Article
Geochemistry & Geophysics
F. Xu, G. Morard, N. Guignot, A. Rivoldini, G. Manthilake, J. Chantel, L. Xie, A. Yoneda, A. King, E. Boulard, S. Pandolfi, F. J. Ryerson, D. Antonangeli
Summary: The local structure and density of liquid Fe-S alloys at high pressure were determined in situ by X-ray diffraction experiments. It was found that top-down solidification is the dominant scenario for Fe-S cores of asteroids and small planetesimals, while bottom-up growth of the inner core may occur in S-poor cases.
EARTH AND PLANETARY SCIENCE LETTERS
(2021)
Article
Multidisciplinary Sciences
Haijun Huang, Lili Fan, Xun Liu, Feng Xu, Ye Wu, Gang Yang, Chunwei Leng, Qingsong Wang, Jidong Weng, Xiang Wang, Lingcang Cai, Yingwei Fei
Summary: Direct measurements of Fe and Fe-8.6 wt%Si under high pressure and high temperature conditions provide insights into the sound velocity and Poisson's ratio of core materials. Adding carbon may be a possible solution to explain the observed anomalies.
NATURE COMMUNICATIONS
(2022)
Article
Geosciences, Multidisciplinary
D. Huang, Y. Li, A. Khan, P. Sossi, D. Giardini, M. Murakami
Summary: Seismic measurements on Mars reveal that the liquid core is rich in light elements, but the effect of these elements on core elasticity is not well understood. Through molecular dynamics simulations, we calculate the elastic properties of different liquid Fe-X (X = Ni, S, C, O, and H) mixtures. Our findings show that the addition of S and O significantly decreases the density of liquid iron in the Martian core, while Ni has minimal effect. Additionally, C increases the compressional sound velocity throughout the core, while both S and O decrease it with diminishing intensity at higher pressures. Assuming a binary mixture for the Martian core, the seismic density measurements suggest the presence of at least 30 wt% S.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Nanoscience & Nanotechnology
Haidong Sun, Zuohua Wang, Lihua Qian, Peng Wang, Jian Zhao, Wu Zhang, Dongli Yu, Hongwang Zhang
Summary: The carbon supersaturation within the lath martensitic lattice was adjusted by thermally treating a Fe-0.45C alloy under hydrostatic pressures of 1-6 GPa. The amount of supersaturated carbon increased linearly with high pressure, reaching up to 84.4% of the nominal carbon content under 6 GPa. The strengthening effect of carbon supersaturation remained proportional to the square root of its content, but the contribution was underestimated.
SCRIPTA MATERIALIA
(2023)
Article
Nanoscience & Nanotechnology
Sheng-Xue Yan, Shao-Hua Luo, Jian Feng, Liu Yang, Peng-Wei Li, Qing Wang, Ya-Hui Zhang, Xin Liu, Long-Jiao Chang
Summary: A new type of flexible electrode material was designed and fabricated based on nanosheet architectures of a Co-Fe alloy coated with ternary metal sulfide composites on silver-sputtered carbon cloth. This material exhibited high specific capacitance and superior rate capability, with potential applications in the field of supercapacitors.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Chemistry, Physical
S. S. Starchikov, V. A. Zayakhanov, A. L. Vasiliev, I. S. Lyubutin, A. O. Baskakov, Yu A. Nikiforova, K. O. Funtov, M. Lyubutina, L. F. Kulikova, V. N. Agafonov, V. A. Davydov
Summary: Under high temperature and high pressure conditions, core@shell nanostructures were formed through a series of reactions, with γ-Fe7C3 iron carbide nanoparticles as the core and an iron oxide shell. By controlling the redox reactions and crystallization processes, the structure and functional properties of the material can be adjusted.
Article
Geochemistry & Geophysics
Yohan Park, Kyoko Yonemitsu, Kei Hirose, Yasuhiro Kuwayama, Shintaro Azuma, Kenji Ohta
Summary: Diffusivity in Fe alloys at high pressures and temperatures imposes constraints on the transport properties of the inner core. The presence of Si must be considered when studying diffusivity, as it is a likely candidate for a light element in the inner core. In this study, we conducted diffusion experiments under high pressure using an internal-resistive-heated diamond-anvil cell, and determined the coefficients of Fe-Ni interdiffusion in the Fe-Si alloy. The results indicate that the effect of Si on Fe-Ni interdiffusion is not significant.
