Action Of Electric Field Research Articles

Electron Diffraction Study of the Temperature --- Time Dependences of Crystallization of Nano thick amorphous CuIn-=SUB=-5-=/SUB=-Te-=SUB=-8-=/SUB=- Films Sublimated Under Normal Conditions and under the Action of an External Electric Field

Kinematic electron diffraction was used to study the crystallization processes of amorphous CuIn5Te8 films obtained under normal conditions and under the influence of an external electric field with a strength of 500 V · cm-1. Isothermal curves of phase transitions are examined and the kinetic parameters of phase transformations are determined: the dimensions of crystal growth and of activation energies are established. It is shown that during the crystallization of amorphous CuIn5Te8 films, the rates of nucleation and their further growth follow the Arrhenius relations. Keywords: electronographic structural analysis, thin films, crystallization isotherms, activation energy.

Effects of Bi<sub>2</sub>Te<sub>3</sub>(111) and Al<sub>2</sub>O<sub>3</sub>(0001) substrates on electronic and topological properties of Bi(111) bilayer

The bilayer and thin films of Bi(111) have demonstrated novel topological properties. Here, we investigate the electronic structures of Bi/Bi<sub>2</sub>Te<sub>3</sub>(111) and Bi/Al<sub>2</sub>O<sub>3</sub>(0001) by combining first-principles and tight-binding approximation calculations. Our results show that the Bi(111) bilayer is a semiconductor with a gap of about 0.2 eV. Its electronic states are strongly disturbed by the interaction with Bi<sub>2</sub>Te<sub>3</sub>(111) thin films, no matter whether the substrate has a band gap or Dirac surface state. Moreover, it is hard to see Rashba-type band splittings in such systems. In contrast, it demonstrates clean and giant Rashba-type splittings as strongly hybridized with insulating Al<sub>2</sub>O<sub>3</sub>(0001), which is due to the broken inversion symmetry induced by interfacing and the strong atomic spin-orbit coupling in Bi. Our tight-binding approximation analyses further reveal that the effect of substrate Al<sub>2</sub>O<sub>3</sub>(0001) on the band structure of the Bi(111) bilayer is equivalent to the action of external electric field in a range between 0.5 and 0.6 V/Å. Moreover, we find that the strong hybridization between Bi(111) bilayer and the electronic state of the substrate Bi<sub>2</sub>Te<sub>3</sub>(111) can lead to a topological phase transition, i.e. the change from a two-dimensional topological insulator into a mediocre insulator. Our study thus provides an insight into the interface-engineering of electronic states of Bi(111) bilayer.

Исследование пьезоэлектрических свойств кристаллов бифталата рубидия методом времяразрешающей трехкристальной рентгеновской дифрактометрии

Using the method of time-resolved X-ray diffractometry in a three-crystal scheme, the lattice deformation of a rubidium biphthalate (С8H5RbO4) crystal was measured in an external electric field. Under the action of an external pulsed electric field along the [001] polar direction, the piezoelectric moduli d31, d32, and d33 were determined independently using three reflections 400, 070, and 004; the obtaind values are –32.8 ± 0.6, 12.8 ± 0.3, and 21.8 ± 1.2 pC/N, respectively. A good agreement was found between the values of the piezoelectric moduli obtained in this work and the values obtained earlier by the quasi-static method.

Strength and Microstructure of Cement Paste Under the Coupling Action of Electric Field and Nano-Carbon Black

Strength and Microstructure of Cement Paste Under the Coupling Action of Electric Field and Nano-Carbon Black

Molecular Dynamics Simulation of Cracking Process of Bisphenol F Epoxy Resin under High-Energy Particle Impact.

The current lead insulation of high-temperature superconductivity equipment is under the combined action of large temperature gradient field and strong electric field. Compared with a uniform temperature field, its electric field distortion is more serious, and it is easy to induce surface discharge to generate high-energy particles, destroy the insulation surface structure and accelerate insulation degradation. In this paper, the degradation reaction process of bisphenol F epoxy resin under the impact of high-energy particles, such as O3−, HO–, H3O+ and NO+, is calculated based on ReaxFF simulation. According to the different types of high-energy particles under different voltage polarities, the micro-degradation mechanism, pyrolysis degree and pyrolysis products of epoxy resin are analyzed. The results show that in addition to the chemical reaction of high-energy particles with epoxy resin, their kinetic energy will also destroy the molecular structure of the material, causing the cross-linked epoxy resin to pyrolyze, and the impact of positive particles has a more obvious impact on the pyrolysis of epoxy resin.

