一维纳米材料组装技术的研究进展

分别分析和讨论了纳米线阵列直接有序生长法、随机组装法和不同驱动机制的组装法,展望了其下一步的研究方向。总体来说,直接有序生长法适用的材料范围受限制,对生长环境要求严格;随机组装法成功率比较低;而将纳米线合成和组装分立并加入驱动机制后,适用的材料范围广泛,组装效果提高。其中,液体剪切力驱动组装法、介电泳法、接触打印法和碾压法的效果最突出,都取得了很好的实验结果。未来的努力方向包括:如何更精确地控制纳米线阵列的位置、密度等参数,如何建立纳米线阵列与电路系统的电联接等。     

简单蚀刻法制备具有可控高度的金属纳米线阵列

采用多孔阳极氧化铝(AAO)作为模板,运用电化学沉积法在模板的微孔中组装金属Ni纳米线,然后用磷铬酸蚀刻表层AAO模板,暴露出规整有序、具有可控长度的Ni纳米线阵列.分别用SEM、TEM与SAED对Ni纳米线阵列进行了表征.研究了蚀刻时间与AAO模板质量的减少及暴露出来的Ni纳米线阵列长度之间的关系.结果表明,磷铬酸是较NaOH溶液更为温和有效的AAO模板蚀刻剂,通过控制模板溶解时间,可以实现对裸露于AAO模板外纳米线长度的精细有效控制.该蚀刻方法普遍适用于以AAO为模板所制得的准一维纳米阵列结构.     

SiO2纳米颗粒复合Bi2Te3纳米线阵列的制备

为结合一维纳米材料和纳米颗粒复合材料的优点,本文尝试进行了在氧化铝模板(AAO)中生长Bi2Te3-Si O2纳米颗粒复合纳米线阵列。通过在电化学溶液中添加Si O2纳米颗粒,制备包含纳米颗粒的Bi-Te纳米线阵列。应用XRD、SEM、TEM等方法对合成的样品进行了分析观察。研究发现Si O2纳米颗粒的加入对纳米线的形貌和结构都有明显的影响。在模板法沉积Bi2Te3纳米线阵列时,添加Si O2纳米颗粒将明显改变纳米线生长方式,Bi2Te3纳米线不再是等径的纳米棒,而是枝晶生长过程,最后形成Z字型的不断反复弯折纳米线,该枝晶状纳米线的直径远小于模板的孔径。这一新颖的现象为制备直径更小,并具备精细界面结构的纳米线热电材料提供了一种新的可能途径。     

图案化ZnO纳米线阵列制备与应用的研究进展

综述了多种图案化制备ZnO纳米线阵列的技术,包括电子束光刻技术、纳米球蚀刻技术、激光干涉光刻技术、纳米压印技术和嵌段共聚物蚀刻技术等。介绍了图案化ZnO纳米线阵列在传感器、太阳能电池和UV检测器等功能器件中的应用进展,分析了图案化ZnO纳米线阵列制备与应用中的优点、意义及存在的问题,并展望了其未来发展趋势。     

应用DNA模版自组装CdS纳米线

近年来,由于具有双螺旋补偿结构,DNA分子作为智能模版被广泛应用于设计棒状或管状类的纳米结构.本文报道了应用DNA双螺旋模版将CdS纳米粒子自组装为CdS纳米线.制备的CdS纳米线由几根纳米线紧密缠绕在一起,也呈螺旋形结构,该结构在无机材料中是很少见的.该结构形成的主要原因归功于CdS纳米粒子和DNA分子间的强烈静电互作用,由于含自由基的CdS纳米粒子带负电荷,而氨基的DNA核酸根带正电荷.研究结果表明应用DNA模版制备纳米线是一种简便、高效的技术和方法.同时,DNA模版法也为从底上制备纳米级的材料和物体提供了广阔的空间.     

电化学组装一维纳米线阵列p型Bi2Te3温差电材料

：对p型Bi2Te3温差电材料的电沉积过程进行了研究，分析了添加剂对电沉积过程的影响．在此基础上，以孔径为50nm的阳极氧化铝多孔膜为模板，采用直流电沉积技术，在氧化铝多孔模板的纳米级微孔内电化学组装出了P型Bi2Te3纳米线阵列温差电材料，性能研究表明，p型Bi2Te3纳米线阵列的温差电性能远远超过具有相同组成的块状温差电材料。     

纳米晶复合有序多孔材料的研究进展

有序多孔材料具有大小均匀、排列有序的孔道,并且其孔径在一定范围内连续可调,因此以有序多孔材料为模板,合成均匀负载的纳米粒子和有序阵列的纳米线得到广泛研究.综述了以氧化铝、氧化硅、氧化钛有序多孔材料为模板,合成纳米颗粒和纳米线阵列的方法.     

