Single-Crystal X-Ray Diffraction of Minerals to Mbar Pressures

矿物单晶 X 射线衍射至毫巴压力

• 批准号: 1213788
• 负责人: Thomas Duffy
• 金额: $ 39.69万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1213788&HistoricalAwards=false
• 关键词: Single; Crystal; Ray; Diffraction; Minerals

The crystal structure is the most fundamental property of a mineral. The structure along with composition determines the mineral?s physical and chemical behavior. Under high-pressure conditions of Earth?s deep interior, minerals often undergo phase transformations to new, denser crystal structures. The purpose of this project is to use advanced experimental techniques to study the evolution of crystal structures under high pressures for some of the most abundant minerals of the Earth?s upper mantle. Pressure will be generated using a diamond anvil cell which is a device in which the sample is squeezed between the tips of small diamonds. The crystal structure is probed with a powerful X-ray beam from a synchrotron radiation facility. Minerals to be studied include the major minerals of Earth?s upper mantle: olivine, pyroxene, and garnet. The work will lead to the discovery of new crystal structures which are relevant for understanding the high-pressure behavior of these important Earth materials. We will use synchrotron-based single-crystal X-ray diffraction techniques to examine the crystal structure and equation of state of mantle minerals to pressures up to 1 Mbar (100 GPa). Compared to more standard powder X-ray diffraction techniques, single-crystal methods have many advantages. Initially, we have collected synchrotron-based single-crystal X-ray diffraction on synthetic olivine, Mg2SiO4, and observed a previously unknown phase transition at 50 GPa. By using small crystals in a nearly isotropic helium pressure-transmitting medium, it is possible to retain single crystals across phase transitions. This opens the opportunity to obtain precise constraints on the lattice parameters, equation of state, and crystal structure of high-pressure phases. We will also work on extending capabilities to simultaneous high P-T conditions using external and laser heating techniques. The application of new single-crystal X-ray techniques has the potential to be a major advance in high-pressure research.

晶体结构是矿物质的最基本特性。结构以及组成决定了矿物质的物理和化学行为。在地球深内部的高压条件下，矿物质经常经历相变，向新的，较密集的晶体结构。该项目的目的是使用先进的实验技术来研究地球上一些最丰富的矿物的高压下晶体结构的演变。将使用钻石砧台产生压力，该钻石芯片电池是在小钻石尖端之间挤压样品的装置。用同步加速器辐射设施的功能强大的X射线梁探测晶体结构。要研究的矿物包括地球上地幔的主要矿物：橄榄石，辉石和石榴石。这项工作将导致发现新的晶体结构，这些结构与理解这些重要的地球材料的高压行为相关。 我们将使用基于同步加速器的单晶X射线衍射技术来检查地幔矿物质状态的晶体结构和方程，以最大为1 MBAR（100 GPA）。与更标准的粉末X射线衍射技术相比，单晶方法具有许多优势。最初，我们在合成橄榄石，MG2SIO4上收集了基于同步加速器的单晶X射线衍射，并观察到50 GPA的先前未知的相变。通过在几乎各向同性的氦气变速培养基中使用小晶体，可以在相变跨相变。这为获得高压阶段的晶格参数，状态方程和晶体结构而获得精确约束的机会。我们还将使用外部和激光加热技术将功能扩展到同时较高的P-T条件。新的单晶X射线技术的应用有可能成为高压研究的重大进步。