稀土离子含量对Sr_2Si_5N_8：Eu^(2＋)红色荧光粉发光性能及其电子结构的影响

Influence of Eu^(2+) content on photoluminescent property and electronic structure of Sr_2Si_5N_8:Eu^(2+) red phosphor

利用碳热还原氮化法制备了Sr2-xSi5N8:xEu2+红色荧光粉,其中x=0.005~0.2,分析了稀土Eu2+离子浓度对荧光粉发光性能的影响规律,采用DFT理论分析了Sr2-xSi5N8:xEu2+的电子结构和发光原理。结果发现,随着Eu2+浓度的升高,荧光粉发射光谱的发射峰值出现红移。实验研究发现其浓度猝灭点为x=0.02,当x=0.02时,发射光强度最大,发射光谱为小于600nm的橙黄光。当x在0.05~0.15的范围时,发光强度衰减幅度较小,且发射光谱为610nm以上的红光。利用第一性原理对Eu2+浓度x=0.015625~0.125的Sr2-xSi5N8:xEu2+荧光粉的能带结构计算显示,随着Eu2+浓度的升高带隙减小,理论计算浓度猝灭点在x=0.0625和x=0.125之间。

Sr2-xSi5N8：xEu2＋red-emitting phosphors with Eu2＋concentration from x=0.005-0.2were synthesized by carbothermal reduction and nitridation（CRN）method.Photoluminescence properties and electronic structures were analysized through experiment and DFT simulation.There was a red-shift of the emission bands of Sr2-xSi5N8：xEu2＋with increasing of Eu2＋concentration and the concentration quenching point was at x=0.02.The electronic structure of Sr2-x Si5N8：xEu2＋（x=0.015625-0.125）by first-principles calculations based on density functional theory（DFT）showed that the band gap decreased with increasing Eu2＋concentration and the theoretical critical concentration quenching point for Eu2＋content was between x=0.0625 and x=0.125.