金属有序纳米孔道阵列模板合成法

评述了采用母板复型法合成金属有序纳米孔道阵列模板合成方法、金属模板的特点及应用的研究进展.用于合成金属模板的母板有:多孔阳极氧化铝、径迹刻蚀高分子聚合物、具有纳米孔道的玻璃及氧化锌晶体阵列等,金属模板的金属沉积方法有化学镀、电镀、物理气相沉积法等.由于金属模板具有金属特性,在纳米阵列材料组装、电极制备及过滤膜制备领域具有重要应用前景,研究直接制备金属模板的方法是一个很有发展前途的方向.     

纳米线电化学储能材料与器件

减少容量衰减、提高能量密度及倍率性能是当前电化学储能器件发展的国际性难题,研发新型高性能纳米储能材料及其器件是解决这一难题和发展高功率密度、高能量密度及高循环稳定性的下一代动力电池的有效途径之一。纳米线电极材料因具有独特的各向异性、快速的轴向电子传输和径向离子扩散等特性使其在纳米线储能器件的组装、原位表征等方面有着块体材料所不具有的独特优势。本文结合当前最新的研究进展和本课题组的研究工作,介绍了通过设计组装单根纳米线全固态电化学储能器件,结合原位表征技术,揭示了电化学储能器件容量衰减与电极材料电导率降低、结构劣化之间的内在规律。基于该规律,一方面从改善纳米线电极材料本征性能入手,提出并实现了纳米线化学预嵌入、拓扑取代、取向有序化等性能优化策略,显著提高了电极材料的电导率及其电化学储能器件的循环稳定性和倍率特性;另一方面从抑制纳米线电极结构劣化入手,设计构筑了纳米线分级结构和一维自缓冲纳米杂化结构,显著增加纳米线的比表面积和电化学活性位点,大幅提高了纳米线储能器件的能量密度、功率密度以及器件可靠性,为纳米线电化学储能器件的发展和应用奠定基础。     

非晶Co及CoP纳米阵列的制备及研究

采用交流电化学沉积法,在多孔阳极氧化铝(AAO)模板孔洞中成功制备出直径50nm的Co纳米线阵列.采用透射电子显微镜(TEM)和选区电子衍射(SAED)观察了样品的微观形貌结构.结果显示,阵列中纳米线均匀有序,形状各向异性较大,其晶体结构为非晶.在沉积Co纳米线阵列的电解液中添加一定的还原剂(NaH2PO2·H2O),制备出非晶CoP纳米阵列,由TEM观察可知,阵列形貌发生变化,沉积产物为离散的纳米粒子而非纳米线.探讨了交流电沉积纳米阵列的生长机理.     

碳纳米管场发射阴极阵列制备研究与进展

碳纳米管具有良好的电子发射特性,成为理想的场致发射阴极材料,碳纳米管阵列制备研究是碳纳米管平板显示应用的前提。介绍了碳纳米管阴极阵列制备技术如丝网印制法、CVD原位生长法、光刻法和自组织法等研究与进展,并从薄膜残留去除、CNTs膜微结构改变及sp3缺陷增加等方面概述了目前CNTs场发射性能优化的进展,指出了目前存在的问题并作了简单分析。     

Beam steering with pulsed two-dimensional transducer arrays

The major problem facing the development of 2-D arrays for imaging is the complexity arising from the large number of elements anticipated in such transducers. The authors have undertaken a theoretical investigation of the focusing and steering properties of pulsed 2-D arrays to characterize the parameters required for medical imaging, such as element size, spacing, and number of elements. Details of the computational methods employed are presented, as well as a discussion of the steered beam properties of wideband 2-D arrays. The effects of apodization and element cross-coupling on the beam properties of a 2-D transducer array are examined. The beam properties of various sparse arrays with elements randomly distributed over the aperture of the transducer are discussed.     

Modeling liquid-crystal gradient-index lenses

The optical properties of one-dimensional gradient-refractive-index lens arrays based on liquid crystals are studied. We find that it is quite possible, using theoretical methods, to predict angular distributions of the light emanating from such arrays when they are illuminated with collimated monochromatic light. We compare four theoretical methods in relation to experiments. The experimental data and the model, based on a combination of eikonal methods and diffraction, are in close correspondence. Features such as maximal beam width and number of extrema in the angular light distribution are discussed and explained theoretically. We also studied dispersion effects, both experimentally and theoretically, with good agreement between the two.     

Performance analysis design

Control of an output value y when it is a function of various variables such as A, B, is usually achieved by controlling those causes A, B. After discussing methods using partial derivatives and Monte-Carlo, which are either inaccurate or inefficient, the use of orthogonal arrays, and the use of analysis of variance for the data calculated or conducted by the arrays, are proposed in this paper as these methods have no such defects. A live example taken from an electric circuit used for a colour T.V. set is used for the explanation.     

