Second generation YBCO coated conductors： A review

The advance in first generation Bi-2223 HTS wire has enabled the demonstration of superconducting power cables, magnetic energy-storage devices, transformers,fault current limiters and motors. However, the low irreversibility field (H^*) prevents application of Bi-2223 at 77 Kin any significant field. Worldwide activities are therefore,focused on developing a second-generation HTS technology based on YBCO, for which H^* (77K)-7 T. In this paper, we discuss the status and commercial prospects of second generation HTS wire technologies. In addition, we review the recent results and discuss the prospects of future applications.     

饱和蒸气压测定方法评述

对纯物质的蒸气压的测定方法进行了评述,指出了各种测定方法所适应的测压范围并阐述测定低蒸气压测定方法的意义.     

Fabrication of tungsten films by metallorganic chemical vapor deposition

Tungsten films growing on copper substrates were fabricated by metallorganic chemical vapor deposition (MOCVD). The chemical purity, crystallographic phase, cross-sectional texture, and resistivity of the deposited films both before and after annealing treatment were investigated by X-ray energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and four-point probe method. It is found that the films deposited at 460℃ are metastable β-W with (211) orientation and can change into α-W when annealed in high-purity hydrogen atmosphere at high temperature. There are small amounts of C and O in the films, and the W content of the films increases with increasing deposition temperature and also goes up after annealing in high-purity hydrogen atmosphere. The films have columnar microstructures and the texture evolution during their growth on copper substrates can be divided into three stages. The resistivity of the as-deposited films is in the range of 87-104 μΩ·cm, and low resistivity is obtained after annealing in high-purity hydrogen atmosphere.     

化学气相浸渗反应器内气体流场的数值模拟

控制化学气相浸渗(CVI)反应器内的反应气体流场是获得理想沉积物的关键技术之一, 通过建立质量守恒、动量守恒、能量守恒和化学反应守恒4个微分方程及其边界条件, 采用有限单元法对CVI反应器中复杂且不可观察的气体流场进行数值计算. 数值计算结果表明, 喷嘴形状及其与衬底相对位置对流场形貌有显著影响. 采用π/6的斜口喷嘴, 并使其中心轴线与通过它和圆柱形衬底交点切线的夹角为π/6时, 反应器内基本消除了回流.     

化学振荡在分析化学中的应用综述

对近十多年(2000—2014年)化学振荡现象在分析化学中的应用进行全面评述.主要综述了Belousov-Zhabotinsky(B-Z)振荡体系、铜催化振荡体系(如Cu(II)-H2O2-KSCN)和Briggs-Rauscher(B-R)振荡体系在分析中的应用,被测物包含了金属离子、阴离子、气体和各种有机物等.化学振荡分析技术具有检测费用低廉、操作简便、仪器简单、较宽的线性检测范围和较低的检测限等优点,是一种检测物质的新方法.     

利用ICP-MS对黄铁矿及烧渣中的铊进行形态提取研究

应用分级提取法考察了黄铁矿及烧渣中铊的赋存形态,包括酸可交换态、易还原态、可氧化态和残余态中铊的浓度,据此讨论了黄铁矿及烧渣中铊的形态分布,认为黄铁矿及烧渣中铊的释放均不容忽视.     

Controllable synthesis of Ni-catalyzed tetragonal tungsten nanowires via chemical vapor deposition

Controllable synthesis of Ni-catalyzed tetragonal tungsten nanowires via chemical vapor deposition     

流动注射-冷蒸汽发生AAS法测定烟草样品中的痕量汞

 研究了以KBH₄为还原剂的流动注射-冷蒸汽发生原子吸收光谱法,测定烟草中痕量汞.就其分析条件对灵敏度影响进行了优化研究.本方法共存离子干扰小,精密度较高(平行测定10ng/mL的标准样品7次的相对标准偏差为2.80%)、检测限好(0.4ng/mL),线性范围在0.4～60ng/mL之间.利用HNO₃-H₂O₂体系微波消解进行了样品前处理,有较高的样品回收率(98.15%).测定结果令人满意.     

Fabrication of copper nanorods by low-temperature metal organic chemical vapor deposition

Copper nanorods have been synthe-sized in mesoporous SBA-15 by a low-temperature metal organic chemical vapor deposition (MOCVD) employing copper (II) acetylacetonate, Cu(acac)2, and hydrogen as a precursor and reactant gas, re- spectively. The hydrogen plays an important role in chemical reduction of oganometallic precursor which enhances mass transfer in the interior of the SBA-15 porous substrate. Such copper nanostructures are of great potentials in the semiconductor due to their unusual optical, magnetic and electronic properties. In addition, it has been found that chemically modi- fying the substrate surface by carbon deposition is crucial to such synthesis of copper nanostructures in the interior of the SBA-15, which is able to change the surface properties of SBA-15 from hydrophilic to hydrophobic to promote the adsorption of organic cupric precursor. It has also been found that the copper nanoparticles deposited on the external sur- face are almost eliminated and the copper nanorods are more distinct while the product was treated with ammonia. This approach could be achieved under a mild condition: a low temperature (400℃) and vac-uum (2 kPa) which is extremely milder than the con- ventional method. It actually sounds as a foundation which is the first time to synthesize a copper nanorod at a mild condition of a low reaction temperature and pressure.     

