Melting of compressed iron-alloys by monitoring atomic dynamics

通过监测原子动力学熔化压缩铁合金

• 批准号: 1727020
• 负责人: Jennifer Jackson
• 金额: $ 32.4万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-15 至 2022-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1727020&HistoricalAwards=false
• 关键词: Melting; compressed; iron; alloys; monitoring

The Earth's core is 16% of the planet by volume. It is composed primarily of iron, but includes a quantity of lighter elements whose presence, but not identity, is inferred from geophysical measurements. The core consists of a solid inner section surrounded by a convecting, liquid outer layer. It creates Earth's magnetic field, protecting the planet from space weather events such as solar flares, and provides the heat for plate tectonics as the liquid core freezes. The core begins approximately 2900 km below the Earth's surface, making it difficult to determine its exact composition and temperature profile, so scientists rely on laboratory experiments and an evolving model to infer core characteristics. Under this NSF award, the PI is developing a new application of the Mössbauer effect utilizing synchrotron X-radiation to populate data points on the melting curve of an iron-nickel alloy, a primary component of Earth's core. This project will provide support and training for students at the undergraduate and graduate level, who will be trained in experimental research utilizing national synchtrotron radiation facilities.Laser heated diamond anvil cells, time-resolved synchrotron Mössbauer spectroscopy, x-ray diffraction and a recently developed fast temperature readout spectrometer are used to carry out these measurements. X-ray photons at one of iron's Mössbauer resonant energies are focused on the sample in a laser heated diamond anvil cell, and when melting occurs, the characteristic Mössbauer signal abruptly decreases. Thus, time-resolved Mössbauer spectroscopy provides an excellent diagnostic for the first melt formed in the sample chamber. These outcomes will represent a significant step towards understanding the melting of iron-rich alloys at conditions of terrestrial-type planetary cores. This is in addition to applying a new method that measures the atomic dynamics to the effort of determining melting at high-pressures. The proposed research agenda offers a unique synergy and training ground for the involved students to apply state-of-the-art experimental techniques at multiple facilities, including advanced radiation sources at national facilities, to scientific problems in the area of high-pressure melting investigations of Earth materials, an active area of research.

地核占地球体积的 16%，主要由铁组成，但也包含一定量的较轻元素​​，这些元素的存在（但不是同一性）是通过地球物理测量推断出的。它形成地球磁场，保护地球免受太阳耀斑等太空天气事件的影响，并在液体核心开始冻结时为板块构造提供热量。地球表面，使得很难确定其确切的成分和温度分布，因此科学家依靠实验室实验和不断发展的模型来推断地核特征。根据这项 NSF 奖项，PI 正在利用同步加速器 X- 开发穆斯堡尔效应的新应用。该项目将为本科生和研究生提供支持和培训，他们将接受利用辐射进行实验研究的培训。国家同步加速器辐射设施。激光加热金刚石砧室、时间分辨同步加速器穆斯堡尔光谱、X射线衍射和最近开发的快速温度读出光谱仪用于以铁的穆斯堡尔共振能量之一进行这些测量。聚焦在激光加热金刚石砧池中的样品上，当发生熔化时，特征穆斯堡尔信号突然减弱。因此，时间分辨穆斯堡尔光谱为样品室中形成的首次熔体提供了良好的诊断，这些结果将代表着在了解地球型行星核心条件下富铁合金的熔化过程中迈出的重要一步。应用一种测量原子动力学的新方法来确定高压下的熔化所提出的研究议程为参与应用的学生提供了独特的协同作用和培训基础。在多个设施（包括国家设施的先进辐射源）中使用最先进的实验技术，解决地球材料高压熔化研究领域的科学问题，这是一个活跃的研究领域。

项目成果

High pressure thermoelasticity and sound velocities of Fe-Ni-Si alloys

Fe-Ni-Si合金的高压热弹性和声速

• DOI: 10.1016/j.pepi.2019.05.011
• 发表时间: 2019-08-07
• 期刊: Physics of the Earth and Planetary Interiors
• 影响因子: 2.3
• 作者: R. Morrison;J. Jackson;W. Sturhahn;Jiyong Zhao;T. Toellner
• 通讯作者: T. Toellner

Equations of State and Anisotropy of Fe‐Ni‐Si Alloys

Fe-Ni-Si合金的状态方程和各向异性

• DOI: 10.1029/2017jb015343
• 发表时间: 2018-06
• 期刊: Journal of Geophysical Research: Solid Earth
• 作者: Morrison, Rachel A.;Jackson, Jennifer M.;Sturhahn, Wolfgang;Zhang, Dongzhou;Greenberg, Eran
• 通讯作者: Greenberg, Eran

Melting and phase relations of Fe-Ni-Si determined by a multi-technique approach

多技术方法测定 Fe-Ni-Si 的熔化和相关系

• DOI: 10.1016/j.epsl.2021.117358
• 发表时间: 2022-04
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: Dobrosavljevic, Vasilije V.;Zhang, Dongzhou;Sturhahn, Wolfgang;Zhao, Jiyong;Toellner, Thomas S.;Chariton, Stella;Prakapenka, Vitali B.;Pardo, Olivia S.;Jackson, Jennifer M.
• 通讯作者: Jackson, Jennifer M.