共查询到20条相似文献,搜索用时 109 毫秒
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纳米碳管的STM研究 总被引:1,自引:0,他引:1
本文应用扫描隧道显微镜对孤光放电方法得到的纳米碳管进行了观察。孤光放电法所产物的纳米碳管以直线型为主,并且多以束状存在。碳管束直径约20nm,而单要碳管的直径大多在2nm到5nm之间。观察到单层碳秋的原子像,其表明为石墨网络的六角结构。纳米碳管的原子像及单极碳管表面均未发现明显缺陷存在,这可能是它具有很高强度质量比的主要原理之一。 相似文献
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纳米碳管增强铜基电接触材料制备的优化设计 总被引:2,自引:0,他引:2
用正交试验法优化了纳米碳管增强铜基电接触材料的制备工艺,探讨了纳米碳管表面处理时间、原料球磨时间和纳米碳管含量对复合材料综合性能的影响。结果表明:最佳制备工艺参数为,表面处理时间1.0h,球磨时间8h,纳米碳管最佳质量分数为0.1%。在优化制备的纳米碳管增强铜基电接触材料中,纳米碳管分散均匀,其布氏硬度为78.3HBS 2.5/62.5/30,电阻率为2.08×10–6Ω·cm,抗熔焊及抗氧化性能均得到较大提高,能够满足电接触材料综合性能的要求。 相似文献
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在现有的商用原子力显微镜上实现了用动态电场力显微术来研究单个纳米颗粒的极化特性。将AOT(bis(2-ethylhexyl)sulfosuccinate disodium)分子包覆的CdS纳米晶和Au纳米晶共同沉积在n型硅片表面,以分析导电探针对其诱导极化,同时研究了纳米碳管和碳纳米颗粒的不同极化特性,对样品的原位观察表明:其半导体和金属介电特性的差别,CdS,Au粒子呈现较大的极化反差,在同一纳米碳管不同位置也能观察到类似反差。通过比较在半导体和金属粒子上探针对外加交变电场的响应幅度,可以估计纳米半导体纳米粒子的介电常数。 相似文献
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高义华 张洪意 王月姣 张清风 韩祥云 李玉宝 刘宗文 占金华 GOLBERG D DOROZHKIN P TOVSTONG S 黄德修 板东义雄 《电子显微学报》2008,27(2):152-166
本文讨论了Ga/In填充纳米碳管和纳米氧化物管温度计的研制、发现、发展及前景,概述了纳米碳管温度计(测量范围为50℃~500℃)的特征、温度记录方法及In作为纳米温度计内工作物质的可能性.通过对填充Ga所具有的特殊凝固和熔化特征的回顾,阐述了Ga填充纳米碳管作为低温纳米温度计(0℃~69℃)及Ga填充纳米MgO管作为高温纳米温度计(高于700℃)的可行性.最后,讲述了采用测量Ga填充纳米碳管的电阻来标定温度的方法及如何解决纳米温度计在实际应用中存在的问题. 相似文献
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“Y”型、竹节型与直纳米碳管的力学特性研究 总被引:1,自引:0,他引:1
采用基于BrennerREAO(reactiveempiricalbondorder)势的分子动力学方法,模拟了“Y”型、竹节型与直纳米碳管的拉伸过程。结合有限元分析,对比并讨论了“Y”型、竹节型纳米碳管与直纳米碳管拉伸力学性能的差异。研究结果表明,拉伸“Y”型、竹节型纳米碳管的屈服与断裂均发生在其粗管与细管过渡的“应力集中”部位;“应力集中”致使“Y”型、竹节型纳米碳管的抗拉强度与韧性明显低于直纳米碳管;然而,“Y”型、竹节型碳管的弹性模量依然与直纳米碳管相当。 相似文献
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In the present work, joining of broken multiwalled carbon nanotubes (MWCNTs) via an electron beam-induced deposition technique is discussed. Current-induced breakdown caused by Joule heating was achieved by applying an appropriate sweep voltage. Scanning electron microscopy images indicated physical joining of broken tubes. To confirm electrical joining of the tubes, current–voltage measurements of the same tube were carried out before and after joining. The current–voltage characteristics remained ohmic after joining of the broken tube. Furthermore, it was found that deposited platinum (Pt) forms ohmic contacts with different shells of MWCNTs after joining, whereas tungsten (W) does not. This approach provides a significant tool for repairing CNTs in interconnect technologies and assembly of three-dimensional (3D) nanostructures. 相似文献
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热解碳基C/C复合材料纤维--基体界面的精细结构 总被引:2,自引:0,他引:2
采用JEM-2010型高分辨透射电镜考察了热解碳基碳/碳复合材料的纤维-基体界面结构.实验发现,由化学气相渗透工艺所获得的热解碳并非仅与碳纤表面进行单一的机械粘合,也不是一个简单平面.其间存在具有感应结构的界面层,它是受碳纤维表面微晶感应而形成的由基本平行于表面且更为细小的微晶所组成的厚约数纳米至数十纳米的过渡层,碳纤维微晶越大,取向性越好,则界面层的厚度也越大,取向性也相应提高.由此可定性解释高模量碳纤维与热解碳粘合效果弱于高强碳纤维. 相似文献
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Selective Enhancement of Inner Tube Photoluminescence in Filled Double‐Walled Carbon Nanotubes
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Philip Rohringer Lei Shi Paola Ayala Thomas Pichler 《Advanced functional materials》2016,26(27):4874-4881
A highly selective enhancement of the optical response of the inner tubes of double‐walled carbon nanotubes has been identified upon transformation of the residual C atoms inside the hollow core to linear carbon chains (LCC). By varying the growth conditions and using standardized suspensions, it has been observed that this optical response depends sensitively on the tube diameter and LCC growth yield. It is reported how the formation of LCC by postsynthesis annealing at 1400 °C leads to an increase of the photoluminescence (PL) signal of the inner tubes up to a factor of 6 for tubes with (8,3) chirality. This behavior can be attributed to a local charge transfer from the inner tubes to the carbon chains, counterbalancing quenching mechanisms induced by the outer tubes. These findings provide a viable pathway to enhance the low PL quantum yield of double‐walled carbon nanotubes and proof the capability of inner tubes to exhibit photoluminescence. 相似文献
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The effect of deuteration (OH ? OD exchange) of the MCVD substrate tube on the absorption loss in fibres was studied using tubes of moderate and low OH content. The OH absorption at 1.39 ?m was reduced from 4 dB/km and 0.9 dB/km to 1 dB/km and 0.7 dB/km, respectively, in fibres made without a barrier layer using deuterated tubes. 相似文献
