Au@Void@Ag Yolk-Shell Nanoclusters Visited by Molecular Dynamics Simulation: The Effects of Structural Factors on Thermodynamic Stability.

Abstract

Au@void@Ag yolk-shell nanoclusters were studied by molecular dynamics simulation in order to study the effects of core and shell sizes on their thermodynamic stability and structural transformation. The results demonstrated that all of simulated nanoclusters with different core and shell sizes are unstable at temperatures lower than 350 K in such a way that Ag atoms are collapsed into the void space and fill it, which leads to creation of a more stable core-shell morphology, and at the melting point, only core-shell structures with altered thickness of the shell exist. Also, at higher temperatures, Au atoms tend to migrate toward the surface, and an increase of both the core and shell sizes leads to an increase of the thermodynamic stability. Moreover, a Au147@void@Ag252 nanocluster with the largest core and shell and minimum void space exhibited the most thermodynamic stability and highest melting point. Generally, the core and shell sizes affect the stability and thermal behavior of yolk-shell nanoclusters cooperatively.