Sol–gel transparent nano-glass–ceramics containing Eu3+-doped NaYF4 nanocrystals

A spectroscopic study has been carried out in transparent nano-glass–ceramics containing Eu3+-doped NaYF4 nanocrystals, successfully developed for the first time by thermal treatment of precursor sol–gel derived glasses. X-ray diffraction and high-resolution transmission electron microscopy measurements confirmed the precipitation of NaYF4 nanocrystals during heat treatment and their corresponding sizes have been calculated by using Scherrer’s equation and from electron microscopy measurements. Changes in the luminescence spectra with the temperature of the heat treatment have been analyzed and correlated with the crystallinity degree of the samples. In addition, emission spectra have been obtained for selected excitation wavelengths, observing large excitation selectivity among the fraction of the rare-earth ions located in near crystalline environments and those remaining in the silica glassy phase.