粉末Ba_(0.95)M_(0.05)FBr:Eu^(2+)(M=Sr,Ca)的光激励发光研究  

Study of photo-stimulated luminescence in Ba_(0.95)M_(0.05)FBr:Eu^(2+)(M=Sr,Ca) Powder

作　　者：周映雪 汪东升 张新夷 

机构地区：[1]中国科学技大术学国家同步辐射实验室,合肥230029

出　　处：《核技术》2001年第7期564-566,共3页Nuclear Techniques

基　　金：中国科学院"九五"特别支持项目(KJ95T-03)

摘　　要：ＢａＦＢｒ：Ｅｕ２＋、Ｂａ０.９５Ｓｒ０.０５ＦＢｒ：Ｅｕ２＋以及Ｂａ０.９５Ｃａ０.０５ＦＢｒ：Ｅｕ２＋粉末样品在未经Ｘ射线或紫外光辐照之前，用长波长（＞４００ｎｍ）光激励样品，都可观测到对应于Ｅｕ２＋４ｆ６５ｄ→４ｆ７跃迁的３９０ｎｍ发光，该发光与样品制备过程中形成的Ｆ心有关。在样品的激励光谱中可以观测到两组峰，中心峰值位于５３５ｎｍ的峰相应于Ｆ（Ｆ－）心电子的激励，而峰值位于７０８ｎｍ的峰可能源于Ｆ（Ｂｒ－）心或Ｆ（Ｂｒ－）心聚合体电子的激励。当少量（５％）半径较小的碱土金属离子Ｃａ２＋（半径为０. ０９９ｎｍ）或Ｓｒ２＋（半径为０．１１３ｎｍ）替代Ｂａ２＋（半径为０．１３５ｎｍ）进入晶格时，随着离子半径的减小，位于５３５ｎｍ和７０８ｎｍ的激励峰强度随之减小，而且分别在５８０ｎｍ和６５０ｎｍ或５７５ｎｍ和６４５ｎｍ处出现肩峰，在波长为５０－４００ｎｍ的吸收光谱中发现，由于小半径碱土金属离子的替代，７９ｎｍ和８３ｎｍ吸收峰红移，且出现新的吸收峰。证实了 Ｓｒ２＋或 Ｃａ２＋部分替代 Ｂａ２＋而产生新的色心： Ｆ（ Ｆ－，Ｓｒ２＋）、Ｆ（Ｂｒ－，Ｓｒ２＋）心或Ｆ （Ｆ－，Ｃａ２＋）、Ｆ（Ｂｒ－，Ｃａ２＋）心，也对应于?The luminescence centered at about 390nm due to 4f65d→4f7 transition of Eu2+ can be observed without X - ray or UV - light pre - irradiation for BaFBr: Eu2+、Ba0.95Sr0.05 FBr: Eu2 + and Ba0.95Ca0.05FBr: Eu2+ powder samples which can be excited by light with wave length longer than 400nm. It could be attributed to F centers which are formed in the preparation of samples. There are two broad bands in the photo - stimulated spectra. One peaked at 535nm results from the excitation of electrons at F(F- ) center, and the other at 708nm might be originated from the electron excitation of F(Br- ) center or F(Br- ) accumulators. If the Ba2+ (ion's radius equals to 0. 135nm) in the samples were replaced by about 50% mol. of Sr2 + (ion's radius equals to 0. 113nm) or Ca2 + (ion 's radius equals to 0. 099nm), the intensities of 535nm and 708nm bands decrease with the decrease of ion radius. On the other hand, the shoulders at 580nm and 650nm or 575nm and 645nm can appeare. In absorption spectra of 50 - 400nm range, one can observe the red - shift of 79nm, 83nm peaks and new absorption peaks. It means that the new color centers: F(F -, Sr2 + ) .F(Br-, Sr2 + ) or F(F-,Ca2+ ) .F(Br-, Ca2+ ) are formed, when Ba2+ were replaced with Sr2+ or Ca2+ in samples. It corresponds to the shoulders in photo - stimulated spectra.

关 键 词：光激励发光 色心 缺陷 BAFBR 光激励发光材料 钡 卤素化合物 

分 类 号：O482.31[理学—固体物理]