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

X-ray diffraction study of multiwalled carbon nanotube (MWNT) grown by are 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 x 10(-5) K-1 to 2.6 x 10(-5) 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 similar to 100 Angstrom. Thicker MWNT's are typically highly defective, and may have the jelly roll (scroll) or defective polygonal structure consisting of flat graphite domains.