Influence of solvent on porosity and microstructure of an yttrium based aerogel

Monolithic yttrium-based aerogels and xerogels were prepared by the epoxide addition method. The effects of changing both the gelation solvent and the yttrium salt precursor in the reaction were investigated. The porous morphology of the resulting aerogel materials was investigated using gas adsorption/desorption analysis, scanning electron microscopy and transmission electron microscopy. The solvent in which the aerogels were formed was found to significantly impact the porous structure and physical morphology of these materials. The counterion used to synthesize the gels also had a profound impact on gel formation. The chloride salt precursor gave successful gels while the nitrate salt gave only precipitates. The yttrium-based xerogels synthesized were annealed at various temperatures in static air, nitrogen, and oxygen atmospheres. The annealed materials were analyzed using powder X-ray diffraction. The amorphous as-synthesized material is found to form the stoichiometric yttrium oxide by way of an oxygen deficient yttrium oxide species which is black in color.