摘要
通过透射谱、X射线激发发射谱 (XSL)的测试 ,研究了Bridgman法生长的掺钇钨酸铅晶体的发光性能 ,并利用正电子湮没寿命谱 (PAT)和X光电子能谱 (XPS)实验手段 ,对掺钇钨酸铅晶体的微观缺陷进行研究。实验表明 ,钇掺杂能够提高钨酸铅晶体的发光快成分比例 ,并使得晶体中的正电子俘获中心浓度下降 ,低价氧浓度下降。提出掺钇钨酸铅晶体中钇的掺杂主要以Y3 + 占据VPb的形式存在。Y3 + 占据VPb可能是钨酸铅晶体吸收边得到改善的原因 ,而由于晶体内低价氧浓度的减少 ,作为绿光发光中心的 (WO3 +O-)基团的减少可能会使发光快成分比例有所增加。
In high energy physics experiments, large arrays of scintillation crystals has been used in electromagnetic for precision measurements of photons and electrons. Lead tungstate is a fast and dense scintillating crystal and has been selected as scintillator for the construction of calorimeter in CMS experiment of Large Hadron Collider (LHC) at CERN (European Organization for Nuclear Research) this century. In the course of studying the effects of various heterovalent ions introduced into the PbWO 4 lattice, we have found that Y 3+ ions can significantly improve the optical transmittance in the short wavelength region. Correlated measurements of transmission, X-ray excited emission, positron annihilation lifetime and X-ray photoelectron spectrometers were performed on a selected set of undoped and Y-doped PbWO 4 single crystals. The samples were grown from 5N purity raw powders by modified Bridgman method and show the blue emission component only. The transmittance, luminescence and point defects of Y doped PbWO 4 crystal have been studied by these methods. The results show that Y dopants can improve the luminescence property of the crystal, i.e. it can increase the ratio of fast luminescent component, and suppress the concentrations of positron capture centers and low-valent oxygen ions. It was tentatively proposed that Y 3+ dopants would mainly occupy the sites of lead vacancies resulted from Pb volatilization but not replace the lattice Pb 2+ ions. This is the reason why the absorption edge of PbWO 4∶Y crystal slightly shifts to shorter wavelength. The low-valent oxygen ions suppression can lead to the decrease of green luminescence centers (WO 3+O -) so as to result in higher ratio of fast luminescent component.
出处
《发光学报》
EI
CAS
CSCD
北大核心
2003年第1期76-80,共5页
Chinese Journal of Luminescence
基金
国家自然科学基金资助项目 ( 197740 43)
高等学校优秀青年教师教学科研奖励计划和教育部高等学校骨干教师资助计划项目
上海市教育委员会重点学科研究项目
曙光计划项目 ( 02SG19)
青年教师项目 ( 0 1QN18)资助项目
