High-Pressure Crystal Chemistry of Earth Materials

研究将侧重于被认为存在于地球上地幔和过渡带的矿物，但也将涉及提供重要晶体化学信息的相关阶段的研究。 我们将研究无序对地幔相类质同象状态方程的影响，包括硅酸盐尖晶石、Mg-Fe辉石、Mg-Fe橄榄石和Mg-Fe相B，以及含Fe 3+和Al的高压相，以量化类质同象状态方程和平衡状态方程之间的差异。 我们将继续分析致密的含水硅酸盐，特别是添加Fe 2+，Fe 3+，Al，Ca，Na和K的影响，以探索与地幔矿物学更相关的矿物成分。 结构晶体学正在经历一场革命，这场革命是由引入新的X射线衍射仪与CCD探测器耦合以用于衍射图案的三维记录而引发的。 在NSF和Keck基金会的支持下购买的带有CCD探测器的新型布鲁克衍射仪将使我们能够测量非常小的晶体的全三维衍射图案，确定影响晶体特性的一系列缺陷的性质，并在一系列增加/减少的压力和/或温度下快速收集数据。 地球物理实验室的这种设备和其他设备可供其他机构的研究人员使用，他们希望进行晶体学实验，特别是在高压和高温下进行实验

Prewitt9973018Research will focus on minerals believed to occur in the Earth's upper mantle and transition zone, but will also involve studies of relevant phases that provide important crystal chemical information. We will study the effects of disorder on equations of state of isomorphs of mantle phases, including silicate spinels, Mg-Fe pyroxenes, Mg-Fe olivines, and Mg-Fe phase B, as well as Fe3+ and Al-bearing high-pressure phases, in order to quantify differences between isostructural and equilibrium equations of state. We will continue our analysis of the dense, hydrous silicates, specifically the effect of adding Fe2+, Fe3+, Al, Ca, Na, and K to explore mineral compositions more relevant to mantle mineralogy. Structural crystallography is undergoing a revolution initiated by the introduction of new x-ray diffractometers coupled with CCD detectors for three-dimensional recording of diffraction patterns. A new Bruker diffractometer with a CCD detector purchased with support from NSF and the Keck Foundation, 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 collect data rapidly at a series of increasing/decreasing pressures and/or temperatures. This and other equipment at the Geophysical Laboratory is available to investigators from other institutions who want to conduct crystallographic experiments, especially at high pressures and temperatures