Synthesis and photoluminescence properties of cerium-doped terbium–yttrium aluminum garnet phosphor for white light-emitting diodes applications

Abstract

Cerium-doped terbium-yttrium aluminum garnet phosphors were synthesized using the solid-state reaction method. The crystalline phase, morphology, and photoluminescence properties were characterized by x-ray diffraction (XRD), scanning electron microscope (SEM), and fluorescence spectrophotometer, respec- tively. The XRD results indicate that with an increase of the amount of x (Tb 3þ ), all of the samples have a pure garnet crystal structure without secondary phases. The SEM images reveal that the samples are composed of sphere-like crystallites, which exhibit different degrees of agglomeration. The luminescent properties of Ce 3þ ions in ðTbxY1−xÞ 2.9 Al5O12∶Ce0.1 have been studied, and it was found that the emission band shifted toward a longer wavelength. The redshift is attributed to the lowering of the 5d energy level centroid of Ce 3þ , which can be explained by the nephelauxetic effect and compression effect. These phosphors were coated on blue light- emitting diode (LED) chips to fabricate white light-emitting diodes (WLEDs), and their color-rendering indices, color temperatures, and luminous efficiencies were measured. As a consequence of the addition of Tb 3þ , the blue LED pumped ðTb0.4Y0.6Þ2.9Al5O12∶Ce0.1 phosphors WLEDs showed good optical properties. © 2015 Society of