电化学沉积金属铜的分形枝晶生长控制与性能

 以CuSO_{4/sub>为前驱体,HCl为添加剂,采用电化学沉积方法,在室温条件下制得了μm级、面心立方结构分形铜的枝状晶体,研究了铜离子浓度、硫酸浓度、电流密度、沉积时间、氯离子浓度等实验参数对分形枝状铜晶体尺寸、结构的影响。结果表明：硫酸的浓度对铜沉积物结构无明显影响;随着Cu^{2+/sup>浓度的不断增大,铜沉积物的分形效果越来越明显;增大电流密度（0.4～1.6 A·cm-2/sup>）,铜沉积物由致密向多分枝的开放型转变;延长沉积时间（大于等于5 min）,可获得含大量次级分枝铜的晶体;适当增加盐酸用量（0.05～0.20 mol/L）,铜沉积物枝晶尺寸显著减小。最后讨论了分形枝晶铜在碱性条件下氧化甲醇的电化学性能。}}     

Theoretical study of photon emission from single quantum dot emitter coupled to surface plasmons

Motivated by the recent pioneering advances on nanoscale plasmonics and also nanophotonics technology based on the surface plasmons (SPs), in this work, we give a master equation model in the Lindblad form and investigate the quantum optical properties of single quantum dot (QD) emitter coupled to the SPs of a metallic nanowire. Our main results demonstrate the QD luminescence results of photon emission show three distinctive regimes depending on the distance between QD and metallic nanowire, which elucidates a crossover passing from being metallic dissipative for much smaller emitter-nanowire distances to surface plasmon (SP) emission for larger separations at the vicinity of plasmonic metallic nanowire. Besides, our results also indicate that, for both the resonant case and the detuning case, through measuring QD emitter luminescence spectra and second-order correlation functions, the information about the QD emitter coupling to the SPs of the dissipative metallic nanowire can be extracted. This theoretical study will serve as an introduction to understanding the nanoplasmonic imaging spectroscopy and pave a new way to realize the quantum information devices.     

一维金属光栅的光学反射吸收

利用RCWA(rigid coupled-wave analysis)方法研究了一维金属光栅的反射特性,考察了 瑞利反常、表面等离激元驻波共振和几何共振三种共振吸收机理,分析了这三种机理的相互作用,如表面等离激元驻波共振和几何共振可以形成混合模式. 在反射式复合金属光栅中,确认了第四种共振形式,即相位共振. 数值计算表明相位共振对光学吸收的影响有两种形式: 当光栅周期大于一个波长时,相位共振导致尖锐的吸收峰,峰位在几何共振吸收峰一侧;当光栅周期小于一个波长时,相位共振导致混合模式的共振吸收峰发生劈裂. 对一维金属光栅反射特性的研究增加了对金属光栅共振吸收模式及其相互作用的认识. 关键词： 一维金属光栅 瑞利反常 表面等离激元 相位共振     

Frequency dispersive complex permittivity and permeability of ferromagnetic metallic granular composite at microwave frequencies

We experimentally studied the frequency dependent complex permittivity ε and permeability μ of composite composed of carbonyl iron powder (CIP) and epoxy resin in the frequency range 1-18 GHz. We found that the intrinsic ε and μ of CIP extracted from the measured ε and μ of composites follow the classical Maxwell equations and the Landau-Lifshitz-Gilbert (LLG) equation, respectively. The dependences of ε and μ of composites on the volume fraction of CIP (vf_CIP) were investigated using the two-exponent phenomenological percolation equation (TEPPE). We found that the TEPPE can fit the experimental results very well. Comparing the results of percolation parameters derived by experimental data at different frequencies, we show that the TEPPE is frequency independent for the composites at microwave frequencies. The results also show that the ε and μ spectrums of composites with definite vf_CIP can be correctly calculated by combining the TEPPE with the theoretical models of intrinsic ε and μ.     

Sensitive determination of diuron on zinc oxide nanoparticles modified carbon paste electrode in soil and water samples

An electrochemical sensor based on Zinc oxide nanoparticles (ZnONPs) modified carbon paste electrode was designed for the toxic diuron pesticide detection. The ZnONPs were synthesized through the hydrothermal route and their structural properties were investigated via scanning electron microscopy (SEM) and X-ray diffraction powder (XRD). The designed ZnONPs-modified carbon paste electrode (ZnONPs-CPE) was characterized using cyclic voltammetry and electrochemical impedance spectroscopy. The sensor showed significantly enhanced sensitivity on the diuron oxidation peak current, compared to the bare carbon paste electrode. Qualitative and quantitative analysis were performed using cyclic voltammetry (CV) and square wave voltammetry (SWV). Experimental parameters such as pH, amount of ZnONPs and frequency were evaluated and the optimized conditions were obtained with 0.1 M phosphate buffer solution at pH=8, a frequency of 50 Hz and a quantity of 5 mg of ZnONPs. Under these conditions, linear responses ranging from 1.3 to 7.7 μM and 8.6 to 30 μM of diuron were obtained, with correlation coefficients of R²=0.994 and 0.996 respectively. Detection and quantification limits of 0.22 μM and 0.84 μM (S/N=3) were respectively achieved based on the 3σ method. The interference of some ions on the oxidation peak of diuron on ZnONPs-CPE was also evaluated and no interference was observed, therefore demonstrating the selectivity of the sensor. The proposed sensor, designed with ecofriendly materials, is sensitive, selective and was effectively used for diuron determination in soils and water samples with recoveries ranging from 98 % to 101.5 %.     

