Characterizing and Modifying Defects that Trap Excitons in Yttrium Aluminum Garnets Doped with Rare-Earth Elements

表征和修改掺杂稀土元素的钇铝石榴石中捕获激子的缺陷

• 批准号: 1359523
• 负责人: FARIDA SELIM
• 金额: $ 3.46万
• 依托单位: Bowling Green State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1359523&HistoricalAwards=false
• 关键词: Characterizing; Modifying; Defects; Trap; Excitons

Technical: This project aims for greater understanding of the interactions between excitons and crystalline defects in rare earth doped yttrium aluminum garnet (YAG) scintillator crystals. The approach toward more in-depth understanding and control of exciton dynamics is through their interactions with activating impurities and lattice defects. Lattice defects in the YAG structure will be characterized using positron lifetime spectrometry through a comprehensive study of their types, sizes and concentrations. Positron parameters will be correlated with optical measurements of exciton behavior, photon emission, and scintillation properties. The correlation between positron parameters and optical properties will be monitored as a function of growth conditions, choice of rare-earth dopant, doping levels, deviations from stoichiometry and postgrowth treatments. The correlation will further be examined following processing steps that include thermal annealing under different atmospheres. Results of the characterizations will be used to modify synthesis and growth conditions in order to improve optical properties. Non-technical: The project addresses basic research issues in a topical area of materials science with technological relevance in electronics and photonics. Through greater understanding of the interactions of excitons with defects this research is expected to lead to significant improvements in scintillator performance. Scintillator materials convert various types of radiation into photons, which can then be collected and analyzed. Two important application areas are medical diagnostics, and gamma and neutron radiation detection. The relationship between crystalline defects and scintillator performance is an important topic and at the present time not well understood. The results of these studies will help to understand how to improve scintillator efficiency by leading to the design of improved scintillator compositions and structure. The research will enhance understanding of defect formation in ionic crystals and selection of improved methods of synthesis/processing for superior optical properties. The project will integrate research and education of undergraduate and graduate student participants. Training will be in a multi-disciplinary environment of basic and applied physics, materials science, electronics and photonics. In addition to providing support and mentoring of graduate students, the PIs will motivate undergraduate and high school students through a web site and make presentations to students on and off campus. The PIs will create a diverse research group that includes women and minority group members. Research results will be disseminated through publications in premier journals and via presentations at conferences and in seminars.

技术：该项目的目的是对稀土掺杂的Yttrium铝石榴石（YAG）闪烁体晶体中的激子与晶体缺陷之间的相互作用进行更多了解。更深入地理解和控制激活的方法是通过与激活杂质和晶格缺陷的相互作用。 YAG结构中的晶格缺陷将通过正电子寿命光谱法对其类型，大小和浓度进行全面研究来表征。正电子参数将与激子行为，光子发射和闪烁特性的光学测量相关。正电子参数与光学性质之间的相关性将作为生长条件，稀土掺杂剂的选择，掺杂水平，偏离化学计量学和后生成处理的函数进行监测。在处理步骤之后，将进一步检查相关性，包括在不同大气下进行热退火。表征的结果将用于修改合成和生长条件，以改善光学特性。非技术：该项目解决了材料科学主题领域的基础研究问题，具有电子和光子学方面的技术相关性。通过对激子与缺陷的相互作用的更多了解，这项研究有望导致闪烁体性能的显着改善。闪烁体材料将各种类型的辐射转换为光子，然后可以收集和分析。两个重要的应用领域是医疗诊断，伽马和中子辐射检测。结晶缺陷与闪烁体性能之间的关系是一个重要的话题，目前尚不清楚。这些研究的结果将有助于了解如何通过设计改进的闪烁体组成和结构来提高闪烁体的效率。这项研究将增强对离子晶体中缺陷形成的理解，并选择改进的优质光学特性合成/加工方法。该项目将整合本科和研究生参与者的研究和教育。培训将在基本物理，材料科学，电子和光子学的基本和应用物理学，材料科学和光子学的多学科环境中。除了提供研究生的支持和指导外，PI还将通过网站激励本科生和高中生，并向校园内外的学生进行演讲。 PI将创建一个多样化的研究小组，其中包括妇女和少数群体成员。研究结果将通过主要期刊的出版物以及会议和研讨会的演讲来传播。