Constraints on core composition from nuclear resonant scattering and x-ray diffraction studies on Fe-light-element compounds

Fe 轻元素化合物的核共振散射和 X 射线衍射研究对核心成分的限制

• 批准号: 1023729
• 负责人: Jie Li
• 金额: $ 11.62万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-01-01 至 2011-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1023729&HistoricalAwards=false
• 关键词: Constraints; core; composition; nuclear; resonant

Constraints on core composition from nuclear resonant scattering and x-ray diffraction studies on iron-light-element compoundsThe light element composition of the Earth's core has been a long-standing mystery in the study of the Earth's interior. The presence of light elements was first inferred from the density deficit and velocity excess of the core relative to that of pure iron under corresponding conditions. In order to test competing core composition models, we need accurate knowledge of the effects of various light elements on the density and velocities of iron as a function of pressure and temperature. Previous work has placed sulfur and carbon among the leading candidates for the principal light element in the core, even though density and sound velocity data for iron-sulfur and iron-carbon alloys are limited to room temperature and moderate pressures. The investigators will extend the data coverage into the Mbar regime and up to 1700 K, over the same pressure and temperature range of the existing measurements on pure iron. X-ray diffraction and nuclear resonant scattering - both established synchrotron radiation techniques - will be applied to determine the phase stability, equation-of-state, and partial phonon density-of-state of iron-rich compounds containing amounts of sulfur and carbon that are within the estimated range for the Earth's core. The new data will permit the team to explore the effects of sulfur and carbon on the density and sound velocities of iron in a previously uncharted pressure-temperature sector. They will be able to conduct stringent tests of candidate models describing sulfur-bearing or carbon-bearing core scenarios. This research will provide fundamental new knowledge about the properties of iron-rich alloys at high pressures and temperatures and the nature of planetary cores.

核共振散射和X射线衍射研究对铁灯元素化合物的核心组成的限制在地球内部研究中一直是一个长期的谜团。首先是从核心的密度不足和速度过高相对于纯铁在相应条件下的密度不足和速度过高推断出的光元素的存在。 为了测试竞争的核心组成模型，我们需要准确了解各种光元素对铁的密度和速度的影响，这是压力和温度的函数。以前的工作使核心主要光元素的主要候选者中的硫和碳置于核心中的主要光元素，尽管铁硫和铁碳合金的密度和声速数据仅限于室温和中等压力。研究人员将在纯铁上现有测量的相同压力和温度范围内将数据覆盖范围扩展到MBAR状态，并最高为1700 K。 X射线衍射和核共振散射（两者都已建立的同步辐射技术）将应用于确定富含铁的化合物的相位稳定性，状态方程和部分声子密度，其中含有大量的硫和碳，这些硫和碳在地球核心的估计范围内。新数据将使团队能够探索硫和碳对以前未知的压力温度部门中铁的密度和声速的影响。他们将能够对描述含硫或碳核心方案的候选模型进行严格的测试。这项研究将提供有关高压和温度以及行星岩心质的铁富合金特性的基本新知识。