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首页> 外文会议>Symposium on Radiation Effects and Ion-Beam Processing of Materials; 20031201-20031205; Boston,MA; US >Radiation-induced Defects in Nonradioactive Natural Minerals: Mineralogical and Environmental Significance
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Radiation-induced Defects in Nonradioactive Natural Minerals: Mineralogical and Environmental Significance

机译：非放射性天然矿物中的辐射诱发缺陷：矿物学和环境意义

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摘要

Natural short-lived radionuclides generate electronic defects in minerals, such as trapped electrons and positive holes, often associated with element impurities, which act as final traps over geological periods. Two main examples will be illustrated. The first example will concern the point defects, which are observed in clay minerals. The high specific surface area makes clay minerals sensitive to the geochemical radiation background and provides a record of the past occurrence of radionuclides in geological systems. In kaolinite, three types of hole-centers are trapped by oxygen atoms linked to Si- or Al-sites. An experimental dosimetry gives the paleodose, which can be used either to assess mean past U-concentration or for kaolinite dating depending on the available geochemical parameters. The detection of past migrations of radioelements in natural analogues may be used in the safety assessment of radioactive waste disposals. The second example will concern the role of mineral impurities in defect formation and stabilization. Natural fluorites (CaF_2) exhibit hole-and electron-centers trapped on several rare earths and oxygen impurities, often present at the ppm level, which are responsible for the wide range of coloration observed in natural fluorites. Ca colloids may form under severe irradiation and give rise to a characteristic absorption. The thermal stability of radiation-induced defects gives constraints on the evolution of fluorites as a function of temperature and time. Other minerals, such as apatite, confirm the importance of impurities in stabilizing radiation-induced defects over geological periods.
机译：天然的短寿命放射性核素会在矿物中产生电子缺陷，例如被捕获的电子和正空穴，这些缺陷通常与元素杂质有关，它们在地质时期是最终的陷阱。将说明两个主要示例。第一个例子将涉及在粘土矿物中观察到的点缺陷。高比表面积使黏土矿物对地球化学辐射背景敏感，并提供了地质系统中放射性核素过去发生的记录。在高岭石中，三种类型的孔中心被连接到Si或Al位点的氧原子捕获。实验剂量法得出了古葡萄糖，它可以根据可用的地球化学参数评估过去的U浓度平均值或用于高岭石定年。在天然类似物中放射性元素过去迁移的检测可用于放射性废物处置的安全评估。第二个例子将涉及矿物杂质在缺陷形成和稳定中的作用。天然萤石（CaF_2）表现出捕获在几种稀土和氧杂质上的空穴中心和电子中心，这些杂质通常以ppm含量存在，这导致在天然萤石中观察到的较宽的着色范围。 Ca胶体可能在强烈的辐射下形成并引起特征吸收。辐射引起的缺陷的热稳定性限制了萤石随温度和时间的变化。其他矿物（例如磷灰石）证实了在稳定地质时期中杂质在稳定辐射诱发的缺陷方面的重要性。

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