基于多功能热释光谱分析的新型稀土发光材料研究

Thermoluminescence experiment can obtain relevant information about traps, such as the depth and the density of traps, in the luminescent materials, which store part of excitation energy in those traps during excitation and release these energy as luminescence when heating up. Comparing with the extensive employment of the thermoluminescence experimental technique as a method of radiation dose detection, the application of the thermoluminescence spectroscopy, which is a luminescence related phenomenon per se, as a research tool in the field of luminescent materials is not fully fulfilled. Today the rapid development in the experimental technology of thermoluminescence spectroscopy and the perpetually more intensive and in-depth research in the luminescent materials make it possible and necessary to realize much more potentials of the thermoluminescence experiment as a research tool in the luminescence study. This project hope to build independently and innovatively a versatile thermoluminescence experimental setup on the basis of our primary thermoluminescence equipments, which will be provided with broader temperature control range (100-700 K), multiple excitation sources, wavelength resolution for both emission and excitation, and a high-level automation. Meanwhile we determine to improve the interpretation theory of the thermoluminescence experimental results. These practical and theoretical development in the thermoluminescence spectroscopy will be put into use in the study on the luminescence kinetics of rare-earth-ion-doped luminescent materials, especially for persistent luminescent materials and scintillators. Problems related with the type and the role of the traps, structural defects, and the relative position of rare earth ion energy levels in host materials, will be addressed specially using thermoluminescence experiment. The elucidation of these problems will definitely increase our knowledge about the luminescence mechanism of the rare earth luminescent materials and guide our search for the new functional high-quality luminescent materials.

某些发光材料在激发过程中将一部分激发能存储在陷阱能级中，热释光实验通过测量材料在升温过程中的发光来了解与陷阱有关的信息，如陷阱深度和浓度。相对于热释光实验技术在辐射剂量探测领域的广泛应用，热释光这一源于材料发光过程的实验现象，在发光材料研究领域的应用却不够充分。现今热释光实验技术的迅速发展和发光材料研究的不断深入，使得非常有必要将热释光实验在发光材料研究中的潜力更多地开发出来。本项目旨在基于我们实验室原有热释光设备的基础上，自主创新搭建一套具备更宽的测温范围（100-700K）、可选择激发源、激发和发射均可光谱分辨、自动化控制程度高的多功能热释光谱实验平台，完善有关热释光实验结果诠释的理论，并将其应用于稀土发光材料（特别是长余辉材料和闪烁体材料）的发光动力学研究，对陷阱类型与作用、结构缺陷、稀土离子能级在基质材料中的相对位置等问题进行深入研究，以期指导进一步的新材料开发。

基于热释光实验分析在发光动力学和发光过程机理研究中的独特优势，本项目旨在将热释光分析更全面、更深入地应用于稀土发光材料的发光机理研究中，以期指导高性能新材料的进一步开发。在项目执行初期，我们对实验室原有的热释光装置进行了全面的升级改造，实现了全温区连续线性升温，和 CCD辅助光谱分辨的热释光采集。在发光材料性能和机理的研究中，我们重点关注了适宜进行热释光测试的长余辉材料和荧光测温材料。在长余辉材料研究方面，较为突出的成果是利用热释光初始升温法研究了蓝色长余辉材料SrAl2O4: Eu2+/Dy3+的陷阱深度与密度分布，给出了其长余辉机理的新模型；利用包括热释光陷阱分析在内的一系列实验研究了自激活的MgGa2O4新型长余辉材料；通过系统性的稀土离子共掺，寻找到一种新型黄色长余辉材料Ca2Al2SiO7:Eu2+，Tm3+。此外，我们对各类长余辉材料还进行了一些扩展性的研究探索。这方面最突出的结果是将长余辉材料的温度特性应用于光学测温技术，这是一种全新的发光测温方案，可以避免直接激发对样品温度的影响。在发光材料温度特性的研究方面，我们研制了几种不同途径的新型发光测温材料，包括混合物测温，如Sr2Mg3P4O15:Eu2+和SrB4O7:Sm2+混合物，Li2TiO3: Mn4+ 和 Y2O3: Dy3+混合物；基于Sm3+的β-NaYF4：Sm3+纳米颗粒；基于Mn4+发光温度猝灭的Ba2LaNbO6: Mn4+/Eu3+，Lu3Al5O12:Mn4+/Tb3+以及BaLaMgNbO6 : Mn4+/Dy3+等等。以上这些成果对于长余辉材料和发光测温材料的开发应用都具有重要指导意义。