Effect of NaF/RE (RE=Yb, Tm) molar ratio on the morphologies and upconversion properties of NaYbF4:Tm3+ microrods

Abstract Tm 3+ doped β-NaYbF 4 with different aspect ratios has been synthesized by a facile hydrothermal method. A different morphology and size of β-NaYbF 4 microrods were obtained by changing the NaF/RE (RE = Yb,Tm, 99.5% Yb 3+ , 0.5% Tm 3+ ) molar ratio. The morphology and size of products were explored by SEM, and the influences of the NaF/RE molar ratio on the microrod size were evidenced by XRD. It is shown that the size and morphology of the products can be precisely controlled by modulation of the NaF/RE molar ratio. β-NaYbF 4 microrods with 35 μm in length and 7.5 μm in diameter were prepared when NaF/RE molar ratio is 6. Intense ultraviolet emissions at 290 nm, 345, and 361 nm and visible emissions at 451 and 494 nm were observed in Tm 3+ doped NaYbF 4 microrods with an excitation of a 980 nm diode laser. The effect of NaF/RE ratio on growth rate has been proposed.