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| 1 | When water meets iron at Earth's core-mantle boundary显示文摘Hydrous minerals in subducted crust can transport large amounts of water into Earth's deep mantle. Our laboratory experiments revealed the surprising pressure-induced chemistry that, when water meets iron at the core-mantle boundary, they react to form an interlayer with an extremely oxygen-rich form of iron, iron dioxide, together with iron hydride. Hydrogen in the layer will escape upon further heating and rise to the crust, sustaining the water cycle. With water supplied by the subducting slabs meeting the nearly inexhaustible iron source in the core, an oxygen-rich layer would cumulate and thicken, leading to major global consequences in our planet. The seismic signature of the D″ layer may echo the chemical complexity of this layer. Over the course of geological time, the enormous oxygen reservoir accumulating between the mantle and core may have eventually reached a critical eruption point. Very large-scale oxygen eruptions could possibly cause major activities in the mantle convection and leave evidence such as the rifting of supercontinents and the Great Oxidation Event. | Ho-Kwang Mao Qingyang Hu Liuxiang Yang Jin Liu Duck Young Kim Yue Meng Li Zhang Vitali B.Prakapenka Wenge Yang Wendy L.Mao | 2017 | National Science Review2017，4，6： | 14 |
| 2 | FeO_(2)H_(x)在地球下地幔底部的化学组分、状态方程及其地球物理意义显示文摘水(氢)从地表到地球深部的输运、循环过程及其对地震传播速度的影响是当前地球科学研究的热点.近期发现的黄铁矿结构FeO_(2)H_(x)是下地幔中罕见的含水矿物之一.它在下地幔温压条件下的化学组分以及弹性性质将直接影响地球深部的水循环过程以及核幔边界的地震波速.但自从这个新相被发现以来,它在下地幔条件下的稳定性以及化学组分一直存在争议.本研究在下地幔温压条件下对黄铁矿结构FeO_(2)H_(x)进行脱氢反应动力学实验,并对同步辐射X射线衍射数据进行P-V-T状态方程分析.我们认为该矿物以部分脱氢的形式存在于地幔深处,而不是FeO2或FeO2H.本研究还从地震横波与纵波波速降低比率的角度阐明了由黄铁矿FeO_(2)H_(x)和部分熔融导致的不同超低速带之间的差别. | 唐瑞莲 刘锦 Duck Young Kim 毛河光 胡清扬 杨斌 李岩 Chris J.Pickard Richard J.Needs 何宇 刘浩哲 Vitali B.Prakapenka 孟悦 闫进元 | 2021 | Science Bulletin2021，66，19： | 1 |
| 3 | Mineralogy of the deep lower mantle in the presence of H_(2)O显示文摘Understanding the mineralogy of the Earth’s interior is a prerequisite for unravelling the evolution and dynamics of our planet.Here,we conducted high pressure-temperature experiments mimicking the conditions of the deep lower mantle(DLM,1800–2890 km in depth)and observed surprising mineralogical transformations in the presence of water.Ferropericlase,(Mg,Fe)O,which is the most abundant oxide mineral in Earth,reacts with H_(2)O to form a previously unknown(Mg,Fe)O_(2)H_(x)(x≤1)phase.The(Mg,Fe)O_(2)H_(x) has a pyrite structure and it coexists with the dominant silicate phases,bridgmanite and post-perovskite.Depending on Mg content and geotherm temperatures,the transformation may occur at 1800 km for(Mg_(0.6)Fe_(0.4))O or beyond 2300 km for(Mg_(0.7)Fe_(0.3))O.The(Mg,Fe)O_(2)H_(x) is an oxygen excess phase that stores an excessive amount of oxygen beyond the charge balance of maximum cation valences(Mg^(2+),Fe^(3+) and H^(+)).This important phase has a number of far-reaching implications including extreme redox inhomogeneity,deep-oxygen reservoirs in the DLM and an internal source for modulating oxygen in the atmosphere. | Qingyang Hu Jin Liu Jiuhua Chen Bingmin Yan Yue Meng Vitali B.Prakapenka Wendy L.Mao Ho-Kwang Mao | 2021 | National Science Review2021，8，4： | 1 |
| 4 | Crystallography of low Z material at ultrahigh pressure:Case study on solid hydrogen显示文摘Diamond anvil cell techniques have been improved to allow access to the multimegabar ultrahigh-pressure region for exploring novel phenomena in condensedmatter.However,the onlyway to determine crystal structures of materials above 100 GPa,namely,X-ray diffraction(XRD),especially for lowZ materials,remains nontrivial in the ultrahigh-pressure region,even with the availability of brilliant synchrotron X-ray sources.In thiswork,we performa systematic study,choosing hydrogen(the lowest X-ray scatterer)as the subject,to understand how to better perform XRD measurements of low Z materials at multimegabar pressures.The techniques that we have developed have been proved to be effective in measuring the crystal structure of solid hydrogen up to 254GPa at room temperature[C.Ji et al.,Nature 573,558–562(2019)].Wepresent our discoveries and experienceswith regard to several aspects of thiswork,namely,diamond anvil selection,sample configuration for ultrahigh-pressure XRDstudies,XRDdiagnostics for low Z materials,and related issues in data interpretation and pressure calibration.Webelieve that these methods can be readily extended to other low Z materials and can pave the way for studying the crystal structure of hydrogen at higher pressures,eventually testing structural models of metallic hydrogen. | Cheng Ji Bing Li Wenjun Liu Jesse S.Smith Alexander Bjoorling Arnab Majumdar Wei Luo Rajeev Ahuja Jinfu Shu Junyue Wang Stanislav Sinogeikin Yue Meng Vitali B.Prakapenka Eran Greenberg Ruqing Xu Xianrong Huang Yang Ding Alexander Soldatov Wenge Yang Guoyin Shen Wendy L.Mao Ho-Kwang Mao | 2020 | Matter and Radiation at Extremes2020，5，3： | 0 |
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