start-ver=1.4
cd-journal=joma
no-vol=13
cd-vols=
no-issue=1
article-no=
start-page=60
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2026
dt-pub=20260920
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Carbon solubility and liquid–liquid immiscibility in Fe–C–S ternary system up to 6 GPa: implications for the core of small planetary bodies
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=High-pressure, high-temperature experiments were conducted in a multi-anvil press using seven different starting compositions to investigate the phase relations of Fe–C–S liquids at pressures up to 6 GPa and temperatures up to 2000 K. Quenched samples revealed immiscible C-rich and S-rich metallic liquids at 2 and 4 GPa, manifesting as either large immiscible zones or emulsified smaller droplets. On the contrary, no immiscibility was observed at 5 or 6 GPa. At these higher pressures, the carbon solubility limit, significantly reduced by increasing sulfur content in the ternary liquid, prevents the formation of a liquid phase rich in both C and S. Our findings thus indicate that super-liquidus immiscibility in Fe-rich compositions does not occur at pressures above 5 GPa, due to the differential pressure dependence of C solubility and miscibility. The limited C solubility in S-rich liquids at higher pressures effectively suppresses immiscibility. Based on these results, terrestrial planetary bodies with fluid cores at pressures exceeding 5 GPa are unlikely to experience liquid–liquid immiscibility, even when both carbon and sulfur are abundant, as sulfur limits carbon solubility and promotes its exsolution. For the Moon, immiscibility-induced core stratification is not expected, though local emulsification could occur near the core–mantle boundary (CMB). In smaller bodies, a two-liquid Fe–C–S core may form at high temperatures, but progressive cooling may lead to graphite crystallization and the potential development of a graphitic crust.
en-copyright=
kn-copyright=

en-aut-name=ZhaoBin
en-aut-sei=Zhao
en-aut-mei=Bin
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=MorardGuillaume
en-aut-sei=Morard
en-aut-mei=Guillaume
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=ManthilakeGeeth
en-aut-sei=Manthilake
en-aut-mei=Geeth
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=ParisiadesParaskevas
en-aut-sei=Parisiades
en-aut-mei=Paraskevas
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

en-aut-name=YangJing
en-aut-sei=Yang
en-aut-mei=Jing
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=

en-aut-name=FeiYingwei
en-aut-sei=Fei
en-aut-mei=Yingwei
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=6
ORCID=

en-aut-name=Le GodecYann
en-aut-sei=Le Godec
en-aut-mei=Yann
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=7
ORCID=

en-aut-name=KondoNozomi
en-aut-sei=Kondo
en-aut-mei=Nozomi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=8
ORCID=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=9
ORCID=

en-aut-name=AntonangeliDaniele
en-aut-sei=Antonangeli
en-aut-mei=Daniele
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=10
ORCID=

affil-num=1
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=2
en-affil=UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, Muséum National d’Histoire Naturelle, Sorbonne Université
kn-affil=

affil-num=3
en-affil=Laboratoire Magmas et Volcans, Université Clermont-Auvergne
kn-affil=

affil-num=4
en-affil=UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, Muséum National d’Histoire Naturelle, Sorbonne Université
kn-affil=

affil-num=5
en-affil=Earth and Planets Laboratory, Carnegie Institution for Science
kn-affil=

affil-num=6
en-affil=Earth and Planets Laboratory, Carnegie Institution for Science
kn-affil=

affil-num=7
en-affil=UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, Muséum National d’Histoire Naturelle, Sorbonne Université
kn-affil=

affil-num=8
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=9
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=10
en-affil=UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, Muséum National d’Histoire Naturelle, Sorbonne Université
kn-affil=
en-keyword=Iron–carbon–sulfur liquids
kn-keyword=Iron–carbon–sulfur liquids
en-keyword=Miscibility
kn-keyword=Miscibility
en-keyword=High pressure and high temperature
kn-keyword=High pressure and high temperature
en-keyword=Planetary cores
kn-keyword=Planetary cores
END

start-ver=1.4
cd-journal=joma
no-vol=131
cd-vols=
no-issue=8
article-no=
start-page=e2025JB033593
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2026
dt-pub=202608
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Effect of Fluorine on the Stability of Dense Hydrous Mg Silicates With Implications for the Deep Water Cycle
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=Water is believed to be transported, at least locally, into the Earth's deep mantle via hydrous minerals. Fluorine not only tends to interact with water but also influences the stability of hydrous minerals. Thus, knowledge of its stability could be important in understanding the deep-water cycle. In this study, we conducted high-pressure experiments to investigate the stability of dense hydrous Mg silicates in the presence of fluorine at pressures ranging from 9 to 23 GPa. In the presence of even small amounts of fluorine, clinohumite or phase E survives up to approximately 17 GPa, allowing it to exist without dehydration at temperatures by about 200°C higher than a fluorine-free system. At pressures above 18 GPa, superhydrous phase B stabilizes as a major fluorine host. Fluorine partitions very little into phase D, leaving its stability field unchanged, but the stability field of superhydrous phase B extends to temperatures above 1400°C, thereby enabling the hydrous phase in the dragged wedge mantle just above the slab to have transport potential into the lower mantle.
en-copyright=
kn-copyright=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=MiaoYunfan
en-aut-sei=Miao
en-aut-mei=Yunfan
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=SajiSatheesh T.
en-aut-sei=Saji
en-aut-mei=Satheesh T.
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=IkutaDaijo
en-aut-sei=Ikuta
en-aut-mei=Daijo
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

en-aut-name=KondoNozomi
en-aut-sei=Kondo
en-aut-mei=Nozomi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=

en-aut-name=IshiiTakayuki
en-aut-sei=Ishii
en-aut-mei=Takayuki
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=6
ORCID=

en-aut-name=HeXuejing
en-aut-sei=He
en-aut-mei=Xuejing
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=7
ORCID=

en-aut-name=OtaTsutomu
en-aut-sei=Ota
en-aut-mei=Tsutomu
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=8
ORCID=

en-aut-name=KunihiroTakuya
en-aut-sei=Kunihiro
en-aut-mei=Takuya
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=9
ORCID=

affil-num=1
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=2
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=3
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=4
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=5
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=6
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=7
en-affil=Geochemical Research Center Graduate School of Science, The University of Tokyo
kn-affil=

affil-num=8
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=9
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=
en-keyword=dense hydrous Mg silicates
kn-keyword=dense hydrous Mg silicates
en-keyword=fluorine
kn-keyword=fluorine
en-keyword=water
kn-keyword=water
en-keyword=transition zone
kn-keyword=transition zone
en-keyword=superhydrous phase B
kn-keyword=superhydrous phase B
en-keyword=phase relation
kn-keyword=phase relation
END

start-ver=1.4
cd-journal=joma
no-vol=131
cd-vols=
no-issue=8
article-no=
start-page=e2026JB034225
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2026
dt-pub=20260816
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Spin Transition of Ferric Iron in Silicate Glasses Inferred by High‐Pressure Electrical Conductivity Measurements
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=Silicate melt has been proposed to exist near the base of the mantle and has been invoked to explain seismic and electrical conductivity anomalies observed near the core-mantle boundary; however, its presence and stability under lowermost-mantle conditions remain uncertain. Here we report high-pressure electrical conductivity measurements of Fe2+- and Fe3+-bearing pyroxene glasses (Fe3+/ΣFe ≈ 0.5), used as analogs of silicate melts, up to megabar pressures at room temperature. At lower pressures, conductivity increases with pressure and iron content, consistent with electron-hole hopping between Fe2+ and Fe3+. Above 77–85 GPa, all samples show a marked conductivity decrease, suggesting a pressure-induced spin transition of Fe3+. Previous studies have suggested that lower-mantle silicate melts may be enriched in Fe3+, and iron spin-state changes may modify iron partitioning between silicate melts and coexisting crystalline phases. Therefore, the Fe3+ spin transition inferred here may affect the evolution of deep-mantle melts through pressure-dependent changes in iron partitioning behavior.
en-copyright=
kn-copyright=

