Synthesis and characterization of silica nanoparticles from Vietnam

In the present study, silica (SiO₂) nanoparticles were synthesized through the decomposition of silica sand in sodium hydroxide (NaOH) molten salt at 500°C under ultrasound waves. The proposed method manifested as a facile preparation technique with a relatively low reaction temperature, uniform dispersion of doping metal ions, an excellent control of stoichiometry and a remarkable chemical homogeneity. Moreover, the current research was aimed at expanding the use of local materials, such as carbonates, clay and silica sands. The structural and the microstructural characterizations of silica nanoparticles were performed using X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy. It is evident from the XRD pattern that the fabricated material had a hexagonal crystal structure, which conforms to the shape of crystalline silica. The silica nanoparticles were spherical in shape with an average size of 10–50 nm that slightly depended on the annealing temperature.