纳米铁氧化物的微波化学制备及TEM表征

纳米铁氧化物（Fe2O3）具有很好的磁性和硬度，及良好的耐候性、耐光性和化学稳定性，并具有半导体特性。电导对温度、湿度和气体比较敏感，是一种有发展潜力的敏感材料。总之，纳米Fe2O3在磁记录材料、精细陶瓷、塑料制品、涂料、催化剂和生物医学工程等方面有广泛的应用价值和开发前景。本文介绍了使用微波促进水解的这一新方法来制备可控形状的纳米Fe2O3。     

ZnO纳米棒的制备与表征

近年来，一维纳米材料如纳米管、纳米线、纳米棒等由于在纳米电子器件和光电子器件中的潜在应用前景而吸引了众多科研小组的兴趣。ZnO纳米材料作为一种宽带系半导体，因其可以在各种高科技产品中的应用如光催化剂、气敏元件、光电二极管、变电阻等已引起人们广泛的研究，到现在为止，许多方法用来制备一维ZnO纳米材料，如电弧法、化学气相沉积、模板法和电化学沉积等。本文用溶液法合成ZnO纳米棒，并对其进行电子显微学的观察与表征。     

一种新型结构碳材料——碳管套碳纳米丝

以氢气和甲烷为气源,利用钟罩式微波等离子体化学气相沉积(MW PCVD)系统制备了一种新型结构碳材料——碳管套碳纳米丝,用扫描电子显微镜和拉曼光谱仪对它的形态结构和成份进行了分析。这种新型结构碳材料,具有与碳纳米管、碳纳米丝相似的性质,并在某些领域(如电子源探针、纳米电子器件等)具有很好的应用前景。     

大规模制备定向排列的碳纳米管阵列

采用一种无模板的化学气相沉积法，在石英衬底上制备了大面积，高定向性、自支撑的碳纳米管阵列。二甲苯和二茂铁分别作为碳源和催化剂，连续进给到反应装置中，在一定温度条件下，碳纳米管自组织生成垂直于衬底方向的定向阵列。这种方法可以获得很高的生长速度，其最大长度可以达到几个毫米。拉曼光谱和高分辨透射电镜检测显示这种方法制备的碳纳米管具有较高的纯度和石墨化程度。     

纳米电路一新时代的电器

在《自然一材料学》上，科学家报告了完全用碳纳米管制作的第一个电子开关和逻辑器件。Prabhakar Bandaru和同事的工作首次表明：可以在不使用金属栅控制电流的情况下制造纳米电子器件。     

实验参数对激光气相法制备纳米Fe/O粒子性能的影响

用激光气相法,研究反应物温度、反应物流量等实验参数对实验过程及Fe/O纳米粒子性能的影响,并用EDTA化学分析法、透射电镜、电子衍射及X射线衍射仪等手段对纳米粒子的化学成分、粒径、形貌、结构等性能进行了表征。     

一种制备纳米Fe3O4的新方法及其磁性能研究

在正丙醇–水体系中,以NaOH为沉淀剂,用共沉淀法制备了纳米Fe3O4粒子,并用TEM和XRD对其进行了表征。考察了制备过程中工艺参数对Fe3O4颗粒大小的影响,并对影响机理进行了探讨。结果表明:纳米Fe3O4的平均粒径约为15nm;其饱和磁化强度可达73.34Am2/kg,比用水热法(42Am2/kg)和共沉淀法(60Am2/kg)制备的Fe3O4纳米粒子的要高。     

负载于碳纳米管上的新型金纳米催化剂

与传统催化剂载体材料相比，碳纳米管因其具有新颖的微观结构和独特的综合性能，更适合作为催化剂的载体材料。本研究采用一种简单的化学镀工艺，制备了负载于碳纳米管上的新型金纳米催化剂，并用高分辨透射电镜(PhilipsTecnai-20，200kV)对所获得的材料进行了表征。     

铁纳米线填充碳纳米管材料的制备与结构分析

本文系统介绍了金属填充碳纳米管的化学气相沉积制备与电子显微学研究。填充金属的形状可控、物相可调。能量损失谱、高分辨成像与微衍射等分析表明：碳管内部填充物完全转变为体心立方的单质铁,铁纳米线与碳管具有一定的取向关系。电子显微学研究支持底部生长机制通过在化学气相沉积过程中控制铁/碳管纳米复合材料的几何形状与结晶程度可以有效地改变其电磁性能。     

A method for characterizing carbon nanotubes

High-resolution transmission electron microscopy and electron energy-loss spectroscopy of a multi-walled carbon nanotube (MWCNT) at elevated temperatures were studied. Although the observation was carried out at 200 kV, the crystal structures of the MWCNT were observed without introducing defects. In addition, contamination on the MWCNT, such as nanobubbles, was removed during the observation at 600 degrees C. In this paper, we report the observation conditions and experimental results. The experimental results obtained both at 600 degrees C and at room temperature were compared.     

