Highly dispersed and uniform α-NaYF4 micron flowers with about 500nm size was synthesized by a simple wet-chemical at a low temperature, then NaYF4:Eu3+@Au hybrid structures with various amount Au nanoparticles (Au NPs) are prepared and single NaYF4:Eu3+@Au hybrid particle is taken to investigate the influence of noble metal nanoparticle on the luminescence emission and present corresponding mechanism. It is found that luminescence emissions of NaYF4:Eu3+ was quenched by introducing Au nanoparticles, and with increase of Au nanoparticles, the fluorescence quenching was more and more serous while emission intensity ratio of electric dipole to magnetic dipole transition of Eu3+ gradually become larger.
Rare-earth doped NaLaF4 nanocrystals were synthesized by solvothermal method in ethanol/oleic acid/water reaction system. The structure and porphology of samples were characterized by X-ray diffraction(XRD), scanning electron microscopy (SEM) and transmission electron microscopy(TEM). By adjusting the amount of NaOH in the precursor, we obtained NaLaF4:Er3+/Yb3+/Gd3+nanocrystals with a rich variety of morphologies, including nanoprisms, nano-dumbbells, nanorods and nanowires. A possible mechanism of formation of the NaLaF4 nanocrystals was proposed based on the time dependent experiments. The upconversion luminescence properties of rare-earth doped NaLaF4 nanocrystals with different morphology was discussed. The experimental results demonstrated that the NaLaF4:Er3+/Yb3+/Gd3+ nanocrystals with different morphologies exhibited similar up-conversion luminescence, with sharp emission peaks near 540 nm and 650 nm, and red color stronger than green light.