Ba2+替代对Sr4Al14O25:Eu2+, Dy3+结构和发光性能的影响

Structure and Luminescence Properties of Sr4Al14O25:Eu2+, Dy3+ by Ba2+ Substitution

摘要:

采用高温固相反应按化学式Sr4-xBaxAl14O25: 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＝0.8时，产物物相为单斜结构SrAl2O4和磁铅矿结构SrAl12O19共存；当x>1.6时，产物主相转变为BaAl2O4六角结构。对所得样品采用360 nm光照，发射光谱表明，样品发光是以Eu2+为发光中心，由Eu2+电子4f65d-4f7跃迁所致，并且随着Ba掺入量的增加，样品发射光谱峰位产生移动，这是由于Sr2+取代产物中Ba2+位置后，导致晶格收缩，影响Eu2+的5d能级劈裂，从而影响电子4f65d-4f7跃迁。余辉光谱显示x>1.6时，产物的余辉发光是以BaAl2O4基质中Eu2+为发光中心。余辉衰减检测和热释光谱分析发现不同掺Ba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

Abstract:

The rare-earth doped strontium aluminate phosphors Sr4-xBaxAl14O25:Eu2+,Dy3+ (x=0, 0.8, 1.6, 2.4, 3.2, 4) were synthesized by a high temperature solid-state reaction method. The phase structures of the phosphors were characterized by X-ray diffraction. The results show that the monoclinic SrAl2O4 and hexagonal SrAl12O19 co-exist in the sample with x=0.8. The major phase of phosphors is hexagonal BaAl2O4 when x>1.6. It is indicated that the phase structure of the samples changes from Sr4Al14O25 to BaAl2O4 when the value of x changes from 0 to 4. The emission spectra of 360 nm irradiation reveal that Eu2+ is the luminescence center of the samples due to 4f65d-4f7 transition of Eu2+ electron. With the Ba doping content increasing, the shift of emission spectra peak occurs, because the lattice shrinkage caused by Sr2+ substitution for Ba2+ affects the 5d level cleavage of Eu2+ and thus influences the 4f65d-4f7 transition. The afterglow spectra show that Eu2+ of BaAl2O4 is the luminescence center for the products when x>1.6. The decay characteristics show that the phosphor samples with different Ba2+ content 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 Ba2+ content is different, and the samples with deeper traps have longer afterglow time.