en-aut-name=MashinoIzumi
en-aut-sei=Mashino
en-aut-mei=Izumi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=KitaoShinji
en-aut-sei=Kitao
en-aut-mei=Shinji
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=MitsuiTakaya
en-aut-sei=Mitsui
en-aut-mei=Takaya
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

en-aut-name=MasudaRyo
en-aut-sei=Masuda
en-aut-mei=Ryo
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=

en-aut-name=SetoMakoto
en-aut-sei=Seto
en-aut-mei=Makoto
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=6
ORCID=

affil-num=1
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=2
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=3
en-affil=Institute for Integrated Radiation and Nuclear Science, Kyoto University
kn-affil=

affil-num=4
en-affil=Synchrotron Radiation Research Center, Kansai Photon Science Institute, Quantum Beam Science Research Directorate, National Institutes for Quantum Science and Technology
kn-affil=

affil-num=5
en-affil=Graduate School of Science and Technology, Hirosaki University
kn-affil=

affil-num=6
en-affil=Institute for Integrated Radiation and Nuclear Science, Kyoto University
kn-affil=
en-keyword=high pressure     
kn-keyword=high pressure     
en-keyword=electrical conductivity
kn-keyword=electrical conductivity
en-keyword=silicate glass
kn-keyword=silicate glass
en-keyword=diamond anvil cell
kn-keyword=diamond anvil cell
en-keyword=the Earth's mantle
kn-keyword=the Earth's mantle
en-keyword=ferric iron
kn-keyword=ferric iron
END

start-ver=1.4
cd-journal=joma
no-vol=53
cd-vols=
no-issue=14
article-no=
start-page=e2026GL122472
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2026
dt-pub=20260728
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Electrical Conductivity of Hydrous Ultramafic Melts With Implications for Origin of Low Velocity Layer Atop of the 410 km Seismic Discontinuity
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=Low-velocity layers (LVLs) above the 410-km discontinuity are commonly attributed to partial melt generated by dehydration melting when hydrous mantle transition-zone material rises into the upper mantle, where water solubility in nominally anhydrous minerals decreases. Interpreting coexisting high-conductivity anomalies requires constraints on the intrinsic conductivity of the melt phase at pressures just above the transition zone. We measured electrical conductivity of hydrous ultramafic melts representative of incipient melts, ranging from 6.3 to 18.6 wt% H2O at 13 GPa using impedance spectroscopy in a Kawai-type multi-anvil apparatus. Hydrous ultramafic melts are extremely conductive, and conductivity increases systematically with H2O content to values comparable to alkali-carbonate melts. The high conductivity implies that even small fractions of interconnected hydrous melt can dominate bulk mantle conductivity. Combining our measurements with geophysical conductance estimates indicates that <1 vol% melt can produce conductive layers thicker than 10 km, consistent with seismological constraints on LVL structure.
en-copyright=
kn-copyright=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=XieLongjian
en-aut-sei=Xie
en-aut-mei=Longjian
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

affil-num=1
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=2
en-affil=Center for High Pressure Science & Technology Advanced Research
kn-affil=
en-keyword=electrical conductivity
kn-keyword=electrical conductivity
en-keyword=water
kn-keyword=water
en-keyword=low velocity zone
kn-keyword=low velocity zone
en-keyword=silicate melt
kn-keyword=silicate melt
en-keyword=mantle
kn-keyword=mantle
END

start-ver=1.4
cd-journal=joma
no-vol=53
cd-vols=
no-issue=14
article-no=
start-page=e2026GL121981
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2026
dt-pub=20260710
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Calcium Solubility of Bridgmanite in Subducted Basalt in Earth's Lower Mantle
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=The calcium solubility in bridgmanite and the resulting abundance of davemaoite under lower-mantle pressure-temperature conditions have been under debate following a recent report of extensive calcium dissolution in bridgmanite. We experimentally investigated the calcium solubility in bridgmanite in a basaltic composition at pressures up to 125 GPa and temperatures up to 3,520 K. Our experimental data are modeled thermodynamically along the bridgmanite-davemaoite solvus to quantify the calcium solubility in bridgmanite and the davemaoite proportion in basaltic and pyrolitic assemblages along lower mantle geotherms. Our results indicate that bridgmanite hosts only 0.001–0.03 Ca cations per formula unit in the lower mantle, while davemaoite remains as an abundant mineral, accounting for 8 and 25 vol% of pyrolitic and basaltic mineralogical models, respectively, along representative lower-mantle geotherms. Our thermoelastic modeling further indicates that the effect of calcium dissolution on the density and bulk sound velocity of lower-mantle assemblages is negligible.
en-copyright=
kn-copyright=

en-aut-name=ZhangChengwei
en-aut-sei=Zhang
en-aut-mei=Chengwei
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=El GhazaouiElias
en-aut-sei=El Ghazaoui
en-aut-mei=Elias
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=CharitonStella
en-aut-sei=Chariton
en-aut-mei=Stella
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

en-aut-name=PrakapenkaVitali B.
en-aut-sei=Prakapenka
en-aut-mei=Vitali B.
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=

en-aut-name=LiLuo
en-aut-sei=Li
en-aut-mei=Luo
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=6
ORCID=

en-aut-name=ZhangYanyao
en-aut-sei=Zhang
en-aut-mei=Yanyao
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=7
ORCID=

en-aut-name=LinJung‐Fu
en-aut-sei=Lin
en-aut-mei=Jung‐Fu
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=8
ORCID=

affil-num=1
en-affil=Department of Earth and Planetary Sciences, Jackson School of Geosciences The University of Texas at Austin
kn-affil=

affil-num=2
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=3
en-affil=School of Earth and Environmental Sciences, Seoul National University
kn-affil=

affil-num=4
en-affil=Center for Advanced Radiation Sources, The University of Chicago
kn-affil=

affil-num=5
en-affil=Center for Advanced Radiation Sources, The University of Chicago
kn-affil=

affil-num=6
en-affil=Department of Earth and Planetary Sciences, Jackson School of Geosciences The University of Texas at Austin
kn-affil=

affil-num=7
en-affil=Earth and Planetary Sciences, Stanford University
kn-affil=

affil-num=8
en-affil=Department of Earth and Planetary Sciences, Jackson School of Geosciences The University of Texas at Austin
kn-affil=
END

start-ver=1.4
cd-journal=joma
no-vol=16
cd-vols=
no-issue=1
article-no=
start-page=1866
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2025
dt-pub=20250221
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Grain boundary diffusion cannot explain the W isotope heterogeneities of the deep mantle
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=The low 182W/184W and high 3He/4He in some ocean island basalts compared to the bulk mantle values may derive from the Earth’s core through long-term core-mantle interactions. It has been proposed that the grain boundary diffusion of siderophile elements is an efficient mechanism for core-mantle interaction and may effectively modify the W isotopic compositions of the plume-source mantle. In this study, we perform large-scale molecular dynamics simulations driven by machine learning potentials of ab initio quality to investigate the diffusion of W along ferropericlase grain boundaries and in (Mg,Fe)O liquid. Here we show that the diffusion of W is sluggish under core-mantle boundary conditions, and thus is unlikely to have observable impacts on the W isotopic compositions of terrestrial igneous rocks.
en-copyright=
kn-copyright=

en-aut-name=PengYihang
en-aut-sei=Peng
en-aut-mei=Yihang
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=DengJie
en-aut-sei=Deng
en-aut-mei=Jie
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

affil-num=1
en-affil=Department of Geosciences, Princeton University
kn-affil=

affil-num=2
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=3
en-affil=Department of Geosciences, Princeton University
kn-affil=
END

