Diffusive redistribution of small spheres in crystallization of highly asymmetric binary hard-sphere mixtures

We report a molecular-dynamics study of crystallization in highly size-asymmetric binary hard-sphere mixtures, in which the large spheres can form a crystal phase while the small ones remain disordered during the crystallization process of the large spheres. By taking advantage of assisting crystal nucleation with a patterned substrate, we find that adding a second, much smaller component will not alter the crystal structure formed by the large spheres. Instead of having fully random distributions, the small spheres are found to diffusively redistribute during the crystal formation of the large spheres and their density profile exhibits a strong coupling with that of the large spheres. We discuss the corresponding changes of the density profile for the small spheres at different crystallization stages. Copyright (C) EPLA, 2012