Lattice Specific Heat of Graphene Nanoribbons

Abstract

The lattice specific heat, C L, of graphene nanoribbons (GNRs) is studied, based on the elastic continuum model. An expression for C L is obtained taking into account the modification of acoustic phonon dispersion due to spatial confinement. Considering the contributions from longitudinal, transverse, torsional and flexural acoustic phonon modes, numerical calculations of C L, as a function of temperature, are presented for T < 3,000 K. With increase in temperature, C L is found to increase up to T < 1,200 K and then tend to saturate to classical limit of 2,078 J/kgK at higher temperatures, the major contribution being from flexural modes. At low temperatures C L is found to decrease with increase in GNR width.