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

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: 0.01Tm(3+) 0.03Dy(3+) were tested by scanning electron microscopy. The particles are ellipsoid, and their average diameter is approximately 0.5 mm. The emission spectra of Ba0.05Sr0.95WO4: Tm3+ show a peak at 454 nm which belongs to the H-3(6) -> D-1(2) 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 F-4(9/2) -> H-6(13/2) dominant transition located at 573 nm, the weaker F-4(9/2) -> H-6(15/2) transition located at 478 and 485 nm, and the weakest F-4(9/2) -> H-6(11/2) 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. (C) 2018 Published by Elsevier B.V. on behalf of Chinese Society of Rare Earths.