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

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 (C_2v) sites; oxygen ions were incorporated in their neighborhood during the glass ceramization.