The composition effect for the thermal properties of PdnAg(42-n)Pt13 ternary nanoalloys: a molecular dynamics study

摘要

In this study, the classical molecular dynamics simulations in canonical ensemble conditions (NVT) were used to investigate the dynamical properties of trimetallic Pd-Pt-Ag nanoalloy clusters with the interatomic interactions modelled by the Gupta many-body potential. The optimisations for best homotops were performed using the basin-hopping algorithm for 55 atom icosahedral PdnAg(42-n)Pt13 trimetallic clusters. We performed optimisations to search the best chemical ordering of icosahedron structure not allowing any geometric changes. The icosahedron structures which are the best homotops have a core-shell segregation. The obtained icosahedral structures with best homotops were taken as the initial configurations for MD simulations. The temperature ranges were explored which the surface sites of the clusters stay thermally stable. We estimated the melting temperatures of PdnAg(42-n)Pt13 trimetallic clusters using caloric curves and Lindemann parameters. No simple correlation between alloy composition and melting temperatures was determined. The Pd35Ag7Pt13 composition has the highest melting temperature, however, the Pd21Ag21Pt13 is the most stable composition according to the relative stability investigation. The simulation results showed that the melting of all PdnAg(42-n)Pt13 clusters takes place as a whole without any surface premelting.