Application Of External Electric Field Research Articles

Theoretical design of alkaline earthides M+(36 adz) Be− (M+ = V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) with excellent nonlinear optical response and ultraviolet transparency

A novel series of alkaline earthides containing eight complexes based upon 36adz complexant are designed by placing carefully transition metals (V–Zn) on inner side and alkaline earth metal outer side of the complexant i.e., M+(36adz) Be− (M+ = V, Cr, Mn, Fe, Co, Ni, Cu and Zn). All the designed compounds are electronically and thermodynamically stable as evaluated by their interaction energy and vertical ionization potential respectively. Moreover, the true nature of alkaline earthides is verified through NBOs and FMO study, showing negative charge and excess electrons on alkaline earth metal respectively. Furthermore, true alkaline earthides characteristics are evaluated graphically by spectra of partial density state (PDOS). The energy gap (HOMO -LUMO gap) is very small (ranging 2.95 eV–1.89 eV), when it is compared with pure cage 36adz HOMO-LUMO gap i.e., 8.50 eV. All the complexes show a very small value of transition energy ranging from 1.68eV to 0.89eV. Also, these possess higher hyper polarizability values up to 2.8 x 105au (for Co+(36adz) Be−). Furthermore, an increase in hyper polarizability was observed by applying external electric field on complexes. The remarkable increase of 100fold in hyper polarizability of Zn+(36adz) Be− complex is determined after application of external electric field i.e., from 1.7 x 104 au to 1.7 x 106 au when complex is subjected to external electric field of 0.001 au strength. So, when external electric field is applied on complexes it enhances the charge transfer, polarizability and hyper polarizability of complexes and proves to be effective for designing of true alkaline earthides with remarkable NLO response.

Acceleration of flow-focused liquid jets in the presence of a strong electric field

This paper investigates the acceleration of flow-focused micro-jets under an applied external electric field. Such thin and fast jets are needed, for example, to deliver protein crystals in X-ray free electron laser experiments. This contribution focuses on analysing the acceleration of liquid jets produced from 50 % vol water and ethanol mixture. Such jets are focused with nitrogen gas and are subjected to 0 - 7 kV electric potential between a submerged electrode and an external electrode downstream of the nozzle. To gain insights into jet geometric properties an automatic image recognition and computer vision algorithm is utilised on already published data. Jet velocities and acceleration calculated for two jetting regimes show that application of external electric field accelerates the jets up to four orders of magnitude larger than the conventional micro-jets.

Unveiling the electronic properties of BiP[formula omitted] triphosphide from bulk to graphene-based heterostructures by first-principles calculations

In our study, we investigated the structural and electronic properties of bismuth triphosphide (BiP3) in its bulk, few-layer, and monolayer forms. We found that BiP3 in bulk exhibits a metallic stable layered structure. The exfoliation energy of 1.07 J/m2 indicates ease exfoliation, comparable to other triphosphides. The band gap varies with thickness, transitioning from semiconductor–metal between four to five layers, influenced by interlayer coupling and quantum confinement. We also investigated the heterostructure created by depositing graphene (G) on few-layer BiP3. In monolayer (G/m-BiP3) and bilayer (G/2L-BiP3) forms, a metal–semiconductor junction is formed, characterized by weak vdW interactions at the interface and exhibiting p-type Schottky contacts. We observed that the Schottky Barrier Height (SBH) can be modulated by altering the interlayer distance between G and BiP3. This adjustment allows transitions between n-type and p-type Schottky contacts in G/m-BiP3 and the formation of an ohmic contact in G/2L-BiP3. Furthermore, applying an electric field affects the SBH, leading to similar transitions and the development of an ohmic contact. Additionally, our study shows that n-doping in graphene increases with the number of BiP3 layers and external electric field application. These properties position BiP3 few-layer as a promising material for nanoelectronic, optoelectronic, and graphene-based devices.

