Synthesis and optical characterizations of undoped and rare-earth-doped CaF2 nanoparticles

The synthesis of undoped as well as Yb or Er-doped CaF2 nanocrystals using a reverse micelle method is reported. X-ray powder diffraction and transmission electron microscopy analysis showed that the products were single phased and rather monodispersed with an average particles size around 20 nm. The emission spectra and fluorescence decay times of both Yb3+ and Er3+ rare earths (RE) ions in CaF2 nanoparticles are presented. The particles size is increased by heating the as-obtained nanoparticles at different temperatures. The effect of annealing on the optical properties of the two RE ions in CaF2 is also investigated.