IR luminescence from subvalent bismuth in phosphate glass and glass-ceramic matrices: A new insight into the nature of luminescent Bi species

摘要

It was demonstrated, that broadband NIR luminescent bismuth species can be prepared by synproportionation reaction of Bi metal and bismuth ions in usual oxidation state +3. This reaction was observed in highly Lux-Flood oxoacidic borate or phosphate glass melts [1], and Lewis acidic chloroaluminate ionic liquid [2]. The various subvalent Bi species, like univalent cation Bi⁺ and polycation clusters (Bi5³⁺, Bi8²⁺ etc.) were considered as possible products of synproportionation 2Bi + Bi³⁺ ↔ 3Bi⁺ or 4Bi + Bi³⁺ ↔ Bi5³⁺ and candidate NIR luminescent species. The equilibrium shifted toward subvalent species by increasing acidity or/and temperature.