Mechanisms governing phonon scattering by topological defects in graphene nanoribbons

Abstract

Understanding phonon scattering by topological defects in graphene is of particular interest for thermal management in graphene-based devices. We present a study that quantifies the roles of the different mechanisms governing defect phonon scattering by comparing the effects of ten different defect structures using molecular dynamics. Our results show that phonon scattering is mainly influenced by mass density difference, with general trends governed by the defect formation energy and typical softening behaviors in the phonon density of state. The phonon scattering cross-section is found to be far larger than that geometrically occupied by the defects. We also show that the lattice thermal conductivity can be reduced by a factor of up to ~30 in the presence of the grain boundaries formed by these defects.

Growth, charge and thermal transport of flowered graphene

“…In pristine systems, the main phonon scattering mechanism is anharmonicity, manifested in three-phonon processes, and graphene owes its high thermal conductivity to the high density of states of its flexural phonon branch at low energies, together with a symmetry-induced selection rule for three-phonon scattering processes [48]. Several theoretical studies have also addressed the broader problem of thermal transport in defect-laden graphene [49][50][51][52][53][54][55] and graphene nanostructures [56][57][58]. However, in general those studies use either classical molecular dynamics or simple parametric models, both of which fail to give a detailed insight into the phonon physics underpinning the complex transport behavior in these systems.…”

Low-Temperature Friction of Suspended Graphene: Negative friction?

“…It involves a many-body bond-torsion term and therefore enables a smooth transition from long-range interaction to chemical bonding. It hence afforded a good description of the structural flexibility and bond formation and breaking in graphene and carbon nanotubes in our previous works [10,20,[33][34][35][36].…”

Bottom up Approach Toward Prediction of Effective Thermophysical Properties of Carbon-Based Nanofluids

“…Second, the thermal conductivity of pristine carbon nanoparticles obtained at lab conditions ( ) is typically reduced by the presence of defects under operative conditions ( where % is the concentration of defects expressed as a percent of CNT surface. Similarly, Zhu et al [66] investigated the thermal conductivity reduction induced by a broad variety of randomly distributed topological defects in graphene nanoribbons. In their work, Zhu et al [66] report a significant drop in thermal conductivity with defects concentration, which eventually achieves 70% reduction at % ≅ 5% (Fig.…”

“…Similarly, Zhu et al [66] investigated the thermal conductivity reduction induced by a broad variety of randomly distributed topological defects in graphene nanoribbons. In their work, Zhu et al [66] report a significant drop in thermal conductivity with defects concentration, which eventually achieves 70% reduction at % ≅ 5% (Fig. 3d, dots).…”

“…(c) Graphene length vs. thermal conductivity [58]. (d) Concentration of defects vs. thermal conductivity reduction in graphene (refers to the pristine one)[66]. Data from the literature (dots) are fitted (dashed lines) by semi-empirical equations, as reported in the text.…”