Luminescence and energy transfer of a color tunable phosphor: Dy super(3+)-, Tm super(3+)-, and Eu super(3+)-coactivated KSr sub(4)(BO sub(3)) sub(3 ) for warm white UV LEDs

A series of Dy super(3+)-, Tm super(3+)-, Eu super(3+)-coactivated KSr sub(4)(BO sub(3)) sub(3 ) phosphors were synthesized viaa standard solid-state reaction under normal ambient air, and the emission colors could be tuned from blue to yellow and then to red, including almost all the white light re...

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Bibliographic Details
Published in:Journal of materials chemistry 2012-03, Vol.22 (13), p.6463-6470
Main Authors: Wu, Li, Zhang, Yi, Gui, Mingyuan, Lu, Pengzhi, Zhao, Lixia, Tian, Shu, Kong, Yongfa, Xu, Jingjun
Format: Article
Language:English
Subjects:
Color
Crystal structure
Emission
Energy transfer
Phosphors
Rare earth metals
Tuning
White light
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Summary:A series of Dy super(3+)-, Tm super(3+)-, Eu super(3+)-coactivated KSr sub(4)(BO sub(3)) sub(3 ) phosphors were synthesized viaa standard solid-state reaction under normal ambient air, and the emission colors could be tuned from blue to yellow and then to red, including almost all the white light region, through tuning the energy transfer. It was discovered that the energy is transferred from Tm super(3+) to Dy super(3+) by: directly observing overlap of the excitation spectrum of Dy super(3+) and the emission spectrum of Tm super(3+); the systematic relative decline and growth of emission bands of Tm super(3+) and Dy super(3+), respectively; and faster decay times of the blue emissions from energy donors. The resonance-type energy transfer from Tm super(3+) to Dy super(3+) was demonstrated to be viathe dipole-quadrupole mechanism and the critical distance of energy transfer was calculated to be 20.7 Aa. Rietveld refinements of the crystal structures of the products obtained from powder X-ray diffraction (XRD) elucidated a preferable occupancy in the crystal unit for the doped rare-earth cations, which well explained the formation of the Tm super(3+)-Dy super(3+) close pair. By utilizing the principle of energy transfer, we have demonstrated that with appropriate tuning of activator content, KSr sub(4)(BO sub(3)) sub(3 ):Dy super(3+),Tm super(3+),Eu super(3+) phosphors exhibit great potential for use as single-component phosphors for warm white ultraviolet light-emitting diodes (UV LEDs).
ISSN:0959-9428
1364-5501
DOI:10.1039/c2jm15506k