Study on multiple near-infrared luminescent centers and effects of aluminum ions in Bi2O3–GeO2 glass system

We report on the near-infrared (NIR) luminescent properties of Bi2O3–GeO2 glass. Apparent differences of NIR luminescence, decay properties and thermal stability manifest the co-existence of more than one active center in this system. The effects of Al ions introduced both unintentionally and intentionally were investigated. 27Al NMR analysis proposes 4-fold Al coordination as dominant structure which can also provide the environment for active centers. We suggest that Al ions play a crucial role to restrain concentration quenching at higher Bi2O3 concentration instead of assisting to construct Bi centers.

► Different behaviors of multiple NIR emission centers were investigated. ► The effects of Al ions depend on the composition of Bi2O3–GeO2 glass. ► Al ions help to restrain concentration quenching at higher Bi2O3 concentration.