Transformation of multiwalled carbon nanotubes to amorphous carbon nanorods under ion irradiation

Abstract

Amorphous carbon nanorods were synthesized from hollow multiwalled carbon nanotubes (MWCNTs) by low-energy Ar ion irradiation at room temperature. The obtained nanorods were investigated by Raman spectroscopy, transmission electron microscopy (TEM), soft X-ray photoelectron spectroscopy (XPS), and soft X-ray absorption spectroscopy (XAS). It was found that the diameter of the MWCNTs significantly increased with increasing the fluence. Finally, the original hollow structure and the graphite (002) TEM diffraction spots of MWCNTs completely disappeared and a broadening of Raman spectra occurred, indicating the amorphization of MWCNTs. The increase in the diameter by the irradiation can be explained by the bending and the randomization of the broken carbon hexagonal networks, and the accumulation of knocked-on atoms. The XPS and XAS measurements also support the formation of amorphous carbon nanorods.