Raman spectra and thermal stability analysis of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mn>0.4</mml:mn><mml:mspace width="0.3em" /><mml:mi>nm</mml:mi></mml:mrow></mml:math>freestanding single-walled carbon nanotubes

Ye, J. T.; Tang, Zikang

doi:10.1103/physrevb.72.045414

Cited by 24 publications

(17 citation statements)

References 32 publications

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“…Although nanotubes can stand very high annealing temperatures [11], the smaller tubes with high curvature are very reactive. The strong curvature was also reported to trigger the destruction of ultrathin SWNTs at the elevated temperature even in vacuum [12]. Our results are in good agreement with this observation.…”

supporting

confidence: 94%

“…However, it has been also reported that for the small diameter tubes, the change of D line position is very pronounced. For instance, the D line in 0.4 nm tube is about 1239 cm À1 with higher intensity due to a significant bending of bonds in small tubes because of curvature effect [12]. The observed 1250 cm À1 is very close to the D-line value and the diameter of inner tube is larger than 0.4 nm.…”

mentioning

confidence: 83%

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Temperature dependence of inner tube growth from ferrocene‐filled single‐walled carbon nanotubes

Liu

Kuzmany

Saito

et al. 2011

Physica Status Solidi (b)

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The growth of inner tubes from ferrocene‐filled single‐walled carbon nanotubes was studied with Raman spectroscopy. Special attention was paid to inner tubes formation based on the annealing temperature and the outer tube diameter. Besides the presence of inner tubes radial breathing mode, a new Raman feature appears around 1250 cm−1, which is always related to the appearance of the inner tube. The thermal stability of the inner tube strongly depends on the outer tube diameter. The inner tube formed inside outer tube with 1 nm diameter is destructed at 1000 °C, but it can survive more than 1300 °C with outer tube diameter of about 1.6 nm. Furthermore, the splitting of G line and the shift of 2D line were discussed regarding to the appearance of inner tubes.

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confidence: 94%

mentioning

confidence: 83%

Temperature dependence of inner tube growth from ferrocene‐filled single‐walled carbon nanotubes

Liu

Kuzmany

Saito

et al. 2011

Physica Status Solidi (b)

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“…C 1 and C 2 indicate the two carbon atoms in the bridge site. previous studies, both theoretically [42] and experimentally [43,44], wherein the (5,0) SWCNT was found to be significantly more robust than the (3,3) and (4,2) SWCNTs, all three of which have similar diameters. So with the exception of the (5,0) SWCNT, a trend can be generalized that relates the charge transfer with the R 0 .…”

Section: Adsorption Of Atomic Oxygenmentioning

confidence: 91%

A computational study on the effect of local curvature on the adsorption of oxygen on single-walled carbon nanotubes

Moreno

Aspera

David

et al. 2015

Carbon

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a b s t r a c tWe investigated the effect of local curvature on the adsorption of oxygen on single-walled carbon nanotubes based on density functional theory calculations with van der Waals corrections. The results showed that as the curvature increases, the interaction of the nanotubes with oxygen increases as well. An oxygen atom was strongly chemisorbed on the bridge site of the nanotubes accompanied by a significant transfer of charge from the surface to the oxygen atom. Larger curvature enhanced both the adsorption energy and charge transfer due to the greater strain on the carbon atoms that led to a better interaction with oxygen. The oxygen molecule was physisorbed on the nanotubes with the interaction arising mostly from the long-range van der Waals interactions. The adsorption energy was also enhanced by greater curvature. The results were compared with the flat graphene sheet to confirm the effects of surface curvature.

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“…3, Raman spectrum of the 4-Angstrom carbon nanotubes is characterized by three significant peaks at 510 cm À1 , 550 cm À1 , 580 cm À1 in the RBM region, attributable to the (4,2), (5,0) and (3,3) nanotubes, respectively. 27 It is noted that the D band splits into three major peaks, a phenomenon which still remains unexplained. It should be noted that the large curvature of the ultra-small SWNTs introduces a re-hybridization of the s * and p * bands, thereby leading to a softening of the RBM mode.…”

Section: Raman Characteristicsmentioning

confidence: 99%

Superconductivity in 4-Angstrom carbon nanotubes—a short review

et al. 2012

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We give an up-to-date review of the superconducting phenomena in 4-Angstrom carbon nanotubes embedded in aligned linear pores of the AlPO 4 -5 (AFI) zeolite, first discovered in 2001 as a fluctuation Meissner effect. With the introduction of a new approach to sample synthesis around 2007, new data confirming the superconductivity have been obtained. These comprise electrical, specific heat, and magnetic measurements which together yield a consistent yet complex physical picture of the superconducting state, largely owing to the one-dimensional (1D) nature of the 4-Angstrom carbon nanotubes. For the electrical transport characteristics, two types of superconducting resistive behaviors were reproducibly observed in different samples. The first type is the quasi 1D fluctuation superconductivity that exhibits a smooth resistance drop with decreasing temperature, initiating at 15 K. At low temperatures the differential resistance also shows a smooth increase with increasing bias current (voltage). Both are unaffected by an applied magnetic field up to 11 Tesla. These manifestations are shown to be consistent with those of a quasi 1D superconductor with thermally activated phase slips as predicted by the Langer-Ambegaokar-McCumber-Halperin (LAMH) theory. The second type is the quasi 1D to 3D superconducting crossover transition, which was observed to initiate at 15 K with a slow resistance decrease switching to a sharp order of magnitude drop at $7.5 K. The latter exhibits anisotropic magnetic field dependence and is attributed to a Berezinskii-Kosterlitz-Thouless (BKT)-like transition that establishes quasi-long-range order in the plane transverse to the c-axis of the aligned nanotubes, thereby mediating a 1D to 3D crossover. The electrical data are complemented by magnetic and thermal specific heat bulk measurements. By using both the SQUID VSM and the magnetic torque technique, the onset of diamagnetism was observed to occur at $15 K, with a rapid increase of the diamagnetic moment below $7 K. The zero-field-cooled and field-cooled branches deviated from each other below 7 K, indicating the establishment of a 3D Meissner state with macroscopic phase coherence. The superconductivity is further supported by the specific heat measurements, which show an anomaly with onset at 15 K and a peak at 11-12 K. In the 3D superconducting state, the nanotube arrays constitute a type-II anisotropic superconductor with H c1 z 60 to 150 Oe, coherence length x z 5 to 15 nm, London penetration length l z 1.5 mm, and Ginzburg-Landau k z 100. We give a physical interpretation to the observed phenomena and note the challenges and prospects ahead.

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Raman spectra and thermal stability analysis of0.4nmfreestanding single-walled carbon nanotubes

Cited by 24 publications

References 32 publications

Temperature dependence of inner tube growth from ferrocene‐filled single‐walled carbon nanotubes

Temperature dependence of inner tube growth from ferrocene‐filled single‐walled carbon nanotubes

A computational study on the effect of local curvature on the adsorption of oxygen on single-walled carbon nanotubes

Superconductivity in 4-Angstrom carbon nanotubes—a short review

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