Surface Effects on the Mechanical Elongation of AuCu Nanowires: De-alloying and the Formation of Mixed Suspended Atomic Chains

TL;DR

This study combines experiments and simulations to explore how surface effects influence the mechanical elongation of AuCu nanowires, revealing de-alloying, mixed atomic chain formation, and implications for nanocatalysis and spin transport.

Contribution

It provides the first experimental observation of mixed atomic chains in transition and noble metals, highlighting surface energy effects on atomic chain composition.

Findings

Surface energies induce chemical gradients on nanowire surfaces.

De-alloying behavior observed during mechanical stretching.

First experimental realization of mixed atomic chains in transition and noble metals.

Abstract

We report here an atomistic study of the mechanical deformation of AuxCu(1-x) atomic-size wires (NWs) by means of high resolution transmission electron microscopy (HRTEM) experiments. Molecular dynamics simulations were also carried out in order to obtain deeper insights on the dynamical properties of stretched NWs. The mechanical properties are significantly dependent on the chemical composition that evolves in time at the junction; some structures exhibit a remarkable de-alloying behavior. Also, our results represent the first experimental realization of mixed linear atomic chains (LACs) among transition and noble metals; in particular, surface energies induce chemical gradients on NW surfaces that can be exploited to control the relative LAC compositions (different number of gold and copper atoms). The implications of these results for nanocatalysis and spin transport of one-atom-thick metal wires are addressed.