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 $1.6\times {10}^{-5}\hspace{0.5em}{\mathrm{K}}^{-1}$ to $2.6\times {10}^{-5}\hspace{0.5em}{\mathrm{K}}^{-1},$ 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 $\sim 100\hspace{0.5em}\mathrm{}\mathrm{\AA }\mathrm{}.$ Thicker MWNT’s are typically highly defective, and may have the jelly roll (scroll) or defective polygonal structure consisting of flat graphite domains.

• Received 11 April 2001

DOI:https://doi.org/10.1103/PhysRevB.64.073105