Electric field-induced phase transitions in PbZrO3 and PbHfO3 single crystals under high hydrostatic pressure

Optical and dielectric studies of lead zirconate and lead hafnate single crystals have been carried out under an extended hydrostatic pressure (up to 1.2 GPa) and high electric field action (up to ). Using the obtained results, new-type phase diagrams have been constructed on the electric field E – hydrostatic pressure p plane. A particular approximate equation of the Clausius – Clapeyron type which refers to the E, p-phase diagrams has been derived and verified.

Hierarchical Co3(PO4)2/CuI/g-CnH2n-2 S-Scheme Heterojunction for Efficient Photocatalytic Hydrogen Evolution.

Graphdiyne (GD), a new type of carbon allotrope formed by sp and sp2 hybrid carbon atoms, has attracted wide attention due to its high π-conjugation degree, special band structure, and uniformly distributed pores. In traditional synthesis methods, hexaethylbenzene was coupled on the substrate catalytic material (copper foil or foamed copper) to generate graphdiyne. In this work, CuI was used as the substrate catalytic material, and the CuI-GD composite was synthesized by cross-coupling in the pyridine solution of hexaethylbenzene. For the first time, Co3(PO4)2 was modified by the CuI-GD composite material to prepare a Co3(PO4)2/CuI-GD S-scheme heterojunction catalyst, which avoided the complicated process of removing the substrate catalytic material. Under the action of the internal electric field, electrons are induced to move quickly and directionally, and the powerful photogenerated electrons in the conduction band (CB) of GD and the holes in the valence band (VB) of CuI are retained to participate in the photocatalytic reaction. These advantages were combined with the high-energy acetylene bond in GD, which accelerated the catalytic reaction of the Co3(PO4)2/CuI-GD heterostructure. Electrochemical and fluorescence analysis showed that Co3(PO4)2/CuI-GD has faster electron and hole separation efficiency, lower hydrogen evolution overpotential, and higher carrier utilization. Therefore, Co3(PO4)2/CuI-GD exhibited good hydrogen evolution activity. This work shows that GD has broad prospects in designing high-performance photocatalyst systems.

Optimization of Extraction Processes of Water-Soluble Polysaccharides under the Electric Field Action

Wydawnictwo SIGMA-NOT wydaje czasopisma fachowe informujące swoich czytelników o najnowszych osiągnięciach naukowych i nowoczesnych rozwiązaniach technicznych w Polsce i na świecie, popularyzuje problemy techniczne oraz poszerza wiedzę i kulturę techniczną.

Electric control of dielectric droplets and films

We investigate the behavior of dielectric droplets and films placed onto a solid surface under the action of electric field of different configurations. The mesoscopic thermal multiphase lattice Boltzmann model [A. Kupershtokh, D. Medvedev, and I. Gribanov, “Thermal lattice Boltzmann method for multiphase flows,” Phys. Rev. E 98, 023308 (2018)] is used for simulation. Different configurations of electric field were produced by using dissected flat electrodes of various shapes. On a simple flat electrode, droplets elongate after the application of electric voltage. Quite different behavior was observed when the central round part of the electrode was made non-conductive. In this case, the droplet spreads under the action of a non-uniform electric field, and the breakup and the formation of an annular structure were observed. A film of dielectric liquid flowing along a solid surface made of conductive and non-conductive transversal stripes exhibits a variety of regimes. When the voltage is low, the action of electric field produces waves at the surface of liquid. At a high voltage, the liquid is pinned to the edges of stripes, and the flow may be stopped completely. The purpose of this article is precisely to attract experimenters to the study of this type of phenomena.

