Measurements of sound velocity and density of core materials by combination of dynamic and static methods

地球的金属核心是地球的引擎，提供能量产生磁场和板块构造的驱动力。核心属性控制引擎的功能.了解地核的物理和化学性质对于了解我们的星球是如何运作的至关重要。岩芯的密度和速度剖面是根据地震观测资料得出的。在同时高压和高温下，核心铁合金的密度和速度的精确测量是导出有意义的核心组成模型所必需的。费英伟博士结合静态和动态实验方法，在较宽的压力-温度范围内研究堆芯材料的密度和声速。研究结果将用于开发一个全面的核心组成模型。这项研究将促进跨学科研究，大大增进对地核及其对地球动力学过程的影响的了解。这些项目将为研究生和博士后提供跨学科研究领域的培训。本项目所发展的高压技术将在先进材料特别是超硬材料的合成中具有普遍的应用，研究的目的是通过静态高压压缩和冲击波实验相结合，获得Fe-S-Si-O系芯材密度和声速的最佳测量值。建议的项目包括（1）用冲击压缩法测量Fe-9wt%O合金和Fe-3wt%S-3wt%Si-3wt%O混合物的密度和声速;（2）用静态和动态压缩法测量Fe-9wt%Si合金的密度和声速。该提案概述了一种新的方法来定义的密度和速度的端元合金的成分接近估计的核心组成的二元系统。对于包括Fe、S、Si和O的多元素堆芯组成，在一套二元系统中获得的数据可以在小范围内插值。将根据多元素成分（Fe-3wt%S-3wt%Si-3wt%O）的新实验测量结果进一步测试插值，并最终缩小与地球物理观测一致的岩心成分范围。

Earth's metallic core is the engine of the planet, providing the energy to generate its magnetic field and the driving force for plate tectonics. The properties the core control the function of the engine. It is fundamentally important to understanding the physical and chemical properties of the core in order to understand how our planet works. The density and velocity profiles of the core have been derived from seismic observations. Accurate measurements of density and velocity of core iron-alloys under simultaneous high pressure and temperature are required to derive meaningful composition models of the core. Dr. Yingwei Fei investigates the density and sound velocity of core materials over a wide pressure-temperature range by combining static and dynamic experimental methods. The results will be used to develop a comprehensive core composition model. The study will promote interdisciplinary research and significantly advance knowledge of the Earth's core and its influence on the dynamics processes of the planet. The projects will provide training in interdisciplinary research areas for graduate students and postdoctoral associates. The high-pressure techniques developed through the project will have general applications for synthesis of advanced materials, particularly super-hard materials.The objective of the research is to obtain the best measurements of the density and sound velocity of core materials in the Fe-S-Si-O system by combination of static high-pressure compression and shockwave experiment. The proposed projects include (1) measurements of density and sound velocity of a Fe-9wt%O alloy and Fe-3wt%S-3wt%Si-3wt%O mixture by shock compression, and (2) additional measurements of density and sound velocity of an Fe-9wt%Si alloy by static and dynamic compressions. The proposal outlines a new approach to define the density and velocity of the end-member alloys whose compositions are close to the estimated core composition in a binary system. The data obtained in a suite of binary systems can be interpolated in a small range for a multi-element core composition that includes Fe, S, Si, and O. The interpolation will be further tested against new experimental measurements on a multi-element composition (Fe-3wt%S-3wt%Si-3wt%O), and ultimately narrow down the core composition range that is consistent with the geophysical observations.