New Lanthanide-Containing Silicate Fluoride Scintillators for Radiation Detection

非技术性的边境保护机构，如国土安全部，必须能够检测到流氓放射源，例如脏弹，然后才能将其运往该国。存在对用于便携式检测设备的大量被称为闪烁体的材料的迫切需求。闪烁体是暴露在辐射下会发出可见光的材料，闪烁体越好，光线就越亮，可以检测到的放射性物质就越少。这项研究由美国国家科学基金会材料研究部的固态和材料化学计划资助，涉及改进闪烁材料晶体生长的基本方面，从而推动了辐射探测领域的发展。此外，本研究项目还为研究生和本科生提供了宝贵的教育经验。开展这项研究对学生进行晶体生长艺术方面的培训，并向他们传授实验设计和方法优化的概念。总体而言，这项研究有助于在固态和材料化学领域对广泛的个人进行教育和培训，包括那些来自代表不足的群体的人。技术新功能材料的开发可以产生巨大影响的一个领域是国土安全。迫切需要大量高效的闪烁材料来改进辐射探测。本研究致力于合成新型的中子、X射线和伽马射线激活的闪烁氧化物。混合阴离子相中的氟被认为是对荧光强度起关键作用的元素之一，而且已经证明氟还可以提高稀土硅酸盐的闪烁效率。具体地说，众所周知，其中氟离子位于LnOxFy多面体中的发光氧氟化物，例如在最近发现的明亮闪烁材料Cs3LnSi4O10F2(Ln=Eu，Tb)中，可以表现出与Lu2SiO5：Ce3一样明亮的闪烁。含有混合阴离子相的氟的定向晶体生长利用了最近开发的一种增强型助熔剂生长技术，该技术已知可以产生氟氧化物和盐包裹体硅酸盐的晶体。为了更好地了解在合成复杂氧化物单晶所用的各种助熔剂环境中混合阴离子相的形成过程，进行了原位中子衍射实验，以确定实验室制备新闪烁体的最佳生长条件，并将晶体生长从经验过程转变为刻意过程。此外，这项研究有助于在固态和材料化学领域对广泛的个人进行教育和培训，包括那些来自代表不足的群体的人，例如通过与HBCU的克拉夫林大学合作。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Non-TechnicalBorder protection agencies, such as Homeland Security, must be able to detect rogue radiation sources, for example dirty bombs, before they are transported into the country. A pressing need exists for large quantities of materials know as scintillators, which are used in portable detection devices. Scintillators are materials that emit visible light when exposed to radiation, and the better the scintillator, the brighter the light and the smaller the amount of radioactive material that can be detected. This research, funded by the Solid State and Materials Chemistry Program in the Division of Materials Research at NSF, involves the fundamental aspects of crystal growth of improved scintillating materials and thereby advances the field of radiation detection. In addition, this research project provides a valuable educational experience for graduate and undergraduate students. Conducting this research trains students in the art of crystal growth and teaches them the concept of experimental design and methods optimization. Overall, this research contributes to the education and training of a wide range of individuals, including those from underrepresented groups, in the area of solid state and materials chemistry.TechnicalOne area where the development of new functional materials can have a tremendous impact is homeland security. There exists a pressing need for large quantities of efficient scintillating materials for improved radiation detection. This research focuses on the synthesis of new neutron, X-ray, and gamma-ray activated scintillating oxides. Fluorine in mixed anion phases has been identified as one element that plays a crucial role in the intensity of fluorescence, and it has been demonstrated that fluorine can also increase the scintillation efficiency of rare earth silicates. Specifically, it is known that luminescent oxyfluorides in which the fluorine anions are located in LnOxFy polyhedra, such as in Cs3LnSi4O10F2 (Ln = Eu, Tb), a recently discovered brightly scintillating material, can exhibit scintillation as bright as Lu2SiO5:Ce3+. The targeted crystal growth of fluorine containing mixed-anion phases takes advantage of a recently developed enhanced flux growth technique that is known to yield crystals of oxyfluorides and salt-inclusion silicates. To better understand the processes involved in the formation of mixed anion phases in the various flux environments that are used for synthesis of complex oxide single crystals, in-situ neutron diffraction experiments are carried out to identify the optimal growth conditions for preparing new scintillators in the laboratory as well as to transform crystal growth from an empirical to a deliberate process. Additionally, this research contributes to the education and training of a wide range of individuals, including those from underrepresented groups, in the area of solid state and materials chemistry, for example through collaboration with Claflin University, an HBCU institution.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.