Reversible nanocracks-induced resistive switching manipulated by ferroelectric polarizing in Te/PMN-PT heterostructures

Ferroelectricity-based storage technology is anticipated to achieve nonvolatile, low-power, and high-density storage in integrated field circuits. Here, the phenomena of electrically reversible switching of nanocracks in the tellurium film/ferroelectric PMN-PT heterojunctions are discussed. Upon the application of external electric fields (±2 kV/cm), the nonvolatile resistance on-off ratio reached over 106 at room temperature. This was achieved through the opening and closing of cracks in the Te film caused by the electric-field-driven flipping of 109° ferroelectric domains in a ferroelectric single crystal. In addition, the ON/OFF resistance states remain stable even after more than 103 cycles and the retention time exceeds 6 h, demonstrating excellent fatigue resistance performance of the device. This work renders a window to design nonvolatile memory by constructing electric-field tunable nanocracks in a semiconductor film/ferroelectrics heterojunction system.

Nonequilibrium Ab Initio Molecular Dynamics Simulation of Water Splitting at Fe2O3-Hematite/Water Interfaces in an External Electric Field.

In the exploration of the optimal material for achieving the photoelectrochemical dissociation of water into hydrogen, hematite (α-Fe2O3) emerges as a highly promising candidate for proof-of-concept demonstrations. Recent studies suggest that the concurrent application of external electric fields could enhance the photoelectrochemical (PEC) process. To delve into this, we conducted nonequilibrium ab initio molecular dynamics (NE-AIMD) simulations in this study, focusing on hematite-water interfaces at room temperature under progressively stronger electric fields. Our findings reveal intriguing evidence of water molecule adsorption and dissociation, as evidenced by an analysis of the structural properties of the hydrated layered surface of the hematite-water interface. Additionally, we scrutinized intermolecular structures using radial distribution functions (RDFs) to explore the interaction between the hematite slab and water. Notably, the presence of a Grotthuss hopping mechanism became apparent as the electric field strength increased. A comprehensive discussion based on intramolecular geometry highlighted aspects such as hydrogen-bond lengths, H-bond angles, average H-bond numbers, and the observed correlation existing among the hydrogen-bond strength, bond-dissociation energy, and H-bond lifetime. Furthermore, we assessed the impact of electric fields on the librational, bending, and stretching modes of hydrogen atoms in water by calculating the vibrational density of states (VDOS). This analysis revealed distinct field effects for the three characteristic band modes, both in the bulk region and at the hematite-water interface. We also evaluated the charge density of active elements at the aqueous hematite surface, delving into field-induced electronic charge-density variations through the Hirshfeld charge density analysis of atomic elements. Throughout this work, we drew clear distinctions between parallel and antiparallel field alignments at the hematite-water interface, aiming to elucidate crucial differences in local behavior for each surface direction of the hematite-water interface.

Dramatic Differences between the Structural Susceptibility of the S1 Pre- and S2 Postfusion States of the SARS-CoV-2 Spike Protein to External Electric Fields Revealed by Molecular Dynamics Simulations.

In its prefusion state, the SARS-CoV-2 spike protein (similarly to other class I viral fusion proteins) is metastable, which is considered to be an important feature for optimizing or regulating its functions. After the binding process of its S1 subunit (S1) with ACE2, the spike protein (S) undergoes a dramatic conformational change where S1 splits from the S2 subunit, which then penetrates the membrane of the host cell, promoting the fusion of the viral and cell membranes. This results in the infection of the host cell. In a previous work, we showed-using large-scale molecular dynamics simulations-that the application of external electric fields (EFs) induces drastic changes and damage in the receptor-binding domain (RBD) of the wild-type spike protein, as well of the Alpha, Beta, and Gamma variants, leaving a structure which cannot be recognized anymore by ACE2. In this work, we first extend the study to the Delta and Omicron variants and confirm the high sensitivity and extreme vulnerability of the RBD of the prefusion state of S to moderate EF (as weak as 104 V/m), but, more importantly, we also show that, in contrast, the S2 subunit of the postfusion state of the spike protein does not suffer structural damage even if electric field intensities four orders of magnitude higher are applied. These results provide a solid scientific basis to confirm the connection between the prefusion-state metastability of the SARS-CoV-2 spike protein and its susceptibility to be damaged by EF. After the virus docks to the ACE2 receptor, the stable and robust postfusion conformation develops, which exhibits a similar resistance to EF (damage threshold higher than 108 V/m) like most globular proteins.