The deformation and breakup of a droplet under the combined influence of electric field and shear flow

A lattice Boltzmann and finite-difference hybrid method is used to simulate the droplet deformation and breakup under the combined action of shear flow and electric field. The hybrid method is first used to validate for the droplet deformation in the combined action of shear flow and electric field. It is then used to simulate the droplet deformation and breakup in two different electric systems. Results of prolate droplets show that the droplet height and deformation both increase with increasing electric capillary number (). In addition, for the breakup mode of prolate droplets, increasing makes the long axis of the droplet incline more towards the wall electrodes and droplet breaks up into more daughter droplets. Results of oblate droplets show that the droplet height decreases with increasing . However, the droplet deformation first decreases and then increases with increasing , and its minima occurs at . For the breakup mode of oblate droplets, the droplet deforms into a more oblate shape with a longer neck and finally breakup into more daughter droplets with increasing .

Influence of an external electric field on plasma parameters around an isolated dust particle

The paper presents new numerical results on the behavior of plasma parameters around an isolated chargeddust particle under the action of the external electric field. For the first time, the model takes into account thedependence of mean electron energy on the reduced electric field strength. As a result of the calculations, thedependencies of self-consistent spatial distributions of the electron and ion densities and electric potentialaround the dust particle on reduced external electric field strength were obtained. These distributions wereanalyzed through the expansion into Legendre polynomials. The processes of ion focusing wakeformation behind the dust particle were studied. The dust particle charge and the dipole moment of the“ion cloud - dust particle” are calculated for different values of the reduced electric field and ion mean freepaths. It is shown that in the determination of electron density spatial profile and the dust particle charge thedependence of electron temperature on electric field strength plays a significant role. Key words: dusty plasma, dust particle charging, dipole moment, wake, plasma polarization.

ON SOME COMPARISON BETWEEN ACCELERATED AGING OF MINERAL OIL UNDER HIGH ELECTRIC FIELD AND HIGH TEMPERATURE

During the operation of electric power transformers,their insulation often made from paper and mineral oil is subjected to thermal, mechanical, and electrical stresses. Therefore, the lifetime of power transformers can be assimilated with their insulation system lifetime. The aim of this paper is to explore and present main degradation aspects for mineral oil, subjected to the action of high electrical field and partial discharge and exposure to thermal stress exclusively, analyzing and pointing out changes in the dielectric properties. Thus, the obtained results indicate that both the thermal and, especially, the electrical stresses produce important variations of the values of the real and imaginary part of the complex relative permittivity, the electrical conductivity, and the loss factor which indicates a severe oil degradation.

Numerical simulation of dynamic characteristics of droplet in oil under a CPPM electric field

The size of droplets in oil are dynamically changes during demulsification, thereby changing the optimum demulsification electric field frequency. Thus, the constant pulsed electric field cannot meet the requirement of optimum frequency. The variable frequency pulsed electric field can cater to the change in optimum demulsification frequency, and has high demulsification ability. However, the dynamic characteristics of the droplet in oil at the variable frequency pulsed electric field are unclear. Therefore, a chaotic pulse position modulation (CPPM) electric field is considered a type of variable frequency pulsed electric field, where the pulse frequency is chaotic but pulse width and field intensity are constant. The droplet deformation dynamic model under the CPPM electric field is established by applying finite element method. The dynamic and chaotic characteristics of the droplet deformation in oil in this electric field are investigated, and the influence of pulse width and electric field intensity on droplet deformation is discussed. Results show that the deformation of droplet in oil is nonstationary vibration with the action of the CPPM electric field, and its deformation is chaotic vibration. The chaos of droplet deformation decreases with the increase in pulse width, and an optimum pulse width can be found to make the droplet have large deformation ratio and high vibration times. The deformation ratio of droplet can be increased by increasing the electric field intensity, but the droplet are easy to split and the deformation is no longer chaotic at high electric field intensity, and an optimum electric field intensity can be found to make the droplet have large deformation ratio and deformation stability.

