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

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.