Titanium reduction processes in oxide glasses under electronic irradiation

Borosilicate and disilicate glasses doped with 0-2 mol% of TiO₂ have been irradiated with 2 MeV electrons. Reduction of Ti⁴⁺ is attested by the presence of an intense electronic paramagnetic resonance (EPR) signal around g = 1.92 corresponding to Ti³⁺, not observed in samples that were not irradiated. Moreover, two distinct sites of Ti³⁺ have been detected in each glass composition. Ti-K-edge X-ray absorption near edge structure (XANES) experiment and more precisely the pre-edge analysis of non-irradiated samples indicates the presence of four, five and six coordinated Ti(IV) in borosilicate glass compositions. In contrast, the average Ti(IV) coordination in DS composition is a mixture between fivefold and sixfold. In irradiated glasses, the Ti-K-edge energy (as well as the pre-edge position) shows a shift to smaller energies, which we suggest is caused by Ti³⁺. Comparison between EPR, Raman and XANES results in a coherent description of Ti⁴⁺ reduction process in the glass samples.