Synthesis and Photoluminescence Properties of Tunable Green-Orange Cerium-Doped Terbium-Lutetium Aluminum Garnet

Cerium-doped terbium-lutetium aluminum garnet ((TbxLu1-x)(2.9)Al5O12: 0.1Ce) were synthesized by solid state reaction method. The crystalline phase, morphology and photoluminescence properties were characterized by using X-ray diffraction (XRD), photoluminescence (PL) spectra, scanning electron microscope (SEM) and color coordinates analysis, respectively. The results show that with the increasing amount of x (Tb3+), Lu3Al5O12 (LuAG) phase changes gradually to Tb3Al5O12 (TAG) phase with single-crystalline characteristic, and the average particle size of the powders increases. Because of the result of a decrease of the difference between the energy centroids of the 5d and 4f configurations and an increase of the effective ligand field on the Ce-5d shell, the emission spectrum of the samples has a red-shift of 37 nm and shifts toward the saturated colors, but the emission intensity decreases. The findings indicate that it could make the garnet phosphors green to orange tunable for the applications of white LED using the mutual doping effects of Lu3+ and Tb3+ in garnet structure.