from Solution.

The role of electric field is investigated in determining the structure, morphology, and crystallographic characteristics of CaCO3 nanostructures crystallized from solution. It is found that the lattice structure and crystalline morphology of CaCO3 can be tailed by the electric field applied to the solution during its crystallization. The calcite structure with cubic-like morphology can be obtained generally without electric field, and the vaterite structure with the morphology of nanorod is formed under the high electric field. The vaterite nanorods can be piled up to the petaliform layers. Both the nanorod and the petaliform layer can have mesocrystal structures which are piled up by much fine units of the rods with the size of several nanometers. Beautiful rose-like nanoflowers can be self-arranged by the petaliform layers. These structures can have potential application as carrier for medicine to involve into metabolism of living cell.

Conductance switching behavior of GeTe/Sb2Te3 superlattice upon hot-electron injection: a scanning probe microscopy study

ABSTRACTTopological (GeTe)/(Sb2Te3) superlattices (SL) are of practical interest for memory applications because of different mechanism of electric conductance switching in the crystalline phase. In the work, electrical switching behavior of individual SL grains was examined employing a multimode scanning probe microscope (MSPM) in a lithography mode at room temperature. Using programmed bias voltage with different amplitude and pulse duration, we observed the position-dependent variations of the switching voltage and the current injection delay for [(GeTe)2 (Sb2Te3)]4 SLs on Si(100). The results shed a light on the role of electric field and hot-electron injection on the SL conductance switching.

Role of electric field and electrode material on the improvement of the ageing effects in hydrogenated amorphous silicon solar cells

The effects of prolonged exposure to reverse bias DC electric fields and illumination as a function of temperature in hydrogenated amorphous Si (a-Si:H) photovoltaic p–i–n cells have been investigated. These are strongly affected by the well known Staebler–Wronski effect, occurring during light soaking of a-Si:H photovoltaic cells. In this work we show that the application of a reverse bias stress in presence of illumination not only slows down the solar cell ageing kinetics but even produces an improvement of the cells parameters as a function of stress time. We discuss the effect of temperature, electric field intensity and illumination level. We also show that different types of bottom contact over which the a-Si:H is grown by PECVD have a strong influence on the recovery-improvement kinetics: SnO:F (FTO) transparent conductive oxide (TCO) and molybdenum bottom contacts to the p-type a-Si:H layer are here compared. Finally, we demonstrate that an analogous improvement (reduction) of sheet resistance is observed in single thin films of doped a-Si:H deposited on SiO2 under the application of high intensity electric fields.

Molecular dynamics simulations of 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide clusters and nanodrops.

Atomistic molecular dynamics simulations of small clusters and nanodroplets of the ionic liquid 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide [EMIM-Tf2N] subject to an external electric field were performed. A 125-ion-pair droplet was found to be nearly spherical with an isotropic distribution of cations and anions under vacuum conditions. The droplet was subjected to external electric fields of varying strength, and ion emission events were observed. The initially spherical droplet is elongated along the electric field axis, resulting in nonspherical behavior and increased net dipole values after the application of strong electric fields. The critical electric field required for ion field emission was determined to be 0.985 V/nm, in agreement with the experimental value of 1.0 V/nm. Excellent agreement is found in the prediction of ionic emission products for a neutral 125-ion-pair droplet of the ionic liquid at an electric field strength of 1.2 V/nm when compared to the results of two independent experiments. Small ionic liquid clusters were investigated with respect to their thermal stabilities and were found to be thermally stable well above room temperature. The role of electric fields in the dissociation of small charged ion clusters was also investigated.

Controlled synthesis of amphiphilic graft copolymer for superhydrophobic electrospun fibres with effective surface fluorine enrichment: the role of electric field and solvent

Ultra-high surface fluorine enriched superhydrophobic fibrous films have been realized by electrospinning amphiphilic graft PMMA-r-PHPA-g-PDFMA, which is ascribed to the electric field and solvent.

Densification of La0.6Sr0.4Co0.2Fe0.8O3 ceramic by flash sintering at temperature less than 100 °C

The effect of DC electric field on sintering and electrical conductivity of La0.6Sr0.4Co0.2Fe0.8O3 (LSCF), considered as highly promising cathode material for solid oxide fuel cell, is investigated in the present work. It is shown that sintering can be carried out at (furnace) temperature <100 °C under electric field ranging from 7.5 to 12.5 V/cm; such extraordinary effect is associated with the high electrical conductivity of LSCF through a peculiar mechanism. Microstructural analysis suggests similar morphology and enhanced grain growth compared to traditional sintering; with the proper choice of processing parameters (electric field and current density) during flash sintering, homogeneous porous microstructure for cathodic application can be obtained in very short time. The role of electric field and specimen temperature in flash sintering is analyzed for the understanding of observed outstanding event. The conductivity is found to be a coupled response of electric field and temperature; 2–3 V/cm and 15–25 °C are sufficient for dense LSCF specimen to stimulate the electric field effect on sintering. Electric field controls the conductivity in the same way as temperature does suggesting that under flash effect conductivity is increased by usual mechanism. On the same basis, flash sintering is proposed to be accelerated by the “polaron hopping” phenomenon.

