We demonstrated that tridoping with F- ions is an effective way to improve the fluorescence quantum efficiency of CaWO4：Eu3＋,Na＋ nanocrystals. F--tridoped samples with different F- concentrations were synthesized by a hydrothermal process. The fluorescence spectra and decay curves were measured at room temperature. The fluorescence intensity of F--tridoped samples is about 3 times that for the non F--doped sample. The fluorescence quantum efficiency can be enhanced by 21% when the atomic ratio of F to W was 0.7.
A Sr3Yb2（BO3）4 single crystal was obtained by the Czochralski method. The structure of Sr3Yb2 （BO3）4 crystal was determined by single-crystal X-ray diffraction. The compound crystallizes in orthorhombic, space group Pnma with a=7.3750（8）, b=15.9265（14）, c=8.6776（9）, V=1019.25（18）3 , Mr=844.18, Z=4, Dc=5.501 g/cm3 , λ（MoKa）=0.71073, μ= 33.835 mm-1 , F（000）=1480, the final R=0.0339 and wR=0.0907 for 1090 observed reflections with I〉2σ（I）. The structure features a three-dimensional framework composed of isolated BO3 planar triangles bridged by YbO8 and SrO8 polyhedra. The Sr2＋ and Yb3＋ occupy statistically three independent sites with a Cm and two C1 local symmetries.
