Direct observation of fast surface dynamics in sub-10-nm nanoglass particles

Preventing the crystallization of metallic glasses is a challenging task, primarily because of their non-equilibrium nature. In this paper, we show that a reduction in size significantly increases the surface dynamics of metallic glasses, thereby favoring the formation of a surface liquid-like layer with near-equilibrium minimum energy. The fast atomic mobility at the surface of sub-10-nm nanoglass particles is directly observed and found to be consistent with the existing theoretical predictions. Our results suggest that the devitrification of glass can be avoided if the nucleation of crystals is too difficult. These results help to elucidate the underlying mechanisms of glass dynamics at the nanoscale, which are useful for designing ultrastable glasses and furthering our understanding of the nature of glass.