Spectroscopic properties of Er3+ and Yb3+ co-doped glass ceramics containing SrF2 nanocrystals
Résumé
The spectroscopic properties of Er3+/Yb3+ co-doped 50SiO2-10Al2O3-20ZnF2-20SrF2 glass and glass ceramic containing SrF2 nanocrystals were investigated. The formation of SrF2 nanocrystals in the glass ceramic was confirmed by XRD. The oscillator strengths for several transitions of the Er3+ ions in the glass ceramic have been obtained and the Judd-Ofelt parameters were then determined. The XRD result and Judd-Ofelt parameters suggested that Er3+ and Yb3+ ions had efficiently enriched in the SrF2 nanocrystals in the glass ceramic. The lifetime of excited states has been used to reveal the surroundings of luminescent Er3+ and Yb3+ and energy transfer (ET) mechanism between Er3+ and Yb3+. Much stronger upconversion luminescence and longer lifetime of the Er3+/Yb3+ co-doped glass ceramic were observed in comparison with the Er3+/Yb3+ co-doped glass, which could be ascribed to more efficient ET from Yb3+ to Er3+ due to the enrichment of Yb3+ and Er3+ and the shortening of the distance between lanthanide ions in the precipitated SrF2 nanocrystals.