Evolving electromechanical properties of defect engineered Pb(Zr,Ti)O3-based piezoceramics

Chemical modification is the frequently-adopted strategy to enhance the electromechanical properties of piezoelectric ceramics. However, chemically modified piezoelectric materials will inevitably produce point defects, such as dopant ions, oxygen vacancies, etc. In this study, we investigated the properties of defect-engineered Pb(Zr,Ti)O3 (denoted by PSZT–Fe) polycrystals after aging, quenching, poling, and de-aging processes. At the same time, a general mechanism on the strength of defect dipole is also put forward to explain the corresponding changes. After aging, the spontaneous polarization of PSZT-Fe can be changed instantly upon application of external electric field, but the defect dipole and its defect symmetry can’t change simultaneously. Therefore, after the external electric field is removed, the defective dipole would drive the electric domain back to its original state, resulting in restorable strain effect and macroscopic pinch polarization. Bipolar electric field cycling can effectively redistribute oxygen vacancies to a random state, so that the aged PSZT-Fe can recover the electrical properties of typical ferroelectrics, similar to quenched samples. The spontaneous polarization and defect dipole in the poled PSZT-Fe ceramics are driven by an external electric field parallel to each other, which results in the emergence of internal bias field, accounting for the asymmetric hysteresis loop.

A three orders of magnitude increase in nonlinear optical response by external electric field on Cryptand[2.2.2] (C222) based alkaline earthides

A new series of alkaline earthides based on Cryptand [2.2.2] (C222) containing nine complexes is designed by carefully placing alkali metals and alkaline earth metals inside and outside the C222 complexant, respectively i.e., M1(C222)M2 (M1 = Li, Na, K; M2 = Be, Mg, Ca). The designed complexes are reasonably stable both electronically and thermodynamically, as revealed through their vertical ionization potentials (VIPs) and interaction energies, respectively. Moreover, the true alkaline earthide nature of the complexes is confirmed through NBO and FMO analyses showing the negative charges and HOMOs over the alkaline earth metals, respectively. The further validity of true earthide characteristic is represented graphically by the spectra of partial density of states (PDOS). HOMO-LUMO gaps of the compounds are also very small (from 2.23 to 2.83 eV) when compared with pure cage's (C222) H-L gap i.e., 5.63 eV. All these features award these complexes with very small values of transition energies (ΔE) ranging from 0.68 to 2.06 eV ultimately resulting in remarkably high hyperpolarizability values up to 2.7 × 105 au (for Na+(C222)Mg−). Furthermore, applying external electric field (EEF) on the complexes enhances hyperpolarizability further. A remarkable increase of 1000 folds has been seen when hyperpolarizability of K+(C222)Ca− is calculated after EEF application i.e., from 8.79 × 104 au to 2.48 × 107 au; when subjected to 0.001 au external electric field.

Two-dimensional MoS2/Ti2CX2 (X = S, Se, Te) heterostructures with tunable electrical contact type

The tunable electrical contact type in van der Waals (vdW) heterostructures plays an important role in promoting the efficiency of ultrathin electronic devices. From the first-principles calculations, the electronic properties and electrical contact type of the MoS2/Ti2C heterostructure and its ramifications MoS2/Ti2CX2 (X = S, Se, Te) heterostructures are verified. The strong interfacial interaction is found in pristine MoS2/Ti2C heterostructure, resulting in the metallization of MoS2 layer. The functionalization of S, Se, and Te atoms can weaken the interfacial interaction, forming metal-semiconductor contact. The p-type Schottky contact is formed in MoS2/Ti2CS2 and MoS2/Ti2CSe2 heterostructures, while Ohmic contact is formed in MoS2/Ti2CTe2 heterostructure. The application of external electric field can efficiently modulate the contact type of MoS2/Ti2CX2 (X = Se and Te) heterostructures. The discrepancy of electron affinity of S, Se, and Te atoms leads to the different interlayer charge transfer, and thus the different electrical contact type can be realized in MoS2/Ti2CX2 (X = S, Se, Te) heterostructures. The tunable contact type makes these heterostructures become potential candidate materials for enhancing the nanoelectronic devices’ efficiency.

