Blue-emitting phosphate glasses synthesized via reduction of tin(IV) by silicon
The Si-reductant route to produce blue-emitting tin-doped phosphate glasses is proposed. SnO2/Si co-doped glasses were prepared in a P2O5:BaO matrix by a simple melt-quench method in ambient atmosphere. This lead to the silicon-driven reduction of tin(IV) to tin(II) resulting in the production of the luminescent glasses. While the as-prepared SnO2-doped glass appeared non-luminescent, the addition of increasing amounts of silicon powder up to 6 mol% to batch materials facilitated developing the blue-emitting character of the glasses under excitation in the ultraviolet (UV). Reductant-induced luminescent defects became readily noticeable upon addition of the highest amount of silicon. Time-resolved UV-excited emission spectra appeared consistent with the different contributors to the exhibited luminescence being the twofold-coordinated tin centers alongside silicon-related defects. Emission from the latter appeared to be analogous to that of carbon-related defects recently reported, thus supporting that the corresponding luminescence results from the presence of oxygen radicals created by the highly reductive environment irrespective of the element (C or Si).