Investigation on stable structures of Au-Pd alloy nanoparticles with high-index facets

Abstract

Based on the Monte Carlo simulation method, this paper employs the tight-binding potentials and the quantum-corrected Sutton-Chen type many-body potentials to investigate the stable structure, the distribution of surface atoms, the core-shell distribution, and the chemical short-range order parameter of tetrahexahedral Au-Pd nanoparticles. Different sizes and different Au contents are considered. Our results show that the surface atom distribution exhibits the same trend for the two types of potentials, that is, Au atoms tend to segregate on the surface while Pd atoms prefer to occupy the inner sites, this is beneficial to lowering the total energy of the structure. Nanoparticles are always present in a core-shell structure for small Au content. With increasing Au content, the Au-Pd nanoparticles will tend to form an onion-like multi-shell structure for the tight-binding potentials. The degree of the segregation of Au-Pd nanoparticles at the quantum-corrected Sutton-Chen type potentials is higher than that for the tight-binding potentials.