电介质和智能材料

本文介绍了电介质和智能材料的基本自然属性及其应用现状，发展前景。     

长寿命导H^＋全固态电致变色器件的研究

研究了导Ｈ＾＋离子全固态电致变色器件性能退化摧在机制，发现有两个因素导致器件性能退化，在器件褪色过程中，存在于ＷＯ３薄膜中的水份将导致ＯＨ＾－在ＷＯ３中积累而在其中产生碱性环境，ＷＯ３溶于碱性环境而生成钨酸盐，在较高电压作用下Ｈ２Ｏ电解释放出气体Ｈ２和Ｏ２而使膜层剥落，通过改进器件结构和改善制备工艺条件，获得了光学密度高达０．５，着色／漂白（Ｃｏｌｏｒ／Ｂｌｅａｃｈ）循环次数高达１０＾６以上的性能     

直流溅射法制备电致变色WO_3膜

采用ＷＯ３陶瓷靶直流溅射制作了电致变色膜．介绍了制膜工艺．分析测试表明，膜有无定形结构；除有正常成分ＷＯ３外，还含有来自衬底及反应室内的微量杂质．电致变色谱响应特性和电化学特性的测量证明，膜的电色活性良好．还对实验结果作了理论分析．     

电介质和智能材料

本文介绍了电介质和智能材料的基本、自然属性及其应用现状,发展前景。     

电调谐光纤布拉格反射滤波器

首次实现了采用磁致伸缩材料制作的电调谐光纤布拉格反射滤波器，实验得到１．３ｎｍ的调谐。滤波器带宽１．５ｎｍ。     

电致流变效应的影响因素浅议

本文通过对几种不同配比悬浮液的电致流变性试验，分析了影响电致流变效应的因素．     

有序GaxIn1—xP（x=0.52）光致发光谱研究

报道了对有序ＧａｘＩｎ１－ｘＰ（ｘ＝０．５２）样品的变温和变激发功率密度的ＰＬ谱的研究。在低温Ｔ＝１７Ｋ，低激发功率密度下，谱线呈双峰结构，在低激发功率密度下升高温度，低能端的发光峰发生热猝灭，并在８５Ｋ完全消失。     

智能材料——材料科学发展新趋势

材料的智能化代表了材料科学发展的最新方向，智能材料的研究主要是依照仿生学方法，采用各种先进复合技术，实现复杂材料体系的多功能复合，并最终实现材料智能能化和器件集成化，文章在简要介绍有关材料概念的基础上，总结了智能材料的设计思想，路线及合成技术途径，综述了最近国内外有关智能材料的发展动向及研究进展，指出了一些应用背景及现在面临的问题。     

XeCl激光诱发SF6气体击穿及高压开关触发特性的研究

给出了ＸｅＣｌ激光诱发ＳＦ６气体击穿及高压开关触发特性的研究结果。ＳＦ６气体击穿所需要的ＸｅＣｌ激光的功率密度很强地随气体压强而变，在ＳＦ６气体压强为０．０２ＭＰａ时，击穿功率密度为４．６ＧＷ／ｃｍ＾２，当压强为０．０４８ＭＰａ时，击穿阈值达最小值为３．２ＧＷ／ｃｍ＾２，而在高气压情况（气压大０．０２ＭＰａ），其所需功率密度触发特性：对自由击穿电压Ｖａｂ≈６０ＫＶ的小型开关，在充电电压Ｖｃｈ＝０．     

智能材料发展概述

文章从仿生、自动调节器（ａｕｔｏｍａｔｏｎ）和信息概念出发，讨论了智能材料的构思 由纳米空 间、介相（ｍｅｓｏｐｈａｓｅ）到超分子不同层次的材料结构分析了智能性，从相转变考察了智能材料的刺激响应 性，提出了材料表面、界面环境响应性与其智能的相关性。文中展现了智能材料研究与开发的前景     

Carbon-Based Materials: Growth,Properties, MEMS/NEMS Technologies,and MEM/NEM Switches

Micro- or nanoelectromechanical system (MEMS/NEMS) is a multidisciplinary field, which has witnessed explosive growth during the past decades. The current materials for MEMS are dominated by Si thanks to the fully based technology for CMOS. However, Si has its own intrinsic limitations such as poor mechanical or tribological properties and poor thermal stability. Carbon-based materials such as diamond, carbon nanotube, and graphene possess excellent properties such as low mass, high Young's modulus, high thermal conductivity, hydrophobic surface, and tailorable electronic configuration, which make these materials promising for MEMS/NEMS applications with diverse and much better performance than Si. In this review, we describe the recent progress of carbon-based materials for MEMS/NEMS with focus on diamond, carbon nanotube, and graphene. The growth of these carbon materials is briefly described and only selected properties are discussed with respect to MEMS/NEMS applications. The fabrication process for suspended structures of these materials toward MEMS/NEMS is comprehensively reviewed from the recent literatures. Special attention is devoted to the state-of-the-art of MEM/NEM switches based on these carbon materials, one of the most important fields in MEMS/NEMS. Finally, the application of carbon-based MEM/NEM switches to microwave field is critically analyzed.     

Review of two microwave applications of carbon nanotubes: nano-antennas and nano-switches

This paper provides an overview of two potential applications of carbon nanotube devices in microwave technology. Firstly, the main structural, mechanical, thermal and electronic properties of carbon nanotubes are briefly reviewed. Then, the possibilities offered by metallic carbon nanotubes as nano-antennas in the E- and W-bands and further are investigated: comparison with macroscopic wire antennas is made, the major advantages brought by nanotubes but also technical issues to be addressed are discussed. Finally, the integration of carbon nanotubes in nano-electro-mechanical-systems (NEMS) is studied through nano-switches: the contribution of carbon nanotubes is detailed, state-of-the-art is described, as well as our future approaches for such nano-devices. To cite this article: S. Demoustier et al., C. R. Physique 9 (2008).     

