10:45 AM - 11:00 AM
[MIS10-06] Growth mechanism of binary colloidal crystals
Keywords:Colloidal crystal, Crystal growth
Polystyrene particles are employed in the experiment. Green fluorescent particles with 500 nm and red with 700 nm are employed. Crystallization of colloidal crystals is induced by depletion attraction.
We have found several features on the growth of binary colloidal crystals. First, it grows on substrate. The AB2 structure (A: 700 nm, B: 500 nm) is found to be grown by utilizing crystals composed only of 700 nm particles. The AB2 crystals also grow on crystals of 500 nm. The specific crystallographic orientations between those crystals are recognized. Combination of orientations between AB2 and substrate are classified into four types. Heteroepitaxial growth is found to occur for growth of AB2 structure. Second, growth rate of binary colloidal crystals is quite small compare to that of single component system under the same particle concentration. We think this is attributed to complex structure of the crystals, which requires each particle incorporating to their own site. This process is not required for crystals composed of single component. Third, cluster formation at the interface is recognized. The ordered structure composed only of 500 nm is formed at growing interface. Particles of 700 nm is incorporated into the ordered structure generates AB2 structure.
These observations provide great hints to reveal overall growth mechanism of binary colloidal crystals, which will lead to establish sophisticated growth technique to grow large and high quality crystals.