Zeren Ye

Surprising arching sheet-like dendrites growing from BaF2 nanocubes

BaF2 nanocubes were prepared from quaternary reverse micelles of cetyl trimethyl ammonium bromide (CTAB), n-butanol, n-octane, and water. Interestingly, there are arching sheet-like dendrites growing between two neighbouring sides of these cubes. X-ray powder diffraction (XRD) analysis showed that the products were BaF2 single phase. Scanning electron microscopy (SEM) or transition electron microscopy (TEM) was used to estimate the size of the final products. The results showed that the shape and size of particles were strongly dependent on the reaction conditions, such as the temperature and reaction time. When the reaction temperature was 25 °C, we obtained cuboid-like particles with clean surfaces (no dendrites growing on them), and when the temperature was 35 °C, we obtained nanocubes with dendrites growing from them between the neighbouring sides. The influence of reaction time at a temperature of 35 °C is also discussed.

Upconversion of Y 2 O 2 S : Tm , Mg, Ti Phosphor and Its Long-lasting Phosphorescence

We report the upconversion luminescence of Tm 3 + in Y 2 O 2 S:Tm, Mg, Ti phosphor. The upconversion luminescence of Y 2 O 2 S:Tm, Mg, Ti phosphor and its unusually long-lasting phosphorescence properties have been discussed.Two upconversion emission bands located at 466 and 545 nm from Tm 3 + in Y 2 O 2 S:Tm, Mg, Ti phosphor are observed after near infrared light (λ = 798 nm) or red light (λ = 648 nm) excitation. The afterglow light of Y 2 O 2 S:Tm, Mg, Ti phosphor is so strong that it can be seen by the naked eye for above an hour. The possible mechanism of the unusual upconversion long-lasting phosphorescence is also discussed.