Ferroelectric SnPz/In2Se3 as a Stable and Durable Non-Volatile 2D Ferroelectric Memory Material

In ferroelectric memory, the repeated application of external electric fields can cause ferroelectric fatigue, limiting its stability and service life, especially as the storage unit size decreases. To address this issue, we conducted first-principles research on a SnPz/In2Se3 structure and examined its structure under different polarization directions. Our analysis revealed significant differences in the adsorption position of Sn atoms depending on the polarization direction, suggesting that SnPz/In2Se3 could be a highly stable ferroelectric storage material. Moreover, the polarization-induced changes in the electronic structure near the Fermi level, which allowed for the use of tunneling current and obtaining stored information without causing the ferroelectric fatigue effect during information readout. These findings highlight the potential of SnPz/In2Se3 to significantly extend the lifespan of ferroelectric materials, reduce energy consumption, and minimize the environmental impact of discarded electronic devices.

Regulating air cushioning and bubble entrapment in charged droplet impact via external electric fields

Air cushioning and bubble entrapment are common phenomena observed during low-velocity droplet impact on solid or fluid surfaces, whereby a thin layer of air mediates the lubrication pressure. Previously, it is found that both charging droplets and the application of external electric fields can eliminate air cushioning and bubble entrapment. In this study, we numerically investigate the air cushioning and bubble entrapment in the charged droplet impacting onto a solid surface under external electric fields. It is found that the presence of net charge has a field enhancement effect on polarized charges on the same side while weakening the electric field of polarized charges on the opposite side, which can be linearly superimposed in the atmospheric environment. Based on the mirror charge model, the scaling law of the electric field threshold required for the impact of charged droplets without air cushioning or bubble entrapment is given. A fitting function based on the scaling law shows a good agreement with the phase diagram of a charged droplet impact modes under electric fields. These findings offer valuable insight for applications that rely on charged droplets' impact under electric fields, such as electrohydrodynamic printing and spray coating, to mitigate the negative impact of air cushioning or bubble entrapment.

Towards an approximate solution of highly viscous electro-osmotic flows in inclined Channel: Applications in petroleum and gas engineering

Electro-osmotic flows (EoF) through an inclined channel are investigated in this article. Differential type non-Newtonian fluid model has been used to form highly viscous bi-phase fluid flows. Two different kinds of metallic particles are considered for disperse phase. The application of external electric fields and gravitational force are the main sources of multiphase flows under the magnetic environment. Nonlinear differential equations are formulated taking the stress tensor of fourth-grade fluid, Poisson equation, and Debye length approximation into account, respectively. An approximate solution is obtained for the nonlinear flow problems. Comparative analyses have also been performed with the previous investigations via tables and graphs and, were found to be in great agreement. A comprehensive parametric study is carried out, as well, which reveals that there is a definite difference between the momentum of the fluid phase and the particles phase. The contribution of the Helmholtz–Smoluchowski parameter in each phase is quite supportive. However, the effects of the transverse magnetic field and electro-osmotic parameter are in full coherence. Moreover, traditional multiphase flows can be derived for the limiting case. Finally, this theoretical study explicitly describes the applications in petroleum and gas engineering.

A Tunable Single‐Molecule Light‐Emitting Diode with Single‐Photon Precision (Adv. Mater. 16/2023)

Single-Molecule Light-Emitting Diodes In article number 2209750, Zitong Liu, Xuefeng Guo, and co-workers integrate a functional electroluminescent molecular bridge into nanogapped graphene electrodes to build a high-performance single-molecule light-emitting diode (SM-LED) with unprecedented levels of stability and reproducibility. Precise tunability of its emission efficiency, color purity, emitted photon number, and energy is achieved upon application of external electric fields, rational molecular engineering, and Förster resonance energy transfer, affording a new practical single-photon emitter, a milestone in developing the next generation of commercial display devices, and for quantum computation and communication.