AMERICAN MINERALOGIST
(2023)
Article
Materials Science, Multidisciplinary
Takahiro Masuda, Shoichi Hirosawa, Zenji Horita
Summary: In this study, an earlier version of the continuous HPT (CHPT) process was further developed to simultaneously process two wires for grain refinement. The modified CHPT process using enlarged anvils achieved a grain size reduction in pure Al to around 1 μm and in the Al-2% Fe alloy to around 400 nm, with a tensile strength of 280 MPa and an equivalent strain of around 25 introduced through the process. The study suggests the feasibility of using multiple wires in the CHPT process when the anvil diameter is increased.
JOURNAL OF MATERIALS SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
Shifeng Luo, Jia Chuan Khong, Dominik Daisenberger, Shi Huang, Paul F. McMillan, Jiawei Mi
Summary: In this study, the local atomic structure evolution of an equiatomic Zr50Cu50 metallic glassy alloy under high pressure compression was investigated. The results showed that the interatomic distances of different atomic pairs were reduced at different rates with increasing pressure, with Cu-Cu pairs exhibiting the highest reduction. With the increase of pressure, Zr atoms moved preferentially towards Zr-Zr pairs, while Cu atoms moved preferentially towards Cu-Cu pairs, resulting in a non-uniform atom reconfiguration in the short atomic range.
Article
Chemistry, Physical
R. Utsumi, M. Morimoto, H. Saitoh, T. Watanuki, T. Sato, S. Takagi, S. Orimo
Summary: The researchers synthesized metal hydrides comprising only metals with low hydrogenation affinity which cannot form metal hydrides below 1 GPa. By clarifying the hydrogenation reaction processes of FexMo1-x alloys, they were able to classify the reaction process into three types and synthesize two novel hydrides, one of which has metal elements at the vertices of hexagonal close-packed lattices.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Geosciences, Multidisciplinary
Peng Ni, Anat Shahar, James Badro, Jing Yang, Wenli Bi, Jiyong Zhao, Michael Y. Hu, Esen E. Alp
Summary: The isotopic composition of iron shows variations in different planetary reservoirs, reflecting the differentiation and evolution processes of their parent bodies. Experimental results suggest that iron isotope fractionation during core formation on terrestrial planets may lead to a heavy mantle.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Chemistry, Physical
Y. T. Shi, W. Y. Lu, W. H. Sun, S. D. Zhang, B. J. Yang, J. Q. Wang
Summary: The pressure-dependent microstructure evolution of gas-atomized Fe-based amorphous alloy powders was investigated experimentally and theoretically. The results showed that the amorphous fraction and nucleation mode of particles were sensitive to the gas pressure. Additionally, the amorphous phase underwent three stages of reactions during devitrification.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Engineering, Mechanical
Baochao Zheng, Yong Wang, Wei Li, Yangliang Yi, Yangzhen Liu, Shaogang Cui, Suocheng Song
Summary: The study found that the Fe-B alloy with Fe2B perpendicular to the interface structure exhibited the best erosion-wear resistance, forming suppressive layers to prevent erosion by liquid zinc. The relationship between Fe2B orientation and ferrite matrix significantly influenced the erosion-wear microdamage mechanism.
Article
Multidisciplinary Sciences
Guanghui Cao, Jingjing Liang, Zenglong Guo, Kena Yang, Gang Wang, Huiliu Wang, Xuhao Wan, Zeyuan Li, Yijia Bai, Yile Zhang, Junlin Liu, Yanpeng Feng, Zhenying Zheng, Cai Lu, Guangzhi He, Zeyou Xiong, Ze Liu, Shengli Chen, Yuzheng Guo, Mengqi Zeng, Junhao Lin, Lei Fu
Summary: High-entropy alloy nanoparticles (HEA-NPs) with different metal elements were synthesized using liquid metal with negative mixing enthalpy as a dynamic mixing reservoir, enabling the exploration and optimization of their properties for various applications. The versatile elements used have a wide range of atomic radii and melting points. The real-time conversion process from liquid metal to crystalline HEA-NPs was captured in situ, confirming a dynamic fission-fusion behavior during alloying.
Article
Multidisciplinary Sciences
E. Edmund, G. Morard, M. A. Baron, A. Rivoldini, S. Yokoo, S. Boccato, K. Hirose, A. Pakhomova, D. Antonangeli
Summary: A phase diagram of the Fe-FeSi system was reconstructed under conditions similar to Mercury's core, revealing complex phase transitions and potential crystallization mechanisms.
