Synthesis and photoluminescence characteristics of Dy3+ doped NaY(WO4)2 phosphors

The novel phosphor powders of NaY(WO4)2 doped with Dy3+ were synthesized by solid state reaction. X-ray diffraction analysis showed that the phosphors sintered at 900 °C for 6 h were a pure NaY(WO4)2 phase for all the Dy3+ doping concentrations. The room temperature excitation spectra of the phosphors vary with the Dy3+ concentration and consist of an intense charge transfer band of WO42− groups and weak f–f transition absorption peaks of Dy3+. The photoluminescence spectra, excited at the peak wavelength of charge transfer band, exhibit three bands centered at 488, 575 and 662 nm, which originate from the transitions of 4F9/2 → 6H15/2 (blue), 4F9/2 → 6H13/2 (yellow) and 4F9/2 → 6H11/2 (red) of Dy3+, respectively. The effects of Dy3+ concentration on luminescence intensity and the yellow-to-blue intensity ratio of the phosphors were investigated. The different behaviors for the doping concentration dependence of luminescence intensity resulted from the different kinds of excitation was discussed.