热释发光-正电子湮灭法研究SrAl_2O_4基磷光体长余辉发光机制

Long Afterglow Luminescence Mechanism of SrAl2O4-based Phosphor by the Thermoluminescence and Positron Annihilation Method

利用传统陶瓷制备方法合成了长余辉SrAl2O4:Eu,Dy发光粉材料,并利用热释发光-正电子湮灭法对该材料的发光性能及机理进行了研究.研究结果表明,掺杂的Eu在基质材料中主要充当发光中心,而Dy离子主要充当陷阱能级.正电子湮灭试验结果表明,Sr0.94Al2O4:Eu0.02和Sr0.94Al2O4:Eu0.02,Dy0.04存在带负电中心的缺陷,共掺杂的Dy3+进到Sr2+位,同时产生一定量的Sr空位.热释发光谱结果表明,单掺杂Eu离子的磷光体中缺陷陷阱深度较深,约为0.95eV.随着Dy的共掺杂,热释发光强度相应增加,陷阱深度降为0.51eV.对于长余辉发光机制,认为陷阱能级捕获的空穴与介稳态(Eu1+)*的复合,导致了长余辉现象的发生.并且由于陷阱深度的变化,导致余辉性能出现较大的差异.

Long afterglow SrAl2O4:Eu,Dy phosphor was prepared by the traditional ceramic synthesis method, and investigated its luminescent mechanism and properties by the thermoluminescence and positron annihilation method. The results indicate that Eu2+ ions act luminescent centers and Dy3+ ions as trap levels. The positron annihilation experiment reveals that traps with negative charge exist in the Sr0.94Al2O4: Eu-0.02 and Sr0.94Al2O4:Eu-0.02, Dy-0.04, the Dy3+ ions enter the Sr2+ sites, and produce some Sr2+ vacancies simultaneously. The thermoluminescence curves imply that the, depth of trap level is about 0.95eV while doped Eu ions simply, and 0.51eV while co-doped Dy3+ in the SrAl2O4 host. As for the long afterglow luminescence mechanism, the trapped holes released from the trap levels are recombined with electrons accompanying with the luminescence, which result in the long afterglow. Due to the different depths of trap levels, the afterglow properties of phosphors vary greatly.