White light-emitting Ba0.05Sr0.95WO4:Tm3+ Dy3+ phosphors

Abstract

Tm3+ and Dy3+ co-doped Ba0.05Sr0.95WO4 phosphors were synthesized by a low temperature combustion method. The structures of the samples were SrWO4 phase and were identified by X-ray diffraction. The surface topographies of Ba0.05Sr0.91WO4:0.01Tm3+ 0.03Dy3+ were tested by scanning electron microscopy. The particles are ellipsoid, and their average diameter is approximately 0.5 μm. The emission spectra of Ba0.05Sr0.95WO4:Tm3+ show a peak at 454 nm which belongs to the 3H6→1D2 transition of Tm3+, and the optimum doping concentration of Tm3+ ions was 0.01. The emission spectra of Ba0.05Sr0.95WO4:Dy3+ consist of the 4F9/2 → 6H13/2 dominant transition located at 573 nm, the weaker 4F9/2 → 6H15/2 transition located at 478 and 485 nm, and the weakest 4F9/2 → 6H11/2 transition located at 660 nm, and the optimum doping concentration of Dy3+ ions was 0.05. A white light is achieved from Tm3+ and Dy3+ co-doped Ba0.05Sr0.95MoO4 crystals excited at 352–366 nm. With the doping concentration of Tm3+ fixed at 0.01, the luminescence of Ba0.05Sr0.95MoO4:Tm3+ Dy3+ is closest to standard white-light emissions when the concentration of Dy3+ is 0.03; the chromaticity coordinates are (0.321, 0.347), and the color temperature is 6000 K.