Laser-assisted growth of microstructures on spatially confined substrates

Laser-assisted growth of microstructures on spatially confined substrates is experimentally studied. The experiments are performed using a copper-vapor laser with pulse duration of 20 ns, and repetition rate of 7.5 kHz. Ropes made of Ni-Cr wires with diameter of 50-100 μm, as well as the edge of 50 μm thick Ni foils were exposed to multiple laser pulses. The morphology of structures that grow on these targets drastically differs from periodic array of micro-cones observed on semi-infinite targets made of the same materials. In case of wires the structures have radial symmetry and do not show any periodicity, while in case of a foil the periodic structures are aligned along its edges. The model of micro-structures formation in spatially confined conditions is elaborated based on the numerical solution of the heat conduction and hydrodynamics equations. It is shown that boundary conditions imposed by confined target onto melt flow strongly affect the structure morphology. The micro-structure formation is related to the confinement of melt flow under combined action of both capillary forces and gradients of surface tension.     

铝合金中十种微量元素的光谱分析

本文叙述的方法是将固体铝合金样品在车床或铣床上加工成平面，然后以选好的仪器测量条件，用铝元素做内标，按照自编分析程序在ＭＢＳ火花台上氩气气氛中激发，进行火花－原子发射光谱法测定。此方法快速、简便，标准样品所得分析结果基本与标称值吻合，３次测定结果相对偏差≤２０％。在重复性实验中，不同时间内测定同一样品１０次，１０个被测元素结果的相对标准偏差ＲＳＤ≤１０％。     

Initial interface study of Au deposition on GaN(0 0 0 1)

Synchrotron radiation photoelectron spectroscopy (SRPES) has been used to study the electronic structure of the Au/GaN(0 0 0 1) system at the initial growth stage. The peak fitting of Au4f_7/2 core-level and the energy shift of valence band indicate that Au–Ga alloy were formed in the interface reaction. According to the Ga3d signal intensity attenuation vs. the gold film thickness, the early growth mode is considered to be 3D mode above the reaction layer. By using the Linear Augmented Plane Wave method the density of states (DOS) for GaN and Au bulk are calculated within the framework of local functional theory. The theoretical results agree with the valence band structure quite well. The mechanism of interface reaction is discussed based on the experimental and theoretical results.     

ICP-AES测定硅锶合金中锶、钙、铝

采用ICP—AES法测定硅锶合金中锶、铝、钙含量，并对样品的溶解方法、分析谱线的选择、基体及共存元素的影响进行了研究。方法简便、快速，精密度和准确度较好。     

Coaxial metal and magnetic alloy nanotubes in polycarbonate templates by electroless deposition

We present a novel technique for the preparation of coaxial metal and magnetic alloy nanotubes, which is demonstrated for the coaxial nanotubes of Ni/Co and Ni/CoNiFe alloys deposited in activated polycarbonate templates using electroless plating. For each metal or alloy the tube wall thickness was controlled to be less than 100 nm. The process involved two consecutive deposition steps from hypophosphite and/or borane reducing agent based electroless plating solutions. We further characterise the magnetic properties of the ternary magnetic alloy films and coaxial nanotubes. The coaxial tubes show homogenous wall thickness and composition, which is delineated from the magnetic measurements.     

Density Functional Theory (DFT) modeling and Monte Carlo simulation assessment of inhibition performance of some carbohydrazide Schiff bases for steel corrosion

DFT and Monte Carlo simulation were performed on three Schiff bases namely, 4-(4-bromophenyl)-N^′-(4-methoxybenzylidene)thiazole-2-carbohydrazide (BMTC), 4-(4-bromophenyl)-N^′-(2,4-dimethoxybenzylidene)thiazole-2-carbohydrazide (BDTC), 4-(4-bromophenyl)-N^′-(4-hydroxybenzylidene)thiazole-2-carbohydrazide (BHTC) recently studied as corrosion inhibitor for steel in acid medium. Electronic parameters relevant to their inhibition activity such as E_HOMO, E_LUMO, Energy gap (ΔE), hardness (η), softness ($\sigma$), the absolute electronegativity (χ), proton affinity $\left(\mathrm{PA}\right)$ and nucleophilicity (ω) etc., were computed and discussed. Monte Carlo simulations were applied to search for the most stable configuration and adsorption energies for the interaction of the inhibitors with Fe (110) surface. The theoretical data obtained are in most cases in agreement with experimental results.     

可充电镁电池负极改性策略

可充电镁电池具有理论体积比容量大、 地壳丰度高、 成本低、 环境友好及更为安全等优点, 是未来高能量存储系统发展的重要方向之一. 在大多数传统电解液中, 镁金属负极表面形成的钝化膜会阻碍镁的可逆沉积溶解过程, 从而限制了可充电镁电池的商业化应用. 由于存在成本高、 合成步骤复杂、 离子电导率低及难以同时与正负极兼容等问题, 聚焦于解决镁负级钝化问题的电解液研究陷入瓶颈. 因此, 通过对镁电池负极进行修饰改性, 使其在传统电解液中实现可逆过程是一种具有发展前景的策略. 本文从合金负极及人工界面形成两方面总结了近年来用于可充电镁电池负极改性的策略, 并在分析对比的基础上提出了进一步发展的结论和展望.     

Au-Pd与Au-Pt合金团簇稳定结构对比

由贵金属元素组成的合金团簇在光、电、磁和催化等领域吸引了广泛的研究兴趣.本文基于多体Gupta势函数采用内核构建的自适应免疫优化算法优化了Au-Pd和Au-Pt团簇最稳定结构.研究结果显示98原子Au-Pd与Au-Pt团簇均包含面心立方结构、十面体、二十面体和Leary四面体结构,但是两者的构型分布上存在着差异.键数变化分析结果显示Au原子分布趋势接近.此外,147原子Au-Pd和AuPt团簇均为完整二十面体结构.序列参数分析显示均形成核层结构.     

Ion implantation of sulphur into GaAs,GaP and ge monocrystals

The possibility of using ion implantation to form high concentration junctions in semiconductors has been explored for the specific case of sulphur in GaAs, GaP and Ge. The effects of ion dose, ion energy, crystal orientation and target temperature have been investigated by means of radiotracers and sectioning techniques.

It is shown that high concentration junctions can be formed using an incident ion having high electronic stopping cross-section and implanted along the <110< channeling directions of the crystals. A large increase in junction concentration may be obtained when the GaAs and GaP crystals are maintained at 150 °C during the implantation process, but this is not the case with Ge. Rutherford back-scattering of 1 MeV He⁺ ions has been used to measure the ion-bombardment induced damage in the crystals and to show how this damage can be annealed by heating the crystal during the implantation. The annealing, at temperatures up to 150 °C, is most effective in GaAs and least effective in Ge.