Surface-luminescence from thermally reduced bismuth-doped sodium aluminosilicate glasses

► The effect of thermal reduction on luminescence of Bi-doped aluminosilicate glasses was studied. ► Variations in luminescence are attributed to variations in the redox state of bismuth species. ► Metallic Bi-particles form near the surface by thermal annealing in reducing atmosphere. ► Thermal reduction was found to be only partially reversible.