In situ construction of Bi4O5I2-Bi2O2CO3-BiOCl0.8I0.2 n-p-n heterojunction for enhanced photocatalytic performance

In this work, Bi 4 O 5 I 2 -Bi 2 O 2 CO 3 -BiOCl 0.8 I 0.2 n-p-n heterojunction was synthesized by in-situ growth method. Different types of BiOX (X = Br, Cl and I) materials were combined to optimize the charge separation of prepared heterogeneous junction so as to improve the photocatalytic performance. It had been proved by various characterization methods that the charge carrier recombination would be greatly suppressed under the action of internal electric field at the interface when n-p-n heterojunction was formed. Specially, 20-Bi 4 O 5 I 2 -Bi 2 O 2 CO 3 -BiOCl 0.8 I 0.2 presented the best photocatalytic performance, which could degrade 99% of Rhodamine B (RhB) in 60 min under 500 W Xe lamp source. BiOCl 0.8 I 0.2 improves the performance of photocatalytic and broaden the light absorption range of pure BiOI. This work provides a new perspective to design ternary structures that enhance photocatalytic performance.

Study of Shock Wave Development in Cold Flow of Gas Circuit Breaker for Improving Capacitive Current Switching

Abstract Capacitive current switching performance of SF6 circuit breaker is determined by combined action of gas flow and electric field in interruption chamber. Computational fluid dynamics method is used to study the development of shock waves inside a SF6 circuit breaker under the condition of capacitive current switching. It was found that a shock wave exists and travels with the pin contact during the contact opening. Existence of shock waves reduces the local gas density around contact head, while the contact head is also stressed by high electric field at the same time. If the region of low gas density coincides with the region with high electric strength, local dielectric performance will be significantly reduced. Using E/ρ as the dielectric performance index, when the local value of E/ρ exceeds the gas breakdown criterion, it will result in restrike to the capacitive current switching. The causes of high E/ρ are studied by analyzing the shock waves during the sequential periods of contact travel. Since the gap between the pin contact and nozzle throat strongly affects the strength of shock wave, the behavior of gap is studied with the calculation of E/ρ to find its influence on capacitive current switching.

Evolution and Shape of Two-Dimensional Stokesian Drops under the Action of Surface Tension and Electric Field: Linear and Nonlinear Theory and Experiment

The creeping-flow theory describing evolution and steady-state shape of two-dimensional ionic-conductor drops under the action of surface tension and the subcritical (in terms of the electric Bond number) electric field imposed in the substrate plane is developed. On the other hand, the experimental data are acquired for drops impacted or softly deposited on dielectric surfaces of different wettability and subjected to an in-plane subcritical electric field. Even though the experimental situation involves viscous friction of drops with the substrates and wettability-driven motion of the contact line, the comparison to the theory reveals that it can accurately describe the steady-state drop shape on a non-wettable substrate. In the latter case, the drop is sufficiently raised above the substrate, which diminishes the three-dimensional effects, making the two-dimensional description (lacking the no-slip condition at the substrate and wettability-driven motion of the contact line) relevant. Accordingly, it is demonstrated how the subcritical electric field deforms the initially circular drops until an elongated steady-state configuration is reached. In particular, the surface tension tends to round off the non-circular drops stretched by the electric Maxwell stresses imposed by the electrodes. A more pronounced substrate wettability leads to more elongated steady-state configurations observed experimentally than those predicted by the two-dimensional theory. The latter cases reveal significant three-dimensional effects in the electrically driven drop stretching. In the supercritical electric fields (corresponding to the supercritical electric Bond numbers), the electrical stretching of drops predicted by the present linearized two-dimensional theory results in splitting into two separate droplets. This scenario is corroborated by the predictions of the fully nonlinear results for similar electrically stretched bubbles in the creeping-flow regime available in the literature as well as by the present experimental results on a substrate with slip.

