Eu3+ probe ion for rare-earth dopant site structure in sol–gel derived LiYF4 oxyfluoride glass–ceramic

• Annealing of Eu3+-doped SiO2–LiYF4 xerogel induces the crystallization of LiYF4 nanocrystals.
• Eu3+-ions are embedded in the nanocrystals most probably as Eu–O centers and/or dimer centers.
• Eu3+-ions site symmetry is C2v and is lower than in the crystal S4.

Sol–gel route using metal alkoxides and trifluoroacetic acid as precursors has been used to prepare oxyfluoride glass–ceramic containing Eu3+-doped LiYF4 nanocrystals of about tens of nm size embedded in a silica matrix through controlled crystallization at higher temperatures of the xerogel. Photoluminescence spectra and decay curves recorded in the Eu3+-doped LiYF4 polycrystalline pellet and glass ceramic have been discussed using group-theoretical arguments. In the glass–ceramic Eu3+ ions are embedded dominantly inside the LiYF4 nanocrystals most probably as Eu–O center and/or dimer centers in low symmetry (C2v) sites; oxygen ions were incorporated in their neighborhood during the glass ceramization.