Three Distinctive Melting Mechanisms in Isolated Nanoparticles

The melting properties of size-selected isolated silver nanoparticles of N = 13−3871 atoms are studied by using molecular dynamics simulations. Three distinctive melting mechanisms are identified. The melting of Ag 258 - 3871 can be explained well by the surface premelting models (SPMs), while the “melting” of Ag 13 - 178 may be described as a transition from a low-energy solidlike structure at low temperatures to a higher-energy liquidlike structure at high temperatures. Acting as a connecting link between such two distinctive melting mechanisms, a new intermediate melting mechanism, in which the melting temperature T m depresses very slowly while the latent heat of fusion Δ u ls has a great enhancement with N decreasing, is identified in Ag 120 - 240 .