Luminescence and structural characterization of transparent nanostructured Eu3+-doped LaF3–SiO2 glass–ceramics prepared by sol–gel method

Glass–ceramics with composition of 89.9SiO2–10LaF3–0.1EuF3 (mol%) were prepared by sol–gel method. LaF3 nanocrystals, precipitated by heat-treatments, were identified by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Besides the well-known red emission of Eu3+ ions, higher energy emissions coming from upper-lying levels 5D1 and 5D2 can be observed at room temperature due to the very low phonon energies of the LaF3 matrix. Moreover, from site selective excitation and emission spectra in the temperature range from 13 to 300 K, it is concluded that the fraction of Eu3+ ions partitioned into LaF3 nanocrystals, substituting La3+ ions, is comparable to the one staying in the SiO2 glassy phase.