石榴石相LuAG:Ce(Pr)闪烁晶体的缺陷控制和性能优化

Ce- or Pr-doped lutetium aluminum garnet crystals is one kind of most promising scintillation crystals for industrial application when the best performance is achieved by its own characteristics, i.e. high light output, high density, fast response time and non-hygroscopy, which could be widely used for nuclear medical imaging, security inspection and high-energy physics. However, the defect control puzzle in LuAG crystals is an essential problem, which constrains its application development. How to efficiently control the point defects and further improve its scintillation performance is the research target of this project. The project intends to start with the crystal thermodynamics research based on the first-principle calculation, analyzes the defect compensation effect caused by the non-stoichiometric problem, and to guide the component design; Under the premise of ensuring the scintillation properties, carry out the secondary component design by selecting appropriate alternative ions to implement "band-gap engineering" and tune the energy level position of the luminescence ions; fabricate the high figure-of-merit LuAG:Ce(Pr) scintillation crystal by optimization of crystal growth technology and after-treatment craft; then thoroughly research the temperature dependent traits, irradiation damage effect and the non-proportionality of light yield. Implement of this project could contribute to clarify the inner relationship among material component, electronic structure and the defect control, furnish and develop the structure design theory of optical function crystals, and promote the defect control theory and the application development of LuAG:Ce(Pr) crystal directly.

铈或镨掺杂铝酸镥石榴石相晶体（LuAG）是一类目前最具有应用前景的闪烁晶体，它们具有高光输出、高密度、快衰减、不潮解等优点，有望在核医学成像、安全检查及高能物理领域获得广泛的应用。但这类单晶的缺陷控制难题是制约其应用发展的核心问题，而如何有效控制点缺陷并提高其闪烁性能是本项目的研究目标。本项目拟以第一性原理计算为基础，从晶体热力学入手，分析由非化学计量比生长所引起的缺陷补偿效应，并指导组分设计；在确保闪烁性能的前提下，通过选取合适的替代离子进行二次组分设计，开展"带隙工程"并调控发光离子的能级位置；通过晶体生长和后处理工艺优化，制备得到高性能LuAG:Ce(Pr)闪烁单晶；进而深入开展晶体温度依赖特性、抗辐照损伤效应和光产额非正比性研究。本项目的研究结果将有助于阐明材料组分、电子结构与缺陷控制之间的关系，丰富和发展光功能晶体结构设计理论，直接推动LuAG:Ce(Pr)晶体的缺陷控制。

铈或镨掺杂铝酸镥石榴石相晶体（LuAG）是一类目前具有应用前景的闪烁晶 体，它们具有高光输出、高密度、快衰减、不潮解等优点，有望在核医学成像、安全检查及 高能物理领域获得广泛的应用。本项目拟以闪烁发光机制研究入手，首先分析镓和钆离子的替代机理，其中包括禁带工程、5d发光离子定位理论和铈离子价态不稳定理论，同时也研究了其他铝位替代离子的二次组分设计；分析了发光中心铈离子或镨离子的热电离现象、能量转移和辐射复合过程。通过组分调整和生长技术优化，制备得到高质量(Gd,Lu,Y)3Ga3Al2O12:Ce3+和Tb2.2Lu0.8Al5O12:Ce3+单晶，进而深入开展晶体闪烁性能及其温度依赖特性的研究。本项目最后针对多组分石榴石结构闪烁晶体存在的慢闪烁衰减时间的问题，筛选得到能有效加快衰减时间的碱土金属离子，并通过第一性原理计算和实验方法构建电子结构，并构建了模型来阐明了稳定的Ce4+离子在新闪烁物理过程。本项目的研究结果将有助于阐明材料组分、电子结构与缺陷控制之间的关系，丰富和发展光功能晶体结构设计理论，直接推动 LuAG:Ce(Pr)晶体的缺陷控制。