High quality photonic opaline structure in one night and their optical reflectance

A high quality silica opal with large crack free areas was synthesized by a quick vertical convection self-assembly method and the optical properties have been studied and confirmed the high quality of these opaline structures. The thermogravimetric analysis of the calcination process of silica spheres revealed that the optimal calcination temperature of deposited colloidal crystal is around 240 degrees C, slightly higher than the dehydroxylation temperature of silanols. An improvement in mechanical strength of the opaline photonic crystal structure was obtained. The whole process has been optimized such that synthesis is feasible in only one night without any intervention, opening the possible production on an industrial scale. (c) 2008 Elsevier B.V. All rights reserved.