SOL-GEL FORMATION OF SILICA ZIRCONIA GLASSES

Bulk samples of gels with composition (100 - x)SiO2 - xZrO2, x = 10 or 30, were prepared using TEOS and Zr(OC3H7)4, complexed 1:1 with acetylacetone, as precursors. Samples of both compositions were dried under hypercritical conditions using ethyl alcohol or liquid CO2 as solvent, as well as slowly dried in air as xerogels. The aim of this work was to verify whether different drying methods could lead to different crystallization behaviours during the gel-to-glass transition. Dried gels were characterized by X-ray diffraction, TGA-DTA and dilatometry.