X-ray Scattering Experiments on Melting and Equations of State of Candidate Compositions of Earth's Core

地核候选成分熔化的X射线散射实验和状态方程

• 批准号: 1427123
• 负责人: Andrew Campbell
• 金额: $ 38万
• 依托单位: University of Chicago
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-15 至 2018-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1427123&HistoricalAwards=false
• 关键词: ray; Scattering; Experiments; Melting; Equations

The results expected from this project will improve our understanding of the temperature and chemical composition of Earth's core. Earth's core is known to be an iron-rich alloy, mostly molten but with a solid inner core. In addition to iron it contains approximately 5% nickel and approximately 10% of a lighter element, whose identity is uncertain but is likely a combination of oxygen, sulfur, silicon, and/or carbon. A more precise understanding of the composition of Earth's core is important to constrain our understanding of the chemical and physical processes that led to the formation of our planet. Furthermore, the temperature structure in the deep Earth is poorly known, and can be better constrained with more accurate measurements of the melting temperatures of candidate core compositions under the relevant pressure, temperature conditions. Accordingly, the aims of this project are to measure the melting temperatures and densities of iron alloys under the extreme pressure, temperature conditions that exist in Earth's core. The experimental results will be applied to place more accurate bounds on the temperatures and composition of Earth's core.The project has several specific experimental research goals. These include (1) Establishing melting temperatures in the ternary systems Fe-O-S, Fe-Si-S, and Fe-Si-O up to pressures appropriate in Earth's outer core; (2) Analyzing X-ray diffuse scattering measured from melts in these ternary systems to place constraints on their liquid densities; (3) Extending the equations of state of Fe3C and Fe3S to higher pressure and temperature conditions, to permit more precise thermodynamic treatment of S,C-bearing Fe-alloys, and more precise density-based constraints on the maximum content of S and C allowable in Earth's core. To achieve these goals the PI will perform synchrotron-based X-ray scattering experiments on samples that are pressurized and laser heated in a diamond anvil cell, reaching the extreme pressure, temperature conditions (in excess of 140 GPa and 4000 K) that exist in Earth's core. In parallel with these investigations, he will continue to develop experimental methods to improve the ability of his lab and others to investigate the material properties of Earth's core. These research projects will also serve as a platform on which the PI's training of graduate and undergraduate students will be trained in laboratory research and scientific pursuit.

该项目的预期结果将提高我们对地球核心温度和化学成分的理解。众所周知，地球的核心是铁富合金，主要是熔融，但具有固体内核。除铁外，它还含有大约5％的镍和约10％的较轻元素​​，其身份不确定，但可能是氧，硫，硅和/或碳的组合。对地球核心组成的更精确的理解对于限制我们对导致地球形成的化学和物理过程的理解很重要。此外，深地球的温度结构是鲜为人知的，可以通过更准确的测量在相关压力，温度条件下更好地测量候选核心组成的熔化温度。因此，该项目的目的是测量在地球核心中存在的极高压力，温度条件下铁合金的熔融温度和密度。实验结果将应用于在地球核心的温度和组成上更加准确的界限。该项目具有多个特定的实验研究目标。其中包括（1）在三元系统Fe-O-S，Fe-Si-S和Fe-Si-O中建立熔融温度，以达到地球外部核心适当的压力； （2）分析从这些三元系统中熔体测得的X射线扩散散射，以对其液态密度放置约束； （3）将Fe3c和Fe3的状态方程扩展到更高的压力和温度条件，以允许对S，C含Fe-Alyoys的更精确的热力学处理，以及对地球核心中S和C的最大含量的基于更精确的密度约束。为了实现这些目标，PI将对在钻石砧室中加压并加热的样品对基于同步加速器的X射线散射实验，达到极端压力，温度条件（超过140 GPA和4000 K），而地球核心中存在。与这些研究同时，他将继续开发实验方法，以提高其实验室和其他人研究地球核心物质特性的能力。这些研究项目还将作为一个平台，PI对研究生和本科生的培训将接受实验室研究和科学追求的培训。