Influence of Triangle Structure Defect on the Carrier Lifetime of the 4H-SiC Ultra-Thick Epilayer

Effect of triangle structure defects in a 180-μm-thick as-grown n-type 4H-SiC homoepitaxial layer on the carrier lifetime is quantitatively analyzed, which is grown by a horizontal hot-wall chemical vapor deposition reactor.By microwave photoconductivity decay lifetime measurements and photoluminescence measurements, the results show that the average carrier lifetime of as-grown epilayer across the whole wafer is 2.59μs, while it is no more than 1.34μs near a triangle defect(TD). The scanning transmission electron microscope results show that the triangle structure defects have originated from 3C-SiC polytype and various types of as-grown stacking faults.Compared with the as-grown stacking faults, the 3C-SiC polytype has a great impact on the lifetime. The reduction of TD is essential to increasing the carrier lifetime of the as-grown thick epilayer.     

塑料片材的组成、结构与其裂纹问题分析

本文用傅立叶红外光谱仪，X-射线荧光光谱仪，电子显微镜，拉力试验机对两种片材进行了组成，结构与性能分析。在此基础上，用自由体积理论和界面化学理论讨论了薄片的断裂问题。研究发现增塑剂的用量十分关键。     

The Influence of Incoherent Particle Size on Defect Structure and Strength Properties of Disperse-hardened Aluminum Alloys

Russian Physics Journal - In this paper, the mathematical modeling is used to study the influence of the incoherent strengthening nanoparticles ranging from nano- to micron size on the formation...     

光子晶体缺陷结构的特性

基于平面波展开法,设计了二维正方晶格和三角晶格光子晶体缺陷结构,数值模拟了TE模、TM模式的光子晶体禁带特性,计算了二维三角晶格光子晶体缺陷结构的模式分布。结果表明,光子晶体缺陷结构能够形成很好的禁带特性和模式结构,研究结论为光子晶体波导器件的开发提供参考。     

电子横向运动对共振隧穿的影响

讨论了电子横纵方向运动耦合时的隧穿现象,对CdSe/Zn1-xCdxSe方形双势垒结构和抛物形双势垒结构的数值计算表明,在零偏压和非零偏压情况下,电子横向运动对共振隧穿的影响是不容忽略的。     

Nucleation of Micro Crack for Brittle Fracture in Magnetic Field

The nature of spin-state phase transition is investigated with [Fe（C4H4N2）{Pt（CN）4}] that is a novel 3D Hofmann—like compound. The bistability of this system is obtained by the first-principles calculation. It is demonstrated that thermal expansion is the intrinsic force involved in spin-state transition. Based on these results, we suggest a thermal exciting bistable model of spin-state transition with a temperature dependent crystal-field splitting （CFS）. Experimental evidence of spin-state phase transition coincides with our theoretical model. This model approaches something fundamental in the mechanism leading to the transition, and it is important in developing new and practical controllable quantum devices.     

Influence of Polycrystalline Structure on Dynamic Strength and Fracture Character of an Aluminum Alloy in Different Welding Joint Zones

Russian Physics Journal - Plastic strain localization and fracture in the nugget and thermo-mechanically affected zone of a friction stir welded Al6061-T6 alloy are numerically investigated....     

Influence of Noncommutativity on the Motion of Sun-Earth-Moon System and the Weak Equivalence Principle

Features of motion of macroscopic body in gravitational field in a space with noncommutativity of coordinates and noncommutativity of momenta are considered in general case when coordinates and momenta of different particles satisfy noncommutative algebra with different parameters of noncommutativity. Influence of noncommutativity on the motion of three-body Sun-Earth-Moon system is examined. We show that because of noncommutativity the free fall accelerations of the Moon and the Earth toward the Sun in the case when the Moon and the Earth are at the same distance to the source of gravity are not the same even if gravitational and inertial masses of the bodies are equal. Therefore, the Eotvos-parameter is not equal to zero and the weak equivalence principle is violated in noncommutative phase space. We estimate the corrections to the Eotvos-parameter caused by noncommutativity on the basis of Lunar laser ranging experiment results. We obtain that with high precision the ratio of parameter of momentum noncommutativity to mass is the same for different particles.     

