Formation of Large Opals via Drying of Wet Colloidal Crystals

Abstract

The formation of opal structures with large crystalline domains is demonstrated through the formation of colloidal crystals in ethanol of surface-modified colloidal silica spheres containing small CdS nuclei, followed by controlled drying at room temperature. The high quality of the opals was characterized by scanning electron microscopy (SEM) and, more importantly, also by small-angle neutron scattering (SANS), which allows probing of the entire sample and provides important information on the crystal structure.