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612089 
Journal Article 
Yellow-Orange-Emitting CaAlSiN3:Ce3+Phosphor: Structure, Photoluminescence, and Application in White LEDs 
Li, YQ; Hirosaki, N; Xie, RJ; Takeda, T; Mitomo, M 
2008 
Yes 
Chemistry of Materials
ISSN: 0897-4756
EISSN: 1520-5002 
20 
21 
6704-6714 
WOS:000260658100023 
The crystal structure and photoluminescence properties of undoped and Ce 3+-doped CaAlSiN 3as well as the application of white-light LEDs are reported. CaAlSiN 3and CaAlSiN 3:Ce 3+have been synthesized, starting from Ca 3N 2, AlN, Si 3N 4, and CeN or CeO 2with and without Li 3N, by a solid state reaction at 1700 °C for 4 h under high purity nitrogen atmosphere. Instead of an ideal CaAlSiN 3, a more appropriate formula is proposed to be CaAl 1−4δ/3Si 1+δN 3(δ ≈ 0.3−0.4) with an Al/Si ratio of about 1:2 on the basis of the bond valence sum calculations, in which Al/Si is disorderly occupied on the 8b site within Cmc2 1space group. Ce 3+can be incorporated into the host lattice of CaAlSiN 3, and the estimated maximum solubility of Ce 3+is about x= 0.02 (e.g., 2.0 mol % with respect to Ca) of Ca 1−2 xCe xLi xAlSiN 3. CaAlSiN 3:Ce 3+can be efficiently excited by blue light (450−480 nm) and yields yellow-orange emission with a broadband peaking in the range of 570−603 nm, originating from the 5d 1→ 4f 1transition of Ce 3+. With an increase of Ce concentration, the emission band of Ce 3+shifts to longer wavelengths due to the increased Stokes shift corresponding to structural relaxation and energy transfer of Ce 3+. Upon excitation in blue light range (450−480 nm), the absorption and external quantum efficiency are about 70% and 56%, respectively, for both Ca 1−2 xCe xLi xAlSiN 3and Ca 1− xCe xAlSiN 3−2 x/3 O 3 x/2 at x= 0.01. In addition, Ca 1−2 xCe xLi xAlSiN 3and Ca 1− xCe xAlSiN 3−2 x/3 O 3 x/2 show high thermal stability in air with the quenching temperature above 300 °C for x= 0.01. Using single CaAlSiN 3:Ce 3+as the wavelength conversion phosphor combined with a blue InGaN LED-chip (450 nm), warm white-light LEDs can be generated, yielding the luminous efficacy of about 50 lm/W at color temperature 3722 K and the color rendering... [ABSTRACT FROM AUTHOR] Copyright of Chemistry of Materials is the property of American Chemical Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts) 
PHOSPHORS; PHOTOLUMINESCENCE; LIGHT emitting diodes; CRYSTALS; CHEMICAL reactions; WAVELENGTHS