Structural and microstructural study of glasses in the Li2O-TiO2-SiO2 system

Glasses from the Li₂O-TiO₂-SiO₂ system with TiO₂ content ranging between 5 and 20 mol % were prepared. The glasses studied have an opal appearance and when their microstructure is studied through transmission electron microscopy, a strong phase separation in droplet form is observed, with the size of the droplets depending on the TiO₂ and the Li₂O content. X-ray diffraction showed that these glasses are non-crystalline and identified the crystalline phases which take place after the corresponding thermal treatment to enhance liquid immiscibility. A structural study of the samples prepared was carried out through infrared spectroscopy. Titanium oxide is incorporated into glasses as a network modifier, so that titanium atoms place themselves in octahedral positions [TiO₆]. This is attributed to the presence of Li₂O which breaks up the glass network, favouring the hexacoordination of titanium atoms.