Competition between stability of icosahedral and cuboctahedral morphologies in bimetallic nanoalloys

Abstract

In this study, we investigated the heating process for pure (Rh₅₅ and Cu₅₅), single dopant (Rh₁Cu₅₄ and Rh₅₄Cu), core@shell (Rh₁₃@Cu₄₂ and Cu₁₃@Rh₄₂), and alloy (Rh₁₃Cu₄₂, Rh₄₂Cu₁₃) nanoclusters in two structures (cuboctahedral and icosahedral) from 0 to 2000 K using molecular dynamics (MD) simulations. Our aim was to investigate the effects of composition and chemical arrangement on the kinetic and thermodynamic stability of Rh–Cu bimetallic nanoalloys. Our results indicated that Cu₅₅, Ir₅₅, Rh₁Cu₅₄, Rh₅₄Cu, and Cu₁₃@Rh₄₂ in the cuboctahedral and icosahedral structures and Rh₄₂Cu₁₃ in the icosahedral structure did not experience any transformation with the exception of melting. It was also observed that the cuboctahedral Rh₄₂Cu₁₃ shows a solid–solid transformation to the icosahedral structure before the melting point. It is also observed that Rh₁₃@Cu₄₂ and Rh₁₃Cu₄₂ nanoclusters in both structures exhibit a transition to a pseudo-spherical structure before the melting point. Our results also illustrated that the Rh and Cu atoms tend to lie in the inner and outer shells of the nanoclusters, respectively. We have also discussed the changes in the melting points of the doped nanoclusters in the different arrangements.