Influence of hydrothermal treatment on the crystalline form of SiO 2 synthesized by the sol-gel method

Abstract

The hydrothermal method and traditional sol-gel process for the synthesis of SiO2 particles were comparatively studied. For the synthesis of SiO2, tetraethyl orthosilicate (tetraethoxysilane or TEOS) and ammonium chloride (NH4OH) (as a catalyst) were used. SiO2 was prepared by the TEOS hydrolysis reaction at room temperature and hydrothermal treatment. Morphology and structure of the final products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrum (FT-IR) and scanning electron micrograph (SEM). It was found that SiO2 product synthesized by the TEOS hydrolysis reaction at room temperature has an amorphous phase. XRD analysis shows the presence of an amorphous halo - a strong peak at Bragg angle 21 °-22 °. The hydrothermal treatment leads to crystallization of the material.