Microstructure and photoluminescence properties of laser sintered YAG:Ce phosphor ceramics

Cerium-doped yttrium aluminum garnet (YAG:Ce) phosphor ceramics were fabricated by CO2 laser sintering under various powers. X-ray diffraction results indicated that all samples crystallized as a YAG phase without any impurity phase in the power range of 15-40 W. The reaction profile caused by laser ablation increased from 0.28 mm (15 W) to 2.68 mm (40 W), and it appeared deeper in the scanning sequence because of the low rigidity of YAG melts compared with solid precursors. Photoluminescence (PL) measurements revealed that the YAG:Ce sample by 15 W laser sintering upon blue light excitation presented more intense yellow emission (enhancement of 54%) as compared with YAG:Ce by solid-state reaction (SSR, 1500 °C). The laser beams were believed to distribute activators (Ce) more homogeneously compared with SSR. Additionally, a rougher surface of YAG:Ce phosphor ceramics with periodic holes caused by laser ablation resulted in more excitation and emissivity of PL.