Effect of cooling rate on solidification points and atomic structures of metal nanoclusters: a molecular dynamics simulation study

Abstract

In this work, the micro-structural evolution during the solidification process of three metal nanoclusters (copper, nickel, and silver) containing 2048 atoms each, subjected to different cooling rates are investigated. Molecular dynamics (MD) simulations in conjunction with modified embedded atom method (MEAM) potentials have been employed to carry out the work. For different cooling rates, the solidification points of the nanoclusters are estimated from the variation in average potential energy of the systems during the crystallization process, and the structural evolutions are analysed by utilising radial distribution function and common neighbour analysis method. The results advocate that the cooling rate has a profound impact on the structures of the solidified nanoclusters. The critical cooling rate for each nanocluster has been captured, where a glassy/amorphous structure is observed. Polycrystalline nano-structures (consisting of amorphous, FCC and HCP) are observed below these critical cooling rates and the number of close-packed structures (FCC, HCP) are found to decrease with the increase in cooling rate. The findings of this work would be helpful in various practical applications of the metal nanoclusters, where the structure of nanoclusters directly affect.