Disorder and Dynamics in Silicate and Aluminosilicate Liquids, Glasses, and Crystals Relevant to Geochemical Processes: Nuclear Magnetic Resonance Studies

该研究计划的重点是硅酸盐矿物、玻璃和岩浆的原子级结构和动力学，这些矿物、玻璃和岩浆是大多数地质过程的中心，从发生在地球表面的过程到地球内部的过程。这项工作的最终目标是更好地从根本上理解并最终更好地预测最终控制自然界中复杂过程的物质性质，其中许多过程对人和社会有巨大影响。在为期两年的赠款期间，重点之一将是高压对硅酸盐熔体结构和性质的影响，硅酸盐熔体代表地球上的岩浆，因此与许多地质过程有关，包括火山的形成和喷发。第二项主要活动将是进一步开发和应用测量地壳和地幔中一些最重要的硅酸盐矿物中微量元素分布的方法，以改进描述它们在自然界中的化学行为的模型，从而提高我们从自然样品中收集地质演化线索的能力。在这个项目中开发的结果和方法应该继续在地球科学之外引起重大兴趣，特别是对于致力于开发和优化用于先进技术的硅酸盐玻璃和陶瓷的研究人员，例如用于数据处理和传输的材料、计算机显示器、用于光伏的基板、燃料电池和许多其他应用。教育是这个项目的核心，因为大部分研究将是博士和本科生通往科学和工程职业道路的培训的一部分。这项研究采取的方法是识别需要中短期结构关键细节并可以通过实验室测量阐明的重要问题，收集关于合成或天然材料的准确数据，并确定结果对关键化学和物理参数的影响。将使用的最重要的实验方法是固态核磁共振光谱，它可以揭示矿物和岩浆中常见的许多成分周围的结构的定量细节，如硅、铝、氧、磷和钠。将合成各种组成的玻璃(代表天然岩浆系统中的高温熔融材料)和晶体材料，并测量它们的结构随组成、温度和压力的变化。一个特别的重点将是继续扩大核磁共振的适用性，传统上用于研究非磁性材料的丰富成分，包括微小甚至微量成分，以及含有大量磁性成分的材料。这些数据在帮助开发更准确的、基于物理的矿物和岩浆性质和行为模型方面尤其重要，这在地球科学中尤其重要，因为许多过程发生在无法直接观测的温度、压力和时间范围内。

The focus of this research program is the atomic-scale structure and dynamics of the silicate minerals, glasses and magmas that are at the center of most geological processes, from those taking place at the Earth's surface to those in the planet's deep interior. The ultimate goal of this work is to provide better fundamental understanding, and eventually better prediction, of the material properties that ultimately control complex processes in nature, many of which have enormous impacts on people and on society. For the two-year grant period, one emphasis will be on the effects of high pressure on the structure and properties of silicate melts that represent magmas in the Earth, and hence are tied to many geological processes including the formation and eruption of volcanoes. A second major activity will be further development and application of methods to measure the distribution of minor elements in some of the most important silicate minerals in the Earth's crust and mantle, in order to improve models that describe their chemical behavior in nature, and thus better our ability to glean clues about geological evolution from natural samples. Results and methods developed in this project should continue to be of major interest outside of the Earth sciences, particularly for researchers working to develop and optimize silicate glasses and ceramics for advanced technologies, such as materials for data processing and transmission, computer displays, substrates for photovoltaics, fuel cells, and many other applications. Education is central to this project, since most of the research will be part of the training of Ph.D. and undergraduate students on their ways to careers in science and engineering.The approach taken in this research is to identify important problems where critical details of short- to intermediate-range structure are needed and can be elucidated by laboratory measurements, collect accurate data on synthetic or natural materials, and determine the consequences of the results for key chemical and physical parameters. The most important experimental approach that will be used is solid-state Nuclear Magnetic Resonance (NMR) spectroscopy, which can reveal quantitative details about the structure around many of the components common in minerals and magmas, such as silicon, aluminum, oxygen, phosphorus, and sodium. A variety of compositions of glasses (representing the high temperature molten materials in natural magma systems) and crystalline materials will be synthesized, and measurements made of how their structures change with composition, temperature and pressure. One particular emphasis will be to continue to extend the applicability of NMR, traditionally used to look at abundant constituents of non-magnetic materials, to minor and even trace components and to materials containing substantial amounts of magnetic components. These data should be particularly important in helping to develop more accurate, physically-based models of mineral and magma properties and behavior, which are especially important in the Earth sciences, as many processes take place in regimes of temperature, pressure, and time that are inaccessible to direct observation.