Effects of copper ions on the near-infrared luminescence in Bi doped silicate glass via copper for sodium ion exchange

• The Cu ions were introduced into glasses by the Cu+ for Na+ ion exchange method.
• Different valence states of Cu, namely, Cu0, Cu+, and Cu2 +, were incorporated into glass.
• Some Bi near infrared active centers formed during the ion exchange process.
• Some lower valence states of Bi were oxidized in the heat treatment procedure.

The copper (Cu) atoms were incorporated into the bismuth (Bi) doped silicate glasses by the copper for sodium (Cu–Na) ion exchange method. After the ion exchange process, the Cu ions were introduced into the glass matrix with different copper valence states, namely, Cu0, Cu+, and Cu2 +. Bi3 + ions could be reduced to lower valence states of Bi containing Bi near infrared (NIR) active centers with the incorporation of the Cu ions, resulting in the enhancement of the Bi NIR luminescence intensity. During the heat treatment process, some lower valence states of Bi containing Bi NIR active centers could be oxidized, resulting in the attenuation of the NIR luminescence of Bi. Our research may extend the understanding of chemical environment modulation in Bi valence states and offer a valuable way to enhance the NIR luminescence intensity of Bi in glasses.