ICP-AES法测定高纯氧化铕中微量稀土和非稀土杂质时光谱干扰的消除及分析条件的优化

本文提出了ＩＣＰ－ＡＥＳ直接同时测定高纯氧化铕中１４个稀土和２０个非稀土杂质元素的分析方法。着重考察了铕基体对分析元素的基体效应，谱线干扰及背景影响等情况。用标准加入法测出氧化铕基准中的微量杂质元素，消除了由于忽略基准中的杂质元素的含量给分析测定带来的误差。同时对仪器的工作条件进行了优化。     

ICP-AES测定钽合金中的钨、铪

建立了ICP-AES直接测定钽合金中钨、铪的分析方法。采用基体匹配与背景扣除法消除钽基体对钨、铪的光谱干扰,选择多谱线平均值法进行了光谱分析。待测元素的回收率为98.0%—102.2%,相对标准偏差小于1.50%。本法简便、快速、准确度高,已用于钽合金产品的检验。     

沉淀分离-电感耦合等离子体质谱法测定高纯钨中铌铼含量

高纯钨具有高熔点、高密度和耐腐蚀等优点,是军事国防、核工业、半导体等领域不可或缺的材料,但其物理化学性能受杂质元素含量的影响较大。电感耦合等离子体质谱(ICP-MS)是一种检出限低、可进行多元素同时快速测定的无机质谱分析技术,但一些元素在测定时会遇到较为严重的基体复合离子质谱干扰问题。采用ICP-MS法测定高纯钨中Nb和Re时,Nb和Re分别受到基体钨的双电荷和氢化物离子干扰,这两种干扰难以通过反应池等技术进行消除。通过乙酸铅沉淀法分离溶液中钨基体从而消除质谱干扰,主要考察了钨基体对Nb和Re元素的干扰强度和内标元素对残留基体及仪器信号漂移的校正效果,探讨了溶样试剂、沉淀剂用量、酸度、沉淀温度和陈化时间等条件对基体分离的影响。实验结果表明,1 mg·mL-1质量浓度钨基体溶液对Nb和Re的测定均有显著的正干扰作用,其干扰强度随着钨质量浓度的增大而增强;当溶液中钨的质量浓度含量小于2 μg·mL-1时,由钨基体引起的质谱干扰可以忽略（考虑测定下限0.10 μg·g-1的要求）。通过各项试验,优化选择的条件为：硝酸-氢氟酸混酸溶样,加入600 μL氨水(1+1)和1.0 mL乙酸-乙酸铵缓冲溶液,在250 ℃条件下滴加2.7 mL 10 g·L-1醋酸铅溶液并陈化5 min,整个分离周期约10 min;基体分离后样品溶液以Cs作为内标进行测定。该方法简单快速,Nb和Re的检出限分别为0.007和0.036 μg·g-1,相对标准偏差分别为12%和4.8%,加标回收率分别为108%和105%,可以满足实际高纯钨样品的测定需求。     

ICP-AES法同时测定氯化锂和氢氧化锂中七种杂质元素

本文报导了用ＩＣＰ－ＡＥＳ法同时测定ＬｉＣｌ和ＬｉＯＨ·Ｈ２Ｏ中７种杂质元素Ａｌ、Ｂａ、Ｃａ、Ｆｅ、Ｍｇ、Ｓｉ、Ｚｎ的分析方法。研究了基体元素锂对被测元素的基体效应，采用基体匹配法与背景扣除法进行校正。被测元素的检出限为０．１－９．４ｎｇ／ｍＬ，加标试验回收率为９２％－１０９％，当杂质元素含量为０．０００１％－０．０２８％时，相对标准偏差小于７％。方法简便、快速、准确，用于样品分析，取得了满意的结果。     

ICP-AES直接测定硅灰石中Al、Mg、Fe

以电荷耦合器件为检测器的ＩＣＰ－ＡＥＳ光谱仪直接测定硅灰石中Ａｌ、Ｍｇ、Ｆｅ。研究了等离子体轴向观测方式下在炬中心通道及偏离中心通道位置，硅灰石中Ｃａ对各元素谱线基体效应。通过选取合适的工作参数与对比来消除基体干扰，测定了合成样及实际硅灰石样中Ａｌ，Ｍｇ，Ｆｅ基体匹配法，结果满意。     

