Glass-forming ability and structural features of melt-quenched and gel-derived SiO2-TiO2 glasses

SiO2-TiO2 glasses produced by aerodynamic levitation coupled to laser heating or sol-gel spray-drying were compared highlight their structural differences. Glass formation was possible melt-quenching up 10 mol% TiO2, while higher contents led devitrification. Raman spectroscopy and solid-state 17O 29Si magic-angle-spinning nuclear magnetic resonance confirmed the clear emergence of Ti-O-Si bonds a tetrahedral oxygen coordination Ti4+ leading full network connectivity, as also substantiated synthesis TiO2-doped cristobalite. In gel-derived glasses, water content induced partial depolymerization, thereby enhancing solubility TiO2 in hydrous silicate matrix. However, dehydration during proved challenging due competing tendency towards devitrification: glass-forming range anhydrous binary system does not therefore appear be significantly enlarged route.