Research on Luminescence Properties of CdWO4:Yb3+/Tm3+

In this paper, the CdWO4 nano-crystal co-doping with Yb3+/Tm3+ ions was synthetized by hydrothermal method. The luminescence properties and structure of the sample were measured by X-ray powder diffractions (XRD) field emission scanning environmental electron microscope (ESEM) and spectral analysis And the CWO was monoclinic system with the mean size of 30 nm. It could be obtained from the image of ESEM that the structure of CWO was nano-rod with the diameter of 30 nm and the length-diameter ratio was between 5 and 8. The emission spectra were obtained when it was excited by 980 nm semi-conductor laser. There was a strong blue emission peak and the value was 48 mm which was due to the transition (1)G(4)-> H-3(6) of Tm3+. The mechanism of Tm3+/Yb3+ co-doped system was also studied. The concentration of rare earths could influence the intensity of the blue emission. The strongest peak was obtained when the concentration of Tm3+ was 2mol% and the concentration ratio of Yb3+/Tm3+ was 10:1. According to the relationship between pump power and luminescence intensity, the emission of blue peak was three photons absorption process. It can be determined from the curve of lg(I/C)-lg(C) that the strong emission band at 481 nm belongs to electric dipole transition.