CSEDI Collaborative Research: Electrical and Thermal Transport in Iron and Iron Alloys at Core Conditions and its Effects on the Geodynamo and Thermal Earth History

CSEDI 合作研究：核心条件下铁和铁合金的电和热传输及其对地球发电机和热地球历史的影响

• 批准号: 1901801
• 负责人: Jung-Fu Lin
• 金额: $ 26.98万
• 依托单位: University of Texas at Austin
• 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: 2019-04-15 至 2024-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1901801&HistoricalAwards=false
• 关键词: CSEDI; Collaborative; Research; Electrical; Thermal

The magnetic field of the Earth and other planetary bodies is generated by the turbulent flow of conducting fluids in their deep interiors. In the Earth, it is generated by the outer core, made of liquid iron with some nickel and light elements. Earth's magnetic field is important, as life may not exist without its shielding of the solar wind. Moreover, the heat rising from the core fuels mantle thermal convection, at the origin of plate tectonics and associated hazards. Understanding Earth's magnetic field and core heat flow requires detailed knowledge of iron-rich material properties at the extreme pressures and temperatures of the core. Yet, existing experimental data and theoretical calculations are inconsistent. Here, the multidisciplinary team investigates the thermal and electrical conductivities of iron alloys at extreme conditions. They use a combination of state-of-the-art experiments, theory, and modeling at both the atomic scale and the scale of the core. Expected results should reconcile experiments and modeling of the core's heat transport and magnetic field evolution. This project supports one graduate student and two postdoctoral associates in the field of Mineral Physics. It has strong implications for Geomagnetism, Geodynamics and Seismology, and broad impacts in Materials Science.High-pressure and temperature experiments are carried out in the laser-heated diamond anvil cell. Extreme pressures and temperatures are generated at the tips of two opposing diamonds, where the iron sample is placed. The team will measure and compute electrical and thermal conductivities at conditions relevant to the core. This allows them to test the applicability of the Wiedemann-Franz law at these conditions. This empirical law relates thermal and electrical conductivities in metals. Here, the electrical conductivity is measured using a four-probe electrical connection brought outside from the cell. Thermal conductivity is measured by optical spectroradiometry in conjunction with pulsed-laser heating and modeling. Similar conditions are simulated using first-principles quantum mechanics to compute the electrical and thermal conductivity in liquid and solid iron, and compare them with experimental observations. These calculations are difficult because they involve the scattering of electrons off each other and off the moving atoms in the fluid or solid. Experimental and theoretical results are used in geophysical models of core cooling and magnetic field generation. This will allow to better constrain the history of Earth's magnetic field and the heat flow at the core-mantle boundary.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.

地球和其他行星体的磁场是由深层内部导电的湍流产生的。在地球上，它是由外部芯产生的，由液态铁制成，并带有一些镍和光元素。地球的磁场很重要，因为如果没有屏蔽太阳风，生命可能就不存在。此外，核心燃料的热对流的热量在板块构造和相关危险的起源处上升。了解地球的磁场和核心热流需要详细了解核心极端压力和温度下的富铁材料特性。但是，现有的实验数据和理论计算是不一致的。在这里，多学科团队在极端条件下研究了铁合金的热电导率和电导率。他们结合了最先进的实验，理论和在原子量表和核心尺度上进行建模。预期结果应调和核心热传输和磁场演化的实验和建模。该项目支持一名研究生和两个矿物质领域的博士后同伴。它对地磁，地球动力学和地震学具有很大的影响，以及对材料科学的广泛影响。在激光加热的钻石砧室中进行了高压和温度实验。 在放置铁样品的两个相对钻石的尖端上产生了极端压力和温度。该团队将在与核心相关的条件下测量和计算电导率和热导率。这使他们可以在这些条件下测试Wiedemann-Franz法律的适用性。这种经验定律将金属的热电导率和电导率涉及。在这里，使用从单元外带来的四探针电连接来测量电导率。通过光谱测量法与脉冲激光加热和建模结合使用光谱测量。使用第一原理量子力学模拟了类似的条件，以计算液体和固体铁中的电导率和热导率，并将其与实验观察结果进行比较。这些计算很困难，因为它们涉及电子散射，并在流体或固体中脱离运动原子。实验和理论结果用于核心冷却和磁场产生的地球物理模型。 这将使该奖项能够更好地限制地球磁场的历史和核心壳边界处的热流。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的评估标准来通过评估来支持的。

项目成果

Collective motion in hcp-Fe at Earth’s inner core conditions

• DOI: 10.1073/pnas.2309952120
• 发表时间: 2023-10
• 期刊: Proceedings of the National Academy of Sciences of the United States of America
• 影响因子: 11.1
• 作者: Youjun Zhang;Yong Wang;Yuqian Huang;Junjie Wang;Zhixin Liang;Long Hao;Zhipeng Gao;Jun Li;Qiang Wu;Hong Zhang;Yun Liu;Jian Sun;Jung-Fu Lin

Equation of State Measurements on Iron Near the Melting Curve at Planetary Core Conditions by Shock and Ramp Compressions

• DOI: 10.1029/2020jb020008
• 发表时间: 2021-02
• 期刊: Journal of Geophysical Research: Solid Earth
• 作者: S. Grant;Tommy Ao;C. Seagle;A. Porwitzky;J. Davis;Kyle R. Cochrane;Daniel H. Dolan;Jung-Fu Lin;T. Ditmire;Aaron C. Bernstein

Molten iron in Earth-like exoplanet cores

类地系外行星核心中的熔铁

• DOI: 10.1126/science.abn2051
• 发表时间: 2022
• 期刊: Science
• 影响因子: 56.9
• 作者: Zhang, Youjun;Lin, Jung-Fu
• 通讯作者: Lin, Jung-Fu

Reconciliation of Experiments and Theory on Transport Properties of Iron and the Geodynamo

铁输运特性与地发电机的实验与理论的协调

• DOI: 10.1103/physrevlett.125.078501
• 发表时间: 2020-08-13
• 期刊: PHYSICAL REVIEW LETTERS
• 影响因子: 8.6
• 作者: Zhang, Youjun;Hou, Mingqiang;Lin, Jung-Fu
• 通讯作者: Lin, Jung-Fu

Transport properties of Fe-Ni-Si alloys at Earth's core conditions: Insight into the viability of thermal and compositional convection

• DOI: 10.1016/j.epsl.2020.116614
• 发表时间: 2021
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: Youjun Zhang;M. Hou;Peter Edward Driscoll;N. Salke;Jin Liu;E. Greenberg;V. Prakapenka;Jung‐Fu Lin