ROLE OF EDGE CHIRALITY AND ISOTOPE DOPING IN THERMAL TRANSPORT AND THERMAL RECTIFICATION IN GRAPHENE NANORIBBONS
Y Wang and XL Ruan, PROCEEDINGS OF THE ASME INTERNATIONAL MECHANICAL ENGINEERING CONGRESS AND EXPOSITION, 2011, VOL 10, PTS A AND B, 315-322 (2012).
Thermal transport processes in graphene nanoribbons (GNRs) within and beyond the linear response regime has been studied using classical molecular dynamics simulations. Zigzag-edged GNRs have higher thermal conductivities than armchair-edged ones, and the difference diminishes with increasing width. Analysis on the cross-sectional distribution of heat flux reveals that edge atoms. cannot transport thermal energy as efficiently as interior ones. Edge localization of phonon modes reduces thermal transport through edge carbon atoms, especially, on armchair edges, which results in a lower thermal conductivity. Isotope (C-13) doping can reduce the thermal conductivity of GNRs by 30% - 40% by an addition of only similar to 20% isotope atoms. The significant reduction in thermal conductivity is partially attributed to phonon localization induced by isotope defects, which is confirmed by phonon mode participation ratio analysis. We also demonstrate that a GNR asymmetric in edge chirality or mass density can generate considerable thermal rectification, which is essential for developing GNR-based thermal management devices.
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