Thermal rectification in restructured graphene with locally modulated temperature dependence of thermal conductivity
Thermal rectification in restructured graphene with locally modulated temperature dependence of thermal conductivity
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DOI：
10.1103/physrevb.96.165419
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发表时间：
2017-10-10
影响因子：
3.7
通讯作者：
Shiomi, Junichiro
中科院分区：
文献类型：
--
作者：
Arora, Anuj;Hori, Takuma;Shiomi, Junichiro
我们通过使用从第一原理获得的频率相关声子输运特性进行偏差声子蒙特卡罗（MC）模拟来研究选择性重构石墨烯中的热整流（TR）。通过在部分石墨烯中引入空位缺陷来实现重组。这些缺陷显着改变了声子传输特性，从而导致热导率的温度依赖性的调制。利用这种调制的温度依赖性，我们通过基于傅里叶定律的迭代方案 (FIS) 来预测 TR 比，其中通过求解具有随空间变化的温度相关热导率的傅里叶热传导定律来分析流经系统的热流。为了确定最大 TR 比率的结构参数，我们通过 FIS 分析研究了缺陷尺寸、缺陷体积百分比和系统（由缺陷区域和非缺陷区域组成）长度的影响。结果，我们发现 TR 比率主要是缺陷区域和无缺陷区域的长度以及缺陷体积百分比的函数，并且大多与缺陷尺寸无关。较长（10μm 量级）的无缺陷边与较短（100 nm 量级）有缺陷的边相结合，可导致较大的 TR 比。最后，对重构石墨烯（完整系统）进行 MC 模拟，以验证 FIS 分析的预测。完整的系统计算给出了类似的趋势，但在 200-500 K 的温度范围内 TR 比率提高了 70%。
We study thermal rectification (TR) in a selectively restructured graphene by performing deviational phonon Monte Carlo (MC) simulations with frequency-dependent phonon transport properties obtained from first principles. The restructuring is achieved by introducing vacancy defects in a portion of graphene. The defects significantly change phonon transport properties, resulting in a modulation of temperature dependence of thermal conductivity. With this modulated temperature dependence, we predict TR ratio through a Fourier's-law-based iterative scheme (FIS), where heat flow through the system is analyzed by solving the Fourier's law of heat conduction with spatially varying temperature-dependent thermal conductivity. To identify structure parameters for maximal TR ratio, we investigate the influence of defect size, volume percentage of defects, and system (consisting of defective and nondefective regions) length through FIS analysis. As a result, we find that the TR ratio is mainly a function of length of defective and nondefective regions and volume percentage of defect, and it is mostly independent of defect size. A longer (of the order of 10 mu m) nondefective side, coupled to a shorter (of the order of 100 nm) defective side, can lead to large TR ratios. Finally, MC simulation for the restructured graphene (full system) is performed to verify the predictions from FIS analysis. The full system calculations give similar trends but with enhanced TR ratios up to 70% for the temperature range of 200-500 K.