  In the present work, we have studied for the first time the combined effect
of both sonication and precipitation pH on the structure of amorphous zirconia
gels synthesized from zirconium(IV) propoxide. The techniques of small-angle
neutron and X-ray scattering (SANS and SAXS) and low temperature nitrogen
adsorption provided the integral data on the changes in the microstructure and
mesostructure of these materials caused by ultrasonic (US) treatment. Amorphous
ZrO2.xH2O synthesized under ultrasonic treatment was found to possess a very
structured surface, characterized by the surface fractal dimension 2.9-3.0,
compared to 2.3-2.5 for the non US-assisted synthesis, and it was also found to
possess a higher specific surface area, while the sizes of the primary
particles remain unchanged.
