Trace defects and radiation damage in minerals and other Earth materials: structural studies and applications

痕量缺陷，包括代表早期辐射损伤的辐射诱发缺陷，对矿物的所有类型的物理化学性质(如颜色、导电性、磁性和反应性)都有重要影响，并在地球科学中有广泛的应用，从地球化学模拟到剂量学、地质年代学、重金属的固定、核废料处理和矿产勘探。对矿物中微量缺陷的定量理解和应用需要关于其物种形成和局部结构环境的准确信息。因此，本研究计划旨在研究矿物及相关材料中微量缺陷的结构和应用。科学方法包括实地调查，以查明具有重要地质应用和/或与环境直接相关的矿物中的微量缺陷。在受控条件下合成这些矿物的实验室实验旨在补充实地调查，并为光谱研究提供合成材料。利用多种光谱技术，特别是电子顺磁共振(EPR)光谱技术，对矿物和合成类似物中的痕量缺陷进行了定量表征。对矿物中缺陷的电子结构的第一性原理计算被用来辅助对光谱研究结果的定量解释。未来五年的具体研究目标是：1)对磷灰石和其他辅助矿物中REE和U吸收的晶体化学控制；2)利用多频EPR光谱发现和表征磷灰石、萤石和长石中的辐射诱导缺陷；3)对选定的磷灰石和萤石中的缺陷进行第一性原理模拟；以及4)在野外地球化学和环境研究以及矿床勘探中的应用。这项关于发现和定量研究矿物和相关材料中新缺陷的研究计划在加拿大地球科学界是独一无二的，具有创新性，其多学科方法和新实验技术的不断发展证明了这一点。

Trace defects, including radiation-induced varieties representing incipient radiation damage, exert important influence on all types of physical-chemical properties of minerals (e.g., color, electrical conductivity, magnetism and reactivity) and have a broad range of applications in Earth sciences from geochemical modeling to dosimetry, geochronology, immobilization of heavy metals, nuclear waste disposal, and mineral exploration. Quantitative understanding and applications of trace defects in minerals require accurate information about their speciation and local structural environments. Accordingly, this research program is directed towards the study of structures and applications of trace defects in minerals and related materials. Scientific approach includes field-based investigations to identify trace defects in minerals of important geological applications and/or of direct environmental relevance. Laboratory experiments on the synthesis of these minerals under controlled conditions are designed to complement field-based investigations and to provide synthetic materials for spectroscopic studies. Trace defects in minerals and synthetic analogs are characterized quantitatively by use of multiple spectroscopic techniques, particularly electron paramagnetic resonance (EPR) spectroscopy. First-principles calculations on the electronic structures of defects in minerals are used to aid quantitative interpretation of results from spectroscopic studies. Specific research objectives for the next five years are: 1) crystal-chemical controls on the uptake of REE and U in apatites and other accessory minerals, 2) discovery and characterization of radiation-induced defects in apatites, fluorite and feldspars by use of multi-frequency EPR spectroscopy, 3) first-principles modeling of selected defects in apatites and fluorite, and 4) applications to field-based geochemical and environmental studies and to exploration of mineral deposits. This research program on the discovery and quantitative study of new defects in minerals and related materials is unique in the Canadian Earth science community and is innovative, as evidenced by its multidisciplinary approach and by the continuing development of new experimental techniques.