Electronic Spin Transition of Iron in the Earth's Lower Mantle

地球下地幔中铁的电子自旋跃迁

• 批准号: 0838221
• 负责人: Jung-Fu Lin
• 金额: $ 30万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0838221&HistoricalAwards=false
• 关键词: Electronic; Spin; Transition; Iron; Earth

Seismic waves traveling through the Earth have provided fundamental knowledge of the Earth?s interior. Mineralogical models of the planet indicate that the lower mantle, the most voluminous layer extending from 670 km to 2900 km in depth (~23 GPa to 140 GPa in pressures and approximately 1800 K to 4000 K in temperatures), consists of approximately 30% ferropericlase [(Mg,Fe)O] and 70% silicate perovskite containing minor amounts of aluminum [Al-(Mg,Fe,)SiO3], in addition to a small amount of calcium silicate perovskite (CaSiO3). Silicate perovskite transforms to a post-perovskite structure just above the core-mantle boundary. The properties of the Earth?s lower mantle are thus thought to be governed by this mineral assemblage, in which iron is the most abundant transition metal that can undergo electronic spin and valence transitions under high pressures and temperatures, and may alter the properties of these minerals.This proposal aims to study the nature of electronic spin transitions of iron in the lower mantle mineral assemblage, including ferropericlase, perovskite, and post-perovskite, with emphasis on associated properties influencing the chemical and physical dynamics of the lower mantle. Using a combination of laboratory and synchrotron-based facilities with high pressure-temperature diamond anvil cells, these experiments will probe physical properties most relevant to modeling the structure and geodynamics of the lower mantle including thermal equations of state, deformation and strength, sound velocities, and transport properties. With an emphasis on the spin transitions, these studies aim broadly to understand properties of the lower-mantle minerals at various pressure-temperature-composition conditions, providing direct mineral physics results for input into understanding the state of the lower-mantle at a time when tomographic images and geophysical models of the lower mantle are rapidly advancing. The expected results are fundamental to geophysics and geodynamics of the Earth and will provide new aspects of information to modeling satisfactorily the seismic, mineralogical, and geodynamic behavior of the lower mantle. The project will also develop new high-pressure techniques that will benefit researchers and students in the broad deep-mantle communities.

穿越地球的地震波提供了地球内部的基本知识。该行星的矿物学模型表明，最大的层从670 km延伸至2900 km深度（压力中〜23 GPA至140 GPA，温度下约1800 K至4000 K），约为30％的Ferropericlase除了少量的硅酸盐钙钛矿（casio3）外，[（mg，fe）O]和70％硅酸盐钙钛矿除外，含有少量铝[al-（mg，fe，sio3]）。硅酸盐钙钛矿转变为核心壳边界上方的玻璃后孔结构。因此，人们认为地球的特性受到这种矿物组合的控制，其中铁是最丰富的过渡金属，可以在高压和温度下进行电子自旋和价转换，并且可能会改变这些特性，并可能改变这些金属该提案旨在研究下地幔矿物质组合中铁的电子自旋跃迁的性质，包括纤维化酶，钙钛矿和植物后的矿物质，重点是影响下层底层化学和物理动力学的相关特性。这些实验结合了实验室和基于同步加速器的设施与高压温度的钻石砧细胞，这些实验将探测与模拟下层的结构和地球动力学最相关的物理特性，包括状态，变形和强度，声速，声速，声速，声速，声速和运输特性。这些研究强调自旋过渡，旨在广泛地了解在各种压力温度组成条件下较低壳矿物的特性，从下地幔的层析成像图像和地球物理模型正在迅速发展。预期的结果是地球的地球物理学和地球动力学的基础，并将提供信息的新方面，以令人满意地建模下地幔的地震，矿物学和地球动力学行为。该项目还将开发新的高压技术，这些技术将使广泛的深层社区中的研究人员和学生受益。