Broadband Near-IR photoluminescence of bismuth-doped pollucite-related phase CsGaGe2O6

Highlights: • CsGaGe₂O₆ pollucite-related phase is a good host for Bi⁺ optically active center. • Bi⁺ ion in CsGaGe₂O₆ demonstrates the broadband Near-IR photoluminescence. • Melt acidity is crucial for high Bi⁺ concentration in crystallized CsGaGe₂O₆. -- Abstract: Polycrystalline samples of bismuth-doped CsGaGe₂O₆ with pollucite-related structure were prepared by crystallization from the melt. Intense broadband near-IR photoluminescence was observed in this phase. The photoluminescence emission and excitation spectra are characteristic for Bi⁺ monocation. Structural disorder in the framework of pollucite-related phase leads to the inhomogeneous broadening of photoluminescence emission spectrum. The influence of melt composition on the stabilization of subvalent Bi⁺ monocation was discussed in the terms of oxoacidity concept.