共查询到20条相似文献,搜索用时 15 毫秒
1.
C.D. Scott S. Arepalli P. Nikolaev R.E. Smalley 《Applied Physics A: Materials Science & Processing》2001,72(5):573-580
Mechanisms proposed in the literature are compared with a current scenario for the formation of single-wall carbon nanotubes
in the laser-ablation process that is based on our spectral emission and laser-induced fluorescence measurements. It is suggested
that the carbon which serves as feedstock for nanotube formation not only comes from the direct ablation of the target, but
also from carbon particles suspended in the reaction zone. Fullerenes formed in the reaction zone may be photo-dissociated
into C2 and other low molecular weight species, and also may serve as feedstock for nanotube growth. Confinement of the nanotubes
in the reaction zone within the laser beam allows the nanotubes to be ‘purified’ and annealed during the formation process
by laser heating.
Received: 2 November 2000 / Accepted: 3 November 2000 / Published online: 23 March 2001 相似文献
2.
J. Lefebvre R. Antonov A.T. Johnson 《Applied Physics A: Materials Science & Processing》1998,67(1):71-74
Received: 10 February 1998 相似文献
3.
A theoretical model for the growth of single-wall carbon nanotubes produced by metal-catalyzed decomposition of hydrocarbons
and fullerenes is presented. The growth process is treated as a thermodynamic equilibrium between carbon in the gas phase
and carbon in the nanotube. The minimum possible nanotube diameters based on several published experimental conditions are
calculated by combining the free energy of the reaction with an equation derived from elastic theory. The model predicts the
possibility of generating nanotubes with extremely small diameters that are smaller than in the corresponding experiments.
Received: 18 July 2001 / Accepted: 19 November 2001 / Published online: 4 March 2002 相似文献
4.
Synthesis and Raman characterization of mono-sized single-wall carbon nanotubes in one-dimensional channels of AlPO4-5 crystals 总被引:1,自引:0,他引:1
H.D. Sun Z.K. Tang J. Chen G. Li 《Applied Physics A: Materials Science & Processing》1999,69(4):381-384
Mono-sized single-wall carbon nanotubes were formed in one-dimensional channels of AlPO4-5 single crystal (AFI) by pyrolysis of tripropylamine (TPA). Raman spectra have been measured for the TPA-AFI crystals thermally
processed at different conditions. TPA molecules are carbonized at 400 °C, and carbon nanotubes were formed at 500 °C or above.
The radial-breathing mode, which is special for carbon nanotube geometry, was observed. Three Raman-active modes with symmetry
A
1g, E
1g, and E
2g were identified by detailed symmetrical analysis for the polarized-Raman spectra.
Received: 29 October 1998 / Accepted: 29 March 1999 / Published online: 24 June 1999 相似文献
5.
Y-branching of single walled carbon nanotubes 总被引:1,自引:0,他引:1
P. Nagy R. Ehlich L.P. Biró J. Gyulai 《Applied Physics A: Materials Science & Processing》2000,70(4):481-483
Y-branching was observed by scanning tunnelling microscopy (STM) in single wall carbon nanotubes grown by thermal decomposition
of C60 fullerene in the presence of transition metals. These novel carbon nanostructures may play an important role in carbon-based
nanoelectronics.
Received: 18 November 1999 / Accepted: 20 January 2000 / Published online: 8 March 2000 相似文献
6.
S. Bandow F. Kokai K. Takahashi M. Yudasaka S. Iijima 《Applied Physics A: Materials Science & Processing》2001,73(3):281-285
The magnetic properties of single-wall carbon nanohorns (SWNH) were studied by electron spin resonance (ESR) and static magnetic
susceptibility measurements. The SWNHs were ESR active with linewidth (ΔH) of ∼6 G in vacuo at room temperature. ΔH was susceptible
to the partial pressure of O2 and became 53 G at 1 atmospheric pressure of O2, while the integrated ESR intensity was independent on O2 pressure and behaved as Curie-like, suggesting an intrinsic ESR origin with localized electron spin character. The diamagnetic
susceptibility for SWNHs indicated a value smaller than that of randomly oriented graphite by an order of magnitude, but showing
a magnitude comparable to those of C60 and C70. It is suggested that the large diamagnetism expecting for sp2 networked carbon materials will be canceled by the Van Vleck constant paramagnetism.
Received: 20 November 2000 / Accepted: 21 November 2000 / Published online: 25 July 2001 相似文献
7.
F. Kokai K. Takahashi D. Kasuya M. Yudasaka S. Iijima 《Applied Physics A: Materials Science & Processing》2001,73(4):401-407
Single-wall carbon nanotubes (SWNTs) were synthesized by the irradiation of 20-ms CO2 laser pulses onto a graphite–Co/Ni target at room temperature. We investigated the effect of laser power density (10–150 kW/cm2) and ambient Ar gas pressure (150–760 Torr) on the abundance of SWNTs with lengths of up to about 200 nm in soot-like carbonaceous
deposits. For a constant power density (30 kW/cm2), depending on the Ar gas pressure, SWNTs with diameters of 1.2–1.4 nm were synthesized. Expansion behavior and temperature-fall
rates of clusters and/or particles in laser plumes were also analyzed by high-speed video imaging and temporally and spatially
resolved emission spectroscopy. The temperature-fall rates were estimated to be 171–427 K/ms. The SWNT growth on the time
scale of a few milliseconds appeared to be related to some features of condensing clusters and/or particles, including resident
densities, collision frequencies and temperatures.
