Structural and Electronic Properties of Nano-brass: CuxZny (x + y = 11 − 13) Clusters

Abstract

Cu–Zn brasses are one kind of the typical Hume-Rothery alloys, of which the phase stability mechanisms are decided by the electronic effects. Cu–Zn clusters can be considered as a sort of alloys with a particle size at nanometer scale. The structures of small-sized Cu–Zn clusters have been well established up to 10 atoms, but the structural evolution behavior of larger clusters is still not well-known. In this work, the geometric structures of CuxZny clusters in a size range (x + y = 11 − 13) are investigated by using a method combining the genetic algorithm with density functional theory. A series of relevant structures of the clusters are obtained, and the structural evolution diagrams are plotted depending on the relative energy. It was found that the Cu–Zn clusters with even number of valence electrons (n*) exhibit high stability. When n* = 12 and 14, the clusters adopt prolate motifs, which have similar electronic structures to O2 and F2 molecules, respectively, based on the super valence bond model. When n* = 18 and 20, the clusters keep spherical cage motifs, which satisfy the magic numbers of Jellium model and could be viewed as stable superatoms.