卡尔曼滤波ICP－AES法分析稀土元素及其对光谱干扰的校正

本文以卡尔曼（Ｋａｌｍａｎ）滤波ＩＣＰ－ＡＥＳ法进行稀土元素分析，并研究了卡尔曼滤波对其光谱干扰的校正，以及富线基体元素对待测元素、待测元素之间的影响，考察了该方法的检出限、精密度和准确度以及影响滤波的因素。结果表明，该法能有效地消除和校正光谱干扰，减少对分析谱线的选择，改善分析的检出限，分析速度快，结果准确可靠，可适合各种稀土试样（高纯稀土、混合稀土）的日常分析。     

ICP—AES法同时测定硼铁中的主要成分及杂质

本文研究了用ＩＣＰ－ＡＥＳ法同时测定硼铁中的主要成分Ｂ、Ｆｅ及杂质元素、Ａｌ、Ｍｎ，Ｓｉ的方法。采用碱熔融法分解样品，选Ｃｄ作为内标元素。     

ICP－AES法测定钒酸钇晶体中的掺杂稀土元素铒和铕的含量

本文用硫酸溶解样品，以ＩＣＰ－ＡＥＳ法对钒酸钇晶体中掺杂稀土元素铒和铕进行测定，取得满意结果，回收率分别是９８％－１０４％和９６％－１０５％；相对标准偏差３％以内。文中选择了相宜的内标元素并研究了硫酸浓度和基体浓度对被测元素的谱线强度的影响。     

ICP—AES法同时测定掺质钒酸钙晶体中的钙,钒,钕,镱,锗

本文采用ＩＣＰ－ＡＥＳ法同时测定了掺质Ｃａ３（ＶＯ４）２，晶体中Ｃａ，Ｖ，Ｎｄ，Ｙｂ，Ｇｅ的含量，选择了合适的分析谱线和积分时间，试样用硝酸溶解后直接测定，方法简便，准确，快速，合成试样中各被测元素的回收率为９８％－１０４％，相对标准偏差〈４．０％，Ｎｄ，Ｙｂ，Ｇｅ的检出限为０．０００２－０．０１８μｇ／ｍＬ。     

ICP—AES中基体干扰效应及其机理研究 Ⅲ.有关干扰机理的探讨

本文对ＩＣＰ－ＡＥＳ中一些基体干扰现象的机理进行了讨论。指出ＩＣＰ低观察区域的增感效应是基体元素电离产生的离子和电子共同发挥作用的结果,基体对分析谱线的零干扰点主要与基体元素特性有关;Ａｌ元素在低观察区域对碱土金属元素的抑制效应仍是一种溶质挥发干扰。     

钨/石墨烯/钨面向等离子体复合材料力学与热学及耐辐照性能衰减的第一性原理计算

通过第一性原理计算研究了钨/石墨烯/钨复合材料相比于纯钨金属在力学与热学性质方面的变化，并用氦原子-空位缔合缺陷模拟核聚变辐照损伤评估等离子体辐照条件下的性能。计算结果表明：钨/石墨烯/钨复合材料的体积弹性模量、杨氏模量与剪切模量呈现一定程度的下降，但是提升了钨基材料的延展性；钨/石墨烯/钨复合材料的热膨胀系数有所增加，但是具有较高的最小热导率。本文阐述了石墨烯界面层可以对基体杂质与缺陷进行吸附的独特机制，通过这种机制，钨/石墨烯/钨复合材料在力学、热膨胀系数以及最小热导率有更低程度的衰减，这显示了钨/石墨烯/钨复合材料在抗辐照性能方面具有较大的应用潜力。     

