共查询到20条相似文献,搜索用时 93 毫秒
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The behavior of composite coated Al electrodes fabricated by surface mechanical alloying ‘SMA’ was studied. The work was accomplished using Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) techniques in alkaline media were done at room temperature. Results show hydroxyl ions accumulate on the surface due to Al deformation micro cavities filling with until full charge blockage reached. A barrier cover layer development causing an increase of both resistance and capacitance as it becomes more stable and thinner with exposure time increase. Migrating hydroxyl ion inside micro cavity changed its composition from Al2O3 to stable tetrahedral aluminate ions. Therefore future benefits could be reached by developing such surfaces having charge accumulation that enables environmental interaction. 相似文献
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First principle calculations have been employed to investigate the effects of Y concentration, pressure and temperature on various properties of () alloys using density functional theory (DFT). The full potential linearized augmented plane wave (FP-LAPW) method within a framework of the generalized gradient approximation (GGA) is used to perform the calculated results of this paper. Phase stability of alloys is studied using the total energy versus unit cell volume calculations. The equilibrium lattice parameters of these alloys are in good agreement with the available experimental results. The mechanical stability of alloys is proved using elastic constants calculations. Also, the influence of Y concentration on elastic properties of alloys such as Young's modulus, shear modulus, Poisson's ratio and anisotropy factor are investigated and analyzed. By considering both Pugh's ratio and Poisson's ratio, the ductility and brittleness of these alloys are studied. In addition, the total density of states and orbital's hybridizations of different atoms are investigated and discussed. Moreover, the effect of pressure and temperature on some important thermodynamic properties is investigated. 相似文献
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《Physics letters. A》2020,384(14):126281
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Ferdinand Grüneis 《Physics letters. A》2019,383(13):1401-1409
Single quantum dots and other materials exhibit irregular switching between on and off states; these on–off states follow power-law statistics giving rise to 1/f noise. We transfer this phenomenon (also referred to as on–off intermittency) to the generation and recombination (= g–r) process in semiconductor materials. In addition to g–r noise we obtain 1/f noise that can be provided in the form of Hooge's relation. The predicted Hooge coefficient is whereby depends on the parameters of the g–r noise and on the parameters of the intermittency. Due to the power-law distribution of the on-times, the coefficient shows a smooth dependence on time t. We also suggest an alternative form of Hooge's 1/f noise formula relating the 1/f noise to the number of centers (such as donor or trap atoms) rather than to the number of charge carriers as defined by Hooge. 相似文献
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The magnetic properties of tetragonal structure of stoichiometric NiMn alloy is investigated using density functional theory within the local spin density approximation. The system studied here, is a free standing film. The effect of thickness and epitaxial strain on the magnetic and structural properties is examined. It is found that while the magnetic moments of Mn surface atoms vary depending on the number of layers being odd (3.60 ) or even (3.55 ) the magnitude of the magnetic moment for surface Ni atoms is constant (0.11 ). By applying epitaxial strain on the slabs, it was observed, for the first time, that the magnetic phase of NiMn films changes from “A-type-like” ferrimagnetic for compressive strains to “G-type-like” ferrimagnetic for tensile strains. 相似文献
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Yi-Qi Yang Chun-Xiang Zhao Shou-Yan Bai Cai-Ping Wang Chun-Yao Niu 《Physics letters. A》2019,383(24):2997-3000
As a non-precious catalyst for the electrochemical hydrogen evolution reaction (HER), the two-dimensional MoS2 has been widely studied. To activate the MoS2 inert basal plane to enable optimal activity, high defect concentration of sulfur vacancies is needed. Herein, based on the first-principles calculations we demonstrate that the HER of MoS2 can be greatly enhanced by As doping and biaxial strain. We show that the As-doping sites are new catalytic sites and the bonding of H can be greatly enhanced. Moreover, the relative hydrogen adsorption free energy () can be further manipulated by the strain effect, which efficiently adjusts the catalytic activity. With the synergy of the biaxial strain (2%–3%) and the uniform doping of the As atoms (3.125% concentration), the can be modulated to zero. Our findings provide a way to achieve the high intrinsic HER activity among molybdenum-sulfide-based catalysts. 相似文献
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Structural and optical properties of graphene with a vacancy and B, N, O and F doped graphene have been investigated computationally using density functional theory (DFT). We find that B is a p-type while N, O and F doped graphene layers, as well as graphene with a vacancy are n-type semiconductors. Optical properties for both cases of in plane and out of plane polarization of light are investigated. It is observed that with the increase in the number of electrons entering the supercell, the amount of absorption of the system decreases and the absorption peaks are transferred to higher energies (blue shift). 相似文献
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