SWCNT bundles

Some explanations could be possible for these contradictory results. One is that a various types of CNTs may be obtained by different methods, since SWCNTs as much as 50 % are chiral and nonmetallic [42]. The other is that the result may be attributable to the contact condition of SWCNT bundles. When the bundles closely contact each other, the SWCNT system will likely become a three-dimensional one just as in the case of contacted MWCNTs. [Pg.86]

After briefly introducing the main electronic features of CNTs (Sec. 2) and some general aspects of electronic conduction and transmission (Sec.. 1), we will show how complex electrical measurements to perform on such tiny entities are (Sec. 4). Then we will present the main experimental results obtained on the electrical resistivity of MWCNT and SWCNT and the very recent data relative to the thermopower of SWCNT bundles (Sec. 5). We will also discuss the effect of intercalation on the electrical resistivity of SWCNT bundles (Sec. 6). Finally, we will present some potential applications (Sec. 7). [Pg.108]

In Fig. 7 we present the effect of Br2 intercalation on the temperature dependence of the electrical resistivity of pristine SWCNT bundles before and after heat treatment in vacuum at 450 K for several hours [35]. In Fig. 8 the effect of fiotassium intercalation is presented for different treatments. [Pg.122]

For SWCNT bundles [35], ID intercalation would occur between the CNTs columns as it is the case for jxilyacetylene. Intercalation either by acceptors (Fig. 6) or donors (Fig. 7) increases the electrical conductivity as expected, however the effect is less pronounced than in bulk graphite [34]. [Pg.122]

In conclusion, wc have shown the interesting information which one can get from electrical resistivity measurements on SWCNT and MWCNT and the exciting applications which can be derived. MWCNTs behave as an ultimate carbon fibre revealing specific 2D quantum transport features at low temperatures weak localisation and universal conductance fluctuations. SWCNTs behave as pure quantum wires which, if limited in length, reduce to quantum dots. Thus, each type of CNT has its own features which are strongly dependent on the dimensionality of the electronic gas. We have also briefly discussed the very recent experimental results obtained on the thermopower of SWCNT bundles and the effect of intercalation on the electrical resistivity of these systems. [Pg.125]

Optimisation of SWCNT production has been attempted within the framework of the arc-discharge method in which anode and cathode were made of graphite rods, a hole in the anode being filled with metal catalysts such as Y (1 at.%) and Ni (4.2 at.%) [7]. A dense collar deposit (ca. 20% of the total mass of graphite rod) formed around the eathode under He (ca. 500 Torr), with 30 V and 100 A de eurrent. It was eonfirmed that this optimal eollar eontained large amounts of SWCNT bundles eonsisting of (10, 10) SWCNTs (diameter 1.4 nm). Such morphology resembles that produced by the laser ablation teehnique [4,5]. [Pg.144]

The force effect is applicable to investigation of the mechanical properties of nanomaterials [28, 29]. We measured TERS spectra of a single wall carbon nanotube (SWCNT) bundle with a metallic tip pressing a SWCNT bundle [28]. Figure 2.13a-e show the Raman spectra of the bundle measured in situ while gradually applying a force up to 2.4 nN by the silver-coated AFM tip. Raman peaks of the radial breathing... [Pg.35]

Figure 2.13 TERS spectra of an SWCNT bundle measured with an applied tip-force up to 2.4 nN.

The possible fatigue failure mechanisms of SWCNT in the composite were also reported (Ren et al., 2004). Possible failure modes mainly include three stages, that is, splitting of SWCNT bundles, kink formation, and subsequent failure in SWCNTs, and the fracture of SWCNT bundles. As shown in Fig. 9.12, for zigzag SWCNT, failure of defect-free tube and tubes with Stone-Wales defect of either A or B mode all resulted in brittle-like, flat fracture surface. A kinetic model for time-dependent fracture of CNTs is also reported (Satapathy et al., 2005). These simulation results are almost consistent with the observed fracture surfaces, which can be reproduced reasonably well, suggesting the possible mechanism should exist in CNT-polymer composites. [Pg.194]

Gd Cg2 was generated by arc discharge using a Gd-graphite rod and isolated by a multistage HPLC technique SWCNT bundles were prepared by pulsed-laser evaporation. The doping of Gd C82 into the inner hollow space of SWCNTs was carried out in a sealed glass ampoule at 500 °C for 24 h. Prior to the introduction of SWCNTs to the ampoule, the SWCNTs were heated in dry air at 420 °C for 20 min [267]. [Pg.48]

Atomic force microscopy [6, 7] is one of the most suitable methods for research carbon nanotubes. AFM allows to receive not only a relief of the studied sample, but also distribution of mechanical characteristics, electric, magnetic and other properties on its surface. With the help of AFM, controllable manipulation of individual CNTs and CNTs bundles became possible. In this paper we report our approach to manipulating SWCNTs bundles with lateral force microscopy. LFM gives possibility to study lateral forces that probe acts upon bundles. In spite of good visualization of LFM, its lack is absence of reliable techniques of quantitative interpretation of results. The new way of calibration developed ourselves has allowed to pass from qualitative estimations to quantitative investigations [8], The given calibration technique is much more exact, than others known till now [9, 10], and does not assume simplification. With the help of new technique we may study adhesion of bundles to substrate and adhesion of CNTs in bundle qualitatively in real time more easy way. This result will provide new possibilities for nanotube application. [Pg.415]

