Resonant Raman spectroscopy of single-wall carbon nanotubes under pressure

Abstract

International audienceWe performed high pressure resonant Raman experiments on well characterized purified single-wall carbon nanotubes up to 40 GPa using argon as pressure transmitting medium. We used two different excitating wavelengths, at 632.8 nm and 514.5 nm. In contrast with other studies no clear sign of phase transformation is observed up to the highest studied pressure of 40 GPa. Our results suggest that the progressive disappearance of the radial breathing modes observed while increasing pressure should not be interpreted as the sign of a structural phase transition. Moreover, a progressive change of profile of the tangential modes is observed. For pressures higher than 20 GPa the profile of those modes is the same for both laser excitations. We conclude that a progressive loss of resonance of single-wall carbon nanotubes under pressure might occur. In addition, after high pressure cycle we observed a decrease of intensity of the radial breathing and tangential modes and a strong increase of the D band

Effect of tetrahedral amorphous carbon coating on the resistivity and wear of single-walled carbon nanotube network

“…6) as is expected in case of SWCNT bundles under stress. [32][33][34] This indicates that the SWCNTs forming the network are not under stress post deposition of ta-C.…”

“…[32][33][34] The Raman spectra of samples (on silicon substrates) post deposition of 20 nm and 50 nm of ta-C were acquired and are shown in Figs. 6(a) and 6(b), respectively.…”

Raman bands of double‐wall carbon nanotubes: comparison with single‐ and triple‐wall carbon nanotubes, and influence of annealing and electron irradiation

“…High-pressure results on SWNTs have been summarized by Loa. 40 Fewer high-pressure reports appeared 44 on MWCNTs probably because of their similarity with graphite. The large diversity of reported data for SWCNTs can be attributed to differences in their syntheses.…”

Nanoscale pressure effects in individual double-wall carbon nanotubes

“…We use argon, oxygen, and methanol-ethanol in the proportion 4:1. Recent studies of Merlen et al 8,9 on CNT bundles ͑CNTs grown by the arc discharge method͒ show no frequency dependence on the media. In this study we use CNTs grown using the catalytic chemical vapor deposition method ͑CCVD͒, which leads to the formation of individual CNT and small bundles allowing nanoscale pressure effects to be investigated.…”

“…This is supported by the fact that in the case of tubes in a bundle ͑i.e., without surrounding pressure medium͒ no medium effect is observed. 8 The medium dependence of the shape of the optical phonon band also indicated that the DWCNTs are surrounded by the pressure transmitting medium. We conclude that the DWCNTs here are surrounded by the pressure medium.…”