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

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.