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Yang K, Wang X, Zhang J, Cheng Y, Zhang C, Zeng Z, Lin H. Effects of vacancy defects on Fe properties incorporated in MgO. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:295701. [PMID: 29873304 DOI: 10.1088/1361-648x/aacabd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Distributions of Fe in MgO containing Mg vacancy, O vacancy, and Schottky defect are investigated based on the density functional theory (DFT). Our results show that since Mg vacancy will remove electrons from MgO, Fe tends to get close to Mg vacancy but far from O vacancy. The Mg vacancy can decrease the magnetic moment of iron and change its valence state from 2+ to 3+, which leads to ~5% decrease of Fe-O bond length comparable to the effect of 30 GPa external pressure. Furthermore, iron incorporation can increase the Schottky defect concentration of MgO especially in the environment of the Earth's lower mantle, where ~20 mol% Fe-bearing MgO locates at extreme high temperature conditions.
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Affiliation(s)
- Kaishuai Yang
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China. University of Science and Technology of China, Hefei 230026, People's Republic of China. Beijing Computational Science Research Center, Beijing 100084, People's Republic of China
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Lin TY, Lin SS, Chen SY, Shen P. Pulsed laser ablation synthesis of magnesiowüstite based phases with special defect clusters, interfaces and internal stress: implications for natural occurrence and engineering applications. CrystEngComm 2015. [DOI: 10.1039/c4ce02476a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Crystal Structure Prediction and Its Application in Earth and Materials Sciences. Top Curr Chem (Cham) 2014; 345:223-56. [DOI: 10.1007/128_2013_508] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Abstract
The ability of pressure to change inter-atomic distances strongly leads to a wide range of pressure-induced phenomena at high pressures: for example metallisation, amorphisation, superconductivity and polymerisation. Key to understanding these phenomena is the determination of the crystal structure using x-ray or neutron diffraction. The tools necessary to compress matter above 1 million atmospheres (1 Megabar or 100 GPa) were established by the mid 1970s, but it is only since the early 1990s that we have been able to determine the detailed crystal structures of materials at such pressures. In this chapter I briefly review the history of high-pressure crystallography, and describe the techniques used to obtain and study materials at high pressure. Recent crystallographic studies of elements are then used to illustrate what is now possible using modern detectors and synchrotron sources. Finally, I speculate as to what crystallographic studies might become possible over the next decade.
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Affiliation(s)
- Malcolm I McMahon
- SUPA, Centre for Science at Extreme Conditions, School of Physics and Astronomy, The University of Edinburgh, Edinburgh, EH9 3JZ, UK.
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Abstract
Abstract
Ab initio simulations play an increasingly important role in the studies of deep planetary interiors. Here we review the current state of this field, concentrating on studies of the materials of the Earth’s deep interior (MgO—SiO2—FeO—Al2O3, Fe—Si—S—O) and of the interiors of giant planets (H—He system, H2O—CH4—NH3 system). In particular, novel phases and phase diagrams, insights into structural and electronic phase transitions, melting curves, thermoelasticity and the effects of impurities on physical properties of planet-forming materials are discussed.
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Speziale S, Lee VE, Clark SM, Lin JF, Pasternak MP, Jeanloz R. Effects of Fe spin transition on the elasticity of (Mg, Fe)O magnesiowüstites and implications for the seismological properties of the Earth's lower mantle. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2006jb004730] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Lin JF, Vankó G, Jacobsen SD, Iota V, Struzhkin VV, Prakapenka VB, Kuznetsov A, Yoo CS. Spin Transition Zone in Earth's Lower Mantle. Science 2007; 317:1740-3. [PMID: 17885134 DOI: 10.1126/science.1144997] [Citation(s) in RCA: 157] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Mineral properties in Earth's lower mantle are affected by iron electronic states, but representative pressures and temperatures have not yet been probed. Spin states of iron in lower-mantle ferropericlase have been measured up to 95 gigapascals and 2000 kelvin with x-ray emission in a laser-heated diamond cell. A gradual spin transition of iron occurs over a pressure-temperature range extending from about 1000 kilometers in depth and 1900 kelvin to 2200 kilometers and 2300 kelvin in the lower mantle. Because low-spin ferropericlase exhibits higher density and faster sound velocities relative to the high-spin ferropericlase, the observed increase in low-spin (Mg,Fe)O at mid-lower mantle conditions would manifest seismically as a lower-mantle spin transition zone characterized by a steeper-than-normal density gradient.
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Affiliation(s)
- Jung-Fu Lin
- Lawrence Livermore National Laboratory (LLNL), 7000 East Avenue, Livermore, CA 94550, USA
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Rost S, Garnero EJ, Williams Q. Fine-scale ultralow-velocity zone structure from high-frequency seismic array data. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005jb004088] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Bovolo CI. The physical and chemical composition of the lower mantle. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2005; 363:2811-35. [PMID: 16286292 DOI: 10.1098/rsta.2005.1675] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
This article reviews some of the recent advances made within the field of mineral physics. In order to link the observed seismic and density structures of the lower mantle with a particular mineral composition, knowledge of the thermodynamic properties of the candidate materials is required. Determining which compositional model best matches the observed data is difficult because of the wide variety of possible mineral structures and compositions. State-of-the-art experimental and analytical techniques have pushed forward our knowledge of mineral physics, yet certain properties, such as the elastic properties of lower mantle minerals at high pressures and temperatures, are difficult to determine experimentally and remain elusive. Fortunately, computational techniques are now sufficiently advanced to enable the prediction of these properties in a self-consistent manner, but more results are required.A fundamental question is whether or not the upper and lower mantles are mixing. Traditional models that involve chemically separate upper and lower mantles cannot yet be ruled out despite recent conflicting seismological evidence showing that subducting slabs penetrate deep into the lower mantle and that chemically distinct layers are, therefore, unlikely.Recent seismic tomography studies giving three-dimensional models of the seismic wave velocities in the Earth also base their interpretations on the thermodynamic properties of minerals. These studies reveal heterogeneous velocity and density anomalies in the lower mantle, which are difficult to reconcile with mineral physics data.
