Multiwalled carbon nanotubes grown in hydrogen atmosphere: An x-ray diffraction study

Abstract

X-ray diffraction study of multiwalled carbon nanotube (MWNT) grown by arc discharge in hydrogen atmosphere is presented. It is found that the thermal-expansion coefficient along the radial direction of MWNT is widely distributed in a range from $1.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5} {\mathrm{K}}^{\ensuremath{-}1}$ to $2.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5} {\mathrm{K}}^{\ensuremath{-}1},$ indicating the existence of both of Russian doll MWNT and highly defective MWNT. Russian doll MWNT is suggested to have the outer diameter less than $\ensuremath{\sim}100 \mathrm{}\mathrm{\AA{}}\mathrm{}.$ Thicker MWNT's are typically highly defective, and may have the jelly roll (scroll) or defective polygonal structure consisting of flat graphite domains.