On the origin of near-IR luminescence in Bi-doped materials (II) Subvalent monocation Bi^+ and cluster Bi_5 ^3+ luminescence in AlCl_3/ZnCl_2/BiCl_3 chloride glass

Broadband NIR photoluminescence (from 1000 to 2500 nm) was observed from partially reduced AlCl₃/ZnCl₂/BiCl₃ glass, containing subvalent bismuth species. The luminescence consists of three bands, assigned to Bi⁺ , Bi₂⁴⁺, and Bi₅³⁺ ions. The physical and optical characteristics of these centers and possible contribution to NIR luminescence from bismuth-doped oxide glasses are discussed.