Adaptive half-metallicity via magnetic proximity in an electrically sensitive 1T’-WTe2/CrBr3 vdW heterostructure

The magnetic proximity effect (MPE) together with electric-field tunability en-routes new physical paradigm in developing nanoscale devices by modulating the functionalities of the materials. By employing first-principles calculation, we investigate MPE in a van der Waals (vdW) heterostructure constituted by a monolayer Weyl semimetal 1T’-WTe2 (tungsten di-telluride), coupled with a monolayer ferromagnet CrBr3 (chromium tribromide) at an interplanar distance of 3.68 Å. The proximity effect infers that the heterostructure system is 100 % spin-polarized leading to half-metallic nature, with a spin-splitting of 25 and 10 meV for two spin configurations. This robustness of MPE arises due to orbital hybridization and charge transfer at the interface of heterostructure system. Moreover, half-metallic nature is tuned and transformed to semiconducting and overlapping states in presence of external bias. The spin-splitting manifests orbital hybridization due to d-orbitals of W and Cr with a notable enhancement of 4 % in the magnetic moment value (12.04 µB per cell). We also observe that proximitized interface is highly sensitive towards an application of external electric field. With external bias, the Fermi level across charge neutrality point is easily tuned and controls charge transport at interface. The consistent nature of conductivity enables the interfacial polarization and coherent electron drift is realized due to seamless proximity interaction across the transport channel of the heterostructure system. This electric field-mediated MPE in vdW heterostructure can strongly recommend for next-generation spin filtering and field effect transistor (FET) devices.

Tuning electronic properties and contact type in van der Waals heterostructures of bilayer SnS and graphene

Using first-principles calculations, we study the structural and electronic properties of the bilayer SnS/graphene, bilayer SnS/bilayer graphene (AA-stacked), bilayer SnS/bilayer graphene (AB-stacked) and monolayer SnS/ graphene/monolayer SnS van der Waals (vdW) heterostructures. Electronic properties of all components of the vdW heterostructures are well preserved, which reflects the weakness of the vdW interaction. In the cases of bilayer SnS/graphene and bilayer SnS/bilayer graphene (AA-stacked), an Ohmic contact is formed which can be turned first into p-type and then into n-type Schottky contacts via application of external electric field. Calculations show that an Ohmic contact is also formed at the interface of bilayer SnS/bilayer graphene (AB-stacked) heterostructure, but interestingly, by applying the perpendicular electric field a transition from semimetal/semiconductor contact to semiconductor/semiconductor one occurs which can enhance its optical properties. Alternatively, in the monolayer SnS/graphene/monolayer SnS vdW heterostructure, a p-type Schottky contact is established that changes into Ohmic contact under an applied electric field. Our results clearly indicate that the electronic properties of the vdW heterostructures can be tuned efficiently by external electric field, which is important in designing of new nanoelectronic devices.

Impacts of external electric fields on the permeation of glycerol and water molecules through aquaglyceroporin-7: molecular dynamics simulation approach.

The aquaglyceroporin-7 (AQP7) protein channels facilitate the permeation of glycerol and water molecules through cell membranes by passive diffusion and play a crucial role in cell physiology. Considering the wide-spirit usage of radiofrequency electromagnetic fields in our daily life, in this study, the effects of constant and GHz electric fields were investigated on the dynamics of glycerol and water molecules inside the AQP7. To this end, four different molecular simulation groups were carried out in the absence and presence of electric fields. The results reveal that the free energy profile of the glycerol permeation inside the channel is reduced in the presence of the field of 0.2mV/nm and the oscillating field of 10GHz. In addition, exposing the channel to the electric field of 0.2mV/nm assisted the water transport through the channel with no considerable effect on channel stability. These observations provide a framework for understanding how such fields could alter normal operation of protein channels, which may lead to disease beginning or being used in disease treatment. Glycerol and water molecules permeation through the aquaglyceroporin-7 channel can be influenced by application of external electric fields.

Electromagnetic hydrodynamic flow and heat transfer of a Casson nanofluid Fe3O4-blood in a porous medium

Magnetohydrodynamic fluid-flows attract a lot of attention in the extrusion of polymers, in the theory of nanofluids, as well as in the consideration of biological fluids. The considered problem in the paper is the flow and heat transfer of nanoand micro-polar fluid in inclined channel. Fluid-flow is steady, while nano- and micro-polar fluids are incompressible, immiscible, and electrically conductive. The upper and lower channel plates are electrically insulated and maintained at constant and different temperatures. External applied magnetic field is perpendicular to the fluid-flow and considered problem is in induction-less approximation. The equations of the considered problem are reduced to ODE, which are analytically solved in closed form. The influence of characteristics parameters of nano- and micro-polar fluids on velocity, micro-rotation and temperature fields are graphically shown and discussed. The general conclusions given through the analysis of graphs can be used for better understanding of the flow and heat transfer of nano- and micro-polar fluid, which have a great practical application. Fluids with nanoparticles innovated the modern era, due to their comprehensive applications in nanotechnology and manufacturing processes, while the theory of micro-polar fluids explains the flow of biological fluids and various types of liquid metals and crystals.