start-ver=1.4
cd-journal=joma
no-vol=16
cd-vols=
no-issue=1
article-no=
start-page=3239
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2025
dt-pub=20250404
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Low melt viscosity enables melt doublets above the 410-km discontinuity
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=Seismic and magnetotelluric studies suggest hydrous silicate melts atop the 410 km discontinuity form 30–100 km thick layers. Importantly, in some regions, two layers are observed. These stagnant layers are related to their comparable density to the surrounding mantle, but their formation mechanisms and detailed structures remain unclear. Here we report a large decrease of silicate melt viscosity at ~14 GPa, from 96(5) to 11.7(6) mPa⋅s, as water content increases from 15.5 to 31.8 mol% H₂O. Such low viscosities facilitate rapid segregation of melt, which would typically prevent thick layer accumulation. Our 1D finite element simulations show that continuous dehydration melting of upwelling mantle material produces a primary melt layer above 410 km and a secondary layer at the depth of equal mantle-melt densities. These layers can merge into a single thick layer under low density contrasts or high upwelling rates, explaining both melt doublets and thick single layers.
en-copyright=
kn-copyright=

en-aut-name=XieLongjian
en-aut-sei=Xie
en-aut-mei=Longjian
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=AndraultDenis
en-aut-sei=Andrault
en-aut-mei=Denis
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=HanCunrui
en-aut-sei=Han
en-aut-mei=Cunrui
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

en-aut-name=HammondJames O. S.
en-aut-sei=Hammond
en-aut-mei=James O. S.
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=

en-aut-name=XuFang
en-aut-sei=Xu
en-aut-mei=Fang
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=6
ORCID=

en-aut-name=ZhaoBin
en-aut-sei=Zhao
en-aut-mei=Bin
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=7
ORCID=

en-aut-name=LordOliver T.
en-aut-sei=Lord
en-aut-mei=Oliver T.
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=8
ORCID=

en-aut-name=FeiYingwei
en-aut-sei=Fei
en-aut-mei=Yingwei
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=9
ORCID=

en-aut-name=FalvardSimon
en-aut-sei=Falvard
en-aut-mei=Simon
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=10
ORCID=

en-aut-name=KakizawaSho
en-aut-sei=Kakizawa
en-aut-mei=Sho
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=11
ORCID=

en-aut-name=TsujinoNoriyoshi
en-aut-sei=Tsujino
en-aut-mei=Noriyoshi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=12
ORCID=

en-aut-name=HigoYuji
en-aut-sei=Higo
en-aut-mei=Yuji
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=13
ORCID=

en-aut-name=HenryLaura
en-aut-sei=Henry
en-aut-mei=Laura
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=14
ORCID=

en-aut-name=GuignotNicolas
en-aut-sei=Guignot
en-aut-mei=Nicolas
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=15
ORCID=

en-aut-name=DobsonDavid P.
en-aut-sei=Dobson
en-aut-mei=David P.
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=16
ORCID=

affil-num=1
en-affil=Center for High Pressure Science & Technology Advanced Research
kn-affil=

affil-num=2
en-affil=Université Clermont Auvergne, CNRS, IRD, OPGC, Laboratoire Magmas et Volcans
kn-affil=

affil-num=3
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=4
en-affil=School of Natural Sciences, Birkbeck, University of London
kn-affil=

affil-num=5
en-affil=School of Natural Sciences, Birkbeck, University of London
kn-affil=

affil-num=6
en-affil=School of Earth Sciences, Zhejiang University
kn-affil=

affil-num=7
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=8
en-affil=School of Earth Sciences, University of Bristol
kn-affil=

affil-num=9
en-affil=Earth & Planets Laboratory, Carnegie Institution for Science
kn-affil=

affil-num=10
en-affil=Université Clermont Auvergne, CNRS, IRD, OPGC, Laboratoire Magmas et Volcans
kn-affil=

affil-num=11
en-affil=Japan Synchrotron Radiation Research Institute
kn-affil=

affil-num=12
en-affil=Japan Synchrotron Radiation Research Institute
kn-affil=

affil-num=13
en-affil=Japan Synchrotron Radiation Research Institute
kn-affil=

affil-num=14
en-affil=Synchrotron SOLEIL
kn-affil=

affil-num=15
en-affil=Synchrotron SOLEIL
kn-affil=

affil-num=16
en-affil=Department of Earth Sciences, University College London
kn-affil=
END

start-ver=1.4
cd-journal=joma
no-vol=78
cd-vols=
no-issue=1
article-no=
start-page=57
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2026
dt-pub=20260216
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Electrical conductivity measurements of rhyolitic glass at high pressure and high temperature
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=We performed electrical conductivity measurements of rhyolite glasses across the glass transition temperature at 1 GPa. Our experimental data show that, in the Arrhenius plot, the conductivity of rhyolite with 0.2 wt% H2O has an inflection point between around 760 K, while for rhyolite with 4.9 wt% H2O the gradient changes between 685 and 825 K. These inflection points correlate with the glass transition temperature, and are compared with results of previous experiments. The degree of welding of clastic and hydrous rock can be constrained by estimating glass transition temperatures of volcanic rocks combined with measurements of electrical conductivity structures obtained from electromagnetic soundings beneath volcanic bodies. This, in turn, can be used to aid predictions of volcanic eruption.
en-copyright=
kn-copyright=

en-aut-name=HaraguchiYusuke
en-aut-sei=Haraguchi
en-aut-mei=Yusuke
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=Fuji-TaKiyoshi
en-aut-sei=Fuji-Ta
en-aut-mei=Kiyoshi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=NakamotoMasashi
en-aut-sei=Nakamoto
en-aut-mei=Masashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

en-aut-name=SuzukiMasanori
en-aut-sei=Suzuki
en-aut-mei=Masanori
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=

en-aut-name=TanakaToshihiro
en-aut-sei=Tanaka
en-aut-mei=Toshihiro
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=6
ORCID=

affil-num=1
en-affil=Graduate School of Engineering, The University of Osaka
kn-affil=

affil-num=2
en-affil=Graduate School of Engineering, The University of Osaka
kn-affil=

affil-num=3
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=4
en-affil=Graduate School of Engineering, The University of Osaka
kn-affil=

affil-num=5
en-affil=Graduate School of Engineering, The University of Osaka
kn-affil=

affil-num=6
en-affil=Graduate School of Engineering, The University of Osaka
kn-affil=
en-keyword=Electrical conductivity
kn-keyword=Electrical conductivity
en-keyword=Glass transition temperature
kn-keyword=Glass transition temperature
en-keyword=melt
kn-keyword=melt
en-keyword=clastics
kn-keyword=clastics
END

start-ver=1.4
cd-journal=joma
no-vol=181
cd-vols=
no-issue=7
article-no=
start-page=55 
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2026
dt-pub=20260610
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Electrical conductivity of geikielite (MgTiO3) at lunar mantle conditions: the role of metastable defect states and thermal history
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=The electrical conductivity of geikielite (MgTiO3), the Mg endmember of the ilmenite group, was investigated at mantle pressures of 2 and 4.3 GPa and temperatures up to 1850 K using a Kawai-type multi-anvil apparatus. Electrical conductivity increases by more than seven orders of magnitude between 800 and 1700 K and exhibits two distinct conduction regimes separated by a transition at ~ 1500–1700 K. The high-temperature regime is characterized by large activation enthalpies (ΔH ≈ 1.8–2.3 eV), whereas the low-temperature regime shows much lower values (ΔH ≈ 0.19–0.31 eV). Stepwise annealing experiments reveal a pronounced thermal-history dependence: repeated heating to progressively higher maximum temperatures (Tmax) produces metastable conductivity states, enhancing low-temperature conductivity by up to six orders of magnitude and systematically reducing activation enthalpy. This behavior indicates activation and freezing-in of defect-related charge carriers. Negative activation volumes further support a hopping-type conduction mechanism. Although Ti³⁺ was not directly detected, the combination of reducing experimental conditions, Al³⁺ impurities (~ 0.35 wt% Al₂O₃), low activation energies, and strong thermal memory is most consistent with small-polaron hopping involving Ti³⁺–Ti⁴⁺ pairs. At lunar core–mantle boundary temperatures, geikielite reaches conductivities of 10¹–10² S/m, exceeding those of olivine and overlapping estimates for the lunar low-velocity zone. Our results demonstrate that solid-state Ti-rich oxides can produce high electrical conductivity without partial melting, providing new constraints on the thermochemical evolution and electromagnetic structure of the lunar interior.
en-copyright=
kn-copyright=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=YamazakiDaisuke
en-aut-sei=Yamazaki
en-aut-mei=Daisuke
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

