Behavior Of Charge Distribution Research Articles

Geometry-modulated dipole polarizability of the two-dimensional Mott-Wannier excitons in gate-defined anisotropic quantum dot

A theoretical investigation on neutral excitons confined to a mono-layer (ML) semiconductor transition metal dichalcogenide (TMDC) materials under the influence of elliptically deformed gate induced confining potential is presented. It has been shown that the anisotropy of the confinement induces the anisotropy of linear response of the system on in-plane external electric field. The linear response is expressed in terms of principal moments of the static dipole polarizability tensor. In this manner the direction-dependent polarizability of the system can be fully controlled by tuning the parameters of gate-induced confining potential. The components of the polarizability tensor are determined using finite-field method based on the exact diagonalization of the electron-hole Hamiltonian including confining potential, Coulomb electron-hole interaction and an external electric field, within effective mass approximation, close to the K-points of the first Brillouin zone of a single-layer MX_2 material. The useful scaling relations for energies and dipole polarizabilities as functions of material parameters have been found. The influence of the anisotropy of the confining potential on correlated behavior of charge distribution inside the neutral system has also been demonstrated.

Thin polymer electrolyte with MXene functional layer for uniform Li+ deposition in all-solid-state lithium battery

Solid polymer electrolyte (SPE) shows great potential for all-solid-state batteries because of the inherent safety and flexibility; however, the unfavourable Li+ deposition and large thickness hamper its development and application. Herein, a laminar MXene functional layer‒thin SPE layer‒cathode integration (MXene-PEO-LFP) is designed and fabricated. The MXene functional layer formed by stacking rigid MXene nanosheets imparts higher compressive strength relative to PEO electrolyte layer. And the abundant negatively-charged groups on MXene functional layer effectively repel anions and attract cations to adjust the charge distribution behavior at electrolyte–anode interface. Furthermore, the functional layer with rich lithiophilic groups and outstanding electronic conductivity results in low Li nucleation overpotential and nucleation energy barrier. In consequence, the cell assembled with MXene-PEO-LFP, where the PEO electrolyte layer is only 12 μm, much thinner than most solid electrolytes, exhibits uniform, dendrite-free Li+ deposition and excellent cycling stability. High capacity (142.8 mAh g−1), stable operation of 140 cycles (capacity decay per cycle, 0.065%), and low polarization potential (0.5 C) are obtained in this Li|MXene-PEO-LFP cell, which is superior to most PEO-based electrolytes under identical condition. This integrated design may provide a strategy for the large-scale application of thin polymer electrolytes in all-solid-state battery.

Charge "Skin Behavior" of Gold Superatoms.

In this work, we investigate the relationship between the charge distribution and electron occupation by exploring neutral gold superatoms Aun and their anion structures [Aun]- (n = 13, 55, and 147). It is shown that there exists "skin behavior" of charge distribution for gold superatoms. For the neutral Aun, there are negative charges of -0.1 e, -0.54 e, and -1.16 e distributed in the surface area of 1D5 SAMOs of Au13, 1F12 1G15 SAMOs of Au55, and 2D6 1H22 2F14 1I6 3S2 1J6 1I8 1J4 3P1 SAMOs of Au147, respectively. For the anion [Aun]-, more negative charges of -1.08 e, -1.55 e, and -2.14 e are distributed in the surface area of 1D SAMO of [Au13]-, 1G SAMO of [Au55]-, and 3P SAMO of [Au147]-. In addition, adding an electron will cause the SAMOs rearrangement and enhance the geometric symmetry of superatoms, especially in [Au13]- and [Au55]-. Our findings provide a new perspective on microelectronic structure in understanding the skin effects.

Electronic and NLO characteristics of small neutral and singly charged iron-doped bismuth clusters

The electronic and optical properties of the iron-doped bismuth nanoclusters having less than 15 atoms are presented here. This doping is especially interesting since it enhances the stability and magnetic properties of the bismuth clusters, as shown here. The effect of singly charging the clusters on their stability and electronic properties is also investigated. Binding energy analysis shows that iron doping enhances the relative stability of the small bismuth clusters. An almost regular pattern is observed for the maximum Raman peak of the first five clusters and the succeeding nine clusters. An oscillating magnetic moment behavior is observed for the neighboring bismuth numbers from 5 to 11. Singly charged clusters also show similar magnetic characteristics. HOMO-LUMO energy gap also follows the expected pattern of the quantum confinement as larger clusters demonstrate the smaller difference between these two levels. Interestingly, this general downward trend falls in the range of visible light. The projected density of states (PDOS) also confirms the obtained results for the energy gap. The charge distribution behavior shows negative charge accumulation on iron atoms except for the case of FeBi.