Electron-spin polarization effect in Rashba spin-orbit coupling modulated single-layered semiconductor nanostructure

Nanothick semiconductors can grow orderly along a desired direction with the help of modern materials growth technology such as molecular beam epitaxy, which allows researchers to fabricate the so-called layered semiconductor nanostructure (LSN) experimentally. Owing to the structure inversion symmetry broken by the layered form in the LSN, the electron spins interact tightly with its momentums, in the literature referred to as the spin-orbit coupling (SOC) effect, which can be modulated well by the interfacial confining electric field or the stain engineering. These significant SOC effects can effectively eliminate the spin degeneracy of the electrons in semiconductor materials, induce the spin splitting phenomenon at the zero magnetic field and generate the electron-spin polarization in the semiconductors. In recent years, the spin-polarized transport for electrons in the LSN has attracted a lot of research interests, which is because of itself scientific importance and potential serving as spin polarized sources in the research field of semiconductor spintronics. Adopting the theoretical analysis combined with the numerical calculation, we investigate the spin-polarized transport induced by the Rashba-type SOC effect for electrons in a single-layered semiconductor nanostructure (SLSN)-InSb. The present research is to explore the new way of generating and manipulating spin current in semiconductor materials without any magnetic field, and focuses on developing new electron-spin filter for semiconductor spintronics device applications. The improved transfer matrix method (ITMM) is exploited to exactly solve Schrödinger equation for an electron in the SLSN-InSb device, which allows us to calculate the spin-dependent transmission coefficient and the spin polarization ratio. Owing to a strong Rashba-type SOC, a considerable electron-spin polarization effect appears in the SLSN-InSb device. Because of the effective potential experienced by the electrons in the SLSN-InSb device, the spin polarization ratio is associated with the electron energy and the in-plane wave vector. In particular, the spin polarization ratio can be manipulated effectively by an externally-applied electric field or the semiconductor-layer thickness, owing to the dependence of the effective potential felt by the electrons in the SLSN-InSb device on the electric field or the layer thickness. Therefore, such an SLSN-InSb device can be used as a controllable electron-spin filter acting as a manipulable spin-polarized source for the research area of semiconductor spintronics.

Electric field-mediated regulation of enzyme orientation for efficient electron transfer at the bioelectrode surface: A molecular dynamics study

Surface immobilization with favorable orientation of biocatalysts is critical for developing bioelectrochemical devices. To improve the performance of electrochemical electrodes, biocatalyst surface modification and engineering has been attempted via expensive and complex fabrication processes. For proper orientation and deposition of biomolecules on the surface, application of external electric field (EF) to small molecules has been suggested. Here, to the best of our knowledge, a unidirectional external EF was applied for the first time to oxygen-reducing enzymes with high catalytic activity and a Laccase-graphene interface was constructed using computational methods. The external EF rotated the active site of laccase, resulting improvement in the electron transfer rate compared to enzymes physically immobilized on graphene. The external EF fabrication process was also evaluated for graphene congeners (graphene oxide (GO) and reduced GO (rGO)). The morphology of the electrode surface was visualized, and computational methods were applied to verify binding conformation, orientations of dipole moment, secondary structure, and binding stability. Graphene was the most promising material compared to GO and rGO by 10 and 5 % for DET rate, respectively. Results suggest that using an external EF to favorably orientate the Laccase-graphene interface may be a simple, economical, and efficient approach for bioelectrode fabrication.

Rashba Spin-Orbit-Coupling Based Electron-Spin Filter in Double-Layered Semiconductor Nanostructure

Based on a double-layered semiconductor nanostructure (DLSN)-InSb/GaSb, we propose a controllable electron-spin filter for spintronics device applications. Electron-spin polarization is induced by Rashba spin-orbit coupling inside the DLSN. Both magnitude and sign of spin polarization ratio can be manipulated by externally-applied electric field or the semiconductor-layer thickness.