释光材料的缺陷结构和发光机制的研究

In this project, several series of typical TL and OSL phosphors will be prepared. These phosphors will be investigated by the crystal structure method, including X-ray diffraction, neutron diffraction and electron spin resonance, etc,for the relationship between the concentration of the impurities and the changes of defect structure, and to assess the correlations between preparation technology and defect structure. The luminescence characteristics of TL and OSL of the phosphors will be measured by using the improved TL 3D spectrometer. As a result, the relationship between parameters of defect complex and luminescence mechanism will be obtained from luminescence characteristic data of the phosphors. Furthermore, the correlation between the defect structure and nonlinear dose response of phosphors will also be investigated after determination of the dosimetric characteristics of these phosphers. Combined the calculation of energy state with the experimental results, energy level structure of luminescence crystal will be explicit. Based on these new understandings of the defect structure and luminescence mechanism, the TL and OSL theoretical model will be improved which will guide our work for new material development,and a few potential TL and OSL phosphors are going to be prepared. This study is important and significant not only to TL and OSL dosimetry, but also to benefit for developement and application of the TL and OSL materials.

系统地制备具有代表性体系的释光磷光体材料，用晶体结构研究方法，包括X射线衍射、中子衍射和电子自旋共振等，研究这些释光材料中掺入不同浓度的杂质后，引起的缺陷结构变化，研究制备工艺与缺陷结构的关系； 用热释光三维光谱研究材料的发光特性，获取有关缺陷复合体参数与发光机制的关系，测定释光材料的剂量特性，研究释光材料中晶体缺陷结构与剂量响应非线性的相关性。通过计算晶体能态，结合实验结果，明确释光晶体的能级结构。 基于对缺陷结构和发光机制的新认识，发展和完善释光理论模型，指导释光新材料的研制，制成剂量特性优良、有应用价值的释光材料。本研究不仅对释光剂量学具有重要意义，而且对释光材料开发和实际应用有促进作用。

本项目通过研究释光材料制备工艺、缺陷结构、发光特性，建立和完善释光材料发光机制的理论模型，提高释光材料研制的效率。研制了多个系列的掺杂稀土和过渡金属离子的释光磷光体，包括碱土金属硫酸盐、硼酸盐、磷酸盐和硅酸盐发光材料。研究了制备工艺、缺陷结构、发光特性之间的关系，通过低温热释光光谱和高温热释光光谱研究材料发光特性和能量转移规律。通过XAFS谱和XRD结构精修数据均发现二价稀土离子掺入后出现等电子陷阱，并研究了等电子陷阱对热释光发光和剂量响应的影响，完善并验证了基于缺陷复合体的复合作用剂量响应模型。制备出光释光性能非常良好的新材料LiMgPO4:Tm, Tb，提出多次退火法计算光释光陷阱参数，并和其他实验结果进行对照分析。.研制出的低温热释光三维光谱仪填补国内该项空白，不仅可以测量低温热释光三维发光谱，还可以测量发光曲线，以及不同温度下的辐射发光（RL）光谱，低温三维热释光光谱的测量方法将为新剂量学材料的开发提供更先进的测试和分析方法，可以用于浅陷阱的研究，丰富晶体结构中陷阱能级分布数据，明确关于发光时间衰减、竞争陷阱等假设，解释相关实验现象。项目还进行了剂量学方面的应用研究，包括事故剂量的重建，Al2O3：C在放射治疗中剂量验证方面的应用，以及一种以LiMgPO4:Tm,Tb磷光体为测量探头的在线测量的光纤剂量计。