The local environment of titanium in glasses of the system TiO2–BaO–ZnO–B2O3 was studied by x-ray absorption spectroscopy. In all glasses, for TiO2 content varying from 35 to 49 mol%, the titanium atoms are mainly fourfold coordinated network formers. For the glass with the highest titanium content, about 20% of the titanium enters into a sixfold environment, indicating the presence of precrystalline nuclei. These nuclei are responsible for the decrease of the optical performance of the glass above threshold titanium content, prior to any observable crystallization.
IODINE LOCAL ENVIRONMENT IN HIGH PRESSURE BOROSILICATE GLASSES: AN X-RAY PHOTOELECTRON SPECTROSCOPY AND X-RAY ABSORPTION SPECTROSCOPY INVESTIGATION
