(Y, Lu)AG:Ce Phosphors Synthesized by Stearate Melting Method and Their Fluorescence Properties

doi:10.15541/jim20140254

Abstract

Abstract:

[(Y_1-_xLu_x)_1-_yCe_y]₃Al₅O₁₂ (x=0-0.5, y=0.005-0.03) garnet powders were prepared by a novel stearate melting method. The phosphor powders were analyzed by XRD, SEM, BET and PL-PLE. The results show that phase-pure garnet can be obtained upon calcination at a relatively low temperature of 800℃, without involvement of YAlO₃ (YAP) and Y₄Al₂O₉(YAM) intermediate phases. The resultant [(Y_1-_xLu_x)_1-_yCe_y]₃Al₅O₁₂ phosphor powders are well dispersed, and show the highest emission at 544 nm under excitation wavelength at 455 nm. The emission intensity increases with increasing calcination temperature, due to improved crystallinity of the powder and removal of surface defects at high temperatures. The quenching concentration of Ce³⁺ is found to be 1.5% and the quenching mechanism is proposed to be Ce-Ce interactions and lattice defects. PL band of the phosphor red shifts with the increase of Ce³⁺ content, while the strongest excitation and emission bands are blue shift with increasing Lu³⁺ doping, due to combination effects of centroid shift and crystal field splitting of the Ce³⁺ 5d energy levels.

Key words: YAG:Ce3+, Lu3+ doping, luminescence properties, energy centroid, crystal field splitting

CLC Number:

TB34

LI Jin-Sheng, SUN Xu-Dong, LI Xiao-Dong, LIU Shao-Hong, ZHU Qi. (Y, Lu)AG:Ce Phosphors Synthesized by Stearate Melting Method and Their Fluorescence Properties[J]. Journal of Inorganic Materials, 2015, 30(2): 177-182.

Figures/Tables 9

Fig. 1 XRD patterns of (Y0.985Ce0.015)3 Al5O12 precursor calcined at different temperatures (a) and a comparison of XRD patterns of [(Y1-xLux)0.985Ce0.015]3Al5O12 powders calcined at 1300℃(b)

Fig. 2 Lattice constants and theoretical densities of the [(Y1-xLux)0.985Ce0.015]3Al5O12 garnet solid solutions calcined at 1300℃, as a function of Lu content

Fig. 3 FE-SEM images showing particle morphologies of the powders calcined at 1000℃ (a), 1150℃ (b), 1300℃ (c) and 1500℃ (d)

Fig. 4 Comparison of the PLE (a) and PL (b) spectra of the (Y1-xCex)AG (x=0.005-0.03) phosphors calcined at 1300℃

Fig. 5 Relationship between lg(I/c) and lg c for the (Y1-xCex)AG (x=0.005-0.03) phosphors calcined at 1300℃

Fig. 6 Relationship between lg(I/c) and lg(1-c) for the (Y1-xCex)AG (x=0.005-0.03) phosphors calcined at 1300℃

Fig. 7 PL spectra of the (Y0.085Ce0.015)AG phosphors calcined at different temperatures.

Fig. 8 Comparison of the PLE (a) and PL (b) spectra of the [(Y1-xLux)0.985Ce0.015]AG phosphors calcined at 1300℃

Fig. 9 Energy level diagram showing the 4f ground state and 5d excited state of YAG:Ce and LuAG:Ce garnets

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