Facile method for enhancing conductivity of printed carbon nanotubes electrode via simple rinsing process

We report a simple rinsing process to enhance the conductivity of printed carbon nanotube (CNT) electrodes. Polystyrene sulfonate(PSS)-wrapped CNTs were well dispersed in ethanol for printing via electrohydrodynamic (EHD) jet printing. PSS as a surfactant reduces the conductivity of CNT electrodes, restricting their applications in electronic devices. Even though the PSS rinsing process is necessary, it promotes delamination of CNTs. The challenges associated with the rinsing process and the delamination of CNTs were overcome in this study by introducing a polymer, poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate) (P(VB-co-VA-co-VAc)) as an adhesion layer. The use of P(VB-co-VA-co-VAc) increased the adhesion between the CNTs printed by the EHD jet technique and the underlying substrate during the CNT rinsing process. The rinsing process led to a significant enhancement in the conductivity of the CNT electrodes, and these electrodes were applied to organic field-effect transistor devices based on TIPS-pentacene. The device exhibited a high field-effect mobility of 0.25 cm²/(V·s).     

Platinum nanoclusters encapsulated in amorphous carbon

Films of a nanocomposite based on Pt and amorphous carbon (a-C), including hydrogenated carbon (a-C:H), are studied. The nanocomposite was synthesized by encapsulation of Pt nanoclusters in amorphous carbon films via dc magnetron co-sputtering of graphite and platinum targets in an argon-hydrogen plasma. The content of platinum in the films was determined by the methods of Rutherford backscattering and instantaneous nuclear reactions. The morphology of nanocomposite films and separate Pt clusters was examined by transmission electron microscopy. It was shown that nanoclusters ～3 nm in size are crystals with well-formed low-defect crystal structure and that their shape in the plane is approximated well with an ellipse. Distribution functions for the eccentricity and average size were constructed for a set of 100 of the best discernible clusters. It was found that introduction of hydrogen into the plasma leads to a decrease in the average size of Pt nanoclusters for a constant ratio between the carbon and platinum concentrations in the nanocomposite.     

A simple method to characterize substrate current in MOSFET's

Experimental verification of substrate current characteristics is thoroughly carried out. VDS- VDSAT, instead of VDS, is shown to be the driving force of all hot-electron effects. A simple relationship between substrate current and VDS- VDSATis found. This relationship provides a convenient tool to characterize the substrate current or the channel electric field, and, hence, all hot-electron effects. Measurements of ISUB/IDand VDS- VDSATat two bias points and any one channel length are sufficient to fully characterize the substrate currents for all channel lengths VDS's and VG's for a given technology.     

电子束致沉积手控生长碳纳米线

用电子束致沉积(EBID)来制备各种纳米尺寸的结构在纳米材料的制备和器件构建方面有着良好的应用前景。相对于聚焦离子束(FIB),它具有对样品损伤小和所得结构尺寸更小等优点。此前,电子束致沉积的工作大多数在扫描电镜中完成,而在透射电镜中沉积直到近两年才发展起来。本文尝试在普通热发射透射电镜中,手动控制生长碳纳米线、点等结构。对碳纳米线的生长过程进行了原位观测,并对电子束斑的大小、形状和辐照时间对沉积物形状的影响作了初步的研究。最后对电子束致沉积可控生长无定型碳纳米线可能的应用作了一些探索。     

A simple method to improve the transients in adaptive systems

A method, based on classical optimization techniques, is proposed to improve the adaptation transients in adaptive systems. Its philosophy consists basically in using a modified adaptation mechanism which alternately works in a priori mode, in which the optimization-correction horizon is slid forward in time, and in a posteriori mode, in which, by using an equivalent system, the parameters (and the adaptation gain matrix, if time varying) are recomputed over this horizon to generate the adaptive plant input.     

Thermoelectric power in carbon nanotubes

The theoretical results for the temperature dependence of the thermoelectric power of graphite and semimetal carbon nanotubes are reported. In the calculations, the cylindrical superatomic range structure of nanotubes is taken into account. The Boltzmann equation and the π-electron model of semimetal carbon nanotubes are used. The basic parameters of the calculation are the concentration of electrons, the Fermi energy, and the energy of the local level associated with the cylindrical structure of carbon nanotubes. The theoretical results are compared with the available experimental data.     

Post-treatment method for improving field emission from carbon nanotubes/nanofibers

Carbon nanotubes/nanofibers(CNTs/CNFs)featurehigh aspect ratios,small radii of curvature at their tips,superior mechanical strength,good thermal conductivityand highchemical stability.Because of these characteris-tics advantageous for electron field emiss…     

纳米铜棒制备的新方法

介绍了一种制备纳米铜棒的新方法,该法采用非对称交流电作为电解电源,采用铜棒为电极,硫酸铜为电解液,在一定的电解工艺参数下,成功制备出纳米铜棒。通过XRD和TEM对制得的铜粉进行了表征分析,表明其为单质铜,且纯度很高,粒度分布均匀,结晶性很好。