Rare Earth Doped Fluoride Nanocrystals Preparation And Luminescent Properties

In this paper, the synthesis process and luminescence behavior of Eu³⁺ doped or Er³⁺-Yb³⁺ co-doped LaF₃ and GdF₃ nanoparticles were investigated. The effect of heat treatment temperature, the concentration of rare earth ions on the synthesis process and luminescence behavior was discussed.Eu³⁺-doped LaF₃ nanoparticles can be prepared by a simple procedure with high yields. The solid solution La_1-xEu_xF₃ has been synthesized. The ⁵D₁ emission of Eu³⁺ in the La_1-xEu_xF₃ nanoparticles can be observed at room temperature when doping concentration of Eu³⁺ ions is lower than 30 mol%. The quenching process of ⁵D₁ emission can be attributed to cross-relaxation. The luminescent intensity of the Eu³⁺-doped LaF₃ nanoparticles increased remarkably with the increasing doping concentration of Eu³⁺ ions and reached a maximum at approximately 30 mol%. The Er³⁺/Yb³⁺ co-doped LaF₃ nanoparticles have been observed to have stronger NIR emission and upconversion luminescence. With increase of heat treatment temperature, the upconversion luminescence intensity increased gradually.The rare earth doped GdF₃ nanoparticles have been produced by a simply hydrothermal synthesis procedure with high yields. The excitation energy of Gd³⁺ is efficiently transferred to Eu³⁺ in the Eu³⁺ doped GdF₃ nanoparticles. The Er³⁺ doped GdF₃ nanoparticles exhibit the typical emission spectra in the near-infrared. The upconversion emission of Er³⁺/Yb³⁺ co-doped GdF₃ nanoparticles can also be observed. However, the upconversion emission intensity of the Er³⁺/Yb³⁺ co-doped GdF₃ nanoparticles was much weaker in comparison with the GdF₃ bulk crystal.