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

摘要

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, respectively. The XRD results indicate that with an increase of the amount of x (Tb~(3+)), 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~(3+) ions in (Tb_xY_(1_x))_(2.9)AI_50_(12)：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~(3+), 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~(3+), the blue LED pumped (Tb_(0.4)Y_(0.6))_(2.9)Al_5O_(12):Ce0.I phosphors WLEDs showed good optical properties.