The purpose of this work is to obtain micrometer sized spherical particles
of silica and silica-chromium from sodium silicate. Spherical particles wer
e prepared by sol-gel method from hydrolysis to polycondensation of aqueous
sodium silicate in alcohol medium. Chromium was added to the system for so
me samples. Compositions and morphologies were achieved by changing the pre
cipitation agent. X-ray diffractometry, electrophoretic mobility, infrared
spectroscopy and scanning electron microscopies were carried out on these p
articles to identify phases, determine particle mobility, morphology, parti
cle sizes, shapes and order at short distance. Non-crystalline silica parti
cles with spherical shapes and micrometric size were obtained. The surface
potentials of the silica particles differed from that of the silica-chromiu
m particles. (C) 1999 Elsevier Science B.V. All rights reserved.