affil-num=1
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=2
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=
en-keyword=Electrical conductivity
kn-keyword=Electrical conductivity
en-keyword=Geikielite
kn-keyword=Geikielite
en-keyword=High-pressure and high-temperature experiment
kn-keyword=High-pressure and high-temperature experiment
en-keyword=Ilmenite
kn-keyword=Ilmenite
en-keyword=Metastable defect states
kn-keyword=Metastable defect states
END

start-ver=1.4
cd-journal=joma
no-vol=53
cd-vols=
no-issue=2
article-no=
start-page=18
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2026
dt-pub=20260524
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=High-pressure spectroscopic investigation of ε-FeOOH: toward a better understanding of pressure-induced hydrogen-bond symmetrization
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=High-pressure spectroscopic measurements of ε-FeOOH were conducted up to ~ 65 GPa at room temperature in diamond anvil cells. The pressure evolution of the Raman vibrational modes confirms that a hydrogen-bond-symmetrization-induced phase transition from P21nm to Pnnm occurs at ~ 18 GPa. Infrared (IR) spectroscopic measurements suggest that the Pnnm phase has a disordered hydrogen state, and no spectroscopic evidence for fully centered hydrogen bonds is observed within the investigated pressure range. Above ~ 45 GPa, Fe3+ in ε-FeOOH undergoes a high-spin to low-spin transition as indicated by a reduction of the unit cell volume, together with reductions in IR transmitted and Raman signals. These results demonstrate that ε‑FeOOH preserves a disordered hydrogen‑bond configuration up to at least 45 GPa, whereas δ-AlOOH transforms to a centered hydrogen-bond configuration at ~ 18 GPa. This compositional contrast suggests that Fe‑bearing oxyhydroxides follow a distinct evolution of hydrogen bonding under compression, providing insight into hydrogen behavior in deep Earth materials.
en-copyright=
kn-copyright=

en-aut-name=MashinoIzumi
en-aut-sei=Mashino
en-aut-mei=Izumi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=YamashitaShigeru
en-aut-sei=Yamashita
en-aut-mei=Shigeru
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

affil-num=1
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=2
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=3
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=
en-keyword=ε-FeOOH
kn-keyword=ε-FeOOH
en-keyword=High pressure
kn-keyword=High pressure
en-keyword=Spin transition
kn-keyword=Spin transition
en-keyword=Hydrogen bond symmetrization
kn-keyword=Hydrogen bond symmetrization
END

start-ver=1.4
cd-journal=joma
no-vol=687
cd-vols=
no-issue=
article-no=
start-page=120087
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2026
dt-pub=202608
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Phase diagram of Fe-C-S ternary system under planetary core conditions
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=High-pressure, high-temperature experiments were conducted to investigate melting relations and phase assemblages in the Fe-C-S ternary system at 5 and 15 GPa, covering a temperature range of 1300–1900 K, conditions directly relevant to the Moon’s and Mercury’s cores. At 1300 K, the system is primarily governed by Fe-S eutectic melting, exhibiting notable complexity in the carbon-rich and sulfur-poor regions. With increasing temperature, the phase diagram simplifies: at 5 GPa and 1700 K, the Fe-Fe₃C-FeS system features three regions (Fe+L, C + L, and L). Similar phase assemblages are observed at 15 GPa, with Fe7C3 and diamond replacing Fe3C and graphite, respectively. Extensive Fe+L, C + L, and L regions are observed at 1900 K.<br>
For a Moon’s core composed of a Fe-C-S alloy, nearly pure Fe is the only viable inner core phase above 1700 K. Below this temperature, both Fe and Fe₃C are potential solid inner core phases, depending on carbon content; a two-phase solid inner core is also theoretically possible. The inferred compositions of the outer core suggest densities of 6200–7300 kg/m³, with tighter constraints for models featuring an Fe₃C core.<br>
At Mercury-relevant pressures, either Fe or Fe₇C₃ may form the solid inner core, again depending on carbon content. If the inner core is nearly pure Fe, the liquid outer core density ranges from 7300 to 7900 kg/m³. In both scenarios, a “snow” regime is plausible, though with distinct settling times. The ternary phase diagram indicates that Mercury is likely to develop a structurally layered inner core during secular cooling.<br>
en-copyright=
kn-copyright=

en-aut-name=ZhaoBin
en-aut-sei=Zhao
en-aut-mei=Bin
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=ZhuJintao
en-aut-sei=Zhu
en-aut-mei=Jintao
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=AntonangeliDaniele
en-aut-sei=Antonangeli
en-aut-mei=Daniele
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=MorardGuillaume
en-aut-sei=Morard
en-aut-mei=Guillaume
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

en-aut-name=ChenQi
en-aut-sei=Chen
en-aut-mei=Qi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=6
ORCID=

affil-num=1
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=2
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=3
en-affil=Muséum National d’Histoire Naturelle, Sorbonne Université, UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC
kn-affil=

affil-num=4
en-affil=Muséum National d’Histoire Naturelle, Sorbonne Université, UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC
kn-affil=

affil-num=5
en-affil=Center for Advanced Radiation Sources, University of Chicago
kn-affil=

affil-num=6
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=
en-keyword=planetary core
kn-keyword=planetary core
en-keyword=phase diagram
kn-keyword=phase diagram
en-keyword=multi-anvil experiments
kn-keyword=multi-anvil experiments
en-keyword=iron alloy
kn-keyword=iron alloy
END

start-ver=1.4
cd-journal=joma
no-vol=7
cd-vols=
no-issue=1
article-no=
start-page=265
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2026
dt-pub=20260325
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Stability and distribution of dense hydrous magnesium silicates in the mantle transition zone under low water activity conditions
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=Water plays a central role in controlling the physical and chemical properties of Earth’s deep interior. It remains uncertain how water is stored in subducting slabs within the mantle transition zone, between depths of about 410 and 660 kilometers, and whether dense hydrous magnesium silicates act as major water carriers to greater depths. Here we report high-pressure and high-temperature laboratory experiments on the Mg-Si-H system at pressures of 16 and 21.5 GPa and a temperature of 1400 K to evaluate hydrous phase stability under transition zone conditions. We find that when bulk water content is below 1.22 wt%, H2O is predominantly incorporated into wadsleyite and ringwoodite rather than forming dense hydrous magnesium silicates. Because estimated water contents in subducted oceanic slabs are typically lower than one weight percent, formation of these silicates is unlikely, suggesting that the mantle transition zone may restrict large scale water transport into the lower mantle.
en-copyright=
kn-copyright=

en-aut-name=SongYunke
en-aut-sei=Song
en-aut-mei=Yunke
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=GuoXinzhuan
en-aut-sei=Guo
en-aut-mei=Xinzhuan
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=ZhaiKuan
en-aut-sei=Zhai
en-aut-mei=Kuan
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=GuoWei
en-aut-sei=Guo
en-aut-mei=Wei
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=

affil-num=1
en-affil=Key Laboratory of High-temperature and High-pressure Study of the Earth’s Interior, Institute of Geochemistry, Chinese Academy of Sciences
kn-affil=

affil-num=2
en-affil=State Key Laboratory of Critical Mineral Research and Exploration, Institute of Geochemistry, Chinese Academy of Sciences
kn-affil=

affil-num=3
en-affil=Key Laboratory of High-temperature and High-pressure Study of the Earth’s Interior, Institute of Geochemistry, Chinese Academy of Sciences
kn-affil=

affil-num=4
en-affil=State Key Laboratory of Geomicrobiology and Environmental Changes, School of Earth Sciences, China University of Geosciences (Wuhan)
kn-affil=

