碳化硅纳米管几何结构和应变能的理论研究

本文采用密度泛函方法研究了碳化硅纳米管的几何结构和相对于3C-SiC的应变能。研究结果表明：1）碳化硅纳米管中的碳原子和硅原子分布在不同直径的两个圆柱面上，碳原子所在圆柱面的直径比硅原子的大，随着纳米管直径的增加这两个圆柱面的直径差别减小；2）在椅型和锯齿型碳化硅纳米管中均存在着长度不相等的两种共价键，随着纳米管直径的增加这两种共价键的键长趋于一致；3）碳化硅纳米管相对于3C-SiC的应变能均大于0．6eV，因此它是一种亚稳态，在适当的条件下有可能合成单壁碳化硅纳米管，但是其结构比较容易向闪锌矿结构转变．

Theoretical Resecrch on Geometric Structures and Strain Energy of Silicon Carbide Nanotubes

In this paper,we perform density functional calculations for the geometric structures and strain energy of silicon carbide nanotubes.The results indicate that: 1) Carbon atoms and silicon atoms,which make up of the silicon carbide nanotubes,arrange in two concentric cylinder with all silicon atoms forming the inner cylinder and all carbon atoms forming the outer cylinder.The difference in the diameter between the two cylinders decreases with increasing tube diameter.2) There are two kinds of C-Si bonds in both zigzag and armchair nanotubes.These bond lengths become to equal when their diameters are very large.3)The strain energy in all silicon carbide nanotubes relative to 3C-SiC is higher than 0.6eV,which shows that silicon carbide nanotubes are metastable phase and could be synthesized under certain conditions on experiment.However,the structure of silicon carbide nanotubes is easy to transform to the zinc-blende structure.