单壁碳纳米管杨氏模量的掺杂效应

用分子动力学方法研究了N,O,Si,P,S等5种杂质对扶手椅型(5，5)和锯齿型(9，0)单壁碳纳米管杨氏模量的影响.结果表明：直径为0.678和0.704 nm的扶手椅型(5，5)和锯齿型(9，0)碳纳米管在无掺杂时其杨氏模量分别为948和804 GPa.在掺杂浓度10％以下，碳纳米管的拉伸杨氏模量均随掺杂浓度增加近似呈线性下降规律，下降率以Si掺杂最大，N掺杂最小.对与C同周期的元素掺杂，随原子序数增加碳纳米管的杨氏模量下降率增大；与C不同周期的元素掺杂，碳纳米管的杨氏模量随掺杂浓度增加下降率更大，但 关键词： 碳纳米管 杂质 杨氏模量 分子动力学方法

The effect of impurities on the Young's modulus of single-walled carbon nanotubes

The molecular dynamics method was used to investigate the effect of the impurities N,O,Si,P and S on the Young's moduli of armchair(5,5)and zigzag(9,0)single-walled carbon nanotubes.The results show that the Young's moduli of armchair(5,5)and zigzag(9,0)single-walled carbon nanotubes are 948 and 804 GPa,respectively.When the impurity concentration is less than 10%,the Young's moduli are approximately linearly decreasing with increasing of the impurity concentration,and the greatest decreasing ratio is induced by the impurity Si and the smallest by the impurity N.The decreasing rate of the Young's modulus increases with increase of the impurity atomic number when the impurity element is of the same period with the element C.The effect of the impurities on the Young's modulus of carbon nanotubes is the stronger when the period of the impurity element is different with the element C,and the decreasing rate of the Young's modulus decreases slightly with increasing of the impurity atomic number.The reasons are analyzed by the laws of the Young's potential energy variation of carbon nanotubes with impure and the electron cloud coupling between two atoms from the theory of the local density approximation based on the density functional theory.