3D Photonic Crystals: Synthesis and Drying in Supercritical Ethanol

Abstract The production of synthetic matrices of precious opal using sol–gel process and their drying in supercritical ethanol are described in detail. The conditions of formation of synthetic opal matrices and reactant concentrations for this process are indicated. The possibility of synthesizing porous matrices of precious opal, with the size of amorphous silica globules being 275 to 1555 nm, is demonstrated. The conditions for drying the silica xerogel in supercritical ethanol and the subsequent heat treatment to give opal-like structures are proposed. The resulting structures have a network of interconnected pores and can be used for the development of promising gas sensors, composite materials, and inverted photonic crystals. All processes were conducted under control of electron microscopy, Raman spectroscopy, and powder X-ray diffraction.