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Mineralogy of the deep lower mantle in the presence of H2O

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National Science Review 2021年第4期8卷 21-28页

作者： Qingyang Hu Jin liu Jiuhua Chen Bingmin Yan Yue Meng Vitali B.Prakapenka wendy l.mao Ho-Kwang mao Center for High Pressure Science and Technology Advanced Research(HPSTAR) Department of Geological Sciences Stanford University Center for Study of Matter under Extreme Conditions Department of Mechanical and Materials Engineering Florida International University High Pressure Collaborative Access Team(HPCAT) X-ray Science Division Argonne National Laboratory Center for Advanced Radiation Sources University of Chicago

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.

关键词： lower mantle water-mantle interaction ferropericlase high pressure mantle mineralogy

Geomimicry—liberating high-pressure research by encapsulation

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Matter and Radiation at Extremes 2022年第6期7卷 79-81页

作者： Ho-Kwang mao wendy l.mao Center for High Pressure Science and Technology Advanced Research 10 Dongbeiwang West RoadHaidianBeijing 100094China Department of Geological Sciences Stanford UniversityStanfordCalifornia 94305USA

High pressures induce changes of properties and structures that could greatly impact materials science if such changes were preserved for ambient *** the geological process of diamond formation that the pressures and high-pressure phases in diamond inclusions can be preserved by the strong diamond envelope,we discuss the perspectives that such process revolutionizes high-pressure science and technology and opens a great potential for creation of functional materials with extremely favorable properties.

关键词： properties ambient process

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Evidence for oxygenation of Fe-Mg oxides at mid-mantle conditions and the rise of deep oxygen

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National Science Review 2021年第4期8卷 29-34页

作者： Jin liu Chenxu Wang Chaojia lv Xiaowan Su Yijin liu Ruilian Tang Jiuhua Chen Qingyang Hu Ho-Kwang mao wendy l.mao Center for High Pressure Science and Technology Advanced Research (HPSTAR) Department of Geological Sciences Stanford University School of Earth and Space Sciences Peking University SlAC National Accelerator laboratory Center for Study of Matter at Extreme Conditions Department of Mechanical and Materials Engineering Florida International University

As the reaction product of subducted water and the iron core, FeO2with more oxygen than hematite(Fe2O3) has been recently recognized as an important component in the D" layer just above the Earth’s core-mantle boundary. Here, we report a new oxygen-excess phase(Mg, Fe)2O3+δ(0 l when(Mg, Fe)-bearing hydrous materials are heated over 1500 kelvin. The OE-phase is fully recoverable to ambient conditions for ex situ investigation using transmission electron microscopy, which indicates that the OE-phase contains ferric iron(Fe3+) as in Fe2O3but holds excess oxygen through interactions between oxygen atoms. The new OE-phase provides strong evidence that H2O has extraordinary oxidation power at high pressure. Unlike the formation of pyrite-type FeO2Hxwhich usually requires saturated water, the OE-phase can be formed with under-saturated water at mid-mantle conditions, and is expected to be more ubiquitous at depths greater than 1000 km in the Earth’s mantle. The emergence of oxygen-excess reservoirs out of primordial or subducted(Mg,Fe)-bearing hydrous materials may revise our view on the deep-mantle redox chemistry.

关键词： subducting slab hydrous phase lower mantle deep oxygen oxygen-excess oxides

Key problems of the four-dimensional Earth system

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Matter and Radiation at Extremes 2020年第3期5卷 31-39页

作者： Ho-kwang mao wendy l.mao Center for High Pressure Science and Technology Advanced Research 10 Dongbeiwang West RoadHaidianBeijing 100094China Department of Geological Sciences Stanford UniversityStanfordCalifornia 94305USA Stanford Institute for Materials and Energy Sciences SLAC National Accelerator LaboratoryMenlo ParkCalifornia 94025USA

Compelling evidence indicates that the solid Earth consists of two physicochemically distinct zones separated radially in the middle of the lower mantle at∼1800 km *** inner zone is governed by pressure-induced physics and chemistry dramatically different from the conventional behavior in the outer *** differences generate large physical and chemical potentials between the two zones that provide fundamental driving forces for triggering major events in Earth’s *** of the main chemical carriers between the two zones isH_(2)Oin hydrous minerals that subducts into the inner zone,releases hydrogen,and leaves oxygen to create superoxides and form oxygen-rich piles at the core–mantle boundary,resulting in localized net oxygen gain in the inner *** of oxygen-rich piles at the base of the mantle could eventually reach a supercritical level that triggers eruptions,injecting materials that cause chemical mantle convection,superplumes,large igneous provinces,extreme climate changes,atmospheric oxygen fluctuations,and mass *** research will be the key for advancing a unified theory of the four-dimensional Earth system.

关键词： zone. Earth mantle

When water meets iron at Earth's core-mantle boundary

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National Science Review 2017年第6期4卷 870-878页

作者： Ho-Kwang mao Qingyang Hu liuxiang Yang Jin liu Duck Young Kim Yue Meng li Zhang Vitali B.Prakapenka Wenge Yang wendy l.mao Center for High Pressure Science and Technology Advanced Research Geophysical laboratory Carnegie Institution Department of Geological Sciences Stanford University High Pressure Collaborative Access Team(HPCAT) Geophysical Laboratory Carnegie Institution Center for Advanced Radiation Sources University of Chicago

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.

