硬脂酸盐熔融法合成(Y,Lu)AG:Ce荧光粉及荧光性能研究

采用硬脂酸盐熔融新方法合成了(Y_1-xLu_x)_1-yCe_y]₃Al₅O₁₂固溶体荧光粉(x=0’0.5, y=0.005’0.03), 并通过XRD、SEM、BET和PL-PLE等方法对该荧光粉进行了表征。结果表明, 纯相石榴石在800℃的低温下即可生成, 而不经过YAM和YAP中间相。煅烧所得(Y_1-xLu_x)_1-yCe_y]₃Al₅O₁₂ 荧光粉具有良好的均一性和分散性, 并在455 nm蓝光激发下于544 nm附近呈现最强黄光发射。粉体的发光强度随煅烧温度升高而增大, 归因于结晶度提高和表面缺陷减少。发现Ce³⁺的荧光猝灭浓度为1.5%, 猝灭机制为Ce-Ce间的交换相互作用和晶格缺陷。发现发射峰位随Ce³⁺含量增加而红移, 而最强激发峰和发射峰随Lu³⁺含量增大而蓝移, 归因于Ce³⁺离子5d激发态能级重心移动和晶体场劈裂的共同作用。

(Y,Lu)AG:Ce Phosphors Synthesized by Stearate Melting Method and Their Fluorescence Properties

(Y_1-xLu_x)_1-yCe_y]₃Al₅O₁₂ (x=0-0.5, y=0.005-0.03) garnet powders were prepared by a novel stearate melting method. The phosphor powders were analyzed by XRD, SEM, BET and PL-PLE. The results show that phase-pure garnet can be obtained upon calcination at a relatively low temperature of 800℃, without involvement of YAlO₃ (YAP) and Y₄Al₂O₉ (YAM) intermediate phases. The resultant (Y_1-xLu_x)_1-yCe_y]₃Al₅O₁₂ phosphor powders are well dispersed, and show the highest emission at 544 nm under excitation wavelength at 455 nm. The emission intensity increases with increasing calcination temperature, due to improved crystallinity of the powder and removal of surface defects at high temperatures. The quenching concentration of Ce³⁺ is found to be 1.5% and the quenching mechanism is proposed to be Ce-Ce interactions and lattice defects. PL band of the phosphor red shifts with the increase of Ce³⁺ content, while the strongest excitation and emission bands are blue shift with increasing Lu³⁺ doping, due to combination effects of centroid shift and crystal field splitting of the Ce³⁺ 5d energy levels.