共查询到20条相似文献,搜索用时 15 毫秒
1.
F. Bonaccorso C. Bongiorno P.G. Gucciardi A. Morone C. Spinella 《Applied Surface Science》2007,254(4):1260-1263
The physical/chemical properties of multiwalled carbon nanotubes have attracted much interest for applications in different fields, from micro-electronic to coating technology due, in particular, to their peculiar conductivity properties, to their hardness and high resistance to thermal stress. The technology to produce carbon nanotubes thin films with the desired properties, however, is still under development. In this work, we report on multiwalled carbon nanotubes thin films deposited by pulsed laser deposition techniques ablating commercially polystyrene-nanotubes pellets on alumina substrates. MicroRaman spectroscopy and high resolution Transmission Electron Microscopy provide the experimental confirmation that carbon nanotubes-like structures are present on the alumina surface with both minimal morphological damage of the tubes and structural changes induced by laser beam. 相似文献
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We report an experimental and a theoretical study of the radial elasticity of multiwalled carbon nanotubes as a function of external radius. We use atomic force microscopy and apply small indentation amplitudes in order to stay in the linear elasticity regime. The number of layers for a given tube radius is inferred from transmission electron microscopy, revealing constant ratios of external to internal radii. This enables a comparison with molecular dynamics results, which also shed some light onto the applicability of Hertz theory in this context. Using this theory, we find a radial Young modulus strongly decreasing with increasing radius and reaching an asymptotic value of 30+/-10 GPa. 相似文献
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V. V. Bolotov V. E. Kan P. M. Korusenko S. N. Nesov S. N. Povoroznyuk I. V. Ponomareva V. E. Roslikov Yu. A. Sten’kin R. V. Shelyagin E. V. Knyazev 《Physics of the Solid State》2012,54(1):166-173
Nanocomposite layers based on multiwalled carbon nanotubes (MWCNTs) and non-stoichiometric tin oxide (SnO
x
) have been grown by magnetron deposition and CVD methods. In the case of the CVD method, the study of the structure and phase
composition of obtained nanocomposite layers has shown that a tin oxide “superlattice” is formed in the MWCNT layer volume,
fixed by SnO
x
islands on the MWCNT surface. During magnetron deposition, the MWCNT surface is uniformly coated with tin oxide islands,
which causes a change in properties of individual nanotubes. Electrical measurements have revealed the sensitivity of nanocomposite
layers to (NO2)− molecule adsorption, which is qualitatively explained by a change in the conductivity of the semiconductor fraction of p-type MWCNTs. 相似文献
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Multishell conduction in multiwalled carbon nanotubes 总被引:3,自引:0,他引:3
The full electronic complexity of multiwalled carbon nanotubes may be explored by sequentially removing individual carbon
shells. This technique is employed to directly measure the number of shells contributing to conduction at room temperature,
as well as the contribution of each shell to the overall conductance. By exploring the gate dependence of the conductance,
the random alternation between semiconducting and metallic shells can also be observed.
Received: 31 August 2001 / Accepted: 3 December 2001 / Published online: 4 March 2002 相似文献
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Selective growth of individual multiwalled carbon nanotubes 总被引:1,自引:0,他引:1
R. E. Morjan M. S. Kabir S. W. Lee O. A. Nerushev P. Lundgren S. Bengtsson Y. W. Park E. E. B. Campbell 《Current Applied Physics》2004,4(6):591-594
Growth of individual, vertically aligned multiwalled carbon nanotubes (VACNT) on patterned Si wafers using dc plasma-enhanced CVD is described. The selective growth of individual VACNT within larger holes etched in Si is demonstrated for the first time. 相似文献
10.
Huiying Yan Zhengyu Bai Shujun Chao Qian Cui Lu Niu Lin Yang Jinli Qiao Kai Jiang 《Ionics》2014,20(2):259-268
Carbon nanotubes are believed to be powerful materials for constructing novel hybrid composites with desirable functionalities and applications in many fields. Therefore, a better understanding of the functionalization of multiwalled carbon nanotubes (MWCNTs) holds the key to a better performance of the hybrid properties. In this paper, with a series of aromatic bifunctional molecule additives, modified MWCNTs were used as composite supports for synthesizing nanostructured palladium catalysts for formic acid oxidation. The additives contain anthranilic acid, o-phenylenediamine, salicylic acid, catechol, and phthalic acid. The influence of the different bifunctional groups (such as –NH2, –OH, –COOH, and their mixed groups) on the morphologies, particle sizes, and electrical properties of Pd nanocrystals was intensively studied. Transmission electron microscopy measurement demonstrates that the palladium nanoparticles were well dispersed on the surface of MWCNTs with a relatively narrow particle size distribution in the presence of the additives. Cyclic voltammetry and chronoamperometry tests demonstrate that the functional groups of the additives play an important role in electrocatalytic activity and stability for formic acid oxidation, and the influence law of various functional groups on electrocatalytic activity and stability is also investigated in this paper. We hope it can provide certain theoretical guidance meaning and practical reference value in future studies. 相似文献
11.
H. Jantoljak J.-P. Salvetat L. Forró C. Thomsen 《Applied Physics A: Materials Science & Processing》1998,67(1):113-116
Received: 8 April 1998/Accepted: 9 April 1998 相似文献
12.