affil-num=5
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=
END

start-ver=1.4
cd-journal=joma
no-vol=53
cd-vols=
no-issue=5
article-no=
start-page=e2025GL119568
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2026
dt-pub=20260303
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Electrical Conductivity of Amorphous and Molten CaCO3 at High Pressures and Its Implications for Mantle Conductivity Anomalies
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=Impedance spectrometry experiments have been conducted on CaCO3 up to 15 GPa and 2,100 K to identify its state under high pressure. The melting temperature of CaCO3 was also determined by the falling of a Re sphere observed via X-ray radiography. The phase transition from aragonite to the amorphous phase does not cause a leap in the Electrical conductivity (EC), while a drastic increase in the EC, by 1.5–2.0 log units, only occurs with the onset of melting. The EC of amorphous CaCO3 is comparable to other hydrous mantle minerals at similar pressure and temperature conditions. The required fraction of amorphous CaCO3 implies that it can be excluded from the potential origins responsible for the observed high EC anomalies in the upper mantle. If the conductivity anomalies are induced by the presence of carbonate, a low-degree melting of carbonate-bearing peridotite is anticipated.
en-copyright=
kn-copyright=

en-aut-name=ZhaoBin
en-aut-sei=Zhao
en-aut-mei=Bin
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=ChenQi
en-aut-sei=Chen
en-aut-mei=Qi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=YuTony
en-aut-sei=Yu
en-aut-mei=Tony
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

en-aut-name=ZhangDongzhou
en-aut-sei=Zhang
en-aut-mei=Dongzhou
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=

en-aut-name=ChenBin
en-aut-sei=Chen
en-aut-mei=Bin
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=6
ORCID=

en-aut-name=WangYanbin
en-aut-sei=Wang
en-aut-mei=Yanbin
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=7
ORCID=

affil-num=1
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=2
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=3
en-affil=Center for Advanced Radiation Sources, The University of Chicago
kn-affil=

affil-num=4
en-affil=Center for Advanced Radiation Sources, The University of Chicago
kn-affil=

affil-num=5
en-affil=Center for Advanced Radiation Sources, The University of Chicago
kn-affil=

affil-num=6
en-affil=School of Ocean and Earth Science and Technology, University of Hawaii at Manoa
kn-affil=

affil-num=7
en-affil=Center for Advanced Radiation Sources, The University of Chicago
kn-affil=
END

start-ver=1.4
cd-journal=joma
no-vol=131
cd-vols=
no-issue=1
article-no=
start-page=e2025JB033390
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2026
dt-pub=202601
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Electrical Conductivity of Carbonatite Melts to 20 GPa: Constraints on Partial Melting Atop the 410‐km Discontinuity and in the Lower Mantle Transition Zone
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=Deep-origin carbonatite melts are considered to be the products of partial-melting of the oceanic crust in the subduction zones. In this study, we conducted electrical conductivity (EC) measurements on two samples, the composition of which resemble the partial-melting products atop the 410-km discontinuity and in the lower part of the transition zone. The EC of carbonatite melts was investigated using impedance spectroscopy combined with a multi-anvil press up to 20 GPa. Pressure has a great effect on the EC of the carbonatite melts. While the EC dropped overall by 0.6 log unit from 3 to 20 GPa for varying compositions, the pressure effect becomes weaker above 10 GPa. The Hashin-Shtrikman mixing model indicates that melt fraction of 0–0.3 vol% is necessary to account for the EC atop the 410-km discontinuity beneath NE China, north Philippine Sea, north Pacific, and Australian craton. However, this value soars to 1–4.5 vol% for the lower part of the transition zone in the same regions, and further increases to 3.7–7.3 vol% for cold subduction regions if the slab surface temperature is 300 K lower. The difference in the needed melt fraction at different depths implies that the magnitude of partial melting is much larger in the lower part of the mantle transition zone, and it is thus likely to be the main barrier to the recycled carbonates towards the deep interior.
en-copyright=
kn-copyright=

en-aut-name=ZhaoBin
en-aut-sei=Zhao
en-aut-mei=Bin
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=ZhuJintao
en-aut-sei=Zhu
en-aut-mei=Jintao
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=ChenQi
en-aut-sei=Chen
en-aut-mei=Qi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

affil-num=1
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=2
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=3
en-affil=Center for Advanced Radiation Sources, University of Chicago
kn-affil=

affil-num=4
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=
en-keyword=carbon
kn-keyword=carbon
en-keyword=carbonatite melts
kn-keyword=carbonatite melts
en-keyword=electrical conductivity
kn-keyword=electrical conductivity
en-keyword=impedance spectroscopy
kn-keyword=impedance spectroscopy
en-keyword=multi-anvil press
kn-keyword=multi-anvil press
END

start-ver=1.4
cd-journal=joma
no-vol=
cd-vols=
no-issue=
article-no=
start-page=
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2025
dt-pub=20251028
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=The effect of pressure on dihedral angle between liquid Fe‐S and orthopyroxene: Implication for percolative core formation in planetesimals and planetary embryos
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=During precursor stages of planet formation, many planetesimals and planetary embryos are considered to have differentiated, forming an iron-alloy core and silicate mantle. Percolation of liquid iron-alloy in solid silicates is one of the major possible differentiation processes in these small bodies. Based on the dihedral angles between Fe-S melts and olivine, a criterion for determining whether melt can percolate through a solid, it has been reported that Fe-S melt can percolate through olivine matrices below 3 GPa in an oxidized environment. However, the dihedral angle between Fe-S melts and orthopyroxene (opx), the second most abundant mineral in the mantles of small bodies, has not yet been determined. In this study, high-pressure and high-temperature experiments were conducted under the conditions of planetesimal and planetary embryo interiors, 0.5–5.0 GPa, to determine the effect of pressure on the dihedral angle between Fe-S melts and opx. Dihedral angles tend to increase with pressure, although the pressure dependence is markedly reduced above 4 GPa. The dihedral angle is below the percolation threshold of 60° at pressures below 1.0–1.5 GPa, indicating that percolative core formation is possible in opx-rich interiors of bodies where internal pressures are lower than 1.0–1.5 GPa. The oxygen content of Fe-S melt decreases with increasing pressure. High oxygen contents in Fe-S melt reduce interfacial tension between Fe-S melt and opx, resulting in reduced dihedral angles at low pressure. Combined with previous results for dihedral angle variation of the olivine/Fe-S system, percolative core formation possibly occurs throughout bodies up to a radius of 1340 km for an olivine-dominated mantle, and up to 770 km for an opx-dominated mantle, in the case of S-rich cores segregating under relatively oxidizing conditions. For mantles of small bodies in which abundant olivine and opx coexist, the mineral with the largest volume fraction and/or smallest grain size will allow formation of interconnected mineral channels, and, therefore, the wetting property of this mineral determines the wettability of the melt, that is, controls core formation.
en-copyright=
kn-copyright=

en-aut-name=MiuraTakumi
en-aut-sei=Miura
en-aut-mei=Takumi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=TerasakiHidenori
en-aut-sei=Terasaki
en-aut-mei=Hidenori
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=TakakiHyu
en-aut-sei=Takaki
en-aut-mei=Hyu
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=KobayashiKotaro
en-aut-sei=Kobayashi
en-aut-mei=Kotaro
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

en-aut-name=BromileyGeoffrey David
en-aut-sei=Bromiley
en-aut-mei=Geoffrey David
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=6
ORCID=

affil-num=1
en-affil=Department of Earth and Space Science, Osaka University
kn-affil=

affil-num=2
en-affil=Department of Earth Sciences, Okayama University
kn-affil=

affil-num=3
en-affil=Department of Earth Sciences, Okayama University
kn-affil=

affil-num=4
en-affil=Department of Earth Sciences, Okayama University
kn-affil=

affil-num=5
en-affil=School of Geosciences, The University of Edinburgh
kn-affil=