Defective Carbon–CoP Nanoparticles Hybrids with Interfacial Charges Polarization for Efficient Bifunctional Oxygen Electrocatalysis

AbstractThe development of efficient catalysts for both oxygen reduction and evolution reactions (oxygen reduction reaction (ORR) and oxygen evolution reaction (OER)) is central to regenerative fuel cells and rechargeable metal–air batteries. It is highly desirable to achieve the efficient integration of dual active components into the catalysts and to understand the interaction between the dual components. Here, a facile approach is demonstrated to construct defective carbon–CoP nanoparticle hybrids as bifunctional oxygen electrocatalysts, and further probe the interfacial charge distribution behavior. By combining multiple synchrotron‐based X‐ray spectroscopic characterizations with density functional theory calculations, the interfacial charge polarization with the electrons gathering at the defective carbon surface and the holes gathering at the CoP surface due to strong interfacial coupling is revealed, which simultaneously facilitates the ORR and OER with remarkable bifunctional oxygen electrode activities. This work not only offers a bifunctional oxygen catalyst with outstanding performance, but also unravels the promoting factor of the hybrids from the view of interfacial charge distribution.

Low-temperature post-deposition annealing investigation for 3D charge trap flash memory by Kelvin probe force microscopy

The influence of post-deposition annealing (PDA) temperature condition on charge distribution behavior of HfO2 thin films was systematically investigated by various-temperature Kelvin probe force microscopy technology. Contact potential difference profiles demonstrated that charge storage capability shrinks with decreasing annealing temperature from 1,000 to 500 °C and lower. Compared to 1,000 °C PDA, it was found that 500 °C PDA causes deeper effective trap energy level, suppresses lateral charge spreading, and improves the retention characteristics. It is concluded that low-temperature PDA can be adopted in 3D HfO2-based charge trap flash memory to improve the thermal treatment compatibility of the bottom peripheral logic and upper memory arrays.

Bending actuation and charge distribution behavior of polyurethane/carbon nanotube electroactive nanocomposites

The electroactive nanocomposite films were fabricated using polyurethane (PU) with modified carbon nanotubes (CNTs) as the filler. The CNTs were modified using microwave‐induced polymerization route and they were found to be highly dispersed in polar solvents such as dimethylformamide. The modified CNTs were characterized using transmission electron microscopy, field emission scanning electron microscopy, thermogravimetric analysis, and X‐ray photoelectron spectroscopy. To evaluate these films we mainly focused on electrical properties such as actuation behavior, resistivity, impedance analysis, and space charge measurements. We found that the PU/CNT films bent toward the cathode when an electric field was applied and they reverted to its original position when the electric field was removed. Upon the incorporation of CNTs as the filler for the polymer, the electrical properties of the films improved significantly. Asymmetric charge accumulation was observed from space charge measurements in some of the films and this explains the bending deformation and the actuation behavior. POLYM. COMPOS., 262–269, 2016. © 2014 Society of Plastics Engineers

Signatures of critical behavior in the multifragmentation of nuclei with chargeZ=12−15and theN/Zdependence

We have investigated the disassembly of light nuclear systems with charge $12\text{\ensuremath{-}}15$ to extract the power-law parameters of the fragmenting nuclear system. Excited nuclei were produced in semiperipheral reactions $^{28}\mathrm{Si}$+$^{112,124}\mathrm{Sn}$ at 30 and 50 MeV/nucleon and the residual cold fragments were detected by the multidetector array for charged particles FAUST. We have studied the power-law parameter \ensuremath{\tau} as a function of the excitation energy of quasiprojectiles. We observe a systematic occurrence of the minimum of \ensuremath{\tau} with respect to the excitation energy accompanied by the maximum of the second moment of the charge distribution in the same region of excitation energy. The main features observed in the characteristics of mass and charge distributions for multifragmentation of heavier systems, such as power-law behavior of charge distribution, are thus observed also for very light systems. Moreover, behavior of the charge distribution with respect to the $N/Z$ degree of freedom has been shown.