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

硅酸盐和铝硅酸盐材料构成了处于地质作用中心的大部分矿物、岩石和岩浆。特别是对于那些在地球内部高压和高温下发生的过程(因此很难直接观察到)，我们从地质记录中解释过去地球历史上发生的事情，从而预测未来可能发生的事情的能力，取决于对原子级结构如何控制物质行为的基本理解。该研究计划专注于测量固体和熔融矿物及其玻璃等当量物的合成、稍微简化的类似物的结构，以便为密度、粘度、热容和能量等关键性质的更准确建模提供输入。特别是，无序材料的结构不能用其他更传统的方法来研究，可以用核磁共振光谱来研究。核磁共振是唯一能够定量含有某些常见结构无序类型的晶体矿物的中短期结构，以及熔体和熔体快速冷却产生的玻璃的结构。这种方法将是这个项目的主要研究工具。将讨论的结构问题包括温度和压力对周围原子排列和离子之间距离的关键影响，但人们仍然知之甚少，如硅、铝、氧、钠、钙和镁等离子，这些离子是天然矿物和岩浆的主要成分。这些离子的无序度的增加，这是火山过程非常高的温度的主要影响，以及它们在地球内部巨大压力下日益致密的堆积，将被测量。结果将根据其整体物理性质的结构模型进行分析，这些结构模型是预测地质过程所需的。将开发新的结构研究方法，利用核磁共振技术研究含有磁性离子的材料，如铁和稀土元素。这些研究不仅对地质材料，而且对陶瓷和玻璃材料都是重要的，这些材料对许多先进技术至关重要，包括燃料电池、光学数据光纤和计算机屏幕和太阳能电池的基板。这一项目的结果应该会使我们对许多类型的硅酸盐材料的基本了解有显著的改善，并开发出分析这些材料的新方法。

Silicate and aluminosilicate materials make up most of the minerals, rocks, and magmas that are at the center of geological processes. Particularly for those processes that take place at the high pressures and temperatures of the Earth's interior (and thus that are hard to observe directly), our ability to interpret what has happened in past Earth history from the geological record, and thus to predict what might take place in the future (for example, when and how volcanoes erupt), depends on a fundamental understanding of how the atomic-scale structure controls material behavior. This research program focuses on measuring this structure for synthetic, somewhat simplified analogs of solid and molten minerals and their glassy equivalents, to provide input for more accurate modeling of critical properties such as density, viscosity, heat capacity, and energy. In particular, the structures of disordered materials, which cannot be readily addressed by other, more conventional methods, are studied using Nuclear Magnetic Resonance (NMR) spectroscopy.NMR is uniquely capable for quantifying the short- to intermediate-range structures of crystalline minerals that contain certain common types of structural disorder, and of molten materials and the glasses produced by rapid cooling of melts. This method will be the primary research tool in this program. Among the structural questions that will be addressed include the critical, but still poorly known, effects of temperature and pressure on the arrangements of atoms around, and distances between, such ions as silicon, aluminum, oxygen, sodium, calcium and magnesium, which are among the predominant constituents of natural minerals and magmas. The increase of disorder among these ions, which is the primary effect of the very high temperatures of volcanic processes, and their increasingly dense packing at the enormous pressures of the Earth's interior, will be measured. The results will be analyzed in terms of structural models for their bulk physical properties, which in term are needed to predict geological processes. New methods for structural studies, using NMR in materials containing magnetic ions such as iron and rare earth elements, will be developed. These studies will be important not only for geological materials, but also for ceramic and glass materials that are critical to a number of advanced technologies, including fuel cells, optical data fibers and substrates for computer screens and solar cells. Results from this project should lead to significant improvements in our fundamental understanding of many types of silicate materials, as well as to the development of new methods for their analysis.