NATURE COMMUNICATIONS
(2022)
Article
Geosciences, Multidisciplinary
Takayuki Ishii, Eiji Ohtani
Summary: Research suggests that even under wet subducting slab conditions, olivine and wadsleyite exhibit dry transformation kinetics, which could contribute to deep-focus earthquakes and large slab deformation.
Article
Physics, Multidisciplinary
Ryo Tsuruoka, Hidenori Terasaki, Seiji Kamada, Fumiya Maeda, Tadashi Kondo, Naohisa Hirao, Saori Kawaguchi, Iori Yamada, Satoru Urakawa, Akihiko Machida
Summary: In this study, the density and elastic properties of liquid gallium at high pressure and high temperature were measured, and it was found that the results obtained from different equations of state were consistent. Additionally, compared with previous studies, the compression curve of liquid gallium obtained in this study showed a slightly stiffer trend at higher pressures.
HIGH PRESSURE RESEARCH
(2021)
Article
Multidisciplinary Sciences
Sujoy Ghosh, Kishan Tiwari, Masaaki Miyahara, Arno Rohrbach, Christian Vollmer, Vincenzo Stagno, Eiji Ohtani, Dwijesh Ray
Summary: This study reports the first natural occurrence of Fe-bearing aluminous bridgmanite in the Katol L6 chondrite, with a composition closely matching those synthesized in high-pressure experiments. The mineral coexists with majorite and metal-sulfide intergrowths, and has a significantly higher Fe3+/Sigma Fe ratio compared to coexisting majorite, in agreement with experimental studies. Textural observations and comparisons with laboratory experiments suggest that the Katol bridgmanite formed directly from chondritic melt generated by a shock event at pressures of around 23 to 25 gigapascals.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Geochemistry & Geophysics
R. Shiraishi, J. Muto, A. Tsunoda, S. Sawa, A. Suzuki
Summary: Deformation experiments on lawsonite under seismogenic conditions in cold subduction zones revealed localized deformation and rapid stress drop before dehydration, followed by gradual strain weakening during dehydration. The microstructures of lawsonite suggest a brittle behavior and partial amorphization along the fault, indicating that fault slip may occur within the stability field of lawsonite in conditions suitable for intermediate depth earthquakes.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Geochemistry & Geophysics
Tomonori Ohashi, Tatsuya Sakamaki, Ken-ichi Funakoshi, Takanori Hattori, Naoki Hisano, Jun Abe, Akio Suzuki
Summary: The structures of cold-compressed basaltic glass were investigated at high pressures, revealing the compression behavior and oxygen packing mechanism. Furthermore, it was found that modified silicate glasses show different compression behaviors compared to silica glasses.
AMERICAN MINERALOGIST
(2022)
Article
Geosciences, Multidisciplinary
Eiji Ohtani, Toru Sakurabayashi, Kosuke Kurosawa
Summary: Neumann band in iron meteorites is a characteristic texture formed by ancient collisions on parent bodies. Through experiments and numerical simulations, we revealed the effects of pressure and temperature on the formation and disappearance of Neumann bands. The results showed that the bands are formed within a specific pressure range and can disappear after annealing at certain temperatures.
PROGRESS IN EARTH AND PLANETARY SCIENCE
(2022)
Article
Geography, Physical
Eiji Ohtani
Summary: Various phase transitions occur in the Earth's interior, causing discontinuities in seismic velocity and density profiles. Major transitions in the lower mantle include spin transition in mantle minerals with iron and post-perovskite transition of bridgmanite. Seismic velocity anomalies are associated with hot mantle plumes and cold slab subduction.