affil-num=6
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=
END

start-ver=1.4
cd-journal=joma
no-vol=130
cd-vols=
no-issue=10
article-no=
start-page=e2025JB032215
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2025
dt-pub=202510
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Electrical Conductivity of Carbonated Hydrous Basaltic Melt: Implications for the Conductivity Anomaly Beneath the Ocean Floors
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=We measured the electrical conductivity of CO2 and H2O-bearing basaltic melts up to 1750 K at 2 GPa, corresponding to pressure around the lithosphere-asthenosphere boundary. The electrical conductivity of the dry and hydrous samples is comparable to those reported by previous studies on the Fe-free basaltic melt. The substantial CO2 can limit the water solubility in basaltic melt at 2 GPa. Both CO2 and H2O, which cannot completely dissolve in the melt, coexist as fluid phases, resulting in reduced electrical conductivity of the basaltic melt, which has a lower water content relative to the amount of volatile components in the bulk starting system. The activation enthalpy of basaltic melt is markedly higher than those of more evolved silicate melts, especially on the H2O-poor condition, due to the more enriched alkaline earth elements. The present results suggest that an overall melt fraction of 0.1–5.3 vol% is needed to account for the high electrical conductivity anomalies (10−1.3 to 10−0.3 S/m) beneath the oceanic plate near the East Pacific Rise and Cocos plate. However, for those regions where the electrical conductivity is extremely high (≥10−0.3 S/m), more than 6 wt% H2O is expected to incorporate to maintain a melt fraction that will not trigger mechanical instability. In turn, it requires a low CO2 budget or degree of carbonation within these regions.
en-copyright=
kn-copyright=

en-aut-name=ZhaoBin
en-aut-sei=Zhao
en-aut-mei=Bin
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=ZhuJintao
en-aut-sei=Zhu
en-aut-mei=Jintao
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=HeJinze
en-aut-sei=He
en-aut-mei=Jinze
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

affil-num=1
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=2
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=3
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=4
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=
en-keyword=electrical conductivity
kn-keyword=electrical conductivity
en-keyword=basaltic melts
kn-keyword=basaltic melts
en-keyword=oceanic floors
kn-keyword=oceanic floors
en-keyword=high pressure
kn-keyword=high pressure
END

start-ver=1.4
cd-journal=joma
no-vol=52
cd-vols=
no-issue=14
article-no=
start-page=e2024GL114146
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2025
dt-pub=20250718
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Unraveling the Complex Features of the Seismic Scatterers in the Mid‐Lower Mantle Through Phase Transition of (Al, H)‐Bearing Stishovite
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=Small-scale scatterers observed in the mid-lower mantle beneath the subduction zones are thought to result from the phase transition of stishovite within subducted oceanic crusts. Here we investigate the phase transition of (Al, H)-bearing stishovite with four compositions at simultaneously high P-T conditions combining Raman spectroscopy and X-ray diffraction. These experimental results reveal that the incorporation of 0.01 a.p.f.u Al into stishovite with H/Al ratio of ∼1/3 lowers the transition pressure by 6.7(3) GPa. However, the Clapeyron slope of this transition is nearly unaffected by changes in the Al content and has a value of 12.2–12.5(3) MPa/K. According to our results, Al content variation ranging from 0 to 0.07 a.p.f.u in SiO2 can reasonably explain the depth distribution from 800 to 1,900 km of the seismic scatterers observed in the circum-Pacific region. These results deepen our understanding on the complex features of mid-lower mantle seismic scatterers and corresponding dynamic processes.
en-copyright=
kn-copyright=

en-aut-name=YuYingxin
en-aut-sei=Yu
en-aut-mei=Yingxin
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=ZhangYouyue
en-aut-sei=Zhang
en-aut-mei=Youyue
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=LiLuo
en-aut-sei=Li
en-aut-mei=Luo
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=ZhangXinyue
en-aut-sei=Zhang
en-aut-mei=Xinyue
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

en-aut-name=WangDenglei
en-aut-sei=Wang
en-aut-mei=Denglei
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=

en-aut-name=MaoZhu
en-aut-sei=Mao
en-aut-mei=Zhu
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=6
ORCID=

en-aut-name=SunNingyu
en-aut-sei=Sun
en-aut-mei=Ningyu
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=7
ORCID=

en-aut-name=ZhangYanyao
en-aut-sei=Zhang
en-aut-mei=Yanyao
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=8
ORCID=

en-aut-name=LiXinyang
en-aut-sei=Li
en-aut-mei=Xinyang
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=9
ORCID=

en-aut-name=LiWancai
en-aut-sei=Li
en-aut-mei=Wancai
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=10
ORCID=

en-aut-name=SpezialeSergio
en-aut-sei=Speziale
en-aut-mei=Sergio
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=11
ORCID=

en-aut-name=ZhangDongzhou
en-aut-sei=Zhang
en-aut-mei=Dongzhou
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=12
ORCID=

en-aut-name=LinJung‐Fu
en-aut-sei=Lin
en-aut-mei=Jung‐Fu
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=13
ORCID=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=14
ORCID=

affil-num=1
en-affil=Deep Space Exploration Laboratory, School of Earth and Space Sciences, University of Science and Technology of China
kn-affil=

affil-num=2
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=3
en-affil=Deep Space Exploration Laboratory, School of Earth and Space Sciences, University of Science and Technology of China
kn-affil=

affil-num=4
en-affil=Deep Space Exploration Laboratory, School of Earth and Space Sciences, University of Science and Technology of China
kn-affil=

affil-num=5
en-affil=Deep Space Exploration Laboratory, School of Earth and Space Sciences, University of Science and Technology of China
kn-affil=

affil-num=6
en-affil=Deep Space Exploration Laboratory, School of Earth and Space Sciences, University of Science and Technology of China
kn-affil=

affil-num=7
en-affil=Deep Space Exploration Laboratory, School of Earth and Space Sciences, University of Science and Technology of China
kn-affil=

affil-num=8
en-affil=Earth and Planetary Sciences, Stanford University
kn-affil=

affil-num=9
en-affil=State Key Laboratory of High Pressure and Superhard Materials, College of Physics, Jilin University
kn-affil=

affil-num=10
en-affil=CAS Key Laboratory of Crust‐Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China
kn-affil=

affil-num=11
en-affil=GFZ German Research Centre for Geosciences
kn-affil=

affil-num=12
en-affil=GeoSoilEnviroCARS, University of Chicago
kn-affil=

affil-num=13
en-affil=Department of Earth and Planetary Sciences, Jackson School of Geosciences, The University of Texas at Austin
kn-affil=

affil-num=14
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=
en-keyword=(Al, H)-bearing stishovite
kn-keyword=(Al, H)-bearing stishovite
en-keyword=phase transition
kn-keyword=phase transition
en-keyword=mid-lower mantle
kn-keyword=mid-lower mantle
en-keyword=small-scale seismic scatterers
kn-keyword=small-scale seismic scatterers
END

start-ver=1.4
cd-journal=joma
no-vol=59
cd-vols=
no-issue=6
article-no=
start-page=1314
end-page=1328
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2024
dt-pub=20240310
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Wetting property of Fe‐S melt in solid core: Implication for the core crystallization process in planetesimals
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=In differentiated planetesimals, the liquid core starts to crystallize during secular cooling, followed by the separation of liquid–solid phases in the core. The wetting property between liquid and solid iron alloys determines whether the core melts are trapped in the solid core or they can separate from the solid core during core crystallization. In this study, we performed high-pressure experiments under the conditions of the interior of small bodies (0.5–3.0 GPa) to study the wetting property (dihedral angle) between solid Fe and liquid Fe-S as a function of pressure and duration. The measured dihedral angles are approximately constant after 2 h and decrease with increasing pressure. The dihedral angles range from 30° to 48°, which are below the percolation threshold of 60° at 0.5–3.0 GPa. The oxygen content in the melt decreases with increasing pressure and there are strong positive correlations between the S + O or O content and the dihedral angle. Therefore, the change in the dihedral angle is likely controlled by the O content of the Fe-S melt, and the dihedral angle tends to decrease with decreasing O content in the Fe-S melt. Consequently, the Fe-S melt can form interconnected networks in the solid core. In the obtained range of the dihedral angle, a certain amount of the Fe-S melt can stably coexist with solid Fe, which would correspond to the “trapped melt” in iron meteorites. Excess amounts of the melt would migrate from the solid core over a long period of core crystallization in planetesimals.
en-copyright=
kn-copyright=

