Evolution of structural defects of SiO-=SUB=-2-=/SUB=--TiO-=SUB=-2-=/SUB=- glasses with a change in TiO-=SUB=-2-=/SUB=- concentration from zero to phase separation

The thermal expansion coefficient (TEC) of binary glasses SiO 2 -TiO decreases as the TiO concentration grows. At in range 4-6 mol% (in dependence applied synthesis method) TEC becomes negative; at 8-11 devitrification occurs. A combination photoluminescence (PL) and IR reflection techniques were for studying evolution point structural defects from zero to phase separation. precision measurements density showed its drop content 7.9 thus evidencing conversion glass into a polycrystalline substance consisting crystallites. In compatibility oxides, an ensemble comprises =SiO-Si= =Ti-O - centers well =Si-Si= =Si-Ti= neutral oxygen-vacancies. dopant specific separation (TiO mol%), PL-active groups go away, while IR-detectable Si-O-Ti bridges remain stable. Keywords: glass, defects, photoluminescence, spectroscopy.