(527c) Crystal Structures Of Dipolar Colloids And Binary Hard- And Charged Spheres | AIChE

(527c) Crystal Structures Of Dipolar Colloids And Binary Hard- And Charged Spheres


Hynninen, A. - Presenter, Princeton University
Panagiotopoulos, A. Z. - Presenter, Princeton University

Using computer simulations, we look at the possible crystal structures in three systems: (i) colloids with dipole-dipole interactions, (ii) oppositely charged colloids with screened-Coulomb interactions, and (iii) binary mixture of large and small hard-spheres. For dipolar colloids, we study how the stability of the crystal structures changes when the relative strengths of spherically symmetric and dipolar interactions is adjusted. For a system where dipoles are electric-field induced, we make a comparison between the theoretical predictions and experiments on micrometer-size PMMA spheres. In the case of oppositely charged spheres with screened-Coulomb interactions, we show that the system exhibits a great variety of crystal structures, some of which display analogs of known binary atomic structures, doped fullerene C60 structures, but also novel structures that do not have an atomic of molecular analog. Three of the structures are also found in experiments. Finally, we show that binary hard-spheres can crystallize into a colloidal analog of the MgCu2 structure. A very interesting feature of the MgCu2 structure is that the large (Mg) and small (Cu) sphere component structures correspond, respectively, to the diamond and pyrocholore lattices, which have applications as photonic crystals with a bandgap in the visible region.