Effect of Hydrogen on the Properties of Fe alloys in the Earth's Core

氢对地核铁合金性能的影响

基本信息

批准号：
1921298
负责人：
Sang-Heon Shim
金额：
$ 29.9万
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：
2019
资助国家：
美国
起止时间：
2019-08-01 至 2022-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1921298&HistoricalAwards=false
关键词：
Effect Hydrogen Properties Fe alloys

项目摘要

For more than half a century, scientists have known that the Earth's core - the 3500-km large ball of mostly iron at the center of the planet - has a density 5-10% lower than that of pure iron. This is because the core contains light elements, such as Si, O, S, C, and H. While the core cools down forming the solid inner core, light elements segregate preferentially in the liquid outer core. This process powers in part the magnetic field which shields us from the solar wind. Furthermore, knowing the composition of the core is critical to constrain its formation and evolution. Light elements in metallic iron have, thus, been extensively studied at the extreme pressure and temperature conditions of the deep Earth. However, because of experimental limitations, the effect of hydrogen on core materials is still largely unknown. Here, the researchers investigate how hydrogen affect the properties of the core. Taking advantage of recent technical developments, they study the iron-hydrogen system at the high pressure and temperature of Earth's interior. The experiments, carried out at national synchrotron facilities, quantify the melting temperature and density of iron-rich alloys. Theoretical calculations at the atomic level guide the experimental approach and the data analysis. The results improve current models of the core with implications for the understanding of its formation, evolution and present-day magnetic field, with numerous ramifications in Earth Sciences. This two-year project provides support for an early-career female scientist and a graduate student, and training opportunities for undergraduate summer interns in state-of-the art Mineral Physics. It also increases the public awareness of the important role of hydrogen in the Earth through presentations during open-house events at Arizona State University.Here, the team investigates Fe-H, Fe-Ni-H and Fe-Si-H alloys in the laser-heated diamond anvil cell (DAC), where specimens are compressed at the tips of two opposing diamonds and heated by focused laser beams. Target pressures and temperatures are up to 150 GPa (~1.5 million atm) and in excess of 2000 K. Quantifying hydrogen-iron alloys at these conditions in the DAC has been challenging because H2 tends to break the anvils on heating. The team has recently demonstrated that this issue can be overcome by pulsed laser heating. This technique, coupled with an improved X-ray detection system at synchrotron facilities, allows the researchers to quantify in situ the effect of hydrogen on the structure, equation of state, bulk modulus and melting temperatures of iron-rich alloys. Run products are investigated by electron microscopy to study their texture and the partitioning of Si and Ni among the phases in presence. Ab initio calculations guide the experimental approach and the data analysis. The key questions leading the research are: (1) Does hydrogen change the crystal structures of iron metal and alloys in the Earth's core? What is the effect of hydrogen on (2) the equations of state of iron metal and alloys and (3) their melting temperatures at core conditions?This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在半个多世纪的时间里，科学家们知道地球的核心 - 3500公里的大球主要是地球中心的铁 - 密度比纯铁的密度低5-10％。这是因为核心包含光元素，例如Si，O，S，C和H。当核心冷却形成固体内核时，在液体外核中优先隔离光元素。此过程在部分磁场上为我们避免了太阳风。此外，了解核心的组成对于限制其形成和进化至关重要。因此，金属铁中的光元素已在深地球的极端压力和温度条件下进行了广泛的研究。但是，由于实验局限性，氢对核心材料的影响仍然在很大程度上未知。在这里，研究人员研究了氢如何影响核心的性质。他们利用最近的技术发展，在地球内部的高压和温度下研究了铁氢系统。该实验在国家同步加速器设施进行，量化了铁富合金的熔化温度和密度。原子水平的理论计算指导实验方法和数据分析。结果改善了核心的当前模型，对理解其形成，进化和当今磁场的影响具有影响，并在地球科学中产生了许多影响。这个为期两年的项目为早期的女性科学家和研究生提供了支持，并为在最先进的矿物质物理学的本科暑期实习生提供了培训机会。它还通过在亚利桑那州立大学的开放式活动中的演讲来提高公众对氢在地球中的重要作用的认识。目标压力和温度高达150 GPA（约150万个ATM），超过2000K。在DAC中，在这些条件下量化氢铁合金是具有挑战性的，因为H2倾向于在加热时打破砧。该团队最近表明，可以通过脉冲激光加热来克服这个问题。该技术以及在同步器设施上改进的X射线检测系统的结合，使研究人员可以原位量化氢对结构，状态方程，块状模量和富含铁合金的融化温度的影响。通过电子显微镜研究运行产品，以研究其质地和在存在各个相之间的Si和Ni分配。从头算计算指导实验方法和数据分析。引导研究的关键问题是：（1）氢是否会改变地球核心中铁金属和合金的晶体结构？氢对（2）铁金属和合金状态的方程是什么影响，以及（3）它们在核心条件下的熔融温度？该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子优点和更广泛影响的评估来评估值得支持的。

项目成果

期刊论文数量（4）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Effect of nickel on the high-pressure phases in FeH

DOI：
10.1103/physrevb.104.224106
发表时间：
2021-12
期刊：
Physical Review B
影响因子：
3.7
作者：
H. Piet;A. Chizmeshya;Bin Chen;S. Chariton;E. Greenberg;V. Prakapenka;S. Shim
通讯作者：
H. Piet;A. Chizmeshya;Bin Chen;S. Chariton;E. Greenberg;V. Prakapenka;S. Shim

Stable hexagonal ternary alloy phase in Fe-Si-H at 28.6–42.2 GPa and 3000 K

Fe-Si-H 中稳定的六方三元合金相，在 28.6–42.2 GPa 和 3000 K 下

DOI：
10.1103/physrevb.105.104111
发表时间：
2022
期刊：
Physical Review B
影响因子：
3.7
作者：
Fu, Suyu;Chariton, Stella;Prakapenka, Vitali B.;Chizmeshya, Andrew;Shim, Sang-Heon
通讯作者：
Shim, Sang-Heon

Hydrogen solubility in FeSi alloy phases at high pressures and temperatures

DOI：
10.2138/am-2022-8295
发表时间：
2022-12-16
期刊：
AMERICAN MINERALOGIST
影响因子：
3.1
作者：
Fu, Suyu;Chariton, Stella;Shim, Sang-Heon
通讯作者：
Shim, Sang-Heon

Water‐Induced Diamond Formation at Earth's Core‐Mantle Boundary

地核-地幔边界处的水诱发钻石形成

DOI：
10.1029/2022gl098271
发表时间：
2022
期刊：
Geophysical Research Letters
影响因子：
5.2
作者：
Ko, Byeongkwan;Chariton, Stella;Prakapenka, Vitali;Chen, Bin;Garnero, Edward J.;Li, Mingming;Shim, Sang‐Heon
通讯作者：
Shim, Sang‐Heon