本研究以CO_2雷射燒結製備摻鈰釔鋁石榴石(YAG:Ce)螢光陶瓷板,並與傳統高溫(1500 °C)固態反應(solid state reaction, SSR)進行比較,探討前驅物材料經不同雷射間隔(0.3 mm、0.7 mm)燒結後之相成份、晶粒取向、微結構與光學性質。研究結果發現以雷射掃描間隔0.3 mm燒結後,表面可完全變態為YAG相,並無異相存在,而當間隔提升至0.7 mm時,表面仍有初始材料Al_2O_3及Y_2O_3等相存在,進一步探討其光致發光(photoluminescence, PL)強度的變化,發現以雷射間隔(0.3 mm)燒結之樣品於放射波長526 nm有較高強度,經計算統計結果可得知,YAG量與適當的表面粗糙度為影響發光強度主要因素。進一步由穿透式電子顯微鏡觀察經雷射燒結後陶瓷,其晶粒尺寸約為1 μm-2 μm且呈現長條型,由選區繞射得知不同區域之晶粒排列皆一致,具優先取向特性。
This study aimed to prepare cerium-doped yttrium aluminum garnet (YAG:Ce) phosphor ceramics by CO_2 laser sintering. The microstructure, grain orientation, phase composition, and optical properties of various laser scanning offsets were investigated. The results were compared with that from conventional high temperature solid state reaction (SSR). XRD results indicated that after laser sintering at 0.3 mm offsets, the surface crystallized as a YAG phase without any detectable impurity phase. When the offset was increased to 0.7 mm, some precursor (Y_2O_3 and Al_2O_3) were present. Also, after laser sintering at an offset of 0.3 mm, the optimal luminous intensity of emission band peaked at 526 nm upon blue light excitation of 450 nm was obtained. We also observed that the amounts of YAG as well as an appropriate surface roughness affected the fluorescence intensity. TEM showed that the grains were elongated in size from 1 μm to 2 μm. It was also found that the grains arranged in some specific crystallographic or preferred orientation from the SAD results.