Luminescent tin-doped phosphate glasses activated by carbon

This paper reports on the use of carbon powder together with tin(IV) oxide to produce rare earth-free blue-emitting phosphate glasses by melting in ambient atmosphere. While the as-prepared SnO₂-doped glass was lacking in luminescent features, increasing amounts of graphite added to batch materials lead to developing the blue-emitting character of the glasses under excitation in the ultraviolet (UV). Upon addition of the highest amount of graphite at 2.0 wt%, the luminescence of carbon-induced defects became noticeable. Time-resolved UV-excited emission spectra appeared consistent with the different contributors to the exhibited luminescence being the twofold-coordinated tin centers alongside carbon-induced defects.