Received: 16 July 2001 / Accepted: 23 July 2001 / Published online: 30 August 2001 相似文献
8.
Z. Wang F. Zhu W. Wang G. Yu M. Ruan 《Applied Physics A: Materials Science & Processing》2000,71(3):353-355
We report the observation of a carbon nanostructure grown on a graphite surface by Ar+ ion bombardment. We demonstrate experimentally that, in view of transmission electron microscopy (TEM)-based evidence, some
of these carbon nanostructures emerged the whiskerlike protrusion and/or the sputtered-surface, suggesting a new growth model
for nanocarbon, distinctly different from that found in arc-discharge and many other methods.
Received: 14 April 2000 / Accepted: 17 April 2000 / Published online: 13 July 2000 相似文献
9.
Z.-X. Wang J. Hu A.-G. Li M.-L. Ruan 《Applied Physics A: Materials Science & Processing》2001,73(4):463-465
When examined under a high-resolution transmission microscope (HRTEM), highly oriented pyrolitic graphite (HOPG), after ultrasound
treatment, is found to contain some bent graphitic sheets. These bent structures are ordered graphitic sheets, which have
specific bend angles that are a multiple of 30° (from 30° to 180°). We speculate that the creation and variation of bend angles
is a result of interplay between the conformation of sp3-like defects and the ultrasound wave impact.
Received 8 September 2000 / Accepted: 6 November 2000 / Published online: 23 May 2001 相似文献
10.
Spectroscopic properties and STM images of carbon nanotubes 总被引:2,自引:0,他引:2
A. Rubio 《Applied Physics A: Materials Science & Processing》1999,68(3):275-282
Received: 23 November 1998 / Accepted: 22 December 1998 相似文献
11.
K. Shimotani K. Anazawa H. Watanabe M. Shimizu 《Applied Physics A: Materials Science & Processing》2001,73(4):451-454
We have synthesized multi-walled carbon nanotubes (MWNTs) using a DC arc discharge method under organic molecular atmospheres.
This method allows us to synthesize about five times more MWNTs than are synthesized using the usual arc discharge method,
using discharge conditions of 100 A and 20 V. We have examined the synthetic yield of MWNTs at various pressures under different
organic atmospheres. The yield of MWNTs increases with the number of carbon atoms in the organic molecule.
Received: 21 September 2000 / Accepted: 18 December 2000 / Published online: 26 April 2001 相似文献
12.
Honeycomb-like alignments of carbon nanotubes were prepared by pyrolysis of a metal phthalocyanine at 950 °C in an Ar/H2 flow. A simple synthetic method has been developed for a large-scale synthesis of aligned carbon nanotubes normal to a substrate
surface.
Received: 15 June 2000 / Accepted: 21 June 2000 / Published online: 2 August 2000 相似文献
13.
Scanning tunneling microscopy of carbon nanotubes 总被引:1,自引:0,他引:1
W. Clauss 《Applied Physics A: Materials Science & Processing》1999,69(3):275-281
This article reports on the application of scanning tunneling microscopy for the study of surface structures and electronic
properties of carbon nanotubes. Geometric effects resulting from the cylindrical shape of the tubes as well as the particular
band structure of the graphitic crystal lattice can lead to a variety of contrast patterns. On the atomic scale, it is sometimes
possible to see the full honeycomb lattice structure but often different structures are observed. Besides distortions caused
by tip–sample interactions, we find that a complex superstructure superimposed on the simple atomic contrast pattern arises
from elastic scattering of the Fermi states at defects or impurities. From a careful analysis of high-resolution images it
is possible to extract information about elastic strain of individual tubes. A new combination of scanning tunneling and scanning
force microscopy enables near-atomic point resolution of the force signal the tubes can be identified without the need of
a conducting substrate. This imaging mode is a crucial step for the characterization of electronic devices based on individual
single-wall tubes. This mode can be further enhanced by the use of single-walled tubes as probe tips.
Received: 17 May 1999 / Accepted: 18 May 1999 / Published online: 4 August 1999 相似文献
14.
G.S. Duesberg J. Muster H.J. Byrne S. Roth M. Burghard 《Applied Physics A: Materials Science & Processing》1999,69(3):269-274
Production methods for carbon nanotubes are now well established and allow their synthesis on a scale of grams per day. For
many potential applications of this unique material, its purification still remains a crucial problem. In this article various
purification methods for single- and multi-wall carbon nanotubes are reviewed. These methods are compared in terms of their
capacity, efficiency, and effects on the tubes. In addition, the use of Raman spectroscopy for monitoring the chromatographic
purification of single-wall nanotubes is described.