We investigate the energy spectra of clean incommensurate double-walled carbon nanotubes, and find that the overall spectral properties are described by the critical statistics similar to that known in the Anderson metal-insulator transition. In the energy spectra, there exist three different regimes characterized by Wigner-Dyson, Poisson, and semi-Poisson distributions. This feature implies that the electron transport in incommensurate multiwalled nanotubes can be either diffusive, ballistic, or intermediate between them, depending on the position of the Fermi energy. 相似文献
13.
Takesue I Haruyama J Kobayashi N Chiashi S Maruyama S Sugai T Shinohara H 《Physical review letters》2006,96(5):057001
We report that entirely end-bonded multiwalled carbon nanotubes (MWNTs) can exhibit superconductivity with a transition temperature (T(c)) as high as 12 K, which is approximately 30 times greater than T(c) reported for ropes of single-walled nanotubes. We find that the emergence of this superconductivity is highly sensitive to the junction structures of the Au electrode/MWNTs. This reveals that only MWNTs with optimal numbers of electrically activated shells, which are realized by end bonding, can allow superconductivity due to intershell effects. 相似文献
14.
文章介绍了多壁碳纳米管弯曲的分子动力学模拟,从原子尺度上解释了由于屈曲失稳而导致的起皱现象,并发现多壁碳纳米管弯曲时会呈现出非线性的力学响应。同时,在模拟过程中,观察到了弯曲诱发扭转的现象,并揭示出扭转变形的内在起因是曲率诱导的晶格错配。 相似文献
15.
We characterize through large-scale simulations the nonlinear elastic response of multiwalled carbon nanotubes (MWCNTs) in torsion and bending. We identify a unified law consisting of two distinct power law regimes in the energy-deformation relation. This law encapsulates the complex mechanics of rippling and is described in terms of elastic constants, a critical length scale, and an anharmonic energy-deformation exponent. The mechanical response of MWCNTs is found to be strongly size dependent, in that the critical strain beyond which they behave nonlinearly scales as the inverse of their diameter. These predictions are consistent with available experimental observations. 相似文献
16.
文章介绍了多壁碳纳米管弯曲的分子动力学模拟,从原子尺度上解释了由于屈曲失稳而导致的起皱现象,并发现多壁碳纳米管弯曲时会呈现出非线性的力学响应。同时,在模拟过程中,观察到了弯曲诱发扭转的现象,并揭示出扭转变形的内在起因是曲率诱导的晶格错配。 相似文献
17.
Rao AM Jorio A Pimenta MA Dantas MS Saito R Dresselhaus G Dresselhaus MS 《Physical review letters》2000,84(8):1820-1823
Polarized Raman spectra of high purity aligned arrays of multiwalled carbon nanotubes, prepared on silica substrates from the thermal decomposition of a ferrocene-xylene mixture, show a strong dependence of the graphitelike G band and the disorder-induced D band on the polarization geometry employed in the experiments. The experimental G-band intensity exhibits a minimum at straight theta(m) = 55 degrees in the VV configuration, in good agreement with theoretical predictions of a characteristic minimum at 54.7 degrees for A(1g) modes in single wall nanotubes, where straight theta(m) denotes the angle between the polarization direction and the nanotube axis. 相似文献
18.
The effect of Fe and Ni catalysts on the synthesis of carbon nanotubes (CNTs) using atmospheric pressure chemical vapor deposition
(APCVD) was investigated. Field emission scanning electron microscopy (FESEM) analysis suggests that the samples grow through
a tip growth mechanism. High-resolution transmission electron microscopy (HRTEM) measurements show multiwalled carbon nanotubes
(MWCNTs) with bamboo structure for Ni catalyst while iron filled straight tubes were obtained with the Fe catalyst. The X-ray
diffraction (XRD) pattern indicates that nanotubes are graphitic in nature and there is no trace of carbide phases in both
the cases. Low frequency Raman analysis of the bamboo-like and filled CNTs confirms the presence of radial breathing modes
(RBM). The degree of graphitization of CNTs synthesized from Fe catalyst is higher than that from Ni catalyst as demonstrated
by the high frequency Raman analysis. Simple models for the growth of bamboo-like and tubular catalyst filled nanotubes are
proposed. 相似文献
19.
研究了多壁碳纳米管(MWNTs)薄膜的湿敏特性,实验所用的多壁碳纳米管是用热灯丝化学气相沉积法(CVD)合成的.分别对未修饰和修饰的多壁碳纳米管膜温度和湿度特性进行研究后发现,修饰的多壁碳纳米管对温度和湿度非常敏感,且对湿度的响应时间和恢复时间短,重复性好.而未修饰的多壁碳纳米管对温度和湿度不太敏感.对修饰多壁碳纳米管的湿敏特性进行了理论分析,给出了其理论表示式.
关键词:
多壁碳纳米管
化学修饰
湿敏特性
物理吸附 相似文献
20.
Chiu HY Deshpande VV Postma HW Lau CN Mikó C Forró L Bockrath M 《Physical review letters》2005,95(22):226101
We report electrical transport experiments, using the phenomenon of electrical breakdown to perform thermometry, that probe the thermal properties of individual multiwalled carbon nanotubes. Our results show that nanotubes can readily conduct heat by ballistic phonon propagation. We determine the thermal conductance quantum, the ultimate limit to thermal conductance for a single phonon channel, and find good agreement with theoretical calculations. Moreover, our results suggest a breakdown mechanism of thermally activated C-C bond breaking coupled with the electrical stress of carrying approximately 10(12) A/m2. We also demonstrate a current-driven self-heating technique to improve the conductance of nanotube devices dramatically. 相似文献