Resumo de eventos cient??ficos
White light emission materials based on simultaneous Tb3+, Eu3+ and Dy3+ doping in CaWO4 single-phased
Registro en:
0000-0001-7028-0878
Autor
BARBOSA, HELLIOMAR P.
SILVA, IVAN G.N.
FELINTO, MARIA C.F.C.
TEOTONIO, ERCULES E.S.
MALTA, OSCAR L.
BRITO, HERMI F.
WORLD CHEMISTRY CONGRESS, 46th; ANNUAL MEETING OF THE BRAZILIAN CHEMICAL SOCIETY, 40th; IUPAC GENERAL ASSEMBLY, 49th
Resumen
Tungstates activated by trivalent rare earth ions (RE3+) can be used for many optical devices [1].
Over the last decades, the solid-state lighting sources based on phosphor converted white lightemitting
diodes (pc-WLEDs) has improved to overtake fluorescent lighting types because of many
advantages such as high ecofriendliness, brightness, low power consumption and fast response
time [2]. Here we report preparation and spectroscopic properties of the single phase new highly
luminescent white emitting of the Tb3+/Eu3+/Dy3+ triply-doped CaWO4 material. The
CaWO4:xTb3+,xEu3+,xDy3+(x mol% of the Ca2+ amount) materials were prepared by fast
coprecipitation method at room temperature with stoichiometry aqueous solutions of Na2WO4,
CaCl2 and RECl3 (RE3+: Tb, Eu and Dy). The XPD measurements revealed the CaWO4:RE3+
particles belong to the tetragonal scheelite phase with I41/a (#88) space group.
The emission spectra exhibit only narrow emission bands arising from the doping Tb3+, Dy3+ and
Eu3+ ions. These emission bands are assigned to the 4f transitions from the 4F9/2 (Dy3+), 5D4 (Tb3+)
and 5D0 (Eu3+) emitting states to their energy levels corresponding to (in nm): 702 5D0???7F4(Eu3+),
655 5D0???7F3(Eu3+), 615 5D0???7F2(Eu3+), 592 5D0???7F1(Eu3+), 575 4F9/2???6H13/2(Dy3+), 544
5D4???7F5(Tb3+), 488 5D4???7F6(Tb3+), 478 4F9/2???6H15/2(Dy3+) (Fig. left). The presence of the
emission bands assigned to the doping Dy3+, Tb3+ and Eu3+ ions suggests clear evidence of nonradiative
energy transfer from 4F9/2 (Dy3+)???5D4 (Tb3+)???5D0 (Eu3+) emitter states (Fig. center). The
white light emission was mainly reached for 5.0 mol% RE3+ with x: 0.333; y: 0.352 CIE
(Commission Internationale l'??clairage) coordinates (Fig. right).
These phosphors could be suitable as triply-doped white light emitters with only single-phased for
solid state lighting applications. Since warm white light is preferred for reading, while cold white
light is preferred for public lighting the tunability of this single-phase emitting phosphor exhibit
promising applications for solid-state lighting.