Controllable synthesis and upconversion luminescenceof NaYF4:Yb3+, Er3+ nanocrystals

Abstract NaYF 4 nanorods, and nanoparticles co-doping with Yb 3+ and Er 3+ were synthesized by hydrothermal method. The effects of doped ion concentration, the ratio of NaF to Ln (NO 3 ) 3 and the reactant content on the luminescence properties of the nanocrystals were investigated in detail in this paper. The materials were characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and photoluminescence (PL) spectra. The results indicate that a doping level of 20 mol% Yb 3+ and 2 mol% Er 3+ gives the strongest luminescence, and concentration quenching occurs, when Er 3+ concentration exceeds 5 mol%. Besides, the reaction of temperature and time were also investigated and the results showed that they have an effect on the shape, size, and crystal phase purity of the nanoparticles. The luminescence mechanism for the NaYF 4 :Yb 3+ , Er 3+ was discussed. Under 980 nm excitation, the Er 3+ ions doped into NaYF 4 samples emitted green fluorescence 520 nm ( 4 H 11/2 → 4 H 15/2 ), 550 nm ( 4 S 3/2 → 4 H 15/2 ) and red fluorescence 650 nm( 4 F 9/2 → 4 I 15/2 ), which were modified and enhanced by Yb 3+ ions.