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Kimmo Mustonen Alexander Markevich Mukesh Tripathi Heena Inani Er‐Xiong Ding Aqeel Hussain Clemens Mangler Esko I. Kauppinen Jani Kotakoski Toma Susi 《Advanced functional materials》2019,29(52)
The recent discovery that impurity atoms in crystals can be manipulated with focused electron irradiation has opened novel perspectives for top‐down atomic engineering. These achievements have been enabled by advances not only in electron optics and microscope stability but also in the preparation of suitable materials with impurity elements incorporated via ion and electron‐beam irradiation or chemical means. Here it is shown that silicon heteroatoms introduced via plasma irradiation into the lattice of single‐walled carbon nanotubes (SWCNTs) can be manipulated using a focused 55–60 keV electron probe aimed at neighboring carbon sites. Moving the silicon atom mainly along the longitudinal axis of large 2.7 nm diameter tubes, more than 90 controlled lattice jumps are recorded and the relevant displacement cross sections are estimated. Molecular dynamics simulations show that even in 2 nm diameter SWCNTs, the threshold energies for out‐of‐plane dynamics are different than in graphene, and depend on the orientation of the silicon‐carbon bond with respect to the electron beam as well as the local bonding of the displaced carbon atom and its neighbors. Atomic‐level engineering of SWCNTs where the electron wave functions are more strictly confined than in 2D materials may enable the fabrication of tunable electronic resonators and other devices. 相似文献
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纳米碳管的电子衍射及其螺旋度测量 总被引:1,自引:0,他引:1
本文对电弧放电和催化剂热解碳氢气法制备的多层直形纳米碳管的倒空间及其螺旋度,采用电子衍射进行了研究。结果表明:尽管制备方法不同,两类多层管的结构相似,皆由螺旋和非螺旋的单层石墨管组成;对其倒空间的分析以及系列倾转电子衍射实验证明,衍射图中测得的表观螺旋度值随和射条件而改变,只有在垂直入射条件下该值才代表碳管的真实螺旋度; 相似文献
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A simple method to decorate mutliwalled carbon nanotubes (MWCNTs) with silver nanoparticles (Ag NPs) to enhance the structural properties is reported in the present study. The Ag NPs of average size 9 nm were deposited uniformly on MWCNTs network by RF sputtering technique. X-ray diffraction (XRD), Raman spectroscopy and Scanning electron microscopy (SEM) are used to compare the structural properties of Ag NPs sputtered nanotubes with those containing functionalized tubes. In addition, effect of these Ag NPs on the surface of nanotubes and optimization of the experimental parameter for uniform deposition of Ag NPs are also discussed. 相似文献
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场发射阵列阴极应用于行波管的不足主要表现在:FEAs发射不稳定、阴极发射电流密度较低及电子束存在散焦的问题.分析了产生这些问题的主要原因。提出了相应的解决方案,主要包括:提高真空度,选择合适的发射体材料,增加电阻层等,以提高电子发射的稳定性;优化发射体结构参量,改善制作方法等,以增大阴极发射的电流密度;对电子枪结构进行修改,解决电子柬散焦等问题。最后,概述了新型材料——碳纳米管在行波管中的应用现状,目前虽然还不成熟,却表现出了极大的潜力: 相似文献
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Jon K. S. Baldwin Nicolai F. Hartmann Stephen K. Doorn Han Htoon 《Advanced functional materials》2015,25(39):6157-6164
A novel procedure for effective fabrication of photostable oxygen‐doped single‐walled carbon nanotubes (SWCNTs) in solid‐state matrices has been developed. SWCNTs drop‐cast on various types of substrates are coated with oxide dielectric thin films by electron‐beam evaporation. Single tube photoluminescence spectroscopy studies performed at room and cryogenic temperatures reveal that such thin film‐coated tubes exhibit characteristic spectral features of oxygen‐doped SWCNTs, indicating the oxide thin film coating process leads to oxygen doping of the tubes. It is also found that the doping efficiency can be effectively controlled by the thin film deposition time and by the types of surfactants wrapping the SWCNTs. Moreover, aside from being the doping agent, the oxide thin film also serves as a passivation layer protecting the SWCNTs from the external environment. Comparing the thin film coated SWCNTs with oxygen‐doped tubes prepared via ozonolysis, the former exhibit significantly higher photostability and photoluminescence on‐time. Therefore, this one‐step deposition/oxygen‐doping procedure provides a possible route toward scalable, versatile incorporation of highly photostable oxygen‐doped SWCNTs in novel optical and optoelectronic devices. 相似文献