The composition effect on the structural and thermodynamic properties of Cu-Ag-Au ternary nanoalloys: A study via molecular dynamics approach

Abstract

Metal ternary nanoalloys or trimetallic nanoparticles have emerged, in recent years, as novel and relevant materials in different fields due to the synergy of three metals in a single system that leads to unique physicochemical properties as compared to mono- and bimetallic nanoparticles. In this study, the influence of composition on the structural and thermodynamic properties of Cu-Ag-Au nanoalloys with 5083 atoms is analyzed using molecular dynamics simulations. Relevant thermodynamic quantities are used to describe the melting and solidification behaviors of three models of Cu-Ag-Au nanoalloys. Our results indicate that the melting temperature presents linear and quadratic dependencies with the composition, i.e., for Cu33 Ag67−x Aux , Ag33 Cu67−x Aux , and Au33 Ag67−x Cux are Tm = 912.6 + 1.9x, Tm = 882.3 + 2.7x, and Tm = 1056.6 − 4.9x + 0.07x2, respectively. In addition, most Ag atoms segregate to the surface and the Au and Cu atoms are localized in the center of the nanoalloy during the heating process, and this trend is maintained in the cooling process. The solidification temperature does not have an explicit correlation with the composition. Furthermore, the structural analysis of cooled nanoalloys exhibits local FCC and HCP symmetries, and the excess energy shows that Cu33Ag27Au40, Au33Ag17Cu50, and Ag33Cu37Au30 are relatively more stable to form nanoalloys. Finally, the possibility of controlling the composition in these metal nanoalloys opens up potential applications in plasmonic, catalysis, and bactericidal (by Ag surface segregation) fields.