Uniform coatings of TiO2 on monodisperse spheres of silica have been obtain
ed. The resulting particle sizes are within the range 0.4 to 1 mu m. The th
ickness of the coating can be controlled by adjusting nuclei sizes (silica
sphere), reaction times, and water and surfactant concentrations. The TiO2/
SiO2 spheres were sedimented to achieve structures with three-dimensional o
rder. Three-dimensional ordered materials with higher refractive index were
obtained by transforming the amorphous titania layer to rutile by thermal
treatment with improved mechanical rigidity. The sphere composition, qualit
y, and morphology have been assessed by different techniques, (C) 2000 Acad
emic Press.