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Song E.,Guangdong University of Technology | Zhao W.,Guangdong University of Technology | Dou X.,Guangdong University of Technology | Yi C.,Huizhou Unihero Semiconductor Lighting Technology Co. | Zhou M.,Huizhou Unihero Semiconductor Lighting Technology Co.
Zhongguo Xitu Xuebao/Journal of the Chinese Rare Earth Society | Year: 2012

Li 2Sr 1-x-ySiO 4:xCe 3+, yTb 3+ phosphors with single Li 2EuSiO 4 phase structure were synthesized by high temperature solid state reaction. The fluorescence spectra showed that Ce 3+ doped Li 2SrSiO 4 phosphors emitted strong blue fluorescence with the exciting peak located at 360 nm, while Tb 3+ doped Li 2SrSiO 4 phosphors emitted strong green light with the exciting peak at 243 nm and no exciting peak exited in the range of 350~410 nm. A resonant energy transfer from Ce 3+ to Tb 3+ was observed and a wide exciting spectrum with peak at 360 nm appeared for Ce 3+ and Tb 3+ co-doped Li 2SrSiO 4. The bicolor of blue and green could be tuned by adjusting the relative content of Ce 3+ and Tb 3+. The bicolor phosphors have the potential application for white LEDs based on UV/NUV chip.


Song E.-H.,Guangdong University of Technology | Zhao W.-R.,Guangdong University of Technology | Zhou G.-X.,Guangdong University of Technology | Dou X.-H.,Guangdong University of Technology | And 2 more authors.
Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis | Year: 2010

The Ba1.97Ca1-x (B3O6)2:Eu2+, Mnx 2+(x=0, 0.03, 0.06, 0.15) phosphors were synthesized by high temperature solid-state reaction, and their phase composition and luminescence properties were studied. In these phosphors, Eu2+ locates at the crystal sites of Ba2+ and Ca2+ ions. Under 317 nm UV light excitation, the 5d → 4f transition of Eu2+ forms a broad blue emission band with a peak at 450 nm. With the energy transfer from Eu2+ ions, Mn2+ ions emit a broad red band with the peak at 600 nm. The mixture of the broad blue emission and a broad red emission forms an approximate white light with the CIE chromaticity (x=0.371, y=0.282). The phosphors can be excited effectively by UV light in the range of 250-400 nm, so they are the potential candidates for single white light-emitting phosphor excited by UV-LED.


Zhou G.-X.,Guangdong University of Technology | Zhao W.-R.,Guangdong University of Technology | Song E.-H.,Guangdong University of Technology | Dou X.-H.,Guangdong University of Technology | And 2 more authors.
Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis | Year: 2011

The Ca 9.95-xNa 0.75K 0.25 (PO 4) 7:Eu 0.05 2+, Mn x 2+ (x=0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 and 0.7) phosphors were synthesized by high temperature solid-state reaction, and their phase composition and fluorescence emission properties were studied. Due to the existence of double phases with similar crystal structure, the 5d-4f transition of Eu 2+ ions in the phosphors emits a fluorescence of wide wavelength with peaks located at 491 nm and 540 nm respectively. The energy transfer between Eu 2+ and Mn 2+, together with the occupation of Mn 2+ ions at the eight coordination sites in the phosphors, makes the 4T 1 ( 4G)- 6A 1 ( 6S) transition of Mn 2+ ions eimit red emission peaked at 635 nm. The combination of fluorescence emtted by Mn 2+ and Eu 2+ ions results in the emission of white light with color coordinates (0.3335, 0.2924), (0.3999, 0.3179) and (0.3307, 0.2564). The nearly pure white light emitting makes the phosphors show great application potential in the white light-emitting LEDs.


Song E.,Guangdong University of Technology | Zhao W.,Guangdong University of Technology | Zhang W.,Guangdong University of Technology | Ming H.,Dongguan Xinguanyuan Electronic Co. | And 2 more authors.
Journal of Luminescence | Year: 2010

Eu2 and Mn2 co-doped Ba2Ca(BO 3)2 phosphors yield two emission bands consisting of green and red components under the excitation of 360 nm, which shows a great potential for white LEDs. Effective energy transfer occurs in Eu 2/Mn2 co-doped Ba2Ca(BO3) 2 host due to the large spectral overlap between the emission of Eu2 and the excitation of Mn2. The energy transfer from Eu2 to Mn2 is thoroughly investigated by their excitation, emission and photoluminescence decay behaviors, and is demonstrated to be via the dipolequadrupole interaction. © 2010 Elsevier B.V. All rights reserved.


Dou X.,Guangdong University of Technology | Zhao W.,Guangdong University of Technology | Song E.,Guangdong University of Technology | Zhou G.,Guangdong University of Technology | And 2 more authors.
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2011

Eu3+-doped Ca10Na(PO4)7 phosphors were successfully synthesized by solid-state reaction techniques. Their structures and photoluminescence characteristics were carefully studied. An efficient red emission under near-ultraviolet excitation is observed. The maximum intensity of luminescence was observed at the Eu3+ concentration around 9 mol%. The quadrupole-quadrupole interaction between Eu3+ ions is the dominant mechanism for concentration quenching of fluorescence emission from Eu3+ ions in Ca10-xNa(PO 4)7:xEu3+. Due to the excitation spectrum is well coupled with near UV light, Ca10-xNa(PO4) 7:xEu3+ phosphors have potential application as red phosphors in near UV chip-based white light emitting diodes. © 2010 Elsevier B.V. All rights reserved.


Song E.,Guangdong University of Technology | Zhao W.,Guangdong University of Technology | Zhou G.,Guangdong University of Technology | Dou X.,Guangdong University of Technology | And 2 more authors.
Journal of Rare Earths | Year: 2011

A series of red phosphors Ca 10Li(PO 4) 7:Eu 3+ were synthesized by high temperature solid-state reaction method. Their luminescence properties were characterized by means of photoluminescence excitation and emission spectra, CIE chromaticity and quantum efficiency. Results indicated that the phosphors could be effectively excited by the near ultraviolet (NUV) light (393 nm). The main emission peaks of the phosphor were ascribed to the transition 5D 0- 7F 2 (613 and 617 nm) of Eu 3+ ion when samples were excited by 393 nm. The CIE chromaticity (x, y) of Ca 9.9Li (PO 4) 7:0.10Eu 3+ was x=0.638, y=0.361 and the quantum efficiency of this phosphor was 75 excited by 393 nm. Therefore, this phosphor could be a promising red component for the applications in white LEDs. © 2011 The Chinese Society of Rare Earths.


Song E.,Guangdong University of Technology | Zhao W.,Guangdong University of Technology | Zhou G.,Guangdong University of Technology | Dou X.,Guangdong University of Technology | And 2 more authors.
Current Applied Physics | Year: 2011

A single phased white light emitting phosphors K 2Ca 1-x-yP 2O 7: xEu 2+, yMn 2+ were synthesized by solid state reaction method. The Effective energy transfer occurs in this phosphor due to the large spectral overlap between the emission of Eu 2+ and the excitation of Mn 2+. The emission hue of K 2Ca 1-x-yP 2O 7: xEu 2+, yMn 2+ from blue to white light can be obtained by tuning the Eu 2+/Mn 2+ content ratio. The energy transfer mechanism from Eu 2+ to Mn 2+ in this phosphor was carefully investigated and demonstrated to be via the dipole-quadrupole interaction. © 2011 Elsevier B.V. All rights reserved.

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