PREPARATION OF SPHERICAL, MIXED SIO2 TIO2 PARTICLES BY THE SOL TECHNIQUE/

Preparation of silica, titania and mixed silica/titania particles has been studied. The region for formation of monodisperse SiO2 particles in the phase diagram tetraethyl orthosilicate (TEOS)-ethanol-H2O was s tudied as a function of NH3 concentration at room temperature. Titania particles could be prepared at lowered temperatures and concentration of ammonia up to 0.01 M. The size of SiO2 particles was 0.03-1 mu m w hereas TiO2 particles were size range 0.5-0.8 mu m. Mixed SiO2/TiO2 pa rticles were prepared from prehydrolyzed TEOS/EtOH solutions by adding tetraethyl orthotitanate (TEOT). This was accomplished at 3 degrees C and slightly alkaline solutions. The final particle size of the mixed particles was about 0.3 mu m.