Strained phonon–phonon scattering in carbon nanotubes

Abstract

Focusing on three-phonon processes, the effect of uniaxial tensile strain on the phonon–phonon scattering rates is studied for (10,10) single-walled carbon nanotube at room temperature. Longitudinal optical (LO) and longitudinal acoustic (LA) phonon scattering rates are reported at 0%, 2.5%, 5%, 10%, 15% and 20% strains. Results show that the presence of strain can change the phonon–phonon scattering rates by as much as three orders of magnitude. For LO phonons, the mean scattering rate increases monotonically with the increasing axial strain. For LA phonons, the mean scattering rate also increases with the increasing strain. However, it decreases significantly at 10% strain. The anomaly observed in the mean scattering rate of LA at 10% strain is explained in light of the effect of strain on the density of states. It is also shown that pre-straining a CNT at 5% or less can improve the decay rate of hot phonons into lower energy phonons.