Preparation of higher-quality SiO2 opals using a new submicrospheres selection technique

Monodisperse colloidal SiO2 submicrospheres were prepared by hydrolysis and condensation of tetraethoxysilane. We measured various relative settle velocities of different aggregated submicrospheres and then developed a submicrospheres selection technique separating single spheres from aggregated spheres. Monodispersity of SiO2 submicrospheres was improved by this submicrospheres selection technique. Higher-quality SiO2 opals were fabricated from selected submicrospheres.