Novel sol-gel SiO2-NaGdF4 transparent nano-glass-ceramics
Authors/Creators
- 1. Dpt. Coating Processes, FunGlass, Alexander Dubček University of Trenčín, Študentská 2, 911 50 Trenčín, Slovakia
- 2. Instituto de Cerámica y Vidrio (ICV-CSIC), C/ Kelsen, 28049 Madrid, Spain
- 3. Applied Physic Department I, Superior School of Engineering, Pais Vasco University, 48013 Bilbao, Spain, Materials Physics Center (CSIC-UPV/EHU), 20018 San Sebastian, Spain
- 4. Donostia International Physics Center (DIPC), 20018 San Sebastian, Spain
Description
Novel transparent oxyfluoride nano-glass-ceramics containing undoped and 0.5 Eu3+ (mol%) doped NaGdF4 nanocrystals (NCs), were obtained by sol-gel for the first
time. X-ray diffraction (XRD) confirms the precipitation of α- and β-NaGdF4 NCs with a size ranging between 5 and 24 nm. When the Na:Gd ratio, temperature and
heating time are fixed to 0.95:1, 550–600 °C and 1–8 h, respectively, only the β-NaGdF4 phase precipitates. These results are confirmed by high-resolution transmission
electron microscopy (HRTEM). The decomposition of trifluoroacetic acid (TFA) and the formation of fluoride lattice bonds were studied by Fourier transform
infrared spectroscopy (FTIR). Thus, the sol-gel route permits NaGdF4 glass-ceramics to be obtained through the control of Na:Gd ratio, temperature and heating time.
The incorporation of dopant ions in the NaGdF4 NCs was confirmed by photoluminescence measurements which show narrow and well-resolved Eu3+ emission and
excitation spectra in GCs. Moreover, the low asymmetry ratio values between the electric dipole (5D0→7F2) to the magnetic dipole (5D0→7F1) transitions indicate
that Eu3+ ions are incorporated in the NaGdF4 NCs. Furthermore, efficient Gd3+→Eu3+ energy transfer results in an enhancement of the reddish Eu3+ emissions,
further supported by fluorescence decay lifetimes.