Detailed analysis of the Raman response of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>n</mml:mi></mml:math>-doped double-wall carbon nanotubes

Rauf, H.; Pichler, Thomas; Pfeiffer, R.; Simón, F.; Kuzmany, H.; Popov, V. N.

doi:10.1103/physrevb.74.235419

Cited by 34 publications

(35 citation statements)

References 35 publications

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“…The G inner exhibits small blueshifts as it is expected to doping processes involving innermost tubes. 23,24 Similar shifts have also been observed in p-doping processes occurring between MWCNTs and bromide molecules. 25 Every Raman peak related to the outermost tubes' diameter distribution of the MWCNTs in the nanocomposite was blueshifted after the ball-milling step.…”

Section: Resultssupporting

confidence: 55%

Raman spectroscopy fingerprint of stainless steel-MWCNTs nanocomposite processed by ball-milling

et al. 2018

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Stainless steel 304L alloy powder and multiwalled carbon nanotubes were mixed by ball-milling under ambient atmosphere and in a broad range of milling times, which spans from 0 to 120 min. Here, we provided spectroscopic signatures for several distinct composites produced, to show that the Raman spectra present interesting splittings of the D-band feature into two main sub-bands, D-left and D-right, together with several other secondary features. The G-band feature also presents multiple splittings that are related to the outer and inner diameter distributions intrinsic to the multiwalled carbon nanotube samples. A discussion about the second order 2D-band (also known as G′-band) is also provided. The results reveal that the multiple spectral features observed in the D-band are related to an increased chemical functionalization. A lower content of amorphous carbon at 60 and 90 min of milling time is verified and the G-band frequencies associated to the tubes in the outer diameters distribution is upshifted, which suggests that doping induced by strain is taking place in the milled samples. The results indicate that Raman spectroscopy can be a powerful tool for a fast and non-destructive characterization of carbon nanocomposites used in powder metallurgy manufacturing processes.

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Section: Resultssupporting

confidence: 55%

Raman spectroscopy fingerprint of stainless steel-MWCNTs nanocomposite processed by ball-milling

et al. 2018

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“…A similar situation exists for the chemical doping of DWCNTs when the dopant is located outside the DWCNTs. [13,14] This assumption has been confirmed by the chemical doping of DWCNTs, [12] and also by recent spectroelectrochemical studies of ex-peapod DWCNTs. [2,15,16] In addition, due to the polydispersity of as-grown DWCNTs, it is challenging to disentangle the properties of DWCNTs as a function of the semiconducting and metallic characters of the outer/inner tubes.…”

Section: Introductionmentioning

confidence: 50%

Probing Charge Transfer between Shells of Double‐Walled Carbon Nanotubes Sorted by Outer‐Wall Electronic Type

Kalbáč¹,

Green²,

Hersam³

et al. 2011

Chemistry A European J

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Double-walled carbon nanotubes (DWCNTs) with outer metallic (M) or semiconducting (S) shells were sorted by density-gradient ultracentrifugation and examined by Raman spectroscopy and in situ Raman spectroelectrochemistry. The combination of sorting and the selection of appropriate laser excitation energies allowed the disentanglement of the effects of different variations of the electronic type (M or S) of the inner and outer tubes in DWCNTs on the doping behavior and charge transfer between the inner and outer walls. Charge transfer from the outer tube to the inner tube occurs only if the electronic states of the outer tube are filled with electrons or holes, and if these filled states are higher in energy than those of the inner tube. Therefore, each combination of inner and outer tube (i.e., inner@outer: M@M, M@S, S@M, and S@S) exhibits a distinct behavior. The potential needed to observe the effects of charge transfer between the inner and outer tubes is found to increase in the following order: M@M < S@M < M@S < S@S.

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“…[51,52,69,73,98,114,121,125,126] However, the metallic inner tubes are considerably more sensitive to doping than semiconducting ones. [69] In contrast to RBM, the G-bands of inner/outer tubes overlap in pristine DWNTs, [51,52,69,98,112,114,121,125,127] but chemical p-doping selectively upshifts the G-bands of outer tubes. [127] This effect was reproduced for anodic charging of DWNTs.…”

Section: Fullerene Peapodsmentioning

confidence: 95%

“…[98] Also the n-doping by K-vapor causes a blue shift in the outer tubes. [112] Spectroelectrochemistry of K-doped DWNT indicates an almost complete recovery of the spectra upon anodic charging. [53] The second-order Raman scattering in DWNTs is useful for analysis, because the inner/outer tubes have distinct G'-modes already in pristine state, both for the ex-peapod [128] and CVDgrown [73] samples.…”

Section: Fullerene Peapodsmentioning

confidence: 99%

“…[18] Non-monotonic trends [19,25] were reported in K + -containing aprotic electrolyte solutions, and a simple mechanical model was suggested to explain this behavior. [112] Further insight into G-mode shifts can be obtained from single nanotube studies (Section 6.1.2), while the effect of bundling can also be extracted. [60] The spectroelectrochemistry of second-order Raman bands G'-and D-modes resembles that of the G-mode.…”

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confidence: 99%

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