STRUCTURAL AND LUMIENESCENT STUDY OF EUROPIUM (III) DOPED TUNGSTATES

Motivated by the need of new red phosphor for white - light - emitting diodes (WLEDs) application, Eu3+ doped Sc2-xInx(WO4)3 (x = 0, 1, 2) solid solutions were synthesized by high temperature solid - state reaction. Structural and luminescent properties were obtained by using X - ray diffraction (XRD), infrared and photoluminescence spectroscopic techniques. IR spectrum of the ScIn(WO4)3 doped with Eu3+ contains the characteristic vibrations of the WO4 and MeO6 , (Me = Sc, In) polyhedral, building the Sc2(WO4)3 and In2(WO4)3 structures. An effective energy transfer from the tungstate matrix to the active Eu3+ ion was observed. Intense red luminescence was obtained in these samples under excitation at 394 nm using the sharp 7F0 → 5L6 transition of Eu3+. The calculated asymmetric ratio ( 5D0 → 7F2 / 5D0 → 7F1 ) was about 7.5, suggesting that the obtained materials are characterized with distorted environment around the rare earth ion and with high red emission intensity. The prepared ScIn(WO4)3 solid solution demonstrates the highest emission intensity. The obtained chromaticity coordinates of the Eu3+ doped Sc2-xInx(WO4)3 solid solutions were very close to the red standard recommended by National Television Standards Committee (NTSC).