氮、硅掺杂对煤基碳纳米管电子性质和杨氏模量的影响研究

Studies on the electronic property and young's modulus of coal-based carbon nanotubes affected by nitrogen and silicon doping

近年来以煤为原料制备获得碳纳米管已经在实验室中得以实现,这开拓了碳纳米管低成本制备的途径。然而,煤基碳纳米管中氮、硅等原子掺杂对于碳管结构和功能性质影响的研究仍然相对较少。本研究使用基于第一性原理的自洽场晶体轨道法对硅、氮原子掺杂的(6,6)碳管进行研究。探讨硅、氮原子掺杂对碳纳米管电子性质和杨氏模量的影响。研究发现,氮原子和硅原子取代掺杂缺陷的形成在能量上是不利的,尤其对于硅掺杂。能带结构的计算表明,氮掺杂碳管显示金属导电性,而硅掺杂碳管发生了金属/半导体性质的转变,为半导体。杨氏模量的结果暗示,氮掺杂可以增强煤基碳管的力学性能。

In recent years the preparation of carbon nanotubes（CNTs） from coal has been implemented in the experiments,which opens up a low-cost synthesis of CNTs.However,studies on the structure and functional properties of coal-based CNTs affected by nitrogen and silicon doping are still very rare.In this paper,the（6,6） tube doped by silicon and nitrogen atoms were investigated by using the first-principles self-consistent field crystal orbital method.The electronic property and young＇s modulus of CNTs affected by silicon or nitrogen doping are explored and discussed.It is found that the defect formations of nitrogen and silicon doping are energetically unfavorable,especially for silicon doping.The band structure calculations show that the tube with nitrogen doping exhibits metallic conducting state,whereas metal/semiconductor transition is occurred to the Si-doped tube,and thus it becomes a semiconductor.Young＇s modulus results indicate that nitrogen doping could enhance the mechanical properties of coal-base CNTs.