荧光分光光度法分析天然水中铝形态的研究

基于衍生试剂与天然水中原生有机质之间对铝的竞争配位,建立了用荧光分光光度法区分天然水中铝形态的方法。以铬蓝黑R和桑色素为分析试剂可以测定无机单核铝,而以8-羟基喹啉为分析试剂则可以测定总单核铝,实验结果与用Driscoll方法所得到的结果基本一致。为有目的地选择分析试剂,在天然水自身pH条件下进行铝形态的直接分析提供了一个新的方法选择。相对来说,荧光分光光度法操作更加简单,条件温和,对原始样品几乎没有扰动,天然水中铝形态分析的结果更符合真实情况。     

氧化铝与Al(100)基体间界面原子结构研究

本文介绍了用MeV离子散射和沟道效应研究单晶铝表面无定型氧化层与基体之间界面原子结构的方法。报道了Al₂O₃/Al(100)界面原子结构的实验结果。实验表明,在纯氧气氛围中400℃下生成的氧化铝膜,铝和氧原子浓度比例严格为2与3之比;Al₂O₃膜和Al(100)基体之间的界面极其陡峭,氧化铝膜下Al(100)基体表面的再构层不大于一个原子层。由实验测量与用Monte Carlo方法计算结果比较,得到再构层原子离开原来晶 关键词：     

峰值积分法分析铝的研究与应用

在直读光谱仪上,用峰值积分法测定低合金钢中铝,酸溶铝和酸不溶铝的含量,确定最佳分析条件,研究峰值积分法的分析机理,本方法用于测定低中不同状态铝,结果符合要求.     

Determination of the Al content in aluminum‐modified SiO2 stationary phases using X‐ray scattering spectroscopy

This paper describes the determination of aluminum in the presence of silica using a method based on X‐ray scattering spectrometry coupled with chemometric tools (principal component analysis and partial least squares) that treat samples according to their Al concentrations. Samples were prepared by mixing Al and Si oxides. X‐ray spectra of all samples, including pure oxides of aluminum and silicon, were submitted to the chemometric tools. Principal component analysis results show that it is possible to classify three subgroups of Al (low, medium and high Al content), whereas partial least squares 1 was used to construct calibration and cross‐validation models for Al in the presence of Si. The method is simple, fast, does not require sample dissolution prior to analysis, is of low cost and can be applied as a routine procedure. The method was used to quantify Al in some chromatographic stationary phases covered with a layer of Al₂O₃. Good correlations with low errors were obtained. Copyright © 2013 John Wiley & Sons, Ltd.     

Phase diagram of the Al–Er–Mo ternary system at 873 K

The phase relationship in the Al–Er–Mo ternary system at 873 K has been investigated based on the equilibrated method mainly by means of X-ray powder diffraction and scanning electron microscopy. The existence of 10 binary compounds and two ternary compounds has been confirmed. The results present that the isothermal section at 873 K is governed by 15 single-phase regions, 29 two-phase regions and 15 three-phase regions. By using the phase-disappearing method, Al₈Mo₃ has a narrow homogeneity range (from 72 to 73 at% Al), while the homogeneity range of AlMo₃ is from 21% to 28.5% at% Al. Also, the maximum solubility of Al in Mo is about 16 at%.     

Lifetime measurements in 29 Al

The lifetimes of the first six excited states of ²⁹Al have been measured by the DSA method with two different reactions,²⁶Mg(α, p)²⁹Al and²⁷Al(t, p)²⁹Al. The recoil distance method was also used to remeasure the mean lifetime of the first excited state, leading to a value τ_m = 6.5 ± 0.5 ps. Experimental results are compared with shell model calculations.     

