Elastic Wave Reflection at the Interface at Preset Stresses

Russian Physics Journal - The problem of elastic wave reflection at the interface at preset constant stresses is discussed. Under the conditions where the reflection laws are fulfilled, analytical...     

Kinetics of Plastic Deformation in CuBr Single Crystals at Low Temperatures

Single crystals of CuBr with zincblende structure, deformed in compression at a strain rate 2×10^-4 s^-1 between room and liquid-nitrogen temperatures, exhibit two well-defined regions in the critical resolved shear stress (CRSS) versus temperature relationship. At rather low temperatures in the range from 78 to 150 K, the slope d ln /dT of the straight line fitted to the data points plotted in log-linear coordinates is found to be 2.9 times greater than that at temperatures between 150 and 300 K. Similar behaviour is also observed in the case of temperature dependence of activation volume associated with the CRSS. Data analysis in terms of the kink-pair nucleation model of plastic flow shows that stress-assisted thermally-activated escape of screw dislocations trapped in Peierls troughs induces slip below about 150 K. At temperatures above 150 K, CRSS is determined by the unpinning of edge-dislocation segments from groups of randomly dispersed point defects, e.g. residual gaseous and metallic impurities, deformation-induced defects formed during the pre-yield stage etc.     

金属/乙腈界面微量水的增强拉曼光谱

本文概述了我们最近利用表面增强拉曼散射技术研究金属 /乙腈界面区痕 /微量水分子的界面行为所取得的进展。研究表明银电极双电层中存在多种吸附模式下的水分子结构。处于非水环境下的水分子的νO H与水系相比存在明显的差别。水分子间的氢键被不同程度地破坏导致几种模式下的水分子νO H均要高于水体系。铂电极表面的研究表明水分子的介入很大程度上限制了铂表面乙腈分子的解离吸附反应。     

Theoretical Reflection Coefficient of Metal Grid Reflectors at a Dielectric Interface

Reflection properties of square apertures metal mesh mirrors are studied theoretically with the Finite-Difference Time-Domain (FDTD) method associated to Floquet Boundary Conditions. The reflector is illuminated by a normally incident plane wave and is located at an interface between two semi infinite low loss dielectric materials. Reflectivity and phase of the reflection coefficient are given in the non diffraction region for a wide range of square apertures, and for the four situations corresponding to an interface between free space and fused quartz.     

Scholte Wave at Air-Metal Interface Generated by a Pulsed Disc-Like Source

The normal displacement and pressure of Scholte and Leaky Rayleigh waves at air-metal interface generated by a pulsed disc-like source are simulated theoretically by the Cagniard-de Hoop method and studied by laser ultrasound technique experimentally. It is found that the Scholte wave detected by a photorefractive interferometer is mainly contributed by the surface pressure and the Leaky Rayleigh wave is dominated by the surface displacement. It is also proven that the pulse width of these interface waves is mainly determined by the acoustic time delay on the generating source size under our experimental conditions.     

Spin Moment of a Surface Wave at the Interface between Hyperbolic and Topological Insulators

Optics and Spectroscopy - Commonly, a surface wave traveling along the interface between isotropic media has a spin moment that lies in the plane of the interface and is perpendicular to the...     

Superconductivity at the Normal Metal/Dirac Semimetal Cd_3As_2 Interface

We investigate the interface between a three-dimensional Dirac semimetal Cd₃As₂ and a normal metal via softpoint contact spectroscopy measurement.The superconducting gap features were detected below 3.8 K and 7.1 K in the case of Cd₃As₂ single crystals sputter-coated with the Pt and Au films,respectively,in the differential conductance dI/dV-V plots of the point contacts.As the applied magnetic field increased,the drop in the zerobias contact resistanc...     

应用多介质PPM方法计算斜激波与物质交界面的相互作用

利用多介质PPM方法研究斜激波与物质交界面的相互作用.采用与体积分数耦合的Euler方程组作为计算模型,用双波近似来求解一般刚性气体状态方程Riemann问题.通过体积分数的计算来获得界面的位置,在整个流场采用统一的高阶PPM格式进行计算.文中对斜激波与不同物质界面相互作用进行了数值模拟,并给出了交界面上由于斜压效应产生的涡列的演化过程,特别是强斜激波与不同物质界面的相互作用的情况.     

用离子辐照模拟研究反应堆结构材料中金属/金属界面原子扩散行为

介绍了利用载能离子辐照模拟研究反应堆结构材料中金属／金属界面原子扩散行为的实验进展,特别是辐照参数（如辐照剂量、辐照温度、核能损、电子能损以及膜结构等）对界面原子扩散行为的影响,并对可能的机理进行了简要的评述。 Atom diffusion at metal/metal interfaces is very important for property of reactor structural materials, which can be simulated by using energetic ion irradiations. The present situation of experimental studies on atom diffusion at metal/metal interfaces induced by energetic ion irradiations is reviewed. The influence of experimental parameters such as the irradiation dose, irradiation temperature, electronic energy loss, nuclear energy loss and the interface structure on the intermixing is emphatically introduced. In addition, the possible mechanisms of metal/ metal intermixing are also briefly described.     

Electronic Properties of a Two-Dimensional Electron Gas at the Interface between Transition Metal Complex Oxides

The structural and electronic properties of heterostructures based on transition metal oxides containing strongly correlated electrons are compared. The investigated structures are LaAlO₃/SrTiO₃ (LAO/STO), LaAlO₃/BaTiO₃ (LAO/BTO), and BaTiO₃/SrTiO₃ (BTO/STO). The role of structural relaxation in the formation of a two-dimensional electron gas at the interface of two dielectrics is revealed. The contribution from different orbitals and atoms to conductivity is analyzed, along with the correlation between structural distortions induced by the dipole moment in an LAO layer and conductivity.     