en-aut-name=MatsubaraShiori
en-aut-sei=Matsubara
en-aut-mei=Shiori
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=TerasakiHidenori
en-aut-sei=Terasaki
en-aut-mei=Hidenori
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=UrakawaSatoru
en-aut-sei=Urakawa
en-aut-mei=Satoru
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

en-aut-name=YumitoriDaisuke
en-aut-sei=Yumitori
en-aut-mei=Daisuke
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=

affil-num=1
en-affil=Department of Earth Sciences, Graduate School of Science and Technology, Okayama University
kn-affil=

affil-num=2
en-affil=Department of Earth Sciences, Graduate School of Science and Technology, Okayama University
kn-affil=

affil-num=3
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=4
en-affil=Department of Earth Sciences, Graduate School of Science and Technology, Okayama University
kn-affil=

affil-num=5
en-affil=Department of Earth Sciences, Graduate School of Science and Technology, Okayama University
kn-affil=
END

start-ver=1.4
cd-journal=joma
no-vol=8
cd-vols=
no-issue=13
article-no=
start-page=eabm1821
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2022
dt-pub=20220330
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Viscosity of bridgmanite determined by in situ stress and strain measurements in uniaxial deformation experiments
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=To understand mantle dynamics, it is important to determine the rheological properties of bridgmanite, the dominant mineral in Earth’s mantle. Nevertheless, experimental data on the viscosity of bridgmanite are quite limited due to experimental difficulties. Here, we report viscosity and deformation mechanism maps of bridgmanite at the uppermost lower mantle conditions obtained through in situ stress-strain measurements of bridgmanite using deformation apparatuses with the Kawai-type cell. Bridgmanite would be the hardest among mantle constituent minerals even under nominally dry conditions in the dislocation creep region, consistent with the observation that the lower mantle is the hardest layer. Deformation mechanism maps of bridgmanite indicate that grain size of bridgmanite and stress conditions at top of the lower mantle would be several millimeters and ~105 Pa to realize viscosity of 1021–22 Pa·s, respectively. This grain size of bridgmanite suggests that the main part of the lower mantle is isolated from the convecting mantle as primordial reservoirs.
en-copyright=
kn-copyright=

en-aut-name=TsujinoNoriyoshi
en-aut-sei=Tsujino
en-aut-mei=Noriyoshi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=YamazakiDaisuke
en-aut-sei=Yamazaki
en-aut-mei=Daisuke
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=NishiharaYu
en-aut-sei=Nishihara
en-aut-mei=Yu
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

en-aut-name=HigoYuji
en-aut-sei=Higo
en-aut-mei=Yuji
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=

en-aut-name=TangeYoshinori
en-aut-sei=Tange
en-aut-mei=Yoshinori
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=6
ORCID=

affil-num=1
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=2
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=3
en-affil=Geodynamics Research Center, Ehime University
kn-affil=

affil-num=4
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=5
en-affil=Japan Synchrotron Radiation Research Institute
kn-affil=

affil-num=6
en-affil=Japan Synchrotron Radiation Research Institute
kn-affil=
END

start-ver=1.4
cd-journal=joma
no-vol=14
cd-vols=
no-issue=19
article-no=
start-page=5476
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2021
dt-pub=20210922
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Electrical Resistivity of Cu and Au at High Pressure above 5 GPa: Implications for the Constant Electrical Resistivity Theory along the Melting Curve of the Simple Metals
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=The electrical resistivity of solid and liquid Cu and Au were measured at high pressures from 6 up to 12 GPa and temperatures & SIM;150 K above melting. The resistivity of the metals was also measured as a function of pressure at room temperature. Their resistivity decreased and increased with increasing pressure and temperature, respectively. With increasing pressure at room temperature, we observed a sharp reduction in the magnitude of resistivity at & SIM;4 GPa in both metals. In comparison with 1 atm data and relatively lower pressure data from previous studies, our measured temperature-dependent resistivity in the solid and liquid states show a similar trend. The observed melting temperatures at various fixed pressure are in reasonable agreement with previous experimental and theoretical studies. Along the melting curve, the present study found the resistivity to be constant within the range of our investigated pressure (6-12 GPa) in agreement with the theoretical prediction. Our results indicate that the invariant resistivity theory could apply to the simple metals but at higher pressure above 5 GPa. These results were discussed in terms of the saturation of the dominant nuclear screening effect caused by the increasing difference in energy level between the Fermi level and the d-band with increasing pressure.
en-copyright=
kn-copyright=

en-aut-name=EzenwaInnocent C.
en-aut-sei=Ezenwa
en-aut-mei=Innocent C.
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

affil-num=1
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=2
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=
en-keyword=electrical resistivity
kn-keyword=electrical resistivity
en-keyword=thermal conductivity
kn-keyword=thermal conductivity
en-keyword=electrons and phonons interactions
kn-keyword=electrons and phonons interactions
en-keyword=high pressure and temperature
kn-keyword=high pressure and temperature
en-keyword=constant resistivity
kn-keyword=constant resistivity
en-keyword=melting curve
kn-keyword=melting curve
END

start-ver=1.4
cd-journal=joma
no-vol=91
cd-vols=
no-issue=3
article-no=
start-page=035115
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2020
dt-pub=20200319
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Measurement of the Seebeck coefficient under high pressure by dual heating 
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=This study presents a new method for measuring the Seebeck coefficient under high pressure in a multi-anvil apparatus. The application of a dual-heating system enables precise control of the temperature difference between both ends of the sample in a high-pressure environment. Two pairs of W–Re thermocouples were employed at both ends of the sample to monitor and control the temperature difference, and independent probes were arranged to monitor the electromotive force (emf) produced by temperature oscillation at a given target temperature. The temperature difference was controlled within 1 K during the resistivity measurements to eliminate the influence of the emf owing to a sample temperature gradient. The Seebeck measurement was successfully measured from room temperature to 1400 K and was obtained by averaging the two measured values with opposite thermal gradient directions (∼20 K). Thermoelectric properties were measured on disk-shaped p-type Si wafers with two different carrier concentrations as a reference for high Seebeck coefficients. This method is effective to determine the thermoelectric power of materials under pressure.
en-copyright=
kn-copyright=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=WangRan
en-aut-sei=Wang
en-aut-mei=Ran
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=GomiHitoshi
en-aut-sei=Gomi
en-aut-mei=Hitoshi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=MoriYoshihisa
en-aut-sei=Mori
en-aut-mei=Yoshihisa
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

affil-num=1
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=2
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=3
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=4
en-affil=3Department of Applied Science, Okayama University of Science
kn-affil=
END

start-ver=1.4
cd-journal=joma
no-vol=530
cd-vols=
no-issue=
article-no=
start-page=115887
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2019
dt-pub=20191023
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Grain boundary diffusion of W in lower mantle phase with implications for isotopic heterogeneity in oceanic island basalts by core-mantle interactions
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=Tungsten isotopes provide important constraints on the ocean-island basalt (OIB) source regions. Recent analyses of μ182W in modern basalts with high 3He/4He originating from the core-mantle boundary region reveal two distinct features: positive μ182W in Phanerozoic flood basalts indicating the presence of primordial reservoir, and negative μ182W in modern OIBs. One possibility to produce large variations in μ182W is interaction between the mantle and outer core. Here, we report grain boundary diffusion of W in lower mantle phases. High pressure experimental results show that grain boundary diffusion of W is fast and strongly temperature dependent. Over Earth's history, diffusive transport of W from the core to the lowermost mantle may have led to significant modification of the W isotopic composition of the lower mantle at length scales exceeding one kilometer. Such grain boundary diffusion can lead to large variations in μ182W in modern basalts as a function of the distance of their source regions from the core mantle boundary. Modern oceanic island basalts from Hawaii, Samoa and Iceland exhibit negative μ182W and likely originated from the modified isotope region just above the core-mantle boundary, whereas those with positive μ182W could be derived from the thick Large Low Shear Velocity Provinces (LLSVPs) far from the core-mantle boundary (CMB). When highly-oxidized slabs accumulate at the CMB oxidizing the outer core at the interface, a large W flux with negative μ182W can be added to the silicate mantle. As a result, the source region of the OIB would be effectively modified to a negative μ182W.
en-copyright=
kn-copyright=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=MakinoYoshiki
en-aut-sei=Makino
en-aut-mei=Yoshiki
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=SuzukiToshihiro
en-aut-sei=Suzuki
en-aut-mei=Toshihiro
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=HirataTakafumi
en-aut-sei=Hirata
en-aut-mei=Takafumi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

