Structural and optical characterizations of sol-gel based fluorides materials:: LiGdF4:Eu3+ and LiYF4:Er3+

Sol-gel synthesis of isostructural LiGdF4:Eu3+ and LiYF4:Er3+ crystallized powders is reported. Furthermore, LiGdF4:Eu3+ coatings were also prepared by dip- and spin-coating methods. In all cases, X-rays diffraction measurements were performed to check materials crystalline purity while infrared spectroscopy analyses showed that the organic groups are removed after annealing treatments at 550 degrees C in F-2 atmosphere. This result was emphasized by long radiative decay time of Er3+ ions in LiYF4 (tau = 10.5 ms) attributed to the absence of both organic residues and hydroxide ions. Laser induced emission spectra of LiGdF4:Eu3+ were recorded upon excitation in both D-5(2) and P-6(5/2) high lying levels of respectively Eu3+ and Gd3+ ions. Eventually fluorescence decays of rare earth ions were measured and compared in both cases. (c) 2005 Elsevier B.V. All rights reserved.