新型电子俘获型材料β-Sr_2SiO_4:Eu^(2+),La^(3+)长余辉和光激励发光性能的研究

Long persistent and photo-stimulated luminescence properties of β-Sr_2SiO_4:Eu^(2+),La^(3+)phosphors

通过高温固相法在还原气体保护下制备出β-Sr2Si O4:Eu2+,La3+系列样品.通过样品光谱显示,光致发光、余辉及光激励发光中心均来自于Eu2+离子;并且La3+的掺入有效增强光致发光、余辉及光激励发光强度.热释光与余辉衰减测试证明,与单掺Eu2+样品所具备的缺陷数量相比,共掺La3+样品在浅陷阱区(T1区)较多的俘获中心数量是导致其余辉性能优化的主要因素;其光激励发光强度的增强则归因于在深陷阱(T3区)的俘获中心数量增加.共掺样品放置15h并在980nm红外激光激励后,表现出光激励长余辉发光现象.此现象的出现,为电子俘获型材料的浅陷阱对深陷阱中的载流子再俘获过程的存在提供了直接证据.因此,β-Sr2Si O4:Eu2+,La3+材料可视为一种潜在的长余辉和光激励发光材料.

A series of β-Sr2SiO4： Eu2＋, La3＋ phosphors have been synthesized via high temperature solid state reaction. Photoluminescence （PL）, long persistent luminescence （LPL）, and the photo-stimulated luminescence （PSL） suggest that Eu2＋ ions occupy St（l） and St（2） sites. Significant enhancement of PL, LPL arid PSL has been observed by co-doping La3＋ in [3-Sr2SiO4： Eu~＋, Laa＋. Meanwhile, the introduction of Las＋ ions increases significantly the intensities of the TL bands （T1 and T3 regions）, and promotes the formation of a large number of traps in LPL and PSL. In addition, the observation of the PSPL（photo-stimulated long persistent luminescence） phenomenon demonstrates the occurrence of electrons which are retrapped by the shallow traps in the LPL process.