JOURNAL OF GEOGRAPHY-CHIGAKU ZASSHI
(2022)
Article
Geosciences, Multidisciplinary
Lu Liu, Hongsheng Yuan, Yao Yao, Ziqiang Yang, Federico Aiace Gorelli, Nico Giordano, Lixin He, Eiji Ohtani, Li Zhang
Summary: This study reports the formation of an Al-rich Nt-phase in model hydrated basalts, suggesting its potential role as a water carrier in subducted oceanic crust to the deep lower mantle.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geosciences, Multidisciplinary
S. Dominijanni, C. A. McCammon, E. Ohtani, D. Ikuta, T. Sakamaki, T. Ishii, G. Criniti, L. S. Dubrovinsky, S. Khandarkhaeva, T. Fedotenko, K. Glazyrin, H. Uchiyama, H. Fukui, A. Q. R. Baron
Summary: The elastic properties of B2-Fe0.67Ni0.06Si0.27 alloy were investigated under high pressure using inelastic X-ray scattering and powder X-ray diffraction. The results were compared with the preliminary reference Earth model, and showed consistency in wave velocities and densities.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geochemistry & Geophysics
Wen-Pin Hsieh, Enrico Marzotto, Takayuki Ishii, Leonid Dubrovinsky, Alena A. Aslandukova, Giacomo Criniti, Yi-Chi Tsao, Chun-Hung Lin, Jun Tsuchiya, Eiji Ohtani
Summary: The deep water cycle of the Earth has a significant impact on its physical and chemical properties, as well as its geodynamics. This study focuses on the influence of dense hydrous magnesium silicates (DHMSs) on the thermal evolution and dynamics of sinking slabs. The research shows that the thermal conductivity of DHMSs is lower than that of other components along slab subduction, which contributes to the formation of a cold hydrous layer within sinking slabs, stabilizes hydrous minerals, and promotes water transportation to the deeper mantle.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Geochemistry & Geophysics
L. Eberhard, M. Thielmann, P. Eichheimer, A. Neri, A. Suzuki, M. Ohl, W. Fujita, K. Uesugi, M. Nakamura, G. J. Golabek, D. J. Frost
Summary: A new method to determine fluid flux at high pressures and temperatures has been developed and used to study serpentinites at subduction zone conditions. The experiments show that the amount and distribution of brucite can indicate fluid flow, and that small deviatoric stresses can cause anisotropic fluid flux.
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
(2022)
Article
Multidisciplinary Sciences
Takayuki Ishii, Giacomo Criniti, Eiji Ohtani, Narangoo Purevjav, Hongzhan Fei, Tomoo Katsura, Ho-kwang Mao
Summary: Water transported by subducted oceanic plates affects the dynamics and evolution of the Earth's interior. The study suggests that water in the lower mantle may be stored in basaltic fragments of subducted slabs. High-temperature aluminous silica minerals in the lower mantle can store significant amounts of water, allowing water circulation between the upper mantle and lower mantle.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Multidisciplinary Sciences
Daijo Ikuta, Eiji Ohtani, Hiroshi Fukui, Takeshi Sakai, Daisuke Ishikawa, Alfred Q. R. Baron
Summary: In this study, the compressional and shear wave velocities of hexagonal close-packed iron were determined at high pressures, providing insights into the composition and evolution of Earth's inner core. The results suggest that the inner core of the Earth is slower in terms of wave velocities compared to pure iron, with the addition of silicon and sulfur to the iron-nickel alloy explaining the observed density and sound velocity. These findings contribute to a better understanding of the Earth's core composition.
NATURE COMMUNICATIONS
(2022)
Article
Physics, Multidisciplinary
Riko Iizuka-Oku, Hirotada Gotou, Akio Suzuki, Hiroyuki Kagi
Summary: The interaction of light elements with iron and silicates in Earth's core-mantle segregation process is crucial for understanding early Earth evolution. This study used in-situ X-ray diffraction and imaging observations to investigate the sequential reactions and formation of iron sulfide and silicates. The results showed that sulfur affected the shape and growth of iron blobs by reducing the interfacial energy between molten iron and silicates. Light elements and remaining silicate grains also played a role in core-mantle segregation as temperatures increased. Carbon and silicon were incorporated into liquid iron during later processes at higher temperatures.
HIGH PRESSURE RESEARCH
(2022)
Article
Materials Science, Multidisciplinary
Maki Hamada, Seiji Kamada, Eiji Ohtani, Tatsuya Sakamaki, Takaya Mitsui, Ryo Masuda, Naohisa Hirao, Yasuo Ohishi, Masahide Akasaka
Summary: The study investigated the structural transition and spin crossover of Fe2+ in synthetic (Mg0.6Fe0.4)O-ferropericlase up to pressures of the lower mantle using synchrotron x-ray diffraction and Mossbauer spectroscopy. The results showed the existence of high-spin and low-spin Fe2+ at pressures ranging from 61 to 136 GPa, with a gradual increase in the ratio of low-spin Fe2+ to high-spin Fe2+ as pressure increases. Above 136 GPa, all Fe2+ was found to be in a low-spin state.
