Au–Ir nanoalloy nucleation during the gas-phase condensation: a comprehensive MD study including different effects

Abstract

We have investigated the formation of pure Ir, Ir_0.75Au_0.25, Ir_0.5Au_0.5, Ir_0.25Au_0.75, and pure Au nanoclusters through the inert-gas condensation method using MD simulation. The effects of mole fraction, temperature, and pressure on the different thermodynamic and structural properties of the produced nanoclusters have been investigated. The results showed that the size and number of the formed clusters increased with the increasing temperature and pressure; this was in good agreement with the experimental results obtained for metallic clusters. Our results also show that the stability of the produced nanoclusters increases as the Au mole fraction increases, whereas their stability decreases as the temperature and pressure increase. The Au atoms tend to lie on the cluster surface, whereas the Ir atoms tend to lie at the cluster cores. The percent of the surface Au atoms also increased as the Au mole fraction, temperature, and pressure increased. The radial distribution function (RDF) results indicate that the core–shell structures have not been produced in these simulations. We have also shown that the sphericity of the produced smaller clusters increases with the increasing Au mole fraction. The sphericity also increased with the increasing temperature and pressure. Our structural investigations also showed that some ordered clusters containing the fcc and hcp atoms were formed during these simulations. The percentage of the fcc atoms also increased with the increasing pressure. However, the surface of the produced clusters contained disordered atoms.