Phononic Thermal Transport along Graphene Grain Boundaries: A Hidden Vulnerability,Advanced Science

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Phononic Thermal Transport along Graphene Grain Boundaries: A Hidden Vulnerability
Advanced Science ( IF 14.3 ) Pub Date : 2021-07-21 , DOI: 10.1002/advs.202101624
Zhen Tong ₁ , Alessandro Pecchia ₂ , ChiYung Yam _{1,

3} , Traian Dumitrică ₄ , Thomas Frauenheim _{1,

3,

5}

Affiliation

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 (κ_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 κ_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 κ_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.

中文翻译：

沿石墨烯晶界的声子热传输：一个隐藏的漏洞

虽然石墨烯晶界（GB）在实验中得到了很好的表征，但它们对传输特性的影响却知之甚少。正如本文所揭示的，即使 GB 超窄且沿温度梯度方向排列，声子热传输也很容易受到 GB 的影响。非平衡分子动力学模拟发现，沿着包含周期性重复的五边形-七边形位错的线性GB，声子热导率（ κ _{p ）大幅降低。}格林函数计算和光谱能量密度分析表明，κ _p降低的根源隐藏在周期性 GB 应变场中，该应变场表现为具有漫反射或镜面声子反射的反射衍射光栅，并且代表非谐波声子-声子的来源散射。这里揭示的κ _p位错密度的非单调依赖性并未被经典克莱门斯理论所解释。它可以帮助识别能够最好地保持声子传输完整性的 GB 结构。

更新日期：2021-09-22

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