Melting of compressed iron-alloys using a multi-technique approach

使用多种技术方法熔化压缩铁合金

• 批准号: 2212068
• 负责人: Jennifer Jackson
• 金额: $ 38.9万
• 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: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2212068&HistoricalAwards=false
• 关键词: Melting; compressed; iron; alloys; using

Accurate estimates of the temperature range of Earth’s core are essential for understanding major processes like inner core crystallization, magnetic field generation, and heat flow through the core-mantle boundary, as well as the compositions, phase relations, and dynamics of complex multiscale structures in Earth's lowermost mantle. With its location several thousand kilometers below the Earth's surface, determining its exact composition and temperature profile is a challenge. Laboratory experiments, theory, seismic observations are used to infer core characteristics. Seismological and cosmochemical observations indicate that Earth's core consists of a solid inner region surrounded by a liquid outer core, with iron as the main compositional constituent, but a lighter element is needed in combination with iron to explain the density of the core. This project explores the possibility of nickel or silicon as elements of the the core. Outreach activities and benefits to society include the strong engagement of the PI and involved graduate student in Caltech’s Seismological Laboratory’s Earthquake Fellows Program, a partnership with the Dr. Lucy Jones Center for Science and Society. This program is part of a multi-pronged program with the goal of bringing geophysical science to the wider community in Southern California, while creating an opportunity for communities that are historically marginalized and underrepresented in the sciences to develop STEM skills.Many studies have suggested silicon as a candidate light element for the core of the Earth to explain the density deficit if one assumes a core that is purely made of iron. However, the effect of silicon on the melting temperatures of core materials and the thermal profile of the core is poorly understood due to disagreements among melt detection techniques, uncertainties in sample pressure evolution during heating, and sparsity of studies investigating the combined effects of nickel and silicon on the phase diagram of iron. This project takes the multi-technique approach developed by this team of researchers for detecting melting of iron-alloys at high pressures that combines results from two independent in-situ probes: synchrotron Mössbauer spectroscopy, sensitive to dynamics of solid-bound iron, and x-ray diffraction, sensitive to long-range crystalline order. They will apply the new multi-technique method of melt detection to Fe, Fe-Ni, and Fe-Ni-Si at pressures equivalent to those in Earth’s core, placing tighter constraints on the temperature of Earth’s core.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.

准确估计地核温度范围对于了解内核结晶、磁场产生和穿过地核-地幔边界的热流等主要过程，以及地核中复杂多尺度结构的成分、相关系和动力学至关重要。地球最底层的地幔位于地球表面以下数千公里处，利用实验室实验、理论和地震观测来推断地核特征是一项挑战。表明地核由被液态外核包围的固体内部区域组成，以铁为主要成分，但需要与铁结合的较轻元素​​来解释地核的密度。该项目探讨了镍的可能性。或硅作为核心元素的推广活动和对社会的好处包括 PI 和参与加州理工学院地震实验室地震研究员计划的研究生的积极参与，该计划是与露西·琼斯博士科学与社会中心的合作伙伴关系。是多管齐下计划的一部分，其目标是将地球物理科学带入南加州更广泛的社区，同时为历史悠久且在科学领域代表性不足的社区创造机会发展 STEM 技能。许多研究表明硅作为一种如果假设地核纯粹由铁制成，则硅是地核的候选轻元素，可以解释密度不足。然而，由于硅对地核材料熔化温度和地核热分布的影响知之甚少。熔化检测之间的分歧该项目采用了该研究团队开发的多技术方法来检测铁合金的熔化。在高压下结合了两个独立原位探针的结果：同步加速器穆斯堡尔光谱（对固体结合铁的动力学敏感）和 X 射线衍射（对长程结晶敏感）他们将在相当于地核压力下对铁、铁-镍和铁-镍-硅应用新型多技术熔融检测方法，对地核温度施加更严格的限制。该奖项是美国国家科学基金会的法定奖项。使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Measurements of the Lamb-Mössbauer factor at simultaneous high-pressure-temperature conditions and estimates of the equilibrium isotopic fractionation of iron

同时高压-温度条件下兰姆-穆斯堡尔因子的测量和铁平衡同位素分馏的估计

• DOI: 10.2138/am-2021-7884
• 发表时间: 2022-03
• 期刊: American Mineralogist
• 影响因子: 3.1
• 作者: Zhang, Dongzhou;Jackson, Jennifer M.;Sturhahn, Wolfgang;Zhao, Jiyong;Alp, E. Ercan;Hu, Michael Y.
• 通讯作者: Hu, Michael Y.