Nanoporous Al sandwich foils using size effect of Al layer thickness during Cu/Al/Cu laminate rolling

The roll bonding technique is one of the most widely used methods to produce metal laminate sheets. Such sheets offer interesting research opportunities for both scientists and engineers. In this paper, we report on an experimental investigation of the ‘thickness effect’ during laminate rolling for the first time. Using a four-high multifunction rolling mill, Cu/Al/Cu laminate sheets were fabricated with a range of thicknesses (16, 40, 70 and 130 μm) of the Al layer. The thickness of the Cu sheets was a constant 300 μm. After rolling, TEM images show good bonding quality between the Cu and Al layers. However, there are many nanoscale pores in the Al layer. The fraction of nanoscale pores in the Al layer increases with a reduction in the Al layer thickness. The finite element method was used to simulate the Cu/Al/Cu rolling process. The simulation results reveal the effect of the Al layer thickness on the deformation characteristics of the Cu/Al/Cu laminate. Finally, we propose that the size effect of the Al layer thickness during Cu/Al/Cu laminate rolling may offer a method to fabricate ‘nanoporous’ Al sandwich laminate foils. Such foils can be used in electromagnetic shielding of electrical devices and noisy shielding of building.     

Chen’s lattice inversion embedded-atom method for Ni-Al alloy

The structural properties,the enthalpies of formation,and the mechanical properties of some Ni-Al intermetallic compounds(NiAl,Ni3Al,NiAl3,Ni5Al3,Ni3Al4) are studied by using Chen’s lattice inversion embedded-atom method(CLI-EAM).Our calculated lattice parameters and cohesive energies of Ni-Al compounds are consistent with the experimental and the other EAM results.The results of enthalpy of formation indicate a strong chemical interaction between Ni and Al in the intermetallic compounds.Through analyzing the alloy elastic constants,we find that all the Ni-Al intermetallic compounds discussed are mechanically stable.The bulk moduli of the compounds increase with the increasing Ni concentration.Our results also suggest that NiAl,Ni3Al,NiAl3,and Ni5Al3 are ductile materials with lower ratios of shear modulus to bulk modulus;while Ni3Al4 is brittle with a higher ratio.     

Co、Ni和Ga合金化对DO_(19)-Ti_3Al弹性性能影响的第一性原理研究

采用第一性原理的方法研究了Co、Ni和Ga元素对DO_(19)-Ti_3Al晶体的弹性性能的影响,结果表明:Co和Ni原子倾向于置换Ti原子而Ga原子则更倾向于置换Al原子;Co和Ni元素固溶可以减弱晶体内部电子杂化效应从而增大Ti_3Al晶体的本征塑性,其中Co元素的对晶体的本征塑性的增大效果显著;Ga元素固溶后Ti_3Al晶体的强度和硬度将得到提高.     

Computational study of the surface properties of aluminum nanoparticles

We calculate the surface energy, surface stress, and lattice contraction of Al nanoparticles using ab initio density functional and empirical computational techniques. Ab initio calculations are carried out using the siesta pseudopotential method combined with the generalized gradient approximation. Empirical calculations are conducted using the embedded atom method. The ab initio density functional approach predicts the surface energies of Al nanoclusters to be in the range of 0.9-2.0 J/m². These values are consistent with the surface energy of bulk aluminum and are close to the surface energies of silver nanoparticles calculated in our previous study. In contrast to our previous results for Ag nanoparticles, we found a significant discrepancy between the theoretical values of surface energy and stress for Al nanoclusters. This result could be explained by a greater degree of surface reconstruction in Al clusters than in Ag clusters.     

激光微等离子体光谱分析法测定土壤中的铝钙

采用YJG-Ⅱ激光微区分析仪结合CCD光栅光谱仪构成的激光微等离子体光谱分析系统,在减压氩气环境下,以土壤标样为样品,测量了土壤中铝元素和钙元素的含量,对激光微等离子体光谱分析法定量分析土壤中元素的准确度与可行性进行了研究。实验中分别以Al Ⅰ 394.40 nm和Ca Ⅱ 396.85 nm为分析线,采用“三标准试样法”,由计算机拟合logI～logC工作曲线,对土壤中铝、钙进行了测量。结果表明：对此两种元素定量分析的相对标准偏差(RSD)最大为5.80%,定量分析结果与标准值的相对偏差最大为7.65%,说明该方法对土壤中铝、钙的测定满足分析精确度的要求。     