Why charged molecules move across a temperature gradient: the role of electric fields.

Methods to move solvated molecules are rare. Apart from electric fields, only thermal gradients are effective enough to move molecules inside a fluid. This effect is termed thermophoresis, and the underlying mechanisms are still poorly understood. Nevertheless, it is successfully used to quantify biomolecule binding in complex liquids. Here we show experiments that reveal that thermophoresis in water is dominated by two electric fields, both established by the salt ions of the solution. A local field around the molecule drives molecules along an energy gradient, whereas a global field moves the molecules by a combined thermoelectrophoresis mechanism known as the Seebeck effect. Both mechanisms combined predict the thermophoresis of DNA and RNA polymers for a wide range of experimental parameters. For example, we correctly predict a complex, nonlinear size transition, a salt-species-dependent offset, a maximum of thermophoresis over temperature, and the dependence of thermophoresis on the molecule concentration.

The role of electric fields in sporadic E layer formation over low latitudes under quiet and magnetic storm conditions

Sporadic E layers are formed dominantly by wind shear mechanism, but their formation and dynamics are driven also by ionospheric electric fields. Investigation of low latitude sporadic E layers under quiet conditions shows that Es layer formation during post sunset hours can be disrupted or enhanced depending upon the vertical structure of the vertical electric field arising from sunset electrodynamic processes. During magnetic storms the formation and disruption of these layers are also strongly controlled by vertical Hall electric field induced by the zonal magnetospheric electric fields that penetrates to equatorial/low latitude ionosphere. Observational results on storm time Es layer responses in the Brazilian and Indian-Asian longitudes are compared. An under-shielding prompt penetration electric field (PPEF) of westward polarity that dominate the night side ionosphere, or an over-shielding electric field also of westward polarity in the evening sector can cause formation of sporadic E layers near 100km, while an eastward polarity electric field, (under-shielding/over-shielding depending upon local time) can lead to disruption of an Es layer in progress. Ionization convergence/divergence leading to the Es layer formation/disruption is driven by a vertical Hall electric field, induced by the primary zonal PPEF, in the presence of storm associated enhanced ratio of field line integrated Hall to Pedersen conductivity (∑H)/(∑P). A downward polarity of the Hall electric field leads to Es layer formation, while an upward polarity causes the Es layer disruption. An enhancement in the ∑H/∑P ratio can result from E layer conductivity enhancement due to energetic particle precipitation peculiar to the longitude of the South Atlantic Magnetic Anomaly (SAMA) and/or from a drastic reduction in integrated Pederson conductivity in the form of reduced foF2 that is observed in all longitudes.

The role of electric field during spray deposition on fluorine doped tin oxide film

The fluorine doped tin oxide film has been deposited on 10cm×10cm glass substrate by using spray technique with a voltage applied between the nozzle and an annular electrode placed 2mm below the nozzle. The effect of the electric field thus created during the spray deposition on structural, optical and electrical properties of SnO2:F (FTO) film was studied. X-ray diffraction pattern revealed the presence of cassiterite structure with (200) orientation for all the FTO film. SEM study revealed the formation of smooth and uniform surface FTO film under the electric field over the entire substrate area. The electrical measurements show that the film prepared under the electric field (for an applied voltage of 2000V) had a resistivity ∼1.2×10−3Ωcm, carrier concentration ∼4.21×1020cm−3 and mobility ∼14.48cm2V−1s−1. The sprayed FTO film have the average transmission in the visible region of more than about 80%.

Role of Electric Field on Electroviscosity

The drag of liquid flow is of interest in micro/nanoscale. Electroviscosity is one of the important factors which can affect drag. By applying electric filed between liquid and surface, the surface charge density can be changed, leading to a change of electroviscosity. This paper experimentally studied the effect of applying electric field on the surface charge density, and analyzed the change of electroviscosity with applying electric field. The electroviscosity is found abated with applying electric field which will decrease the drag of liquid flow.