过渡金属锆铁对钨中氢氦行为的影响

钨被广泛地认为是最具潜力的面向等离子体材料。钨在聚变堆中的服役过程中,会受到强束低能的氢氦粒子流的影响,其结果是钨的性能下降。本工作通过第一性原理计算的方法研究了过渡金属锆铁对钨中氢氦行为的影响。研究结果表明,锆或铁的掺入会使钨的机械强度降低,延展性增加;锆铁的掺入不会改变氢氦在钨中的最佳占位,但是它们对氢氦在钨中的稳定性有一定影响;锆和铁对钨中氢氦的捕获作用存在一个最佳作用半径;铁原子在短距离（< 3.626 Å）时对氦有捕获作用,在长距离（> 3.626 Å）时存在排斥作用,而锆对钨中氢氦均具有捕获作用;钨中氢表现为亲电子的性质,而氦表现出疏电子的特性。总体上讲,锆对钨中氢氦的捕获作用要强于铁对钨中氢氦的捕获作用。本研究工作能够为钨基面向等离子体材料制备提供理论指导。Tungsten was widely considered as a highly promising candidate of plasma facing material, while the presence of hydrogen and helium has an adverse effect on the performance of the tungsten. The effects of transition metals (zirconium, iron) on the behavior of hydrogen and helium in tungsten were investigated by using the first-principles calculation method. The results show that doping of zirconium and iron decreases the mechanical strength of tungsten a little, but they increase the ductility of tungsten; zirconium and iron can't change the best occupied site of hydrogen and helium in tungsten, but they have some effect on the stability of the point defects formed by hydrogen and helium in tungsten; there is the best attraction radius between the transition metals (zirconium, iron) and hydrogen or helium in tungsten; there is an attractive interaction between iron and helium in a short distance (<3.626 Å), but a repulsion interaction in a long distance (>3.626 Å). An attractive interaction exists between zirconium and helium or hydrogen in tungsten whatever the distance is; the hydrogen that in tungsten has an electrophilic nature, while the helium has opposite features. The attraction interaction between zirconium and hydrogen or helium in tungsten is stronger than that of iron. Our works in this paper might provide a theory guide for the selection and preparation of the tungsten based alloy that is used as the plasma facing materials.     

Spectral,fluorescent, photochemical and laser properties of some organic compound vapors

The mechanism of the recently discovered growth of tungsten needles by vapourphase deposition of tungsten in high electric fields is discussed. The process consists of microneedle growth on a cathode producing an electric discharge by decomposition of hexacarbonyltungsten under high-field conditions. A self controlling mechanism is suggested which draws ions preferably to the top of the growing tungsten needles. The ions can also trigger the deposit of neutral tungsten atoms on the needles. The process is not restricted to tungsten, but can be used also for production of a variety of needles of different metals including alloys.     

The tungsten powder study of the dispenser cathode

The intercorrelation of tungsten powder properties, such as grain size, distribution and morphology, and porous matrix parameters with electron emission capability and longevity of Ba dispenser cathodes has been investigated for the different grain morphologies. It is shown that a fully cleaning step of the tungsten powder is so necessary that the tungsten powder will be reduction of oxide in hydrogen atmosphere above 700 °C. The porosity of the tungsten matrix distributes more even and the closed pore is fewer, the average granule size of the tungsten powder distributes more convergent. The porosity of the tungsten matrix and the evaporation of the activator are bigger and the pulse of the cathode is smaller when the granularity is bigger by the analysis of the electronic microscope and diode experiment.     

H+辐照前后W涂层表面的XPS分析

对离子束混合技术在不锈钢基体上沉积的W膜进行了H+辐照前后的XPS分析,研究了H+辐照对W的结合能的影响.分析结果表明,沉积的W膜中除了单质钨外,还有部分钨的氧化物,H+辐照结果表明,H+的辐照使钨的结合能向低能方向偏移;钨的氧化物有所减少,说明污染的氧化物在一定程度上被择优溅射掉.     

