Nanoparticle coalescence and sintering: molecular dynamics simulation

Abstract

Molecular Dynamics (MD) simulations are employed to better understand coalescence and sintering processes of gold nanoparticles. During coalescence in the liquid phase, the initial neck growth can be well described by the viscous flow model. With initial temperature right below the single particle melting temperature, the initial neck growth is controlled by viscous flow at first and then, by grain boundary diffusion. At initial temperatures well below melting, the sintering process occurs very rapidly, which may be attributed to a formation of liquid-like neck regions. The sintering of two free Au nanoparticles irradiated by a femtosecond laser pulse is also simulated by combining the two-temperature and MD models. It is shown that by increasing laser input energy, nanoparticles can be melted forming a single larger nanoparticle. The effects of multinanoparticle melting, solidification and sintering are also investigated.