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The Preparation and Optical Properties of Novel LiLa(MoO4)2:Sm3+,Eu3+ Red Phosphor

1
School of Physics & Optoelectric Engineering, Guangdong University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006, China
2
Guangzhou LEDteen Optoelectronics Co., Ltd. 2F A4 Building, No. 11 Kaiyuan Avenue, Science City, Guangzhou Hi-tech Industrial Development Zone, Guangzhou 510663, China
*
Author to whom correspondence should be addressed.
Materials 2018, 11(2), 297; https://doi.org/10.3390/ma11020297
Received: 27 November 2017 / Revised: 8 February 2018 / Accepted: 12 February 2018 / Published: 14 February 2018
(This article belongs to the Special Issue Luminescent Materials 2017)
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Abstract

Novel LiLa1−xy(MoO4)2:xSm3+,yEu3+ (in short: LL1−xyM:xSm3+,yEu3+) double molybdate red phosphors were synthesized by a solid-state reaction at as low temperature as 610 °C. The optimal doping concentration of Sm3+ in LiLa1−x(MoO4)2:xSm3+ (LL1−xM:xSm3+) phosphor is x = 0.05 and higher concentrations lead to emission quenching by the electric dipole—electric dipole mechanism. In the samples co-doped with Eu3+ ions, the absorption spectrum in the near ultraviolet and blue regions became broader and stronger than these of the Sm3+ single-doped samples. The efficient energy transfer from Sm3+ to Eu3+ was found and the energy transfer efficiency was calculated. Under the excitation at 403 nm, the chromaticity coordinates of LL0.95−yM:0.05Sm3+,yEu3+ approach to the NTSC standard values (0.670, 0.330) continuously with increasing Eu3+ doping concentration. The phosphor exhibits high luminous efficiency under near UV or blue light excitation and remarkable thermal stability. At 150 °C, the integrated emission intensity of the Eu3+ remained 85% of the initial intensity at room temperature and the activation energy is calculated to be 0.254 eV. The addition of the LL0.83M:0.05Sm3+,0.12Eu3+ red phosphors can improve the color purity and reduce the correlated color temperature of WLED lamps. Hence, LL1−xyM:xSm3+,yEu3+ is a promising WLED red phosphor. View Full-Text
Keywords: molybdate; red phosphor; energy transfer; thermal stability molybdate; red phosphor; energy transfer; thermal stability
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Wang, J.; Luo, L.; Huang, B.; He, J.; Zhang, W.; Zhao, W.; Wang, J. The Preparation and Optical Properties of Novel LiLa(MoO4)2:Sm3+,Eu3+ Red Phosphor. Materials 2018, 11, 297.

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