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石墨烯是近年纳米材料研究领域的一个热点,其独特的热学性质受到了广泛关注,为了实现对石墨烯传热特性的预期与可控,利用氮掺杂和空位缺陷对石墨烯进行改性.采用非平衡态分子动力学方法研究了扶手形石墨烯纳米带中氮掺杂浓度、位置及空位缺陷对热导率影响并从理论上分析了热导率变化原因.研究表明氮掺杂后石墨烯纳米带热导率急剧下降,氮浓度达到30%时,热导率下降了75.8%;氮掺杂位置从冷浴向热浴移动过程中,热导率先近似的呈线性下降后上升;同时发现单原子三角形氮掺杂结构比多原子平行氮掺杂结构对热传递抑制作用强;空位缺陷的存在降低了石墨烯纳米带热导率,空位缺陷位置从冷浴向热浴移动过程中,热导率先下降后上升,空位缺陷距离冷浴边缘长度相对于整个石墨烯纳米带长度的3/10时,热导率达到最小.石墨烯纳米带热导率降低的原因主要源于结构中声子平均自由程和声子移动速度随着氮掺杂浓度、位置及空位缺陷位置的改变发生了明显变化.这些结果有利于纳米尺度下对石墨烯传热过程进行调控及为新材料的合成应用提供了理论支持.
Graphene is a hotspot in the field of nanomaterials research in recent years, and its unique thermal properties have drawn wide attention. In order to realize the expected and controllable heat transfer characteristics of graphene, graphene is modified by nitrogen doping and vacancy defects. The effects of nitrogen doping concentration, position and vacancy defects on the thermal conductivity of the handrail-shaped graphene nanoribbons were investigated by non-equilibrium molecular dynamics method and the reason of the thermal conductivity was analyzed theoretically.The results show that the nitrogen-doped graphite When the nitrogen concentration reaches 30%, the thermal conductivity decreases by 75.8%. When the nitrogen doping position moves linearly from the cold bath to the hot bath, the thermal conductivity first decreases linearly and then increases. At the same time, It is found that the structure of the monatomic triangle nitrogen doping is more effective than that of the polyatomic parallel nitrogen doping structure in the heat transfer. The presence of vacancy defects reduces the thermal conductivity of the graphene nanoribbons. The thermal conductivity first decreases and then increases, and the vacancy defects reach the minimum when the distance from the edge of the cold bath is 3/10 with respect to the length of the whole graphene nanoribbon. The reason for the decrease of the thermal conductivity of the graphene nanoribbons is mainly The change of phonon mean free path and phonon moving speed from structure to structure changes with the change of nitrogen doping concentration, position and vacancy defects.These results are helpful to control the heat transfer process of graphene at nanoscale and to new materials The synthetic application provides a theoretical support.