Phononic Thermal Transport along Graphene Grain Boundaries: A Hidden Vulnerability

Abstract

While graphene grain boundaries (GBs) are well characterized experimentally, their influence on transport properties is less understood. As revealed here, phononic thermal transport is vulnerable to GBs even when they are ultra-narrow and aligned along the temperature gradient direction. Non-equilibrium molecular dynamics simulations uncover large reductions in the phononic thermal conductivity ( p ) along linear GBs comprising periodically repeating pentagon-heptagon dislocations. Green's function calculations and spectral energy density analysis indicate that the origin of the p reduction is hidden in the periodic GB strain field, which behaves as a reflective diffraction grating with either diffuse or specular phonon reflections, and represents a source of anharmonic phonon-phonon scattering. The non-monotonic dependence with dislocation density of p uncovered here is unaccounted for by the classical Klemens theory. It can help identify GB structures that can best preserve the integrity of the phononic transport.

Significant Increase of Electron Thermal Conductivity in Dirac Semimetal Beryllonitrene by Doping Beyond Van Hove Singularity

“…Although thermal properties of 2D materials are intensely investigated, [ 11–13,16–27 ] less is known about thermal conductivity of 2D Dirac materials [ 28 ] especially the impact of VHS on the energy carrier (electron and phonon) transport properties. High‐pressure technologies demonstrated great potential [ 29 ] for enriching the variety of 2D Dirac materials, which are rare compared with the numerous 2D materials.…”

“…Determining the properties of 2D matter in the one-atom-thin limit is a current frontier of science. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] One such emergent quantum phenomenon is the electronic transport through Dirac cones, which were first identified in graphene. [1][2][3] Close to the charge neutrality point, the graphene dispersion relation is linear and well described by the relativistic Dirac equation [4] with charge electronic structure.…”

Ultrahigh Electron Thermal Conductivity in T‐Graphene, Biphenylene, and Net‐Graphene

“…The corresponding lattice constants of those 2D carbon allotropes are provided in Figure S1, Supporting Information. In strained bonds, anharmonicity effects [26,27] can decrease significantly the phonon thermal conductivity (κ ph ). [28][29][30][31] In this work, we conduct a comprehensive ab initio calculation to consistently compare the phonon-and electron-based conduction of pristine graphene with that of the T-graphene, biphenylene, and net-graphene carbon allotropes.…”

“…The corresponding lattice constants of those 2D carbon allotropes are provided in Figure S1, Supporting Information. In strained bonds, anharmonicity effects [ 26,27 ] can decrease significantly the phonon thermal conductivity (κ ph ). [ 28–31 ]…”

Efficient modulation of thermal transport in two-dimensional materials for thermal management in device applications

“…However, when the GB energy is high enough, κ is more sensitive to the grain size than the GB energy. 101 In addition, when grains and GBs are present in 2D materials, some modulation means, such as strain, 96 doping, 102 and tilt angle, 103 will also have different effects on its thermal transport properties than in the single crystal case.…”