Role of Electric Field on Sensing Mechanism of Carbon Nanotube Based Ammonia Gas Sensor

Multi-walled carbon nanotubes (MWCNTs) grown on SiO2/Si substrate, were investigated as resistive sensors for Ammonia (NH3 gas detection upto 100 ppm concentration in the presence of dry carrier gas N2. Sensitivity and recovery time are serious problem in case of NH3 sensing and these are related to the interaction mechanism between NH3 molecules and CNTs surface and the defect level of CNT. It was found that the chemisorption of NH3 molecules on the side-wall defect sites of CNTs enhances the sensitivity along with a poor recovery. We have demonstrated by an effective approach to get improved sensitivity and fast recovery. Best sensor performance and desorption of NH3 were done by tuning the DC excitation electric field applied across the sensor electrodes. Such stimulation process provides sufficient energy to the electrons to jump through defective sites due to Poole-Frenkel effect resulting in the desorption of gas.

The Role of Electric Field and Ultrasonication in the Deposition and Alignment of Single-Walled Carbon Nanotube Networks Using Dielectrophoresis

The effects of electric field and ultrasonication on the deposition and alignment of single-walled carbon nanotubes (SWCNTs) across a 10 μm electrode gap have been studied. It was found that a frequency of ~1 MHz of the applied field yields the largest current independent of the magnitude of the voltage or the ultrasonication time of the sample. Increasing the ultrasonication time of a SWCNT solution changes the I-V characteristics of the deposited nanotubes from linear to nonlinear for all the voltages and frequencies of the applied field. Even in the absence of an electric field, SWCNTs bridged the electrode gap up to a critical sonication time which depends on the concentration of nanotubes in the solution.

Role of electrical field in quantum Hall effect of graphene

The ballistic motion of carriers of graphene in an orthogonal electromagnetic field is investigated to explain quantum Hall effect of graphene under experimental conditions. With the electrical field, all electronic eigen-states have the same expectation value of the velocity operator, or classically, all carriers move in cycloid-like curves with the same average velocity. This velocity is the origin of the Hall conductance and its magnitude is just appropriate so that the quantized Hall conductance is exactly independent of the external field. Electrical field changes each Landau level into a bundle of energies. Hall conductance plateaus occur in small fields as bundle gaps exist and are destroyed in intermediate fields as bundles overlap. As the electrical field tends to the critical point, all bundles have the same width, and bundle gaps increase to infinity rapidly. As a result, saturation of the Hall conductance may be observed. Electrical field thus demonstrates nonlinear effects on the Hall conductance.

Electric-field controlled liposome formation with embedded superparamagnetic iron oxide nanoparticles

Liposomes are one of the most promising biomaterial carriers to deliver DNA, 1 1 DNA – deoxyribonucleic acid. proteins, drugs and medicine in human bodies. However, artificially formed liposomes have to satisfy some crucial functions such as: (i) to efficiently carry drugs to targeted systems, (ii) to be biologically stable until they are removed from human body, (iii) to be biodegradable, and (iv) to be sufficiently small in size for effective drug delivery. Here, we report an efficient and novel method to simultaneously manufacture and incorporate super-paramagnetic iron-oxide nanoparticles (efficient target finder in the presence of external magnetic field) into the liposome's interior and its bilayer. In this technique, we use electric field to control the formation of liposomes and the incorporation of iron oxide nanoparticles. Our preparation procedure does not require any chemical or ultrasound treatments. Apart from that, we also provide further experimental investigations on the role of electric fields on the formation of liposomes using XPS 2 2 XPS – X-ray photoelectron spectroscopy. and the magnetic-optical microscope.

Why the water bridge does not collapse

In 2007 an interesting phenomenon was discovered [J. Phys. D 40, 6112 (2007)]: a horizontal thread of water, the so-called water bridge, hangs in a horizontal electrostatic field. A different explanation of the water bridge stability is proposed herein: the force supporting it is the surface tension of water, while the role of the electric field is to not allow the water bridge to reduce its surface energy by breaking into separate drops. It is proven that electrostatic field is not the origin of the tension holding the bridge.

Phosphate Vibrations Probe Local Electric Fields and Hydration in Biomolecules

The role of electric fields in important biological processes such as binding and catalysis has been studied almost exclusively by computational methods. Experimental measurements of the local electric field in macromolecules are possible using suitably calibrated vibrational probes. Here we demonstrate that the vibrational transitions of phosphate groups are highly sensitive to an electric field and show how that sensitivity can be quantified, allowing electric field measurements to be made in phosphate-containing biological systems without chemical modification.