A potential ultraviolet light-emitting diode (UV-LED) blue phosphor, Li2Sr1−3x/2CexSiO4, was synthesized by firing at 900°C for 4 h in a reducing atmosphere of N2/H2 (5%). The crystal structure and photoluminescence properties of Li2Sr1−3x/2CexSiO4 were reported. On the basis of the Rietveld refinement of X-ray powder diffraction measurement, the synthesized phosphor is nearly a single-phase material in the trigonal system with the space group P3121 (No. 152) and Z=3. It is confirmed that Ce3+ occupies the Sr2+ site, which is located in the channels formed by two [SiO4] and three [LiO4] tetrahedral with eight coordination. The Li2Sr1−3x/2CexSiO4 could be efficiently excited by UV light and yielded a blue emission band centered at 442 nm, originating from the 4f 05d1→4f 1 of Ce3+. The concentration quenching occurs at x=0.03 and no shift in emission band is observed with the increase of x value. Upon the 358 nm excitation, the absorption, internal, and external quantum efficiencies are 81%, 81%, and 65.9%, respectively. Furthermore, the sample shows high thermal stability, the luminescence intensity of which, measured at 150°C, maintains about 92% of that at room temperature.
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Document Type: Research Article
Nitride Particle Group, Nano Ceramics Center, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan
College of Materials Science and Engineering, Nanjing University of Technology, Nanjing, Jiangsu 210009, China
Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Materials and Metallurgy, Northeastern University, Shenyang, Liaoning 110004, China
Publication date: 01 July 2010