Structural diagrams and thermodynamics relating to temperature and compositions of Ag561−nCun (n = 0-561) nanoalloys during cooling from atomic simulations

Abstract

The packing changes of Ag_561-nCu_n (n = 0-561) nanoparticles during cooling were studied by molecular dynamics simulations at atomic scale. Structural diagrams as well as packing images presented liquid, disordered, and some ordered patterns. Pair distribution functions were used to characterize some typical structures. Potential energy and shape factors identified the transition’s temperature regime and the effect of cooling on the shape’s changes of the alloyed particles. The simulation results show composition effect on the transition temperatures and complex structural patterns. For these Cu-Ag nanoalloys, which contain small amount of Cu or Ag atoms, they show alternating FCC and icosahedral packing patterns at low temperatures, and core-shell configurations prefer to occur in the Cu-rich particles, where the Cu occupy the interior of the particles. Compositions and degree of orderliness in packing contribute to the entropy of the alloyed nanoparticles.