FeH_(x)的稳定性以及氢在地球核-幔边界的传输  

The stability of FeH_(x)and hydrogen transport at Earth's core mantle boundary

作　　者：何宇 Duck Young Kim Viktor V.Struzhkin Zachary M.Geballe Vitali Prakapenka 毛河光 Yu He;Duck Young Kim;Viktor V.Struzhkin;Zachary M.Geballe;Vitali Prakapenka;Ho-kwang Mao(Key Laboratory of High-Temperature and High-Pressure Study of the Earth’s Interior,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,China;Center for High Pressure Science and Technology Advanced Research,Shanghai 201203,China;Division of Advanced Nuclear Engineering,Pohang University of Science and Technology,Pohang 37673,Republic of Korea;Geophysical Laboratory,Carnegie Institution,Washington DC 20015,USA;Center for Advanced Radiation Sources,University of Chicago,Chicago IL 60637,USA)

机构地区：[1]Key Laboratory of High-Temperature and High-Pressure Study of the Earth’s Interior,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,China [2]Center for High Pressure Science and Technology Advanced Research,Shanghai 201203,China [3]Division of Advanced Nuclear Engineering,Pohang University of Science and Technology,Pohang 37673,Republic of Korea [4]Geophysical Laboratory,Carnegie Institution,Washington DC 20015,USA [5]Center for Advanced Radiation Sources,University of Chicago,Chicago IL 60637,USA

出　　处：《Science Bulletin》2023年第14期1567-1573,M0004,共8页科学通报（英文版）

基　　金：supported by the National Natural Science Foundation of China(42074104,11774015,and U1930401);Youth Interdisciplinary Team of Chinese Academy of Sciences(JCTD2022-16);Youth Innovation Promotion Association of Chinese Academy of Sciences(2020394);Guizhou Provincial 2020 Science and Technology Subsidies(GZ2020SIG);the support from the National Research Foundation of Korea(NRF-2020R1A2C1005236);supported by the National Science Foundation-Earth Sciences(EAR-1634415)。

摘　　要：地球内部水和铁的反应可以生成铁-氢合金.研究铁-氢合金可以增进对地球内部氢传输的认知.我们通过高压实验和第一性原理计算的方法,对高温高压下具有面心立方结构(fcc)FeH_(x)(x≤1)的相稳定性、密度、氢的输运性质和熔点进行了系统研究,证实了FeH_(x)在165 GPa时的稳定性.通过高温的分子动力学模拟,发现FeH_(x)在下地幔温压下转变为超离子态.在超离子态FeH_(x)中,氢离子快速扩散表现出类似流体的性质,扩散系数高达3.710^(-4)cm~2s^(-1).与超离子态冰类似,氢离子的快速扩散可以导致体系的熵增,使其的熔化温度增加.FeH_(x)可以将氢从地幔传输到外地核,使得外核成为H的潜在储库,并在核-幔边界上方留下了富氧的块状结构.Iron hydride in Earth's interior can be formed by the reaction between hydrous minerals(water)and iron.Studying iron hydride improves our understanding of hydrogen transportation in Earth's interior.Our high-pressure experiments found that face-centered cubic(fcc)FeH_x(x≤1)is stable up to 165 GPa,and our ab initio molecular dynamics simulations predicted that fcc FeH_(x)transforms to a superionic state under lower mantle conditions.In the superionic state,H-ions in fcc FeH become highly diffusive-like fluids with a high diffusion coefficient of~3.7×10~(-4)cm~2 s~(-1),which is comparable to that in the liquid Fe-H phase.The densities and melting temperatures of fcc FeH_(x)were systematically calculated.Similar to superionic ice,the extra entropy of diffusive H-ions increases the melting temperature of fcc FeH.The wide stability field of fcc FeH enables hydrogen transport into the outer core to create a potential hydrogen reservoir in Earth's interior,leaving oxygen-rich patches(ORP)above the core mantle boundary(CMB).

关 键 词：离子态 第一性原理计算 氢离子 相稳定性 地球内部 熔化温度 高压实验 分子动力学模拟 

分 类 号：P542[天文地球—构造地质学] O613.2[天文地球—地质学]