Preparation of monodispersed magnesia coated silica particles through a surface-induced precipitation method

Monodispersed magnesia coated silica particles were prepared by the surface-induced precipitation method, in which a sol type of magnesium precursor was deposited on the surface of spherical silica particles via electrostatic attraction route, and then calcined at 700°C for 90 min. The magnesium precursor was synthesized by the sol-gel technique, which employs ethanol as a solvent. The resulting particles were characterized with field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermal (TG/DTA) analysis, Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). The results show the formation of a well-crystallized magnesia layer on the surface of the core silica particles. The resultant coated particles exhibited the spherical shape without the formation of a hard aggregate in spite of the heat treatment. XPS and FTIR investigations also confirmed that the magnesia coating layer and core silica particle were connected through the Mg-O-Si chemical bonding at the interface.