Crystal Structural Analysis of New Phases Formed Under Mantle Conditions in Geological Systems

地质系统中地幔条件下形成的新相的晶体结构分析

• 批准号: 0074089
• 负责人: Kurt Leinenweber
• 金额: $ 6.92万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-06-15 至 2003-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0074089&HistoricalAwards=false
• 关键词: Crystal; Structural; Analysis; New; Phases

LeinenweberEAR-0074089High pressure silicate and titanate crystals are being grown using a multianvil apparatus at pressures from 5 GPa to over 20 GPa, and the structures solved using single-crystal x-ray diffraction, in order to understand more about how the atomic structures of rock-forming minerals change during high pressure phase transitions in the Earth's mantle. The targets in this study include magnesium- and calcium-bearing silicates and titanates with H2O and/or fluorine, and so the basic idea is to extend the understanding of minerals under pressure to include more diverse compositions than are currently understood. The study takes advantage of the multianvil facility at Arizona State University for high pressure synthesis, along with a new single-crystal x-ray diffractometer installed in the Chemistry Department. New methods of crystal growth, in particular the growth of large crystals using unusual high pressure liquids such as molten Ca(OH)2 as a growth medium, are being used to produce the samples. Also, in some cases the samples must be recovered in liquid nitrogen (-196 degrees Centigrade), because they will not survive decompression at room temperature. Materials such as CaSiO3 perovskite behave this way, and this material in particular will be targeted for this type of treatment. The crystals will be transferred over to the diffractometer cold, and the diffractometer has a liquid nitrogen attachment so the sample stays cold while it is studied. The knowledge of the existence of these high pressure silicates and their atomic structures will be used to help understand what happens to elements in the Earth's mantle; what kind of structures they can occur in, and how they might be transported during dynamic processes.

LeinenweberEAR-0074089高压硅酸盐和钛酸盐晶体是在5 Gpa到20 Gpa以上的压力下使用多顶锤设备生长的，并使用单晶X射线衍射进行了结构解析，以便更多地了解在地球地幔高压相变期间造岩矿物的原子结构是如何变化的。这项研究的目标包括含镁和钙的硅酸盐和含水和/或氟的钛酸盐，因此基本思想是扩大对压力下矿物的理解，包括比目前了解的更多不同的成分。这项研究利用亚利桑那州立大学的多顶锤设备进行高压合成，并在化学系安装了一种新的单晶X射线衍射仪。新的晶体生长方法，特别是使用不寻常的高压液体，如熔融的Ca(OH)2作为生长介质，生长大晶体的方法正在被用来生产样品。此外，在某些情况下，样品必须在液氮(-196摄氏度)中回收，因为它们不能在室温下减压。像CaSiO_3钙钛矿这样的材料就是这样的，这种材料将特别成为这种类型处理的目标。晶体将被转移到冷的衍射仪，而衍射仪有一个液氮附件，因此样品在研究过程中保持冷。这些高压硅酸盐的存在及其原子结构的知识将被用来帮助理解地幔中的元素发生了什么；它们可以出现在什么样的结构中，以及它们在动态过程中可能如何运输。