X-ray diffractograms for pristine and PEI-wrapped arc-SWCNTs are presented in Figure 10.6. The peak corresponding to SWCNT bundles (appearing at low diffraction angles (43), 20 = 6°) disappear after the purification and wrapping processes. Raman spectroscopy can also be applied to characterize these dispersions. The G/D ratio decreases drastically for the shrouded carbon nanotubes after the wrapping process (see Table 10.1), attributed to an increase in the... [Pg.293]

The observed M feature near 1,750 cm for SWCNT bundles and for several laser lines is shown on Fig. 7.5 [68]. This feature have been analyzed in terms of two components with frequencies co and ct)+, where the lower frequency mode ca exhibits a weakly dispersive behavior 30 cm as El is varied from 1.58 to... [Pg.144]

A high-resolution matrix-isolation IR study of 13C02 in the v2 and v3 regions shows that (in a neon matrix) v2 is split (649.37, 648.73 cm-1), while v3 shows as a singlet at 2282.15 cm-1.344 The phase behaviour of C02 was followed by in situ Raman spectroscopy up to 67 GPa and 1660 K.345 A high-resolution IR study has been made of the (30°1) band of C02 (6230-6250 cm-1).346 IR spectra and DFT calculations were used to probe the effects on C02 vibrations of adsorption on SWCNT.347 IR spectra were also used to study C02 trapped in SWCNT bundles, via behaviour of the vas mode near 2330 cm-1.348... [Pg.214]

Figure 26.12 A nanotube FET obtained through back-gate assisted selective ECM of SWCNT bundles containing both m- and s-SWCNTs. The gate dependence of conductance initially shows metaUic behaviour (sohd line). After selective ECM, the conductance shows a variation of around five orders of magnitude (dash-dotted hne) signifying that the m-SWCNTs have been eliminated. was 10 mV before ECM and 50 mV after ECM.

Collins et al. [63] and Sumannasekera et al. [64] later reported that electrical resistance R and thermoelectric power (TEP) of SWCNT bundles and thin films are sensitive to gas adsorption [Figure 14.7(b)]. The film conductance is changed dramatically upon exposure to O2, NO2, and NH3 gases, presumably due to charge transfer from the adsorbates on semiconducting tubes [6,63]. The TEP of SWCNT bundles was also found sensitive to inert gas such as N2 and... [Pg.519]

To prepare the CNT/MOX liquids for spin-coating, the SWCNT bundles were dispersed in the organometallic solutions (Sn [OOCCH(C2H5)-QH9]2,aq. tin (H) 2-ethylhexanoate -90% in 2-ethylhexanoic acid) by ultrasonic vibration. Alternatively, MWCNTs bundles with Sn02 nanoparticles and cetyltrimethyl ammonium bromide can be dispersed in water. ° In... [Pg.392]

In this study we report SWCNT properties calculated by using a fiill-potential all-electron DFT approach, showing that structural and mechanical properties agree well witii other theoretical results and experiment, with only small effects of intertube coupling. The RBMs are shown to be sensitive to the intertube separation, and the (2R+3.4A) estimate is to be used with care when simulating SWCNT bundles. [Pg.273]

Figure 4.10 TEM images of SWCNT (a) Individual SWCNTs (reprinted with permission from [53]) and (b) SWCNT bundle with diffraction pattern in the inset (reprinted with permission from [88]).

$Figure 4.10 TEM images of SWCNT (a) Individual SWCNTs (reprinted with permission from [53]) and (b) SWCNT bundle with diffraction pattern in the inset (reprinted with permission from [88]).$

Figure 1.13 (a) Raman spectra of the G band at several potentials applied to a SWCNT bundle. (b,c) Variation of the G+ band and G- band frequency, respectively, with the applied potential for three different electrolyte solutions. (Adapted from Ref. [80].)... [Pg.15]

SWCNT bundles containing nanotubes with different diameters are easy to obtain experimentally, but such samples may lead to overlapping RBM modes and complex Raman spectra that are difficult to interpret. In contrast, SWCNTs synthesized via the HiPCO method are favored for spectroelectrochemical studies due to their small diameters, which lead to well-separated RBM peaks, thereby simplifying nanotube chirality assignments significantly [58, 72]. [Pg.16]

Kalbac, M., Kavan, L., Dunsch, L., and Dresselhaus, M.S. (2008) Development of the tangential mode in the Raman spectra of SWCNT bundles during electrochemical charging. Nano Lett, 8, 1257-1264. [Pg.25]

L. (2009) In situ Raman spectroelec-trochemistry of SWCNT bundles development of the tangential mode during electrochemical charging in different electrolyte solutions. Diamond Relat. Mater., 18(5-8), 972-974. [Pg.26]

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