若干典型闪烁晶体中的结构缺陷与掺杂效应

On the doping effects and structural defects in some classical inorganic scintillation crystals

无机闪烁晶体是一种能够吸收高能粒子并将其能量转化成紫外或可见光的功能晶体材料,在辐射探测技术领域发挥着日益重要的作用。但晶体中存在的生长缺陷严重削弱了晶体的闪烁性能,并限制了晶体的实际应用。为了克服这些缺陷,某些元素被有意识地掺入到晶体中,从而使晶体的闪烁性能得到显著改善和提高,起到了“四两拨千斤”的效果。因此,掺杂改性成为优化晶体性能的重要手段,但掺杂效应所涉及的内在过程和机理往往比较复杂,以至于长期处于争论状态。本文介绍了若干典型闪烁晶体——钨酸铅(PbWO_(4))、锗酸铋(Bi_(4)Ge_(3)O_(12))、氟化钡(BaF_(2))和硅酸镥(Lu_(2)SiO_(5))晶体中存在的主要缺陷和为克服这些缺陷所采用的掺杂离子以及所获得的掺杂效应,试图从微观层面揭示和探究掺杂效应的内在机理,以期对未来相关材料的开发提供借鉴和参考。

Inorganic scintillation crystals belong to optical functional crystal materials which can convert high energy particles to UV or visible light,and therefore have been widely applied in radiation detection technology.However,some structural defects formed in the crystal growth process are detrimental to the scintillation properties of the crystals,so that some practical applications of the crystals are hampered.In order to eliminate these defects,some elements are intentionally doped into the crystal to suppress the detriments of the defects and to significantly improve the scintillation performance of the crystals.Even though the doping concentration is very few,little thing can make a big difference.Therefore,the doping modification has been regarded as an important method to optimize the crystal performance.However,the micro processes and mechanisms on the doping effects are very complicated so that different explanations have been debated for a long time.Based on our recent measurement results,in this article,we have reviewed the main defects and doping effects of some classical scintillation crystals,such as lead tungstate(PbWO_(4)),bismuth germanate(Bi_(4)Ge_(3)O_(12)),barium fluoride(BaF_(2))and lutetium silicate(Lu_(2)SiO_(5)),proposed some new explanations for attempting to explore and elucidate the internal mechanism of doping effects in these crystals from the microscopic level in order to provide reference for the development of related materials in the future.