Morphological change of multiwalled carbon nanotubes through high-energy (MeV) ion irradiation

Abstract

Multiwalled carbon nanotubes (MWCNTs) were expanded by 2.5 times in diameter through high-energy (MeV) ion irradiation. Pristine MWCNTs were synthesized onto SiO 2 substrate by chemical vapor deposition. The 4 MeV Cl 2+ ions with a dose of 3 ϫ 10 16 ions/ cm 2 were irradiated on MWCNTs. From high-resolution transmission electron microscopy (HR-TEM) images, the average diameter of the high-energy-ion-irradiated MWCNTs was ϳ180 nm, while that of the pristine MWCNTs was ϳ70 nm. The wall thickness of the pristine and the high-energy-ion-irradiated MWCNT samples was ϳ20 nm and 40-50 nm, respectively. We observed the clear formation of nanocompartments with bamboolike structure inside the tubes after ion irradiation. The amorphous carbon structure in the ion-irradiated MWCNT shells was observed from Raman spectra. Based on the results of HR-TEM and Raman spectra, the expansion of the systems represents morphological transition from crystalline graphite structure to amorphous carbon or finite sized graphite structure due to the ion impact. We suggest that high-energy ion irradiation can be useful for the modification of MWCNT structures.

Swift heavy ion induced modifications of single walled carbon nanotube thin films

“…3(b)), where optical transition energies are plotted with diameter, it has been found that both values correspond to semiconducting nanotubes. The D band, observed at 1345 cm À1 is due to the pores, impurity and other symmetry breaking defects in sp 2 carbon samples [9]. The intensity of this peak is related to the defects as well as amorphous carbon present in the samples.…”

“…Due to their radiation stability, CNTs can also be used as radiation shields in nuclear reactors [6]. Irradiation causes defects on the surface of CNTs which give rise to various types of structural modifications such as welding and bending [7,8], formation of nanocompartments [9], transformation of single walled nanotubes to multi-walled carbon nanotubes [10], reordering, healing of the system [10][11][12][13][14].…”

Dynamics of fragmentation and multiple vacancy generation in irradiated single-walled carbon nanotubes

“…The irradiation damage induces local structural changes and, in extreme circumstances, transformations that are dependent on the energy and the dose of the irradiating ion. The structural changes in the diameter and transformation of MWCNTs to amorphous carbon rods and wires under the higher fluence of ion irradiation are re-ported by various researchers [16][17][18][19][20][21][22]. Changes in the electronic structure, e.g., in the band gap of CNTs, have been studied due to the impact of energetic ions.…”

Optically transparent carbon nanowire thin film

“…Furthermore, the ion-irradiation-induced transformation of multiwalled carbon nanotubes (MWCNTs) to a-CNWs has been studied [11][12][13][14]. However, this transformation is part of a larger class of radiation-induced transformations to the amorphous state that has received considerable recent attention as a result of ion and electron-beam experiments on MWCNTs [14][15][16]. Kumar et al [17] have been conducting studies on fabrication of carbon nano-pattern/wires in polymer matrix by heavy ion irradiation.…”