Fluorescence properties of Eu-doped GeO2–SiO2 glass heated under an H2 atmosphere

Eu-doped GeO2–SiO2 glass was prepared using a sol–gel method and its optical absorption and fluorescence properties were measured during heating under an H2 atmosphere. In the glass obtained by heating in air at 1000°C, the Eu3+ ions cluster and an optical absorption band associated with the oxygen-deficiency defects in the Ge–O bonds is observed at 250 nm wavelength. When heated in H2 gas atmosphere, the formation of the oxygen-deficiency defects is significantly enhanced in the presence of the Eu3+ ions. The electron released from the Ge–O bonds are captured to the Eu3+ ions to form the [Eu3+]− state. According to this reaction, no fluorescence is observed from the Eu ions.