(Gd,La)2Si2O7:Ce3+闪烁体的结构相变、格位占据和VUV/XEL光谱研究

近年来，(Gd,La)2Si2O7:Ce因具有优良的闪烁性能和光输出热稳定性，有望应用于高温辐射探测领域而受到广泛关注，如晶体生长技术的研究。科学地理解其构效关系是优化其性能和生长工艺以及发展相关新材料的核心，这要求我们要对该固溶体材料的晶体结构、Ce3+格位占据和发光性质等开展深入研究。本项目将基于前期工作，利用实验(Rietveld结构精修、29Si固态NMR、同步辐射VUV光谱和XEL等)和理论(DFT和晶体场理论计算)手段，研究La3+掺杂对(Gd,La)2Si2O7:Ce结构(相变与Ce3+格位占据)、电子(能级结构)和光学(发光与热稳定性)性质的影响。预期研究成果将实现对(Gd,La)2Si2O7:Ce结构演化的理解，特别是针对此前常被误判的中间组分；建立Gd2Si2O7–La2Si2O7相图；并预期基于结构组分设计和优化该晶体性能的方案可对相关领域的研究起一定启发作用。

In recent years, (Gd,La)2Si2O7:Ce has drawn considerable attentions, such as in the growth technique of bulk crystals, for its potential application in the field of monitoring high-energy radiation at high temperature benefitting from its excellent scintillation performance and thermal stability of light output. Scientifically understanding the structure-property relationship is a key issue for optimizing its performance and growth technique as well as developing related new materials, which requires us to get insight into the crystal structure, Ce3+ site occupation, and luminescent property of this solid-solution material. On the basis of preliminary work, in this research proposal we plan to study the doping effect of La3+ on the structural (phase transition and Ce3+ occupation), electronic (level structures), and optical (luminescence and thermal stability) properties of (Gd,La)2Si2O7:Ce based on a combined experimental (Rietveld refinements, 29Si solid-state NMR, synchrotron radiation VUV spectra, XEL, and so on) and theoretical (DFT and crystal-field theory calculations) method. The expected results will provide (i) the understanding of the structural evolution of (Gd,La)2Si2O7:Ce, especially for the intermediate compositions that are frequently misinterpreted in previous reports; (ii) the Gd2Si2O7-La2Si2O7 phase diagram; and (iii) an inspiration to the related fields for a proposed strategy towards optimizing the (Gd,La)2Si2O7:Ce performance based on the structural composition designs.