affil-num=1
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=2
en-affil=Geochemical Research Center, The University of Tokyo
kn-affil=

affil-num=3
en-affil=Geochemical Research Center, The University of Tokyo
kn-affil=

affil-num=4
en-affil=Geochemical Research Center, The University of Tokyo
kn-affil=
en-keyword=core mantle interaction
kn-keyword=core mantle interaction
en-keyword=grain boundary diffusion
kn-keyword=grain boundary diffusion
en-keyword=high pressure experiment
kn-keyword=high pressure experiment
en-keyword=postspinel
kn-keyword=postspinel
en-keyword=W isotope
kn-keyword=W isotope
en-keyword=core mantle boundary
kn-keyword=core mantle boundary
END

start-ver=1.4
cd-journal=joma
no-vol=100
cd-vols=
no-issue=21
article-no=
start-page=214302
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2019
dt-pub=20191205
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Resistivity, Seebeck coefficient, and thermal conductivity of platinum at high pressure and temperature
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract= Platinum (Pt) is one of the most widely used functional materials for high-pressure and high-temperature experiments. Despite the crucial importance of its transport properties, both experimental and theoretical studies are very limited. In this study, we conducted density functional theory calculations on the electrical resistivity, the Seebeck coefficient, and the thermal conductivity of solid face-centered cubic Pt at pressures up to 200 GPa and temperatures up to 4800 K by using the Kubo-Greenwood formula. The thermal lattice displacements were treated within the alloy analogy, which is represented by means of the Korringa-Kohn-Rostoker method with the coherent potential approximation. The electrical resistivity decreases with pressure and increases with temperature. These two conflicting effects yield a constant resistivity of similar to 70 mu Omega cm along the melting curve. Both pressure and temperature effects enhance the thermal conductivity at low temperatures, but the temperature effect becomes weaker at high temperatures. Although the pressure dependence of the Seebeck coefficient is negligibly small at temperatures below similar to 1500 K, it becomes larger at higher temperatures. It requires a calibration of a thermocouple such as Pt-Rh in high-pressure and -temperature experiments.
en-copyright=
kn-copyright=

en-aut-name=GomiHitoshi
en-aut-sei=Gomi
en-aut-mei=Hitoshi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

affil-num=1
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=2
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=
END

start-ver=1.4
cd-journal=joma
no-vol=103
cd-vols=
no-issue=8
article-no=
start-page=1271
end-page=1281
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2018
dt-pub=20180801
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=The effects of ferromagnetism and interstitial hydrogen on the equation of states of hcp and dhcp FeHx: Implications for the Earth's inner core age
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract= Hydrogen has been considered as an important candidate of light elements in the Earth's core. Because iron hydrides are unquenchable, hydrogen content is usually estimated from in situ X-ray diffraction measurements that assume the following linear relation: x = (V-FeHx - V-Fe)/Delta V-H, where x is the hydrogen content, Delta V-H is the volume expansion caused by unit concentration of hydrogen, and V-FeHx and V-Fe are volumes of FeHx and pure iron, respectively. To verify the linear relationship, we computed the equation of states of hexagonal iron with interstitial hydrogen by using the Korringa-Kohn-Rostoker method with the coherent potential approximation (KKR-CPA). The results indicate a discontinuous volume change at the magnetic transition and almost no compositional (x) dependence in the ferromagnetic phase at 20 GPa, whereas the linearity is confirmed in the non-magnetic phase. In addition to their effect on the density-composition relationship in the Fe-FeHx system, which is important for estimating the hydrogen incorporation in planetary cores, the magnetism and interstitial hydrogen also affect the electrical resistivity of FeHx. The thermal conductivity can be calculated from the electrical resistivity by using the Wiedemann-Franz law, which is a critical parameter for modeling the thermal evolution of the Earth. Assuming an Fe1-ySiyHx ternary outer core model (0.0 <= x <= 0.7), we calculated the thermal conductivity and the age of the inner core. The resultant thermal conductivity is similar to 100 W/m/K and the maximum inner core age ranges from 0.49 to 0.86 Gyr.
en-copyright=
kn-copyright=

en-aut-name=GomiHitoshi
en-aut-sei=Gomi
en-aut-mei=Hitoshi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=FeiYingwei
en-aut-sei=Fei
en-aut-mei=Yingwei
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

affil-num=1
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=2
en-affil=Geophysical Laboratory, Carnegie Institution of Washington
kn-affil=

affil-num=3
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=
en-keyword=FeHx
kn-keyword=FeHx
en-keyword=ferromagnetism
kn-keyword=ferromagnetism
en-keyword=chemical disorder
kn-keyword=chemical disorder
en-keyword=equation of states
kn-keyword=equation of states
en-keyword=KKR-CPA
kn-keyword=KKR-CPA
END

start-ver=1.4
cd-journal=joma
no-vol=6
cd-vols=
no-issue=
article-no=
start-page=217
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2018
dt-pub=20181129
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Impurity Resistivity of fcc and hcp Fe-Based Alloys: Thermal Stratification at the Top of the Core of Super-Earths
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract= It is widely known that the Earth's Fe dominant core contains a certain amount of light elements such as H, C, N, O, Si, and S. We report the results of first-principles calculations on the band structure and the impurity resistivity of substitutionally disordered hcp and fcc Fe based alloys. The calculation was conducted by using the AkaiKKR (machikaneyama) package, which employed the Korringa-Kohn-Rostoker (KKR) method with the atomic sphere approximation (ASA). The local density approximation (LDA) was adopted for the exchange-correlation potential. The coherent potential approximation (CPA) was used to treat substitutional disorder effect. The impurity resistivity is calculated from the Kubo-Greenwood formula with the vertex correction. In dilute alloys with 1 at. % impurity concentration, calculated impurity resistivities of C, N, O, S are comparable to that of Si. On the other hand, in concentrated alloys up to 30 at. %, Si impurity resistivity is the highest followed by C impurity resistivity. Ni impurity resistivity is the smallest. N, O, and S impurity resistivities lie between Si and Ni. Impurity resistivities of hcp-based alloys show systematically higher values than fcc alloys. We also calculated the electronic specific heat from the density of states (DOS). For pure Fe, the results show the deviation from the Sommerfeld value at high temperature, which is consistent with previous calculation. However, the degree of deviation becomes smaller with increasing impurity concentration. The violation of the Sommerfeld expansion is one of the possible sources of the violation of the Wiedemann-Franz law, but the present results could not resolve the inconsistency between recent electrical resistivity and thermal conductivity measurements. Based on the present thermal conductivity model, we calculated the conductive heat flux at the top of terrestrial cores, which is comparable to the heat flux across the thermal boundary layer at the bottom of the mantle. This indicates that the thermal stratification may develop at the top of the liquid core of super-Earths, and hence, chemical buoyancies associated with the inner core growth and/or precipitations are required to generate the global magnetic field through the geodynamo.
en-copyright=
kn-copyright=

en-aut-name=GomiHitoshi
en-aut-sei=Gomi
en-aut-mei=Hitoshi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=YoshinoTakashi
en-aut-sei=Yoshino
en-aut-mei=Takashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

affil-num=1
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=

affil-num=2
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=
en-keyword=band structure
kn-keyword=band structure
en-keyword=density of states
kn-keyword=density of states
en-keyword=electrical resistivity
kn-keyword=electrical resistivity
en-keyword=thermal conductivity
kn-keyword=thermal conductivity
en-keyword=Linde's rule
kn-keyword=Linde's rule
en-keyword=KKR-CPA
kn-keyword=KKR-CPA
END