In situ removal of cadmium by short-distance migration under the action of a low-voltage electric field and granular activated carbon

Cd pollution in soil is a global environmental issue of great concern. The secondary release and low removal rate of Cd are obstacles to the use of adsorption techniques. To develop a sustainable and effective remediation technique, low-voltage direct current (DC) and granular activated carbon (GAC) were applied for in situ Cd removal. The results showed that a low-voltage gradient was more favourable than a high-voltage gradient for Cd removal. A voltage gradient of 0.2 V cm−1 acted as a driving force for Cd migration while limiting the side effects caused by DC. As an auxiliary enhancement measure, polarity exchange was effective in maintaining uniform distributions of soil moisture and temperature as well as a stable pH while improving Cd removal by weakening inhibition caused by OH− generated at the cathodes. The average removal rates of total and bioavailable Cd were 61.05% and 76.96%, respectively. The potential mobility of Cd in soil was assessed by the mobility factor (MF). The MF was lowered from 42.66% to 8.96%, indicating that the risks of Cd mobility were reduced to low levels. The energy consumption and utilization efficiency of the method were 5.65 KWh m−3 and 11.25, respectively. The energy utilization efficiency was significantly higher than the efficiencies of other methods that use DC to improve Cd removal. The results suggested that the in situ removal of Cd by low-voltage DC and GAC was efficient and avoided the secondary release of Cd.

Electrophysical characteristics of germanium MIS structures with rare-earth element fluorides

The electrical properties of MIS structures with rare-earth element fluorides on germanium substrates were studied to analyze the possibility of using these materials as gate dielectrics of devices. The structures are also studied from the point of view of assessing the degradation of their electrophysical properties under the action of electric fields of ~108 V/m, which act on the dielectric during electroforming, since the MIS structures with rare-earth element fluorides have the property of bistable switching. Studies of the I-V and C-V characteristics show that all structures have approximately the same value of the density of surface states at the rare-earth element / Ge fluoride interface. The leakage currents in the MIS structures with TmF3 and SmF3 film are less than in the MIS structures with NdF3 film of greater thickness. There is also no effect of reducing the current density when using the double film structure CeF3/DyF3. The most promising material with a low leakage current at a fairly high value of the dielectric constant in germanium MIS structures is thin-film samarium fluoride.

Lateral deformations of a crystal of potassium acid phthalate in an external electric field

The anisotropy of deformations in potassium acid phthalate crystals arising under the action of an external electric field up to 1 kV mm−1 applied along the [001] polar axis was studied using X-ray diffraction methods at room temperature. Electrical conductivity was measured and rocking curves for reflections 400, 070 and 004 were obtained by time-resolved X-ray diffractometry in Laue and Bragg geometries. Two saturation processes were observed from the time dependences of the electrical conductivity. A shift in the diffraction peaks and a change in their intensity were found, which indicated a deformation of the crystal structure. Rapid piezoelectric deformation and reversible relaxation-like deformation, kinetically similar to the electrical conductivity of a crystal, were revealed. The deformation depended on the polarity and strength of the applied field. The deformation was more noticeable in the [100] direction and was practically absent in the [001] direction of the applied field. X-ray diffraction analysis revealed a disordered arrangement of potassium atoms, i.e. additional positions and vacancies. The heights of potential barriers between the positions of K+ ions and the paths of their possible migration in the crystal structure of potassium acid phthalate were determined. The data obtained by time-resolved X-ray diffractometry and X-ray structure analysis, along with additional electrophysical measurements, allow the conclusion that the migration of charge carriers (potassium cations) leads to lateral deformation of the crystal structure of potassium phthalate in an external electric field.

Nematic Structures under Conical Anchoring at Various Director Tilt Angles Specified by Polymethacrylate Compositions.

Dependence of the director tilt angle of nematic liquid crystal (LC) under conical anchoring from the two-component polymer mixture composition has been studied. We varied the ratio of poly(isobutyl methacrylate) (PiBMA), which specifies a conical anchoring for the nematic liquid crystal LN-396, and poly(methylmethacrylate) (PMMA) assigning a tangential alignment for the same nematic. An oblique incidence light technique to determine a tilt angle has been used. It has been shown that the tilt angle increases from to when PiBMA:PMMA ratio changes in the range 30:70 to 100:0. The specific optical textures viewed under the polarizing microscope and proper orientational structures have been considered for various compositions of the polymer films. An electric field action on the formed orientational structures has been investigated. The obtained results are promising for the application in various electro-optical LC devices with a conical anchoring in which the director tilt angle is a crucial parameter: a controlled diffraction gratings, an electrically operated achromatic rotators of linear light polarization, etc.