Carbon nanotube chemistry and assembly for electronic devices

Carbon nanotubes (CNTs) have exceptional physical properties that make them one of the most promising building blocks for future nanotechnologies. They may in particular play an important role in the development of innovative electronic devices in the fields of flexible electronics, ultra-high sensitivity sensors, high frequency electronics, opto-electronics, energy sources and nano-electromechanical systems (NEMS). Proofs of concept of several high performance devices already exist, usually at the single device level, but there remain many serious scientific issues to be solved before the viability of such routes can be evaluated. In particular, the main concern regards the controlled synthesis and positioning of nanotubes. In our opinion, truly innovative use of these nano-objects will come from: (i) the combination of some of their complementary physical properties, such as combining their electrical and mechanical properties; (ii) the combination of their properties with additional benefits coming from other molecules grafted on the nanotubes (this route being particularly relevant for gas- and bio-sensors, opto-electronic devices and energy sources); and (iii) the use of chemically- or bio-directed self-assembly processes to allow the efficient combination of several devices into functional arrays or circuits. In this article, we review our recent results concerning nanotube chemistry and assembly and their use to develop electronic devices. In particular, we present carbon nanotube field effect transistors and their chemical optimization, high frequency nanotube transistors, nanotube-based opto-electronic devices with memory capabilities and nanotube-based nano-electromechanical systems (NEMS). The impact of chemical functionalization on the electronic properties of CNTs is analyzed on the basis of theoretical calculations. To cite this article: V. Derycke et al., C. R. Physique 10 (2009).     

Proton conductivity of single-walled carbon nanotubes: A semiempirical study

The possibility of using single-walled carbon nanotubes as materials with proton conductivity is investigated. Two possible mechanisms of migration of a proton over the surface of single-walled carbon nanotubes are proposed. The proton transfer over the outer surface of carbon nanotubes is calculated at the semiempirical quantum-mechanical level. The surface profiles of the potential energy are constructed and used to calculate the activation energy of proton hopping from one carbon atom to another carbon atom. This activation energy can be useful for determining a temperature dependence of the relative hopping conductivity of a nanotube.     

Measurement of the optical Stark effect in semiconducting carbon nanotubes

A strong optical Stark effect has been observed in (6,5) semiconducting single-walled carbon nanotubes by femtosecond pump-probe spectroscopy. The response is characterized by an instantaneous blueshift of the excitonic resonance upon application of pump radiation at photon energy well below the band gap. The large Stark effect is attributed to the enhanced Coulomb interactions present in these one-dimensional materials.     

Strain induced correlation gaps in carbon nanotubes

We calculate the change in the correlation gap of armchair carbon nanotubes with uniaxial elastic strain. We predict that such a stretching will enlarge the correlation gap for all carbon nanotubes by a change that could be as large as several meV per percent of applied strain, in contrast with pure band structure calculations where no change for armchair carbon nanotubes is predicted. The correlation effects are considered within a self-consistent Hartree-Fock approximation to the Hubbard model with on-site repulsion only.Received: 29 December 2003, Published online: 20 April 2004PACS: 62.25. + g Mechanical properties of nanoscale materials - 71.10.Pm Fermions in reduced dimensions (anyons, composite fermions, Luttinger liquid, etc.) - 71.20.Tx Fullerenes and related materials; intercalation compounds     

Structural and surface features of multiwall carbon nanotube

We present the direct evidence of defective and disorder places on the surface of multiwall carbon nanotube (MWCNT), visualizing the presence of amorphous carbon at those sites. These defective surfaces being higher in energy are the key features of functionalization with different materials. The interaction of the π orbital electrons of different carbon atoms of adjacent layers is more at the bent portion, than that of regular portion of the CNT. Hence the tubular structure of the bent portion of nanotubes is spaced more than that of regular portion of the nanotubes, minimizing the stress.     

Carbon nanotube based bolometer

The contacts of single carbon nanotubes and bundles of carbon nanotubes with superconducting and metallic electrodes are investigated in order to create bolometers and electron coolers. Tunneling contacts of the carbon nanotubes with aluminum electrodes are obtained. The current-voltage characteristics of junctions are analyzed for temperatures from room temperature to 300 mK. The resistance of individual nanotubes is primarily determined by defects and is too large for applications. The use of the bundles of carbon nanotubes makes it possible to considerably reduce the resistance of the bolometer, which is determined by a small number of conducting tubes with good tunneling contacts with the electrodes. The energy gap is equal to hundreds and tens of millivolt in the former and latter cases, respectively. Structures containing bundles of carbon nanotubes can be described in a model with a Schottky barrier. The samples with bundles of carbon nanotubes exhibit the bolometric response to external high-frequency radiation at a frequency of 110 GHz with an amplitude up to 100 μV and a temperature voltage response to 0.4 mV/K.     

碳纳米管的能隙特性和态密度特性

基于MATLAB语言数值模拟了碳纳米管的能隙特性和态密度特性,得出碳纳米管能隙的变化与碳纳米管的手性有关。数值模拟了碳纳米管的态密度表示,通过态密度表示与能隙对比,结果吻合的较好。结论为碳纳米管器件的制作提供参考。