Equations of state of iron and nickel to the pressure at the center of the Earth

IF 4.8 1区物理与天体物理 Q1 PHYSICS, MULTIDISCIPLINARY

Matter and Radiation at Extremes Pub Date : 2022-05-01 DOI:10.1063/5.0074340

N. Hirao, Y. Akahama, Y. Ohishi

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引用次数: 6

Abstract

Synchrotron radiation x-ray diffraction investigations of iron (Fe) and nickel (Ni) are conducted at pressures up to 354 and 368 GPa, respectively, and the equations of state (EOSs) at 298 K for the two elements are obtained for data extending to pressures as high as those at the center of the Earth, using the latest Pt-EOS pressure scale. From a least-squares fit to the Vinet equation using the observed pressure–volume data, the isothermal bulk modulus K0 and its pressure derivative [Formula: see text] are estimated to be 159.27(99) GPa and 5.86(4) for hcp-Fe, and 173.5(1.4) GPa and 5.55(5) for Ni. By comparing the present EOSs and extrapolated EOSs reported in the literature for Fe and Ni, the volumes of Fe and Ni at 365 GPa are found to be 2.3% and 1.5% larger than those estimated from extrapolated EOSs in previous studies, respectively. It is concluded that these discrepancies are due to the pressure scale. The present results suggest that the densities of Fe and Ni at a pressure of 365 GPa corresponding to the center of the Earth are 2.3% and 1.5%, respectively, lower than previously thought.

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铁和镍的状态方程与地心压强的关系

在354和368 GPa的压力下，对铁(Fe)和镍(Ni)进行了同步辐射x射线衍射研究，并利用最新的Pt-EOS压力标度，得到了这两种元素在298 K时的状态方程(EOSs)，数据扩展到地球中心的压力。利用观察到的压力-体积数据对Vinet方程进行最小二乘拟合，估计hcp-Fe的等温体积模量K0及其压力导数为159.27(99)GPa和5.86(4)，Ni的等温体积模量K0为173.5(1.4)GPa和5.55(5)。通过比较现有的Fe和Ni的EOSs和文献中报道的外推EOSs，发现在365 GPa处Fe和Ni的体积分别比以往研究中外推EOSs估计的体积大2.3%和1.5%。由此得出结论，这些差异是由压力尺度引起的。目前的结果表明，在365 GPa对应地球中心的压力下，Fe和Ni的密度分别比之前认为的低2.3%和1.5%。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Matter and Radiation at Extremes Physics and Astronomy-Atomic and Molecular Physics, and Optics

CiteScore

8.60

自引率

9.80%

发文量

160

审稿时长

15 weeks

期刊介绍： Matter and Radiation at Extremes (MRE), is committed to the publication of original and impactful research and review papers that address extreme states of matter and radiation, and the associated science and technology that are employed to produce and diagnose these conditions in the laboratory. Drivers, targets and diagnostics are included along with related numerical simulation and computational methods. It aims to provide a peer-reviewed platform for the international physics community and promote worldwide dissemination of the latest and impactful research in related fields.