Equation of the Crack Front with Allowance for the Metric Properties of the Material

The geometric representation of the crack front propagation is examined in a Finsler space in the context of the discontinuity theory. The structure of the medium is taken into account via the connectivity coefficients of the Finsler space and its metric. It is demonstrated that this approach leads to the construction of fiber spaces and allows the gauge invariance to be introduced correctly and noncontradictorily into the fracture theory. The Lie derivative is used to proceed from discontinuities to differentials. The equation of the front crack surface is retrieved.     

压力下替位氢对金属锂能带结构的影响

 利用第一原理的平面波-赝势密度泛函方法,研究了零温下体心立方（bcc）金属锂由于氢的替位掺杂和外界压力的改变所引起的电子结构变化。结果表明：掺杂体系仍然呈金属性,但是由于氢原子俘获了一个金属自由电子,具有了离子属性,使得费米面以下出现了孤立能带和带隙,最低金属价带偏离了自由电子带,形成鞍型带底,其它价带和导带均出现不同程度的简并解除和带型畸变。在压力的作用下,带隙加宽,费米面下的孤立带趋向于一条直线,成为一条能级。     

Manipulating Skyrmion Motion on a Nanotrack with Varied Material Parameters and Tilted Spin Currents

Magnetic skyrmions are topological quasiparticles with nanoscale size and high mobility, which have potential applications in information storage and spintronic devices. The manipulation of skyrmion’s dynamics in the track is an important topic due to the skyrmion Hall effect, which can deviate the skyrmions from the preferred direction. We propose a new model based on the ferromagnetic skyrmion, where the skyrmion velocity can be well controlled by adjusting the direction of the current. Using ...     

运动状态对卫星多谱段光学特性的影响分析

综合考虑卫星的背景特性、材料特性、结构特性和轨道特性,研究了在轨运行卫星存在的自旋稳定、三轴稳定和"翻滚"三种运动状态对卫星光学特性的影响。基于光辐射理论,结合探测器的性能参数,建立了自旋稳定、三轴稳定和"翻滚"三种运动类型卫星的多谱段光学特性计算的数学模型,并进行了实验验证。以海洋一号卫星和实践二号卫星为例,进行了运动状态对卫星多谱段光学特性影响的仿真分析。仿真结果表明,不同运动状态的卫星多谱段辐射特性存在较大的差异。分析结果可为卫星的探测和辨识提供一定的参考价值。     

高Q腔中原子内态布居对原子平移运动的影响

基于原子作双光子共振跃迁的原子－场缀饰态，讨论了驻波腔场中两能级原子的量子化平移运动与原子内态布居间的相互影响，结果表明原子平移运动敏感地依赖于原子的内态布居，特别当原子处于两内态等权重同相位叠加态时，平移运动呈现出很稳定的特征。     

Influence of the Yarkovsky Effect on Motion of Asteroids with Small Perihelion Distance

Russian Physics Journal - We present estimates of the transversal acceleration associated with the Yarkovsky effect for a set of asteroids with small perihelion distance. It is shown that in most...     

富铁原料对铁系析晶釉的影响机制初探

黑釉瓷是我国古代最普遍的色釉瓷品种之一,由于原料易得,故各地都有烧造,尤其在宋代得到迅猛发展.目前,在古代黑釉中已发现α-Fe2 O3,ε-Fe2 O3,Fe3 O4等多种铁的氧化物析晶,但关于富铁原料对晶体种类的影响机制却鲜有报道.因此,本研究以汝州大峪青石头、红石头和杭州紫金土作为研究对象,采用超景深显微镜、X射线...     