Spin Angular Momentum of a Nonlinear Surface Wave at the Interface between Ordinary and Topological Insulators

Optics and Spectroscopy - The surface waves that propagate along the interface of a dielectric with nonlinear susceptibility of the third order and topological insulator have been considered. The...     

Kinetics of Spherical Interface in Crystal Growth

The growth kinetics of spherical NiAl and CuZr crystals are studied by using molecular dynamics simulations.The growth rates of crystals are found to increase with the grain radius. The simulations show that the interface thickness and the Jackson α-factor increase as the growth proceeds, indicating that the interface becomes increasingly rough during growth. Due to the increasing interface roughening, the fraction of repeatable growth sites at interface f is proposed to actually increase in growth. An attachment rate, which is defined as the fraction of atoms that join the crystal interface without leaving, is used to approximate f, displaying a linear increase. With this approximation, we predict the growth rates as a function of the crystal radius, and the results qualitatively agree with those from the direct simulations.     

The Interface Kinetics of Crystal Growth Processes

A brief review of the present state of our understanding of the kinetic processes which take place on the atomic scale at the interface during crystal growth is presented in this paper. Computer simulations have played a central role in the development of this understanding. Three aspects will be discussed:(1) There are two classes of materials based on their different modes of crystallization. Molecular dynamics modeling has demonstrated that the growth rate for many simple materials is not thermally activated, but instead depends on the thermal velocity of the atoms.(2) The cooperative processes which give rise to the surface roughening transition. Kinetic Monte Carlo studies played a central role in the development of our understanding of how interface roughness dominates growth morphologies.(3) Solute trapping in alloys. Kinetic Monte Carlo simulations of alloys have led to an understanding of these kinetic effects during alloy crystallization.     

Kinetics of Macrolocalization Patterns of Plastic Flow of Metals

The features of the macroscopic inhomogeneity of plastic deformation in the form of autowaves with a pulsating amplitude are analyzed, and data on the localization of sources of acoustic emission at different stages of plastic flow in the stretching of fcc mono- and polycrystals are presented. The relationship between the local components of the plastic distortion tensor in the strain localization zone is traced. The role of acoustic phenomena accompanying the localization of plastic strain in the development of the process of plastic deformation is considered.     

Structure of a Converging Rarefaction Wave and Development of Cavitation Beyond Its Front in a Multiphase Liquid

Acoustical Physics - An experimental analysis of the flow structure and dynamics of the formation of a quasi-empty discontinuity upon shock excitation of a liquid layer showed that closure of the...     

离子辐照引起的金属／绝缘体界面混合与相变研究

载能离子穿过固体界面引起界面原子迁移使界面原子混合和物质成分变化，从而导致界面发生材料相变。简要介绍了载能离子辐照引起金属／绝缘体界面混合效应及相变现象的主要实验研究进展、低能离子和高能离子辐照引起金属／绝缘体界面现象差异，并对离子辐照引起界面混合及相变的机制进行了初步探讨。When penetrating an interface between two kind of solids, energetic ions can induce atomic diffusion at both sides of the interface and then result in intermixing, atom re-distribution or composition change, as well as phase transformation. Main progress on the study of intermixing and phase change at metal/insulator interface induced by energetic ion irradiations, the difference of phenomena occurred at metal/insulator interfaces induced by high-and low-energy ions were briefly reviewed. Furthermore, the possible mechanisms related to intermixing and phase change at metal/insulator interface produced by energetic ion irradiations were also discussed in short words.     

湍流大气中高斯谢尔光束的波前位错

在Rytov近似下,通过引入短期统计平均位错位置的概念,研究了高斯谢尔光束通过近地面弱湍流大气传播时,波前圆形位错形成和位错位置与湍流大气起伏强度和传播距离等参数间的关系.基于湍流大气中平行和交叉双光束的简化近似传输模型,研究了湍流大气中传播高斯谢尔光束波前位错位置与大气湍流强度、传输距离等参数间的相关机制.在远小于光波位相起伏周期的条件下,分别得出了束径不同同轴双光束和交叉双光束传播情况下波前圆位错位置的湍流系综统计平均理论关系.所得结果表明,同轴平行光束干涉和交叉光束干涉所产生的光束波前位错受大气湍流强度、传输距离等参数调制的规律是不同的.     

Combustion Wave Stability in Transition through the Interface of Gasless Systems

In this paper, using mathematical modeling, we study combustion wave stability in transition through the interface of gasless systems. The effect of a gas layer separating two chemically active gasless layers on the combustion wave stability was studied at all stages of the transition. Using the criteria obtained, we estimate the stability conditions of the transition combustion wave. The nonstationary dynamics of the combustion wave transition through the gas gap is studied with allowance for competing mechanisms of heat transfer, such as conductive and radiant transfer. We analyze the effect of radiation heat transfer in the gas gap on the characteristics and stability of the transient combustion process. The failure region of the igniter combustion wave is determined through the approach to the ignition system, while estimates of temperature and heat flux at the interface of the systems are given with respect to the time of the igniter combustion completion under conditions of dominant conductive and radiant heat transfer.     

Structure and Liquid-Vapor Interface of a Simple Metal

This paper presents the results of a theoretical study of the structure of the liquidvapor interface of gallium, based on density functional pseudopotential representation of the electron-ion and the ion-ion interactions, and self-consistent quantum Monte Carlo simulation. These predictions of the bulk pair correlation function and the longitudinal density distribution are in very good agreement with the results of recent experimental studies.     

Experimental Study of Ar-Gas Radiation Behind the Front of a Strong Shock Wave

Journal of Applied Spectroscopy - Emission spectra of argon behind the front of a strong shock wave are studied in the range of shock-wave velocities of 4.6–8.3 km/s and pressures before the...