Structural and optical characterizations of sol–gel based composites constituted of LiGdF4 : Eu3+ nanocrystallites dispersed into a silica matrix

Abstract

The sol–gel process was utilized for preparing fluoride–oxide composites as powders constituted of undoped or Eu³⁺ doped LiGdF₄ nanocrystallites which are embedded in a silica network. Crystallization of the fluoride phase occurs after 700 °C heat treatment under inert atmosphere (Ar) using trifluoroacetic acid as in-situfluorine source. Formation of well-crystallized and submicronic LiGdF₄ crystallites were evidenced by X-ray diffraction and transmission electron microscopy respectively. Besides emission spectra as well as decay times of Eu³⁺ recorded from SiO₂–LiGdF₄ : Eu³⁺ samples are similar to those obtained from single LiGdF₄ : Eu³⁺ fluoride emphasizing the formation of well-dispersed and pure fluoride nanocrystallites with a selective incorporation of Eu³⁺ ions inside this latter.