New MgLi based Mg-Li-Cu-(Y, Gd) BMGs: Preparation, glass forming ability and mechanical properties

Through calculating the forming enthalpy by Modified Miedema Model, new MgLi-based bulk amorphous alloys Mg-Li-Cu-(Y, Gd) have been successfully designed and fabricated by conventional copper mold injection casting method. The X-ray diffractometer and differential scanning calorimeter results indicated that the as-cast Mg-Li-Cu-(Y, Gd) alloys were fully amorphous structure after casting to critical diameter as large as 4 mm and 2 mm. The experimental results also proved that with increasing Li content (3 at.%-8 at.%), the supercooled liquid region temperature of Mg-Li-Cu-(Y, Gd) alloys gradually decreased accompanying the reduce of glass forming ability. It was also found that appropriate addition of metal Li effectively increased the fracture strength and elastic strain and reduced their corresponding densities. The maximal fracture strength reached 468 MPa and 478 MPa, respectively, which were much higher than normal MgLi-based crystalline alloys (~ 300 MPa).     

A network model with free-strand dynamics for polymer melts

 A network model for polymer melts is presented in which disentangled strands relax under flow conditions and may rejoin the network before complete relaxation. For simplicity, we study Gaussian strands that move affinely when incorporated in the network. Network strands are created and lost according to a time constant λ. Free strands have their dynamics given by the Bird-DeAguiar model as a crude representation of reptation and the hindered rotation experienced by polymer strands in melts. The model yields a shear-thinning viscosity with overshoot in the start-up viscosity η⁺ (t). The double-step strain results compare well with available experimental data. Received: 10 July 2000 Accepted: 10 July 2001     

卵形钢弹对铝合金靶板侵彻问题的数值模拟

 基于球形空穴膨胀理论（SCE）,采用ABAQUS有限元商业软件并结合其子程序的二次开发功能对钢弹侵彻金属靶进行3D有限元数值模拟。根据空穴膨胀理论,靶体对侵彻弹体的影响可以用一个作用在弹体表面的力函数代替,这样在进行数值模拟时就无须划分靶体网格,也避免了复杂的接触问题,从而使模拟大大简化。模拟所用卵形弹为VAR 4340钢弹,靶体为6061-T6511铝合金。模拟过程中考虑到弹体的可变形性和入射时的微小偏航角等实际情况,并且考虑到了弹身在运动过程中和靶体的接触分离效应。所得模拟结果与文献中的实验结果进行了比较,发现模拟结果与实验结果吻合得很好,并得到了一些有意义的推论。     

Fe-B-Y-Nb bulk metallic glasses in relation to clusters

Bulk metallic glass formations in the Fe-B-Y-Nb quaternary alloy system were investigated by using the cluster line rule in combination with the minor alloying principle. The Fe-B-Y ternary system was selected as the basic system and the intersections of cluster lines were taken as the basic ternary compositions. The basic compositions were further alloyed with minor amounts of Nb. After 3–5 at.% Nb was added, the basic composition Fe_68.6B_25.7Y_5.7, which was developed from the most densely packed cluster Fe₈B₃, formed 3 mm bulk metallic glasses. These quaternary bulk metallic glasses (Fe_68.6B_25.7Y_5.7)_100−x Nb _x (x = 3–5 at.%) are expressed approximately with a unified simple composition formula: (Fe₈B₃)₁(Y, Nb)₁. The (Fe_68.6B_25.7Y_5.7)₉₇Nb₃ bulk metallic glass has the largest glass forming ability with the following characteristic parameters T _g = 907 K, T _x = 1006 K, T _g/T _l = 0.644, γ = 0.434, and longness t = 22 mm. The combination of the cluster line rule and the minor-alloying principle is a promising new route towards the quantitative composition design of multi-component metallic glasses. Supported by the National Natural Science Foundation of China (Grant Nos. 50671018, 50631010 and 50401020) and the National Basic Research Program of China (Grant No. 2007CB613902)     

在金属基片上激光沉积YBCO超导薄膜

介绍了在金属基片上激光沉积缓冲层和ＹＢａ２Ｃｕ３ｏ７－ｘ（ＹＢＣＯ）高温超导薄膜的研究结果。在带ｙｔｔｒｉａ－ｓｔａｂｉｌｉｚｅｄ－ｚｉｒｃｏｎｉａ（ＹＳＺ）缓冲层的ＮｉＣｒ合金基片上,激光原位沉积出ＹＢＣＯ超导薄膜,薄膜的零电阻转变温度度４８Ｋ,７７Ｋ时临界电流密度约为２００Ａ／ｃｍ＾２;缓冲层的取向可以通过选择适当的沉积参数来改善;用扫描隧道电子显微镜对ＹＢＣＯ薄膜的微观结构分析表明：完善的螺