EXAFS investigation on the local environiment of rare earth ions in Ge-Ga-S-CsBr glasses

Abstract

The local environment Of rare earth ions in (1-x)(Ge0.25Ga0.10S0.65)-xCsBr glasses was investigated. The emission intensity and lifetime of the Tm3+:H-3(4) -> F-3(4), transition increased sharply when the amount of CsBr exceeded the Ga concentration in glasses. Ga K-edge EXAFS spectra showed that Ga ions are coordinated with three sulfurs and one bromine ion in 0.9(Ge0.25Ga0.10S0.65)-0.1CsBr glass. Analysis of cross-relaxation in Tm3+ ions also proved that this energy transfer process is strongly dependent on the vibration energy of Ga-Br bonds. Analysis of the phonon side-band spectrum of Eu3+ indicated that the emission properties of Eu3+ are influenced by the Ga-Br bonds located next to Eu3+ ions. These results indicate that the rare-earth ions were located next to the [GaS3/2Br](-) structural units in 0.9(Ge0.25Ga0.10S0.65)-0.1CsBr glass.