Materials Chemistry and Physics, Vol.193, 339-347, 2017
Improvement of photoluminescence intensity of Ce-doped Y3Al5O12 phosphor by Si3N4 addition
Yttrium aluminum garnet (Y3Al5O12, YAG) has been widely used as a host for luminescent ions. The present paper describes the effects of Si3N4 addition on the formation and photoluminescence properties of the Ce-doped YAG yellow phosphors. Phosphor powders with the nominal compositions of Y2.95Ce0.05Al5-mSimO12-mNm (m = 0-0.6) were prepared by calcining the mixed raw materials at 1500 degrees C in nitrogen atmosphere. X-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscope, and transmission electron microscopy equipped with an energy dispersive x-ray spectrometer were used to characterize the structure of the calcined powders. The photoluminescence properties were measured with fluorescence spectrophotometry. It was found that in the range of m = 0-0.27, single phase YAG solid solution (s.s.) in which the Y, Al, and 0 sites are partially occupied by Ce, Si, and N ions, respectively. The nitrogen ions do not distribute homogeneously over the YAG lattice. The tendency to bond with nitrogen ion for the cations is (Y, Ce) > Si > Al. With the increase in the Si3N4 content, the increase in both the Ce3+/(Ce3+ Ce4+) ratio and the Ce N bonds improve the intensity of the photo luminescent emission. At m = 0.27, the emission intensity reaches a maximum which is about 2.5 and 1.6 times of that for the Si3N4-free composition (m = 0) calcined in air and nitrogen, respectively. When the Si3N4 content (m) is higher than 0.27, the emission intensity decreases due to the existence of residual Si3N4 phase. (C) 2017 Elsevier B.V. All rights reserved.