Preparation of Crystal Quartz by Hydrothermal Synthesis

Abstract

Adopting high-purified SiCl4 as raw material and taking Na2CO3 as mineralizer, crystallized SiO2 was prepared with hydrothermal process. Particularly, the effect of processing temperature, precursor concentration and pH on the crystallization of SiO2 were taken into consideration. To analyze the growing mechanism, the structure and morphologies of hydrothermal product were studied with XRD and SEM. The results showed three factors, including synthesis temperature, precursor concentration and pH, influenced the crystallization and morphologies of crystalline SiO2 significantly. Proper hydrothermal processing, 220 ℃ hydrothermal environment, 1.2 mol/L precursor, pH 10.5 and Na2CO3 mineralizer, resulted in 8 μm well-crystallized columnar grain crystal. The crystallization process of SiO2 followed the “dissolution-precipitation” mechanism in the hydrothermal synthesis and contained the aggregation-growth.