Ca^(2+)离子替代对Sr_4Al_(14)O_(25):Eu^(2+),Dy^(3+)结构和发光性能的影响

Structure and luminescence properties of Sr_4Al_(14)O_(25):Eu^(2+),Dy^(3+) by Ca^(2+) doping

采用高温固相反应按化学式Sr4-xCaxAl14O25:Eu2+,Dy3+(x=0,0.8,1.6,2.4,3.2,4)配比原料,合成长余辉发光材料.X射线衍射分析表明当x<2.4时,产物物相均为Sr4Al14O25正交结构;当x>2.4时,产物物相转变为CaAl4O7单斜结构.对掺Ca量不同,但结构仍保持Sr4Al14O25的样品采用360nm激光照射,发射光谱表明样品发光均由以Eu2+为发光中心的电子4f65d→4f7跃迁所致,并且随着Ca掺入量的增加,样品发射光谱峰位逐渐蓝移.这是由于Ca2+取代Sr2+位置后,导致晶格收缩,影响Eu2+的5d能级劈裂情况,从而影响电子4f65d→4f7跃迁.余辉衰减检测和热释光谱分析发现,不同Ca掺入量的样品余辉衰减快慢不同,是由于其中存在的陷阱能级深度不同,且陷阱能级越深,其余辉时间越长.

The rare-earth doped strontium aluminate phosphors SrxCa4-xAl14O25：Eu^2＋,Dy^3＋（x=0,0.8,1.6,2.4,3.2,4） were synthesized by a high temperature solid-state reaction method. The X-ray diffraction studies show that phase of the phosphors is orthorhombic Sr4Al14O25 for x〈 2.4, whereas the phase is hexagonal CaAl4O7 for x 〉 2.4. The results indicate that the phase structure of the samples changes from Sr4Al14O25 to CaAl4O7 when the value of x changes from 0 to 4. In addition, a blue shift was found in the emission spectra due to the change in nature of the Eu^2＋ surroundings. The decay characteristics show that the phosphor samples with different Ca^2＋ contents have different afterglow time, and the afterglow time also changes with the value of x. The measurement of thermoluminescence reveals that the trap depth of the phosphor samples with different Ca^2＋ contents is different. The samples with deeper traps have longer afterglow time.