Zirconia by the gel route

Abstract

Zirconia gels are synthesized by hydrolysis of zirconium n-propoxide under acidic conditions in an alcoholic medium. The Raman spectroscopy shows that the hydrolysis of the alkoxide occurs as soon as the reactants are mixed. Small angle X-ray scattering analyses allow us to propose a mechanism which takes account of the formation of the gel backbone. The gelation is related to the aggregation of primary clusters which are very quickly produced in the solution. The mean size of these clusters is 2 nm. The wet gel shows a fractal structure. The xerogel is demonstrated to be an amorphous compound of zirconium hydroxyoxide. This compound retains nitrate anions which are present in the solution. The structural evolution of the thermally treated xerogels is followed using X-ray diffraction and Raman spectroscopy.