Au-Ag合金纳米管填充碳纳米管特性的第一性原理研究

First-principles study of the properties of Au-Ag nanotube encapsulated into carbon nanotube

摘要:

于密度泛函理论框架下的第一性原理计算，研究了Au-Ag合金纳米管同轴填充不同线径锯齿型(n, 0)碳纳米管所形成复合系统的稳定性、电子特性和力学性能. 结果表明，内、外管间距约为4.20 ?的AuxAg4-x@(15, 0)复合系统为具有较大填充率的最稳定结构. 能带结构分析表明，相对于自由Au-Ag合金纳米管复合系统的量子电导有所增加，电子态密度分析表明复合系统中的传导电子主要来源于内部Au原子和Ag原子的s电子以及外部C原子的p电子. 相对于自由金属纳米管而言，碳纳米的包裹使得金属纳米管的轴向拉伸临界应变和理想强度大大增加，有效地提高了其力学性能.

Abstract:

By using first-principles calculation based on density-functional theory, we have systematically investigated the stability, electronic and mechanical properties of (4, 2) Au-Ag alloy nanotubes encapsulated in a series of zigzag (n, 0) carbon nanotubes with various diameters. The most stable combined system with larger filling rate is AuxAg4-x@(15, 0) with an optimal tube-tube distance of about 4.20 ?. The analysis of band structure shows that the quantum conductance of the composite system is much higher than that of the corresponding isolated alloy nanotubes. The energy states near the Fermi level are mainly attributed to the s electrons of the inner Au and Ag atoms as well as the p electrons of the outer C atoms. The critical strains and the ideal strengths of the combined systems are remarkably higher than those of the freestanding alloy nanotubes, suggesting that the mechanical properties of the alloy nanotubes are signi?cantly enhanced by the carbon nanotube coating.