Effect of fluoride ions on the optical properties of Eu3+:PbF2 nanocrystals embedded into sol-gel host materials

In this research, the effects of fluoride ions concentration on luminescence properties of Eu3+:PbF2 nanocrystals in silicate sol-gel materials have been investigated. Optical and structural properties of Eu3+:PbF2 nanocrystals have been examined using X-ray diffraction analysis (XRD) and luminescence spectroscopy. Formation of the cubic β-PbF2 nanocrystalline phase was confirmed. The crystal size was estimated using Scherrer's equation and Williamson-Hall formula. The optical behavior of Eu3+ ions in studied materials is strongly dependent on amount of incorporated fluorides in the host lattice and the optimal concentration about 3.0 mass. % give the more intense emission of Eu3+. The luminescence spectra showed the characteristic orange-red emission due to the 5D0 → 7F1 and 5D0 → 7F2 electron transitions, respectively. The luminescence intensity ratio R (I(5D0 → 7F2)/I(5D0 → 7F1)) and luminescence lifetimes for the 5D0 excited state of Eu3+ ions were determined for each sample before and after heat treatment process. Obtained results indicate the partially incorporation of Eu3+ ions into β-PbF2 nanocrystalline phase during ceramization process.