Enhanced red emission induced by Tb{sup 3+} doping in europium-based molybdate phosphors
Graphical abstract: The introduction of Tb3+ significantly enhances the red emission of Eu3+ in europium-based molybdate phosphors. The enhanced red emission intensity is discussed by the relaxation of parity-forbidden selection rules of Eu3+ ions, whereas the contribution of Tb3+ → Eu3+ energy transfer is little in our case. - Highlights: • The introduction of Tb{sup 3+} significantly enhances the red emission of Eu{sup 3+} in europium-based molybdate phosphors. • At x = 0.02, the red-emitting intensity of LiEuMo{sub 2}O{sub 8} is enhanced by 30% under excitation at ultraviolet light 395 nm. • The enhanced red emission intensity is discussed by the relaxation of parity-forbidden selection rules of Eu{sup 3+} ions, whereas the contribution of Tb{sup 3+} → Eu{sup 3+} energy transfer is little in our case. - Abstract: A series of Tb{sup 3+}-doped europium-based molybdate red-emitting phosphors (LiEuMo{sub 2}O{sub 8}) were prepared by solid-state reaction method, their crystal structure and luminescence properties have been investigated by X-ray diffraction, micro-Raman spectra, diffuse reflectance spectra, photoluminescence and photoluminescence excitation spectra. Partial substitution of Li{sup +} by Tb{sup 3+} slightly distorts the host lattice, red-shifts the absorption edge of host and improves Eu{sup 3+} red-emitting intensity in LiEuMo{sub 2}O{sub 8} compound. The red-emitting intensity of LiEuMo{sub 2}O{sub 8} powder is enhanced by 30% at the doping level of 0.02 under excitation at 395 nm. In present study, we found that the contribution of Tb{sup 3+} → Eu{sup 3+} energy transfer to the enhanced Eu{sup 3+} emission is little since the Tb{sup 3+} ions are not responsive to the near ultraviolet (∼395 nm), the enhanced red emission is tentatively ascribed to the relaxation of parity-forbidden selection rules of Eu{sup 3+} ions. White light-emitting diodes are fabricated by using near ultraviolet light-emitting diode chips (∼395 nm) and the blends of the commercial blue, green and as-prepared red Li{sub 0.98}Tb{sub 0.02}EuMo{sub 2}O{sub 8} phosphor, the resulting white light-emitting diode shows a color-rendering index of 93.5, luminous efficacy of 14 lm/W and chromaticity coordinates of (0.292, 0.329).
- OSTI ID:
- 22730405
- Journal Information:
- Materials Research Bulletin, Vol. 94; Other Information: Copyright (c) 2017 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0025-5408
- Country of Publication:
- United States
- Language:
- English
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