作　　者： ; ; ; ; ; ;

机构地区： 暨南大学生命科学技术学院化学系

出　　处： 《发光学报》 2005年第2期211-214,共4页

摘　　要： 系统地研究了三价镧系离子在Cd3Al2Ge3O12基质中的长余辉发光。总结了余辉性能与激活离子电负性的关系。研究发现该体系中易失电子的激活离子产生的余辉效果较好。在254nm紫外光激发下,基质和所有镧系离子(Pm除外)掺杂的样品都有发光和余辉。按照发光和余辉性质的不同可以将激活离子分为三类:Pr3+、Tb3+和Dy3+等是有特征余辉发光的离子;Eu3+和Sm3+等是有特征发射,但没有特征余辉发光的离子;Ce4+、La3+、Nd3+以及其他是没有特征发光的镧系离子。长余辉的产生是由缺陷引起的。由于Cd2+离子在高温下容易挥发,基质中存在大量的Cd2+离子空位,这种空位可以作为俘获电子的陷阱。同时为了补偿Cd2+所产生的正电荷,在Cd2+离子空位周围会有相应的负离子空位产生,比如氧离子空位。这种补偿作用的存在使得基质本身的缺陷种类和数量十分丰富,使得该体系的余辉性能比较优越。 Though the long afterglow phosphors have been improved greatly since its invention in the nineteenth century, the mechanism of the occurrence of long afterglow is still unknown clearly. In this work, trivalent rare earth ions activated garnet-typed cadmium aluminium germanate Cd 3Al 2 Ge 3O 12 ∶Ln phosphors were studied to discover the relation between the ion electronegativity and afterglow performance. All samples were synthesized by a traditional solid-state reaction method. The luminescent properties were investigated. Long afterglow were observed excitation by 254 nm light for all of the samples. The rare earth ions can be divided into three kinds based on their long afterglow performance. The first one is Pr 3+ ,Tb 3+ and Dy 3+ . Characteristic emissions with afterglow were generated after excitation by 254 nm light. The second one is Eu 3+ and Sm 3+ . These ions can produce characteristic emission with excitation by 254 nm light, but without afterglow. The third one is Ce 3+ ,La 3+ ,Nd 3+ and other rare earth ions. These ions can not produce characteristic emission, and have no distinctly influence on the afterglow performance of the host. By comparing their electronegativity, we found that the electronegativity was consistent with the afterglow performance. Basing on the phenomena mentioned above, we concluded that the afterglow performance of reductive ions was better than that of oxidative ions in this host. The mechanism of the long afterglow may be depicted as two steps. For example of Pr 3+ , at first, Pr 3+ electrons are excited to the conduction band and are trapped at the electron traps. This process leaves Pr 4+ ions in the sample. Then the electrons at the electron traps escape from the electron traps and are captured by Pr 4+ ions to produce Pr 3+ ions in excited stated. The excited state Pr 3+ ions emit photons and return to ground state. The Pr 3+ ,Tb 3+ and Dy 3+ can be photoionizated t

关 键 词： 长余辉 热释光

领　　域： [理学] [理学]