碳纳米管用于场效应晶体管的应用研究

 传统硅晶体管在微小化方面遇到瓶颈,碳纳米管作为一维量子材料,成为未来晶体管最具潜力的候选者。介绍了几种典型的碳纳米管场效应晶体管结构的基本工作原理及独特性能;着重介绍了近年来几种常见的碳纳米管场效应晶体管,并结合其结构与工作原理,论述了一系列技术革新和性能改进;总结了碳纳米管场效应晶体管未来需解决的几个重要问题。     

Application of ICP-MS trace element analysis in study of ancient Chinese ceramics

Chemical analysis plays a significant role in the study of ancient ceramics[1,2]. Most ancient Chinese kilns used clays mined from the local areas and differences in the geochemistry and mineralogy of these raw materials may be expected. The chemical composition of ceramics may also be influenced by production techniques, such as processing by washing and mixing of different sorts of raw materials. These may also vary from kiln to kiln and even change over time. Thus the raw materials and pro…     

Progress of graphene growth on copper by chemical vapor deposition: Growth behavior and controlled synthesis

Recently,chemical vapor deposition (CVD) on copper has been becoming a main method for preparing large-area and highquality monolayer graphene.In this paper,we first briefly introduce the preliminary understanding of the microstructure and growth behavior of graphene on copper,and then focus on the recent progress on the quality improvement,number of layers control and transfer-free growth of graphene.In the end,we attempt to analyze the possible development of CVD growth of graphene in future,including the controlled growth of large-size single-crystal graphene and bilayer graphene with different stacking orders.     

Synthesis of carbon nanotube array using corona discharge plasma-enhanced chemical vapor deposition

Carbon nanotube array plays an important role in the area of nanomaterials due to its potential applications, e.g. as field emitter in flat panel display[1,2] and as template for synthesizing arrays of other important nanomaterials[3]. Anodic aluminum oxide (AAO) template possesses an ordered porous structure that is formed through self-or- ganization during anodization[4,5], and is widely used to synthesize one-dimensional nanomaterial arrays[6]. Carbon nanotubes are usually assembled into t…     

Catalyst enhanced chemical vapor deposition of nano-particle nickel films on teflon surface

Films formed with nanosized nickel particles on teflon surface were prepared by means of catalyst enhanced chemical vapor deposition (CECVD) with Ni(dmg)₂, Ni(acac)₂, Ni(hfac)₂, Ni(TMHD)₂, and Ni(cp)₂ as precursors, and complexes Pd(hfac)₂, PdCl₂ and Pd(η ³-2-methylallyl)acac as catalyst under carrier gas (H₂). The film growth rate depends on the precursors and substrate temperature. The chemical value, purity and surface morphology of the Ni particle films were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The films obtained were shiny with silvery color, and consisted of grains with a particle size of 50–140 nm. The Ni was metallic of which the purity was about 90%–95% from XPS analysis. SEM micrograph showed that the film had good morphology.      

Synthesis of carbon nanotube array using corona discharge plasma-enhanced chemical vapor deposition

A corona discharge phasma-enhanced chemical vapor deposition with the features of atmospheric pressure and low temperature has been developed to synthesize the carbon nanotube array ,The array was synthesized from methane and hydrogen mixture in anodic aluminum oxide template channels in that cobalt was electrodeposited at the bottom.The characterization results by the scanning electron microscopy,transmission electron microscopy,energy dispersive X-ray spectroscopy and Raman spectroscopy indicate that the array consists of carbon nanotubes with the diameter of about 40 nm and the length of more than 4 μm, and the carbon anotubes are mainly restrained within the channels of templates.     

野罂粟生物碱化学成分及生物活性研究进展

1987年卫生部“关于野罂粟、阿朴吗啡和烯炳吗啡不再列入麻醉药品管理范围的通知”,为野罂粟的研究工作带来新的契机.本文利用CNKI、清华同方、万方和ISI数据库,得到1970以来有关野罂粟(Papaver nudicaule L.)的中外文文献共140篇.通过对文献的系统整理与分析,已确定野罂粟生物碱的34个生物碱单体及其药理作用.这些将为野罂粟的药化与药理研究及其种质资源的开发与持续利用提供科学依据.     

溶胶凝胶法制备二氧化硅膜及其无显影气相光刻

为使无显影气相光刻应用于非硅衬底材料的刻蚀,扩宽其应用范围,研究了无显影气相光刻在溶胶 凝胶法制备的二氧化硅膜中的应用。通过对溶胶 凝胶化学过程的分析,考察了凝胶二氧化硅薄膜制备过程中的几个重要工艺参数,制备了结构均匀的二氧化硅薄膜。并将无显影气相光刻的方法应用于这种二氧化硅膜的刻蚀,通过优化后的光刻工艺参数得到了反差明显的光刻图形。     

Well-aligned carbon nanotube array membrane synthesized in porous alumina template by chemical vapor deposition

A new simple approach was devetoped for preparing wetl-aligned and monodispersed carbon nanotube (CNT) array membrane within the cylindrical pores of anodic aluminum oxide (AAO) template by chemical vapor deposition (CVD). Acetylene and hydrogen were used in the CVD process with Fe-catalyzer at 700°C under 250 Pa. Scanning etectron microscope (SEM) and transmission etectron microscope (TEM) were employed to characterize the resulting highly-oriented uniform hollow tube array which had a diameter of about 250 nm, a tube density of 5.3x10⁸ cm² and a length of about 60 μm. The length and diameter of the tubes depend on the thickness and pore diameter of the template. The growth properties of the CNT array film can be achieved by controlling the structure of the template, the particle size of Fe-catalyzer, the temperature in the reactor, the flow ratio and the deposition time. The highly-oriented and uniform CNT array membrane fabricated by this simple method is very much useful in a variety of applications.