| Fluoride as lanthanide doped inorganic substrate has good chemical stability and low phonon energy. Considering the high specific surface area of nanoparticle, surface quenching caused by defects and impurities ion affect the luminescence. As a consequence, coating the nanoparticles with a homogeneous shell is a feasible strategy to reduce energy losses on the nanoparticle surface.The main researches are as follows:First of all after coating the LaF3:Eu3+core particles with the undoped LaF3, the enhancement of Eu3+emission in LaF3:Eu3+/LaF3core-shell nanoparticles were observed. In comparison with the LaF3:Eu3+core, the luminescence lifetime of Eu3+emission in core-shell nanoparticles was increased. The decay curves of LaF3:Eu3+/LaF3core/shell nanoparticles with different thickness had also been studied. The increase of the luminescence lifetime of Eu3+emission resulted from the effective shielding of the luminescence center Eu3+ions, the quenching at or near the surface of the nanoparticles was reduced.Secondly, deionized water was used to verify the quenching of Eu3+emission. We discussed the enhancement of Eu3+emission of different thickness of shell and the decrease of quenching effect by water.In addition, the core-shell structure containing noble metals also can enhance the luminescence performance. Preparation and comparison of the Au modified LaF3: Eu3+@SiO2nanoparticles show that Eu3+emission was enhanced. The radiation scattering and the absorption of Au nanoparticles will weaken the plasma fluorescence enhancement. |
