High-temperature shrinkage of single-walled carbon nanotube bundles up to 1600 K

Abstract

An experimental study of x-ray diffraction of single-walled carbon nanotube (SWNT) bundles in the temperature range from 290 to 1600 K is reported. The lattice constant (L0) of a close-packed trigonal arrangement of SWNTs in the bundles shrank over the entire temperature range. The hysteretic temperature dependence of L0 was observed and discussed in terms of desorption of molecules from the bundle surface and of a magnetic phase transition of ferromagnetic metal catalyst particles. The coefficient of volume thermal expansion for the bundles is suggested to be negative over the measured temperature range by assuming that the tube-axis expansion is similar to the in-plane expansion for graphite.