Ideal strength of a Cu multi-shell nano-wire

摘要

The ideal strength of a nano-component, which is the maximum stress of the structure, provides an insight into minute material. We conducted tensile simulations for a cylindrical-shaped Cu nano-wire composed of an atomic chain as a core wrapped around by shell(s) with the structure of (111) layers in a fcc crystal. Young's moduli and the ideal strengths of the wires are less than a single atomic chain and sheet. The mechanical strength of the wire is weakened by the following three factors: ( a) changes in electron arrangement caused by combining core and shell; (b) a larger interatomic distance ( inherent tensile strain) of the outer shell introduced for combining with the core chain; and ( c) weak bonding ( gap) on the outer shell caused by the mismatch of atomic layers due to the curvature difference. Factor ( a) weakens the bonding of the shell( s) that occupy a greater part of the wire. A 5-1 wire, which consists of a core and a shell, is weakened compared with the single atomic chain and the single sheet due to ( a) and ( b). A 10-5-1 wire, consisting of a core and two shells, has less strength than a 5-1 wire due to ( c) in addition to ( a) and ( b).