场致发射阳极用钨网的寿命特性分析

 通过扫描电镜分析和实验验证，分析了场致发射阳极用钨网被破坏的成因。对钨网进行淬火处理，使钨网表面形成一定厚度的氧化膜，可显著提高钨网使用寿命。不同的淬火温度,将使钨网表面形成不同厚度的氧化膜。实验结果表明，氧化膜厚度的改变，将明显影响钨网的使用寿命。当脉宽90ns、束流6kA、能量1MeV的电子束透过钨网时，钨网表面的氧化膜厚度选在0.4μm左右为宜。     

Controllable preparation of tungsten/tungsten carbide nanowires or nanodots in nanostructured carbon with hollow macroporous core/mesoporous shell

Large scale tungsten nanowires and tungsten nanodots are prepared in a controllable way. The preparation is based on mechanisms of chemical vapor transportation and phase transformation during the reduction of ammonium metatungstate (AMT) in H₂. The AMT is first encapsulated into the hollow core of nanostructured carbon with hollow macroporous core/mesoporous shell (NC-HMC/MS) and forms nanorods, which are the precursors of both tungsten nanowires and tungsten nanodots. Just by controlling H₂ flow rate and heating rate in the reduction process, the AMT nanorods could turn into nanowires (under low rate condition) or nanodots (under high rate condition). Besides, via heat treatment at 1200℃, the as-obtained nano-sized tungsten could convert into W₂C nanorods or WC nanodots respectively. Furthermore, the diameter of the as-obtained tungsten or tungsten carbide is confined within 50 nm by the NC-HMC/MS, and no agglomeration appears in the obtained nanomaterials.     

中能高浓度氦离子注入对钨微观结构的影响

采用15 keV, 剂量1×10¹⁷/cm², 温度为600 ℃氦离子注入钨, 分别以块体钨研究氦离子对钨的表面损伤; 以超薄的钨透射电镜样品直接注入氦离子, 研究该条件下钨的微观结构变化, 以了解氦离子与钨的相互作用过程; 采用扫描电子显微镜、聚焦离子束扫描显微镜、透射电子显微镜、高分辨透射电子显微镜等分析手段研究氦离子注入对钨表面显微结构的影响及氦泡在钨微观结构演化中的作用.     

高温高压下碳化钨晶体的结构、力学、电子、光学以及热力学性能的第一性原理计算

本文利用密度泛函理论中的广义梯度近似对碳化钨晶体的三种结构(碳化钨相、闪锌矿相以及纤锌矿相)进行了优化,得到能量最低的稳定构型,并在此基础上计算了它的力学、电子、光学和高温高压下的热力学性质.研究表明:在0～300 GPa压力范围内,碳化钨相具有最高的稳定性.同时,高压下碳化钨相的弹性常数满足Born-Huang准则,且0 GPa和300 GPa下的声子色散没有虚频,证明了高压下碳化钨相的静力学稳定性和动力学稳定性.电子性质表明了碳化钨的金属性.光学性质表明碳化钨在高能区很难吸收光.热力学性质的研究表明:体积比V/V_0对压强的变化更敏感;高温时C_V曲线近似一条直线;给定压强下热膨胀系数α在600 K温度以上增长非常缓慢;压强对德拜温度Θ_D的影响较大;在低压下格林艾森系数γ的变化较大.     

Reconstruction at a metallic interface studied by field ion and field emission microscopy

Reconstruction of a tungsten surface by adsorbed layers of gold, silver and copper has been studied by field emission and field ion microscopy. Gold reconstructs the surface in three ways, termed the α, β and γ rearrangements. The α rearrangement, which results in a smoothing of the tungsten surface, takes place at around 400° K with gold coverages of 5 monolayers (5θ), and is thought to be an increase in structural perfection of the tungsten surface by gold-assisted surface diffusion of tungsten atoms, β-reconstruction takes place in the temperature range 480–950°K at coverages ? 1.7θ, producing a faceted surface which comprises {211} and {110} facets, and is thought to result from the need to minimise the free energy at the gold/tungsten interface. The γ structure, which appears above 1400°K, is believed to represent a change in the shape of the tip by transport of tungsten to the (110) locality. Adsorbed silver produces neither β nor γ structures, and the degree of α rearrangement is very small, being confined to the {230} regions of the substrate. Copper lies between silver and gold in its ability to rearrange the tungsten surface, some degree of α rearrangement is detectable, and the β structure is very poorly developed unlike the γ structure which is clearly formed. The binding strength of copper to tungsten is greater than that of silver, but less than that of gold; the capacity of an adsorbate, to reconstruct the tungsten substrate is therefore thought to be related to the strength of the adsorbate-substrate bond.