High Pressure Melting of the Earth's Core Material

该提案旨在利用新的同步加速器X射线衍射和吸收方法，对（1）候选堆芯材料的高压熔融行为和（2）堆芯形成液体在高压和高温下的性质进行实验研究。对于拟议的熔化研究，研究人员将使用他们建立的技术，即通过熔体出现漫x射线散射来识别熔化的开始，同时不存在晶体衍射。将使用双面激光加热金刚石对顶砧系统结合区域探测器和同步加速器X射线束对堆芯材料进行研究。与此同时，熔化研究将导致测量的熔体在高压下的辉煌的同步加速器X射线束的漫散射，提供重要的信息熔体的局部结构，并进一步了解相关的宏观性能。利用单色X射线吸收，将确定在高压-温度条件下形成地核的液体的密度，从而得出地球内部深处熔体的压力-体积-温度状态方程。这些测量的成功将提供（1）铁和铁合金的熔化曲线，（2）在高压和室温下无定形铁的结构和密度，（3）接近熔化的结晶铁相的结构和熔化以上熔体的局部结构，和（4）熔体（例如，Fe-FeS）。结合这些结果将为地球的动态，热和化学分化模型提供关键的约束。

EAR-0229987ShenThis proposal is to pursue experimental studies of (1) high pressure melting behavior of candidate core materials, and (2) the properties of core-forming liquids at high pressure and high temperature using new synchrotron x-ray diffraction and absorption methods. For the proposed melting studies, the investigators will use the technique they established of identifying the onset of melting by the appearance of diffuse x-ray scattering from the melt with the simultaneous absence of crystalline diffraction. Research will be conducted on core materials using a double-sided laser heated diamond anvil cell system combined with an area detector and synchrotron x-ray beam. At the same time, the melting studies will lead to measurements of diffuse scattering of melts at high pressures by the brilliant synchrotron x-ray beam, providing important information on the local structure of melts and, further, the understanding of related macroscopic properties. Using monochromatic x-ray absorption, densities of core forming liquids at high pressure-temperature conditions will be determined, resulting in pressure-volume-temperature equations of state for melts in the Earth's deep interior. The success of these measurements will provide (1) melting curves for iron and iron alloys, (2) the structure and density of amorphous iron at high pressures and at room temperature, (3) the structure of crystalline iron phase near melting and the local structure of melts above melting, and (4) densities of melts (e.g., Fe-FeS) at high pressures. Combined these results will provide crucial constraints for dynamic, thermal and chemical differentiation models of the Earth.--