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- Title
Luminescent properties of red-light-emitting phosphors CaWO : Eu, Li for near UV LED.
- Authors
XIONG, F; LIN, H; WANG, L; SHEN, H; WANG, Y; ZHU, W
- Abstract
A series of red phosphors CaWO : xEu, xLi ( x = 0.01, 0.02, 0.04, 0.06, 0.12, 0.20 and 0.30) in pure phase were synthesized via high-temperature solid-state reaction and their luminescent properties were investigated. For comparison, the 6 mol% Eu-doped CaWO was also obtained and investigated. The crystal structures of these phosphors were characterized by powder X-ray diffraction, and the luminescent properties of Eu-, Li-codoped CaWO were investigated by diffuse reflectance spectra, photoluminescence emission spectra, photoluminescence excitation spectra, and the Commission International de L' Eclairage (CIE) chromaticity indexes. These spectra illustrated that Eu-, Li-codoped CaWO phosphors could effectively be excited by a 270 nm ultraviolet (UV) or 394 nm near UV chip, and exhibit red emission originated from theD →F ( J = 1 and 2) transitions of Eu. The fluorescent intensities of red emission band centred at 610 nm of 6 mol% Eu-, Li-codoped CaWO were about 1.27 times stronger than that of 6 mol% Eu-doped CaWO under 394 nm excitation. The 12 mol% doping concentration of Eu ions in CaWO is optimum when excited at 394 nm, while excited at 270 nm the sample with 6 mol% was the best one. The concentration quenching mechanism could be attributed to the dipole-dipole interaction between the Eu ions. The CIE colour coordinates can be tuned from yellowish red to deep red with varying concentrations of Eu. The present work suggests that Eu-, Li-codoped CaWO as red phosphors exhibit great potential application in the near UV excited white-light-emitting diode.
- Subjects
LIGHT emitting diodes; LUMINESCENCE spectroscopy; PHOSPHORS; CRYSTAL structure; CALCIUM tungstate crystals; EUROPIUM
- Publication
Bulletin of Materials Science, 2015, Vol 38, Issue 7, p1867
- ISSN
0250-4707
- Publication type
Article
- DOI
10.1007/s12034-015-1039-0