Structure, melting, and thermal stability of 55 atom Ag-Au nanoalloys

Alloy nanoclusters ("nanoalloys") are of interest because of their novel properties compared to bulk alloys. In this paper, the thermal behavior, including melting, of 55 atom Ag - Au nanoalloys has been investigated by molecular dynamics simulations using the Gupta many-body potential. Single melting runs exhibit a sharp transition from the cluster ground structures to the melt, while averaged results indicate that melting occurs in a size - and composition-dependent temperature range. The transition point (melting point) decreases with increasing Au concentration. Gold-rich Aun-Ag 55-n nanoalloys with n= 30-55 exhibit a very smooth transition from the ground state to their undercooled melt. Their thermal stability is influenced by the glass transition behavior of the pure amorphous Aun cluster. \ua9 2007 American Chemical Society