Monodispersed silica-titania core-shell particles with a controllable thickness and crystallinity were prepared by a simple peptization process in an aqueous acidic solution without the use of any external additives such as polyelectrolytes, polymers, and surfactants. The crystallinity of the titania nanocrystals coated on core-shell particles was controlled by adjusting the pH of the reaction medium. The shell thickness was found to increase as the reaction temperature, time, and the amount of Ti source material were increased. As-prepared core-shell particles with a smooth surface roughness were transformed into coreshell particles covered with largely grown titania crystals with different phases depending on the heat treatment temperature. The morphology and phase development of the particles were characterized via SEM, TEM, and XRD.

Keywords: Silica, Titania, Nanocrystals, Core-shell particles, Peptization.