Luminescent properties of phosphors can be modified and improved by constructing energy transfer. In this article, a series of Ce3+- and/or Eu2+-doped Ca-α-sialon phosphors were synthesized through the traditional solid-state reaction method. The construction of an efficient energy transfer enables the modulation of a wide range of light colors, thereby facilitating a gradual color change from blue-green (0.1844, 0.2535) to yellow (0.4282, 0.5051). Moreover, the codoping of Ce3+ enhances the luminescence intensity of Eu2+ by approximately 2.2 times. Within the experimental gradient, the energy-transfer efficiency can reach up to 58.7%, and the energy-transfer mechanism is a quadrupole–quadrupole interaction. Gaussian fitting of the emission spectrum of the codoped samples reveals that the intensities of the Eu2+ and Ce3+ emission peaks of the codoped samples at 423 K are 78 and 87% of those at room temperature, respectively. Moreover, the thermal stability of the characteristic peaks of Ce3+ in the codoped samples is significantly enhanced compared to those doped alone. These excellent properties highlight the potential application of CaSi9Al3ON15/Ce3+, Eu2+ phosphor in white light WLEDs.
Lin Gan,Zhi-Yong Mao,Yi-Fei Wang,Fang-Fang Xu,Ying-Chun Zhu,Qing Huang,Xue-Jian Liu
Cerium-doped Ca–α-SiAlON phosphors with Ca n −1.5 x Si 12− m − n Al m + n O n N 16− n :Ce x ( m =2 n , 0.8≤ m ≤2.4, and 0.02≤ x ≤0.40) nominal compositions have been synthesized by gas pressure sintering (GPS). The photoluminescence (PL) properties were studied in relation to phase composition, particle morphology , and microstructure. Continuous addition of Ce rare-earth (RE) could enhance the emission intensity of phosphors, which was partially attributed to the formation of increased amount of planar defects where dense doping of Ce ions is achieved. Such enhancement could hold up to x =0.32, above which the emission intensity fell slightly due to the formation of more secondary phases and a surface glassy phase rather than concentration quenching. Finally, possible ways to improve the luminescence properties of Ce-doped α-SiAlON phosphors were discussed through tailoring the composition and microstructure.
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