|
 |
 |
 |
 |
 |
 |
 |
 |
 |
 
|
 |
 |
||
     |
|||
 |
|||
 |
|||
|
Self-assembly of colloidal particles provides one of the easiest ways of creating 3D photonic crystals. We have demonstrated a new method of rapidly producing such photonic crystals. A suspension of highly monodisperse silica particles of diameter 200 nm in water was densified by a repeated centrifugation process. The dense colloidal suspension exhibits opalescent colors due to Bragg reflection, as soon as it is placed between two glass plates. The opal crystal undergoes a structural phase transition from a partially ordered state (green) to a close-packed ordered state (blue), a blue front advancing toward the green region as water evaporates from the edge of the cell. The osmotic pressure at the interface drives the fluid-like ordered particles into a close-packed solid state. The propagation velocity of the fronts is constant for a given volume fraction. |
 |
||
 |
 |
||
Home | Center Overview | Research & Publications | Education & Outreach | Shared Experimental Facilities
|
|||