硅功能化石墨烯热导率的分子动力学模拟

摘要

Direct non-equilibrium molecular dynamics (NEMD) was used to simulate the thermal conductivities of the mono-layer and the bilayer silicon functionalized graphenes along the length direction respectively, with the Tersoff potential and the Lennard-Jones potential, based on the velocity Verlet time stepping algorithm and the Fourier law. Simulation results indicate that the thermal conductivity of the monolayer silicon functionalized graphene decreases rapidly with increasing amount of silicon atoms. This phenomenon could be primarily attributed to the changes of graphene phonon modes, mean free path, and motion speed after silicon atoms are embedded in the graphene layer. Meanwhile, the thermal conductivity of the monolayer graphene is declined in the temperature range from 300 to 1000 K. As for the bilayer silicon functionalized graphene, its thermal conductivity increases as a few silicon atoms are inserted into the layer, but decreases when the number of silicon atoms reaches a certain value.%采用Tersoff势函数与Lennard-Jones势函数，结合速度形式的Verlet算法和Fourier定律，对单层和两层硅功能化石墨烯沿长度方向的导热性能进行了正向非平衡态分子动力学模拟。通过模拟发现，硅原子的加入改变了石墨烯声子的模式、平均自由程和移动速度，使得单层硅功能化石墨烯模型的热导率随着硅原子数目的增加而急剧地减小。在300 K至1000 K温度变化范围内，单层硅功能化石墨烯的热导率呈下降趋势，具有明显的温度效应。对双层硅功能化石墨烯而言，少量的硅原子嵌入，起到了提高热导率的作用，但当硅原子数目达到一定数量后，材料的导热性能下降。