Synthesis of precious opal in a hydrothermal solution

Abstract

The nucleation of orthosilicic acid and the growth of colloidal silica particles in hydrothermal solutions are investigated. The results obtained are compared with the data on the formation of supramolecular matrices of precious opal. Ordered supramolecular structures are experimentally grown in a model solution through the precipitation of colloidal silica particles synthesized by hydrolysis of tetraethoxysilane in an organic solvent. The type of packing of spherical particles in the supramolecular structure is studied as a function of the component concentration, particle size, and pH and temperature of the model solution. The experimental data can be used to reveal the mechanism of formation of precious opal and to design methods for preparing three-dimensional nanocomposites.

Hydrothermal SiO2 Nanopowders: Obtaining Them and Their Characteristics

“…The range of silica concentrations in the initial solution is Ct = 400-800 mg/kg (t indicates the total silica content equal to the sum of the concentrations of the colloidal phase and dissolved Cs). The nucleation rate of silicic acid in an aqueous solution (nucl/(kg • s)) is described by Equation (1) [48][49][50]:…”