A novel scheelite-type LiCaGd(WO4)3:Eu3+ red phosphors with prominent thermal stability and high quantum efficiency |
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Authors: | Dong Wang Xufeng Guan Guifang Li |
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Affiliation: | School of Advanced Materials and Nano Technology, Xidian University, Xi'an, P. R. China |
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Abstract: | A series of LiCaGd(WO4)3 : xEu3+ (0 ≤ x ≤ 1.0) red phosphors with tetragonal scheelite structure were synthesized via the conventional solid-state reaction. Their crystal structure, photoluminescence excitation (PLE), and photoluminescence (PL) spectra, thermal stability and quantum efficiency were investigated. The phosphors exhibit a typical red light upon 395 nm near ultraviolet excitation, and the strongest emission peak at 617 nm is dominated by the 5D0→7F2 transition of Eu3+ ions. The PL intensity of the phosphors gradually increases with the increase of Eu3+ doping concentration, and the concentration quenching phenomenon is hardly observed. The quantum efficiency and the color purity of the phosphor reach maximum values of about 94.2 and 96.6% at x = 1.0, respectively. More importantly, LiCaGd(WO4)3:xEu3+ phosphors have prominent thermal stability. The temperature-dependent PL intensity of the phosphors at 423 K is only reduced to 89.1% of the PL intensity at 303 K, which is superior to that of commercial red phosphors Y2O3:Eu3+. Finally, LiCaGd(WO4)3:Eu3+ phosphor is packaged with near ultraviolet InGaN chips to fabricate white light emitting diodes, which has a low color temperature (CCT = 4622 K) and a high color rendering index (CRI= 89.6). |
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Keywords: | phosphor quantum efficiency scheelite structure thermal stability |
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