X-Ray Spectroscopic Studies of the Structure of Rare Earth Element Aqueous Ion Complexes under Hydrothermal Conditions

水热条件下稀土元素水离子配合物结构的X射线光谱研究

• 批准号: 0337338
• 负责人: Robert Mayanovic
• 金额: $ 11.69万
• 依托单位: Missouri State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-01-01 至 2006-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0337338&HistoricalAwards=false
• 关键词: Ray; Spectroscopic; Studies; Structure; Rare

A detailed understanding of the interaction of rare earth element (REE) ions with ligands common in crustal fluids (H2O, Cl-, F-, OH- and others), covering a range of pressures and temperatures representative of hydrothermal conditions, is presently lacking. Such knowledge is critical for a full assessment of the degree of association of ligands with REE cations and of the stability of the resultant aqueous ion complexes, which play a direct role in the transport, fractionation, and mineralization of REE in deposits of hydrothermal origin. Our lack of understanding of such geologic processes is in large measure due to insufficient experimental data on the structure and bonding properties of aqueous REE complexes in hydrothermal solutions, covering a broad range of temperatures and pressures. This project involves experimental investigations of the structure properties of REE bearing aqueous solutions under hydrothermal conditions using the synchrotron x-ray absorption fine structure (XAFS) technique and the hydrothermal diamond anvil cell. The structure and related properties of REE aquo ion and chloro complexes will be determined from a detailed analysis of the XAFS spectra measured from REE bearing hydrothermal solutions at temperatures up to 500 degrees C and pressures up to 1 GPa. A systematic study of the effects of uniform trivalent charge, decreasing ionic radius with increasing atomic number, and possibly of 4f electron shell filling across a significant portion of the series on the structure of REE aquo and chloro complexes will be accomplished. The results will serve to test established thermodynamic calculations of the stability of REE aqueous ion complexes and as a basis for future modeling of REE in hydrothermal solutions. Because of similar chemistry, it is anticipated that the results from this project will be used to address issues of fate and transport of actinides in radioactive waste repositories. This project includes the scientific training of students within synchrotron facilities.

目前缺乏对稀土元素（REE）离子与地壳液（H2O，Cl-，F-，OH-等）常见的配体的相互作用的详细理解，涵盖了代表水热条件的一系列压力和温度。这种知识对于对配体与REE阳离子的关联程度以及所得水离子络合物的稳定性的全面评估至关重要，后者在热热起源的沉积物中直接作用REE的运输，分级和矿物质。由于关于水热溶液中水性雷克复合物的结构和键合特性的实验数据不足，我们对这种地质过程的了解不足，因此很大程度上是因为涵盖了广泛的温度和压力。该项目涉及使用Synchrotron X射线吸收良好结构（XAFS）技术和水热钻石小动脉细胞在水热条件下对REE轴承溶液的结构特性进行的实验研究。 REE Aquo离子和Chloro复合物的结构和相关特性将取决于对XAFS光谱的详细分析，这些XAFS光谱是在高达500摄氏度的REE中测得的XAFS光谱，最高为500摄氏度和高达1 GPA的压力。对均匀三价电荷的影响的系统研究，随着原子数的增加而减小离子半径，可能会在该系列的很大一部分中填充Ree Aquo和Chloro复合物的结构的4F电子壳。该结果将用于测试REE水溶液络合物稳定性的已建立的热力学计算，以及作为水热溶液中REE将来建模的基础。由于化学类似，预计该项目的结果将用于解决放射性废物存储库中actinides的命运和运输问题。该项目包括对同步器设施中学生的科学培训。