Received: 17 May 1999 / Accepted: 18 May 1999 / Published online: 29 July 1999 相似文献
15.
Single-walled carbon nanotubes (SWNTs) encapsulating C70s, so-called C70 peapods, were synthesized in high yield by a vapor-phase doping method. Raman spectra, high resolution transmission electron microscopy (HRTEM), and selected area electron diffraction (SAED) measurement indicate that the tube diameter is one of the important factors to determine the orientation of C70 molecules inside the SWNTs. SWNTs with different diameters give different alignment of C70 molecules. The lying orientation is favorable over the standing orientation in thin nanotube, i.e. 1.36 nm nanotubes, whereas the standing orientation is favorable in thick nanotubes, i.e. 1.49 and 1.61 nm nanotubes. 相似文献
16.
K. Suenaga F. Willaime A. Loiseau C. Colliex 《Applied Physics A: Materials Science & Processing》1999,68(3):301-308
2 bonds attests for the presence of ordered BN domains and of carbon domains; (ii) the elemental profiles show that BN layers
and carbon layers are immiscible with a radial organisation into two to five domains; and (iii) the sets of layers at free
surfaces – including the inner surfaces of tubes – are always made of carbon. The origin of this chemical organisation, which
is most likely obtained during the growth, is discussed. For the hafnium-boride metallic particles coated by C/BN envelopes,
a model based on the solidification from the outside to the inside of isolated liquid-like droplets is proposed: the carbon
phase solidifies first according to theoretical phase diagrams, and forms the outer shells. For the tubes, a directional eutectic
solidification process is shown to account for the observed C/BN/C sequence, in a vapour–liquid–solid scheme, with an hafnium-rich
liquid-like particle at the tip of the tube.
Received: 26 November 1998 / Accepted: 14 January 1999 相似文献
17.
V. Turco Liveri M. Rossi G. D’Arrigo D. Manno G. Micocci 《Applied Physics A: Materials Science & Processing》1999,69(4):369-373
ZnS nanoparticles were synthetized using water-containing AOT reversed micelles as nanoreactors and characterized by UV-Vis
spectrophotometry, HRTEM (high-resolution transmission electron microscopy), SAED (selected-area electron diffraction), and
digital image processing. The experimental data evidence a slow growing process of fractal-like ZnS nanoparticles’ coupled
with a change of their photophysical properties. Both these processes are well described by power laws. The nanoparticles
size is mainly controlled by the micellar size. After evaporation of the organic solvent, it has been found that the deposit
is constituted by smaller and more stable ZnS nanoparticles bathed in a surfactant matrix.
Received: 20 April 1999 / Accepted: 23 April 1999 / Published online: 8 September 1999 相似文献
18.
Synthesis, integration, and electrical properties of individual single-walled carbon nanotubes 总被引:4,自引:0,他引:4
J. Kong C. Zhou A. Morpurgo H.T. Soh C.F. Quate C. Marcus H. Dai 《Applied Physics A: Materials Science & Processing》1999,69(3):305-308
High-quality single-walled carbon nanotubes (SWNTs) are synthesized by chemical vapor deposition (CVD) of methane on silicon-dioxide
substrates at controlled locations using patterned catalytic islands. With the synthesized nanotube chips, microfabrication
techniques are used to reliably contact individual SWNTs and obtain low contact resistance. The combined chemical synthesis
and microfabrication approaches enable systematic characterization of electron transport properties of a large number of individual
SWNTs. Results of electrical properties of representative semiconducting and metallic SWNTs are presented. The lowest two-terminal
resistance for individual metallic SWNTs (≈5 μm long) is ≈16.5 kΩ measured at 4.2 K.
Received: 17 May 1999 / Accepted: 18 May 1999 / Published online: 14 July 1999 相似文献
19.
Filling carbon nanotubes 总被引:12,自引:0,他引:12
D. Ugarte T. Stöckli J.M. Bonard A. Châtelain W.A. de Heer 《Applied Physics A: Materials Science & Processing》1998,67(1):101-105
Received: 2 March 1998 相似文献
20.
K. Yamamoto Y. Koga S. Fujiwara F. Kokai R.B. Heimann 《Applied Physics A: Materials Science & Processing》1998,66(1):115-117
3 bonds in the carbon films prepared by pulsed laser deposition of carbon obtained from graphite was investigated by electron
energy loss spectroscopy (EELS) and X-ray photoelectron spectroscopy (XPS). The fraction of sp3 bonds increased with a decreasing laser wavelength. Energetic C+ ion species were effectively produced by using a short-wavelength laser. The sp3 bond fraction increased with an increasing amount of energetic C+ ion species. The fractions of sp3 bonds in the carbon film were 80%, 42%, 26% and 15% at wavelengths of 193, 248, 532 and 1064 nm, respectively.
Received: 28 October 1997/Accepted:29 October 1997 相似文献