关键词： high pressure core-mantle boundary water and iron

Crystallography of low Z material at ultrahigh pressure:Case study on solid hydrogen

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Matter and Radiation at Extremes 2020年第3期5卷 40-54页

作者： 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 Center for High Pressure Science and Technology Advanced Research Beijing 100094China High Pressure Collaborative AccessTeam Geophysical LaboratoryCarnegie Institution of WashingtonArgonneIllinois 60439USA Center for the Study of Matter at Extreme Conditions and Department of Mechanical and Materials Engineering Florida International UniversityMiamiFlorida 33199USA Advanced Photon Source Argonne National LaboratoryLemontIllinois 60439USA HPCAT X-Ray Science DivisionArgonne National LaboratoryLemontIllinois 60439USA MAX IV laboratory Lund University22100 LundSweden Condensed Matter Theory Group Materials Theory DivisionDepartment of Physics and AstronomyUppsala UniversityUppsala S-75120Sweden Center for Advanced Radiation Sources University of ChicagoChicagoIllinois 60637USA Department of Engineering Sciences and Mathematics Lule°a University of Technology97187 Lule°aSweden Department of Geological Sciences Stanford UniversityStanfordCalifornia 94305USA Stanford Institute for Materials and Energy Sciences SLAC National Accelerator LaboratoryMenlo ParkCalifornia 94025USA

Diamond anvil cell techniques have been improved to allow access to the multimegabar ultrahigh-pressure region for exploring novel phenomena in ***,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 *** 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 *** 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[*** 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 *** 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.

关键词： ultrahigh solid eventually

Disproportionation of(Mg,Fe)SiO3 in Earth's deep lower mantle

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Disproportionation of(Mg,Fe)SiO3 in Earth's deep lower mantl...

Applications for Nanoscale X-ray Imaging at High Pressure

2014年中国地球科学联合学术年会——专题9：深部地幔物质成分与结构探测

作者： li Zhang Yue Meng Wenge Yang lin Wang wendy l.mao Qiao-Shi Zeng Jong Seok Jeong Andrew J.Wagner K.Andre Mkhoyan Wenjun liu Ruqing Xu Ho-kwang mao Center for High Pressure Science and Technology Advanced Research Geophysical laboratory Carnegie InstitutionWashington DC 20015 USA High Pressure Collaborative Access Team Geophysical Laboratory Carnegie InstitutionArgonne IL 60439 USA High Pressure Synergetic Consortium Geophysical Laboratory Carnegie InstitutionArgonne IL 60439 USA Geological and Environmental Sciences Stanford UniversityStanford CA 94305 USA Photon Science SLAC National Accelerator LaboratoryMenlo Park CA 94025 USA Department of Chemical Engineering and Materials Science University of MinnesotaMinneapolis MN 55455 USA Advanced Photon Source Argonne National LaboratoryArgonne IL 60439 USA

The lower mantle extends over the enormous pressure(P)-temperature(T)range from the bottom of the transition zone at 670 km depth(24 GPa)to the core-mantle boundary(CMB)at 2900km(136 GPa).Seismic observations suggested a discontinuity beyond000 kilometers depth(1).Our recent study using laser-heated diamond anvil cell(DAC)technology coupled with synchrotron x-ray diffraction(XRD)has demonstrated the disproportionation reaction of(Mg,Fe)SiO3 perovskite(pv)to a nearly Fe-free pv and an Fe-rich H-phase at95 to 101 GPa and 2200 to 2400 K(2).Therefore,we suggest that(Mg,Fe)SiO3 pv may not be the major silicate throughout the lower mantle down to the top of the D″*** have studied the P-T-x relations of pv,ppv,and the H-phase to the core mantle boundary *** a two-phase or three-phase mixed XRD

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Engineering 2019年第3期5卷 479-489页

作者： wendy l. mao Yu lin Yijin liu Jin liu Department of Geological Sciences Stanford University Stanford CA 94305 USA Stanford Institute for Materials and Energy Sciences SLAC National Accelerator Laboratory Menlo Park CA 94025 USA Stanford Synchrotron Radiation lightsource SLAC National Accelerator Laboratory Menlo Park CA 94025 USA

Coupling nanoscale transmission X-ray microscopy (nanoTXM) with a diamond anvil cell (DAC) has exciting potential as a powerful three-dimensional probe for non-destructive imaging at high spatial resolution of materials under extreme conditions. In this article, we discuss current developments in high-resolution X-ray imaging and its application in high-pressure nanoTXM experiments in a DAC with third-generation synchrotron X-ray sources, including technical considerations for preparing successful measurements. We then present results from a number of recent in situ high-pressure measurements investigating equations of state (EOS) in amorphous or poorly crystalline materials and in pressureinduced phase transitions and electronic changes. These results illustrate the potential this technique holds for addressing a wide range of research areas, ranging from condensed matter physics and solidstate chemistry to materials science and planetary interiors. Future directions for this exciting technique and opportunities to improve its capabilities for broader application in high-pressure science are discussed.

关键词： X-ray imaging High pressure Diamond anvil cell

Pressure-induced Elastic Anomaly in a Polyamorphous Metallic Glass

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Pressure-induced Elastic Anomaly in a Polyamorphous Metallic...