Metal-ceramic contact angles determined by thin film techniques

A method of estimating contact angles is described in which 1000 A thick layers of metals are condensed from the vapour. If condensation takes place at temperatures greater than about 0.8 T_m the film is observed to break up into drops which are approximately segments of spheres, and the contact angle may be calculated from measurements on the drop size when the average film thickness is known. The experimental method is straightforward and relatively very fast, yet gives results in good agreement with earlier measurements. Results for the following metals on sapphire are presented: Al, Ag, Au, Cu, In, Sn. In addition results for Al on quartz are discussed, and it is suggested that the method may give meaningful results even when, as in this case, chemical reaction takes place.     

Study of Ni/Si(1 0 0) solid-state reaction with Al addition

The characteristics of Ni/Si(1 0 0) solid-state reaction with Al addition (Ni/Al/Si(1 0 0), Ni/Al/Ni/Si(1 0 0) and Al/Ni/Si(1 0 0)) is studied. Ni and Al films were deposited on Si(1 0 0) substrate by ion beam sputtering. The solid-state reaction between metal films and Si was performed by rapid thermal annealing. The sheet resistance of the formed silicide film was measured by four-point probe method. The X-ray diffraction (XRD) was employed to detect the phases in the silicide film. The Auger electron spectroscopy was applied to reveal the element profiles in depth. The influence of Al addition on the Schottky barrier heights of the formed silicide/Si diodes was investigated by current-voltage measurements. The experimental results show that NiSi forms even with the addition of Al, although the formation temperature correspondingly changes. It is revealed that Ni silicidation is accompanied with Al diffusion in Ni film toward the film top surface and Al is the dominant diffusion species in Ni/Al system. However, no Ni_xAl_y phase is detected in the films and no significant Schottky barrier height modulation by the addition of Al is observed.     

Al高掺杂浓度对ZnO禁带和吸收光谱影响的第一性原理研究

采用密度泛函理论框架下的第一性原理平面波超软赝势方法, 建立了未掺杂与不同浓度的Al原子取代Zn原子的两种Zn_1-xAl_xO超胞模型,分别对模型进行了几何结构优化、态密度分布和能带分布的计算. 结果表明: ZnO高掺杂Al的条件下, 掺杂的Al原子浓度越大,间隙带越窄, 蓝移越弱. 计算结果和实验结果相一致.     

H,O,N,He原子掺杂Al原子的第一性原理研究

采用密度泛函理论框架下的第一性原理平面波赝势方法,对Al中分别加入H,O,N和He原子后的晶体状态进行了研究.通过晶体结构和形成能分析比较了杂质原子占据不同位置的难易程度及对晶体稳定性的影响,并从态密度、电荷密度和电荷布居的角度,分析了其电子结构.结果表明:H、O和N原子占据金属Al的四面体间隙最稳定,而He原子主要占据金属Al的八面体间隙. O和N原子与Al原子具有强烈的共价作用,H原子与Al原子存在共价作用但相对较弱,而He原子与Al原子的相互作用以范德华力为主.进一步揭示了四种原子在金属Al中不同行为的电子机制.     

B（N）掺杂单壁碳纳米管的Al原子吸附性能的第一性原理研究

采用基于密度泛函理论的平面波赝势方法和广义梯度近似,对未掺杂、掺B、掺N的碳纳米管(CNT)不同位置上Al原子的吸附进行了几何优化,计算了吸附Al、掺杂前后CNT的能带结构、态密度、差分电荷密度、电荷布居数和吸附能.计算结果表明,掺B使CNT形成缺电子状态,利于具有自由电子的Al原子的吸附结合,可显著提高Al在金属性的(5,5)CNT和半导性的(8,0)CNT外壁的吸附能;掺杂N形成多电子状态,在费米能级附近半满的施主能级也利于填充Al的价电子,改善Al在(5,5)CNT和(8,0)CNT外壁的吸附结合性 关键词： 密度泛函理论 单壁碳纳米管 B(N)掺杂 Al原子吸附     

