On the origin of near-IR luminescence in Bi-doped materials (I). Generation of low-valence bismuth species by Bi3+ and Bi0 synproportionation

Creation of bismuth-containing near-infrared (NIR) luminescent centers by synproportionation reaction of Bi3+ and Bi0 was demonstrated in borate and phosphate glasses. This finding is discussed in the light of low-valence nature of bismuth NIR-luminescent centers. The experimental data is consistent with the hypothesis of univalent Bi+ (and, possible, subvalent cluster Bi ions) as a source of NIR luminescence. The dependence of Bi luminescent centers stability on oxoacidity of glass melts was discussed.

Research highlights
► Subvalent bismuth species possess NIR luminescence in glass matrices.
► Luminescent centers prepared by Bi3+ reaction with Bi metal in glass melt.
► High oxoacidity of melt is required for luminescent centers stabilization.