▎ 摘　　要

The phonon conductivity in suspended graphene and in graphene nanoribbons has been studied within the framework of Callaway's effective relaxation time theory. The conductivity expression has been computed by employing analytical expressions for phonon dispersion relations and vibrational density of states based on the semicontinuum model by Nihira and Iwata. It is found that the Normal-drift contribution to the conductivity, arising from the consideration of the momentum conserving nature of three-phonon Normal processes, is very important for explaining the magnitude as well as the temperature dependence of the experimentally measured results for suspended graphene. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4733690]