ZnS nanostructure arrays: a developing material star

Semiconductor nanostructure arrays are of great scientific and technical interest because of the strong non-linear and electro-optic effects that occur due to carrier confinement in three dimensions. The use of such nanostructure arrays with tailored geometry, array density, and length-diameter-ratio as building blocks are expected to play a crucial role in future nanoscale devices. With the unique properties of a direct wide-bandgap semiconductor, such as the presence of polar surfaces, excellent transport properties, good thermal stability, and high electronic mobility, ZnS nanostructure arrays has been a developing material star. The research on ZnS nanostructure arrays has seen remarkable progress over the last five years due to the unique properties and important potential applications of nanostructure arrays, which are summarized here. Firstly, a survey of various methods to the synthesis of ZnS nanostructure arrays will be introduced. Next recent efforts on exploiting the unique properties and applications of ZnS nanostructure arrays are discussed. Potential future directions of this research field are also highlighted.     

Zinc Sulfide Nanostructure Arrays: ZnS Nanostructure Arrays: A Developing Material Star (Adv. Mater. 5/2011)

Semiconductor nanostructure arrays are of great scientific and technical interest because of the strong non‐linear and electro‐optic effects that occur due to carrier confinement in three dimensions. The use of such nanostructure arrays with tailored geometry, array density, and length‐diameter‐ratio as building blocks are expected to play a crucial role in future nanoscale devices. With the unique properties of a direct wide‐bandgap semiconductor, such as the presence of polar surfaces, excellent transport properties, good thermal stability, and high electronic mobility, ZnS nanostructure arrays has been a developing material star. The research on ZnS nanostructure arrays has seen remarkable progress over the last five years due to the unique properties and important potential applications of nanostructure arrays, which are summarized here. Firstly, a survey of various methods to the synthesis of ZnS nanostructure arrays will be introduced. Next recent efforts on exploiting the unique properties and applications of ZnS nanostructure arrays are discussed. Potential future directions of this research field are also highlighted.     

Theoretical and experimental investigation of phase coherence in shorted 2D arrays of high-T c Josephson junctions

Phase coherence in shorted 2D Josephson junction arrays shunted by resistive load in presence of disorder and magnetic field are investigated theoretically and experimentally. Using computer simulation it is shown that magnetic field negatively influences radiation properties of such arrays. Similarly to XY-type of 2D arrays maximal spread in junction parameters which allows stable phase-locking state is ±11%. 2D arrays with topology of those investigated theoretically were fabricated using high-T_c superconductor junction technology. The phase-coherence (voltage locking) between rows was observed experimentally.     

A study of emitter formation by various etching techniques and its application to flat panel display

Abstract

In view of the potential advantages of using field‐emission cathodes as electron sources, a renewed interest in advanced IC technology utilizing silicon‐based coldcathode microelectronics is emerging. However, some etching results concerning emitter formation are still unknown. This paper presents a study of emitter formation by various wet and dry etching methods. Some geometrical models are given for the analysis of anisotropic etching results. The emission features from different emitter arrays are also given for comparison. Through understanding the emission characteristics of various emitter arrays, a novel design for Field‐Emission Flat Panel Display is proposed.     

Large-scale, reliable and robust SERS-active nanowire substrates prepared using porous alumina templates

nanowire arrays for surface-enhanced Raman scattering applications. These nanowire films were synthesized via electrodeposition using porous alumina templates of varying order, thickness and pore diameters. Mechanical polishing has been shown to be a very effective method to prepare nanowire arrays with monodisperse length over comprehensively large dimensions. On the other hand, a convenient synthesis route has been suggested that allows the formation of nanoparticle rrays using very thin and/or large area porous alumina films. It is reckoned that even films with the smallest obtainable pore sizes can be utilized to prepare large area, fine nanoparticle arrays. Such arrays may also find use in other areas, such as solar cells and electrochemistry. Preliminary Raman experiments indicated that the nanowire/nanoparticle arrays are indeed surface-enhanced Raman scattering-active. Finally, the potentials offered by the reported processing methods for fabricating substrates with predictable and high Raman amplifications are discussed.     

Chemical-assisted bonding of thermoplastics/elastomer for fabricating microfluidic valves

Thermoplastics such as cyclic olefin copolymer (COC) and polymethylmethacrylate (PMMA) have been increasingly used in fabricating microfluidic devices. However, the state-of-the-art microvalve technology is a polydimethylsiloxane (PDMS)-based three-layer structure. In order to integrate such a valve with a thermoplastics-based microfluidic device, a bonding method for thermoplastics/PDMS must be developed. We report here a method to bond COC with PDMS through surface activation by corona discharge, surface modification using 3-(trimethoxysilyl)propyl methacrylate (TMSPMA), and thermal annealing. The method is also applicable to PMMA. The bonding strength between thermoplastics and PDMS was represented by the peeling force, which was measured using a method established by the International Organization for Standardization (ISO). The bonding strength measurement offered an objective and quantitative indicator for protocol optimization, as well as comparison with other PDMS-associated bonding methods. Using optimized bonding conditions, two valve arrays were fabricated in a COC/PDMS/COC device and cyclic operations of valve closing/opening were successfully demonstrated. The valve-containing devices withstood 100 psi (～689 KPa) without delamination. Further, we integrated such valve arrays in a device for protein separation and demonstrated isoelectric focusing in the presence of valves.