摘要
BaFCl:Eu^(2+)是一种优良的X射线存储成像材料,其X射线存储及光释光过程与晶体中的F心有紧密关系。本文制备了BaF_xCl_(2-x):Eu^(2+)系列粉末样品。利用正电子湮灭技术及光谱手段,测得这些样品的正电子湮灭谱和光激励谱。我们分解了3种不同F/Cl配比的光激励谱,得到443nm和561nm附近的2个峰,其相对强度随F/Cl比的不同发生了变化,而峰位并未改变。其实验结果表明:当其晶体中的F/Cl<1时,可以有效地产生F^-离子的空位缺陷。而当F/Cl>1时,不利于Cl^-离子空位缺陷的形成。另外,我们简单地讨论了BaF_xCl_(2-x):Eu^(2+)系列样品光激励发光强度的变化。
BaFCl:Eu^(2+) is the kind of excellent material of X—ray's storage, and its process of X—ray' s storage strongly depends on F centers. The F center is regarded as an electron trapped in a vacancy of anion, such as the F^- ion or the Cl^- ion. So the change of F/Cl ratio in BaFCl:Eu^(2+) may artificially produce a certain kind of anion's vacancy so that the F center of the anion is easily formed in the material after X-ray irradiation. The experimental resultsin the positive electron annihilation, spectra and photostimulated spectra indicate: the vacant defects of F^- ions may be effectively created in the BaFCl:Eu^(2+) compound, when the F/Cl ratio is less than 1, that in to add much more Cl^- ions in the material, and X—ray's storage increases in the samples of BaFCl:Eu^(2+) phosphors. But when the F/Cl ratio is more than 1, the vacancies of Cl^- ions can not be produced and their X—ray' s stroage decreases. These photostimulated spectra have been analysed and the change of the relative intensity was near 443nm and 560nm. In addition, it is also fact in the experiments that the chemical ratio in the host becomes larger, the materials are not advantageous to X—ray's storage.
出处
《功能材料》
EI
CAS
CSCD
1993年第1期55-59,共5页
Journal of Functional Materials
基金
国家自然基金
关键词
F心
正电子湮灭谱
光激励谱
材料
F center
Positive electron annihilation spectra
photostimulated pectra