Dynamic Response and Fracture Mechanism of a Novel Structural Radar Absorbing Material

A novel structural radar absorbing material （SRAM）, which gives the normal resin-base composites new function, is prepared. The dynamic compressive tests of SRAM are carried out in both in-plane and normal directions of composites by means of the split Hopkinson pressure bar （SHPB）. In the compressive test along in-plane direction, failure occurs at the interface between a fibre and the matrix. A fracture mode and mechanism was proposed to explain these results. The addition of absorbing particles results in the deterioration of the compressive properties. However, there is no obvious decrease on compressive strength of SRAM with the radar absorbing properties.     

Fine Structure and Fracture Surface of Low-Carbon Steel Welds

Russian Physics Journal - Using the methods of modern physical materials science, the structural phase state, the defect substructure and the fracture surface of low-carbon alloy steel welds formed...     

La-Ce共掺杂锐钛矿TiO2的缺陷形成能和电子结构分析

采用基于密度泛函的第一性原理研究了稀土元素La、Ce共掺杂锐钛矿相TiO₂的缺陷形成能,缺陷电荷转变能级以及电子结构.研究发现,富氧状态下La、Ce掺杂以及La-Ce共掺的缺陷形成能均为负值,而贫氧状态下La、Ce掺杂形成能为正,表明La、Ce的掺杂TiO₂只能在氧气氛制备条件下进行;替代Ti掺杂缺陷电荷转变能级计算结果表明:0/1-的缺陷电荷转变能级分别位于VBM上面0.522 eV及2.440 eV处;与纯锐钛矿相TiO₂相比,La、Ce单掺杂以及La-Ce共掺杂均能减小TiO₂的禁带宽度,但共掺杂体系的禁带宽度更窄,因此共掺杂体系将更有利于提高TiO₂对可见光的响应能力和光催化性能.     

Effects of Stone-Wales Defect Symmetry on the Electronic Structure and Transport Properties of Narrow Armchair Graphene Nanoribbon

We report a first principles calculation to investigate the electron transport properties of defected armchair graphene nanoribbon (AGNR) influenced by Stone-Wales (SW) defect. The SW defect is found to be able to effectively influence the electronic structure of the defected AGNRs, and their electron transport behaviors can exhibit prominent differences depending on the symmetry of the nanostructured morphology. Moreover, our simulations have revealed that the introducing of the SW defect could be favorable for the electron transport of the defective AGNR. Our investigation has confirmed the possibility of tuning the electron transport of graphene nanoribbon by introducing a topological defect, which could be helpful to extending the field of applications for graphene nanoribbon-based nanodevices.     

方孔微通道板结构缺陷对成像质量的影响

方孔微通道板(MCP)作为一种新型X射线波段光学成像系统,因其具有大视场、高分辨率、能够收集大量辐射并将其准直或聚焦等优点,越来越多地受到了人们的关注。但在MCP制作和加工过程中,难免会使微通道产生一定的结构缺陷,对其成像质量造成严重的影响。利用Tracepro软件建立了标准方孔MCP模型和具有不同结构缺陷的MCP模型,并基于蒙特卡罗(MTC)光线追迹方法对这些模型进行模拟成像。分别讨论了Taper型、Twist型和Nonsquare型结构缺陷对成像质量的影响。然后以溴钨灯作为光源,在可见光波段对实验室现有的4块方孔MCP进行了成像实验,所得实验结果与模拟结果基本吻合,验证了模拟结果的正确性。模拟和实验结果表明,以上3种结构缺陷均会造成十字像中央亮斑面积增大、强度降低等情况,所不同的是Taper型结构缺陷使会聚光线分裂成两条,而这两组平行的会聚线相交形成4个焦点,其能量要比单一聚焦能量衰减很多,从而对成像质量影响更大。该研究为今后研究曲面MCP和基于MCP的X射线光学系统奠定了重要基础。