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Affiliation(s)
- C Isabella Bovolo
- University of Newcastle upon Tyne School of Civil Engineering & Geosciences Newcastle upon Tyne NE1 7RU, UK.
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Speziale S, Milner A, Lee VE, Clark SM, Pasternak MP, Jeanloz R. Iron spin transition in Earth's mantle. Proc Natl Acad Sci U S A 2005; 102:17918-22. [PMID: 16330758 PMCID: PMC1312404 DOI: 10.1073/pnas.0508919102] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
High-pressure Mössbauer spectroscopy on several compositions across the (Mg,Fe)O magnesiowüstite solid solution confirms that ferrous iron (Fe(2+)) undergoes a high-spin to low-spin transition at pressures and for compositions relevant to the bulk of the Earth's mantle. High-resolution x-ray diffraction measurements document a volume change of 4-5% across the pressure-induced spin transition, which is thus expected to cause seismological anomalies in the lower mantle. The spin transition can lead to dissociation of Fe-bearing phases such as magnesiowüstite, and it reveals an unexpected richness in mineral properties and phase equilibria for the Earth's deep interior.
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Affiliation(s)
- S Speziale
- Department of Earth and Planetary Science, University of California, Berkeley, 94720, USA
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Lin JF, Struzhkin VV, Jacobsen SD, Hu MY, Chow P, Kung J, Liu H, Mao HK, Hemley RJ. Spin transition of iron in magnesiowüstite in the Earth's lower mantle. Nature 2005; 436:377-80. [PMID: 16034415 DOI: 10.1038/nature03825] [Citation(s) in RCA: 263] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2005] [Accepted: 05/13/2005] [Indexed: 11/09/2022]
Abstract
Iron is the most abundant transition-metal element in the mantle and therefore plays an important role in the geochemistry and geodynamics of the Earth's interior. Pressure-induced electronic spin transitions of iron occur in magnesiowüstite, silicate perovskite and post-perovskite. Here we have studied the spin states of iron in magnesiowüstite and the isolated effects of the electronic transitions on the elasticity of magnesiowüstite with in situ X-ray emission spectroscopy and X-ray diffraction to pressures of the lowermost mantle. An observed high-spin to low-spin transition of iron in magnesiowüstite results in an abnormal compressional behaviour between the high-spin and the low-spin states. The high-pressure, low-spin state exhibits a much higher bulk modulus and bulk sound velocity than the low-pressure, high-spin state; the bulk modulus jumps by approximately 35 percent and bulk sound velocity increases by approximately 15 percent across the transition in (Mg0.83,Fe0.17)O. Although no significant density change is observed across the electronic transition, the jump in the sound velocities and the bulk modulus across the transition provides an additional explanation for the seismic wave heterogeneity in the lowermost mantle. The transition also affects current interpretations of the geophysical and geochemical models using extrapolated or calculated thermal equation-of-state data without considering the effects of the electronic transition.
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Affiliation(s)
- Jung-Fu Lin
- Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road NW, Washington, DC 20015, USA.
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Badro J, Fiquet G, Guyot F. Thermochemical state of the lower mantle: New insights from mineral physics. EARTH'S DEEP MANTLE: STRUCTURE, COMPOSITION, AND EVOLUTION 2005. [DOI: 10.1029/160gm15] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Jacobsen SD, Spetzler H, Reichmann HJ, Smyth JR. Shear waves in the diamond-anvil cell reveal pressure-induced instability in (Mg,Fe)O. Proc Natl Acad Sci U S A 2004; 101:5867-71. [PMID: 15079080 PMCID: PMC395889 DOI: 10.1073/pnas.0401564101] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The emerging picture of Earth's deep interior from seismic tomography indicates more complexity than previously thought. The presence of lateral anisotropy and heterogeneity in Earth's mantle highlights the need for fully anisotropic elasticity data from mineral physics. A breakthrough in high-frequency (gigahertz) ultrasound has resulted in transmission of pure-mode elastic shear waves into a high-pressure diamond-anvil cell using a P-to-S elastic-wave conversion. The full elastic tensor (c(ij)) of high-pressure minerals or metals can be measured at extreme conditions without optical constraints. Here we report the effects of pressure and composition on shear-wave velocities in the major lower-mantle oxide, magnesiowüstite-(Mg,Fe)O. Magnesiowüstite containing more than approximately 50% iron exhibits pressure-induced c(44) shear-mode softening, indicating an instability in the rocksalt structure. The oxide closer to expected lower-mantle compositions ( approximately 20% iron) shows increasing shear velocities more similar to MgO, indicating that it also should have a wide pressure-stability field. A complete sign reversal in the c(44) pressure derivative points to a change in the topology of the (Mg,Fe)O phase diagram at approximately 50-60% iron. The relative stability of Mg-rich (Mg,Fe)O and the strong compositional dependence of shear-wave velocities (and partial differential c(44)/ partial differential P) in (Mg,Fe)O implies that seismic heterogeneity in Earth's lower mantle may result from compositional variations rather than phase changes in (Mg,Fe)O.
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Affiliation(s)
- Steven D Jacobsen
- Bayerisches Geoinstitut, Universität Bayreuth, 95440 Bayreuth, Germany.
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