High-Pressure Crystal Chemistry of Earth Materials

9805282 Prewitt/哈岑/芬格地球内部的动态历史和现状源于地球物质的性质;对地球过程的详细了解从根本上取决于这些物质在高压和高温下的结构表征。地球物理实验室是开发在极端条件下对单晶和粉末样品进行现场衍射研究的技术的先驱。美国国家科学基金会最近的设备赠款支持购买一个新的衍射仪与CCD探测器将使我们能够测量非常小的晶体的全三维衍射图案，确定影响晶体性能的缺陷范围的性质，并在一系列增加/减少压力和/或温度迅速收集数据。 具体的实验将集中在硅酸盐，氧化物和硫化物的结构研究，致密含水镁硅酸盐的氢键模型，多阳离子氧化物中的阳离子排序，以及可以提供有关地球过程和材料信息的各种模拟化合物。我们还将继续为希望进行晶体学实验的外部研究人员提供设施和支持，特别是在高压和高温下。

9805282Prewitt/Hazen/FingerThe dynamic history and present state of the Earth's interior result from properties of earth materials; detailed understanding of earth processes depend fundamentally on structural characterization of these materials at high pressures and temperatures. The Geophysical Laboratory has been a pioneer in developing techniques for in-situ diffraction studies on both single crystal and powder samples under extreme conditions. A recent NSF equipment grant supporting the purchase of a new diffractometer with a CCD detector will enable us to measure full three-dimensional diffraction patterns of very small crystals, determine the nature of a range of defects affecting crystal properties, and to collect data rapidly at a series of increasing/decreasing pressures and/or temperatures. Specific experiments will focus on structure investigations of silicates, oxides, and sulfides, hydrogen bonding models for dense hydrous magnesium silicates, cation ordering in multi-cation oxides, and various analog compounds that can provide information about earth processes and materials. We will also continue to provide facilities and support to outside investigators who want to conduct crystallographic experiments, especially at high pressures and temperatures.