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地质作用中心的大部分矿物、岩石和岩浆。特别是对于那些发生在地球内部的高压和高温下的过程（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中发生的事情，从而预测未来可能发生的事情的能力（例如，火山何时以及如何爆发），取决于对原子尺度结构如何控制物质行为的基本理解。该研究计划的重点是测量这种结构的合成，有点简化的固体和熔融矿物及其玻璃等价物的类似物，提供输入的关键属性，如密度，粘度，热容和能量更准确的建模。特别是，无序材料的结构，这不能很容易地解决其他，更传统的方法，使用核磁共振（NMR）光谱学进行研究。NMR是唯一能够量化的短期到中期结构的结晶矿物，含有某些常见类型的结构紊乱，熔融材料和玻璃熔体快速冷却产生的。该方法将是该计划的主要研究工具。 在将要解决的结构问题中，包括关键的，但仍然知之甚少的，温度和压力对周围原子排列的影响，以及硅，铝，氧，钠，钙和镁等离子之间的距离，这些离子是天然矿物和岩浆的主要成分。将测量这些离子之间无序度的增加，这是火山过程的极高温度的主要影响，以及它们在地球内部巨大压力下越来越密集的堆积。结果将被分析的结构模型，其散装物理性质，这在长期需要预测地质过程。 将开发新的结构研究方法，在含有铁和稀土元素等磁性离子的材料中使用NMR。 这些研究不仅对地质材料很重要，而且对陶瓷和玻璃材料也很重要，这些材料对一些先进技术至关重要，包括燃料电池、光学数据纤维和计算机屏幕和太阳能电池的基板。该项目的结果将导致我们对许多类型硅酸盐材料的基本理解的显着改善，以及对其分析的新方法的开发。

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.