School of Engineering, Brown University, Providence, Rhode Island 02912, United States.
Nano Lett. 2011 Sep 14;11(9):3917-21. doi: 10.1021/nl202118d. Epub 2011 Aug 25.
We have studied the thermal conductance of tilt grain boundaries in graphene using nonequilibrium molecular dynamics simulations. When a constant heat flux is allowed to flow, we observe sharp jumps in temperature at the boundaries, characteristic of interfaces between materials of differing thermal properties. On the basis of the magnitude of these jumps, we have computed the boundary conductance of twin grain boundaries as a function of their misorientation angles. We find the boundary conductance to be in the range 1.5 × 10(10) to 4.5 × 10(10) W/(m(2) K), which is significantly higher than that of any other thermoelectric interfaces reported in the literature. Using the computed values of boundary conductances, we have identified a critical grain size of 0.1 μm below which the contribution of the tilt boundaries to the conductivity becomes comparable to that of the contribution from the grains themselves. Experiments to test the predictions of our simulations are proposed.
我们使用非平衡分子动力学模拟研究了石墨烯中倾斜晶界的热导率。当允许恒定热通量流动时，我们观察到边界处温度的急剧跳跃，这是具有不同热性质的材料之间界面的特征。基于这些跳跃的幅度，我们计算了孪晶界的边界电导率作为其取向角的函数。我们发现边界电导率在 1.5×10(10)到 4.5×10(10) W/(m(2) K)之间，明显高于文献中报道的任何其他热电界面的值。利用计算得到的边界电导率值，我们确定了一个临界晶粒尺寸为 0.1μm，低于该尺寸时，倾斜边界对电导率的贡献可与晶粒本身的贡献相媲美。提出了实验来测试我们模拟的预测。
