Ultrasmall nanoparticles inducing order-to-disorder transition

The vitrification of single-element metallic glass remains a challenging research topic and attracts a great deal of attention. It is reported that the propensity for formation of the amorphous phase increases as the size of the system decreases in experiments. However, the thermodynamic contributions to this phenomenon are still elusive. Here, we study the size effects on the thermodynamic properties of the Cu nanoparticles in both crystalline and amorphous phases using the Frenkel-Ladd methods. Smaller particles show stronger size dependences on these quantities. From the perspective of free-energy difference between the amorphous phase and the crystalline phase, the thermodynamic driving force for vitrification of single-element metallic liquids catches up with that for crystallization dramatically, given the particle diameter smaller than a critical value (i.e., $\ensuremath{\sim}4$ nm for Cu), which provides a thermodynamic interpretation for the size dependence of the glass-forming ability.