嵌入线型缺陷的石墨纳米带的热输运性质

摘要

采用非平衡格林函数方法研究了嵌入有限长、半无限长、无限长线型缺陷的锯齿型石墨纳米带(ZGNR)的热输运性质。结果表明,缺陷类型和缺陷长度对ZGNR的热导有重要影响。当嵌入的线型缺陷长度相同时,包含t5t7线型缺陷的石墨纳米带比包含Stone-Wales线型缺陷的条带热导低。对于嵌入有限长、同种缺陷的ZGNR,其热导随线型缺陷的长度增加而降低,但是当线型缺陷很长时,其热导对缺陷长度的变化不再敏感。通过比较嵌入有限长、半无限长、无限长线型缺陷的ZGNR,我们发现嵌入无限长缺陷的条带比嵌入半无限长缺陷的条带热导高,而后者比嵌入有限长线型缺陷的条带热导高。这主要是因为在这几种结构中声子传输方向的散射界面数不同所导致的。散射界面越多,对应的热导就越低。通过分析透射曲线和声子局域态密度图,解释了这些热输运现象。这些研究结果表明线型缺陷能够有效地调控石墨纳米带的热输运性质。%Using nonequilibrium Green’s function method, the thermal transport properties of zigzag graphene nanoribbons (ZGNR) em-bedding a finite (semi-infinite or infinite) long linear defect are investigated in this paper. The results show that defect type and defect length have significant influence on the thermal conductance of ZGNR. When the embedded linear defects have the same lengths, thermal conductance of ZGNR embedding t5t7 defect is lower than that of ZGNR embedding Stone-Wales defect. As for the ZGNR embedding finite and the same type defects, their thermal conductance reduce with the increase of the defect length. However, as the linear defect is long enough, the thermal conductance is insensitive to the change of length. By comparing the ZGNRs embedding finite, semi-infinite and infinite long defects, we find that the thermal conductance of ZGNR embedding an infinite long defect is higher than that of ZGNR embedding a semi-infinite defect, while the thermal conductance of the latter is higher than that of ZGNR embedding a finite long defect. This is due to the fact that different structures possess different numbers of scattering interfaces in the phonon transmission direction. The more the scattering interfaces, the lower the thermal conductance is. These thermal transport phenomena are explained by analyzing transmission coefficient and local density of states. These results indicate that linear defects can tune thermal transport property of ZGNR efficiently.