SONOGELS

In sol-gel processing of glasses based on hydrolysis and polycondensat ion of alkoxides, ultrasonic irradiation avoids the addition of a comm on solvent (alcohol) to the otherwise immiscible water/alkoxide mixtur e. The 'sonogels' thus obtained by cavitation phenomena, which affect the gelation process, differ from classic gels in a number of points; in particular they are more dense and their structure is finer and mor e homogeneous, and this makes them interesting candidates for the prep aration of composites and non-linear optical materials.