High pressure Raman study of single-wall carbon nanotubes

High pressure Raman measurements on single-wall carbon nanotubes(SWNTs) with diameters around 1.3 nm have been carried out in a diamond anvil cell.The results show that the changes of nanotube cross-section follow the sequences from circular to elliptical and then to a flattened type structure,which is consistent with our earlier studies.Upon decompression from a high pressure cycle of 31 GPa,the SWNTs are almost recovered to ambient pressure,a pressure well beyond the stability field of traditional sp2 C=C bonds below ~20 GPa.Through the detailed analysis of the linewidth of G-band,we proposed that at a critical pressure the inter-linked configuration is formed among the SWNTs,which can be taken as a more stable structure.This configuration can protect nanotubes experiencing very high pressure compression,so that the nanotubes are still reversible even after such high pressure cycle.