Surface structure and energy of B2 type intermetallic compound NiAl

The surface structure and energies for 22 surfaces of NiAl, an ordered intermetallic compound of B2 structure, have been studied by using embedded atom method. The results show that, for alternating Ni and Al surfaces with odd numbers of the sum of their three Miller indices, the energy difference between the Ni terminated surface and Al terminated surface increase linearly with increasing the interlayer distance. So from surface energy minimization, the Al terminated surface is favorable for each alternating Ni and Al surface. This is in agreement with experimental results. However, the energy of the (1 1 0) surface belonged to the other kind of the surface consisted of stoichiometric atomic layers and with even numbers of the sum of their three Miller indices, is the lowest in all two kinds of the surfaces. Therefore the (1 1 0) texture of NiAl appears mostly in the experiments.     

Acceleration ability of high explosives and their mixtures with fuel additives. 1. Assessment by the M-40 method

The relationship between the chemical composition of the detonation products and the acceleration ability of explosives is considered. Based on theoretical and experimental studies, it is concluded that, at volumetric energy content, the most important parameter is the average atomicity of the molecules constituting the detonation products. Among the CHNOF-containing explosives, groups with high acceleration ability were identified. The experimental results on the acceleration ability obtained using the M-40 method are reported for mixtures of dispersed Al with HEs with different oxygen balance and for mixtures of HMX-based HE with Al, Mg, Y, Ta, ZrH₂. An analysis of the acceleration ability on the charge density for BTNEN and mixtures thereof with Al made is possible to estimate the degree of conversion of the energy of combustion of Al under the gasdynamic conditions typical of the M-40 method, which turned out to be 20–40%.     

Effect of shape of Fe3Al particles on their microwave permeability and absorption properties

Flake-shaped and sphere-shaped Fe₃Al powder-paraffine composites have been studied in the microwave frequency range. Mössbauer results show that the flake-shaped Fe₃Al particles have easy magnetization plane, which indicates that it is planar-anisotropy. Enhanced permeability is achieved in flake-shaped Fe₃Al compared with the sphere-shaped Fe₃Al. The permeability is further enhanced by using a rotational orientation method. The complex permeability can be characterized by the superposition of two types of magnetic resonance. The resonance peak at high frequency is attributed to the natural resonance, while the peak at low frequency is attributed to the domain-wall resonance. By employing the shape effect and the rotational orientation, the peak frequency of reflection loss for the oriented sample was adjusted to L-band. The planar-anisotropy Fe₃Al powder-paraffine composite can be attractive candidates for thinner microwave absorbers in L-band (1-2 GHz).     

稀土对镁合金应力腐蚀影响电子理论研究

建立了镁合金纯净晶界及其析出Mg₁₇Al₁₂相的晶界原子集团，应用实空间的递归方法计算了铝、稀土元素在晶界的偏聚能，晶界处铝、稀土原子间相互作用能和不同体系的费米能级.讨论了铝、稀土在晶界的偏聚行为，铝、稀土原子间的相互作用与有序化的关系及稀土对镁合金晶间应力腐蚀影响的物理本质.研究发现：铝、稀土原子偏聚于晶界；铝原子间相互排斥，在晶界区形成有序相Mg₁₇Al₁₂，稀土原子间互相吸引，形成原子团簇；稀土原子团吸引铝原子，使铝原子渗入稀土团簇中，形成稀土化合物.因此，稀土具有抑制铝在晶界形成导致应力腐蚀的阴极相Mg₁₇Al₁₂的作用，提高镁合金的晶间应力腐蚀抗力. 关键词： 电子理论 镁合金 应力腐蚀 稀土