Publications

2024 and Papers in press

[54] Okuda, Y., Hirose, K., Ohta, K., Kawaguchi-Imada, S., & Oka, K. Electrical conductivity of dense MgSiO3 melt under static compression. Geophysical Research Letters. 51, e2024GL109741. https://doi.org/10.1029/ 2024GL109741

[53] Kawaguchi-Imada, S., Sinmyo, R., Ohta, K., Kawaguchi, S., & Kobayashi, T. Submillisecond in situ X-ray diffraction measurement system with changing temperature and pressure using diamond anvil cells at beamline BL10XU/SPring-8. Journal of Synchrotron Radiation. 31, 343–354.


2023

[52] Ohta, K., Suehiro, S., Kawaguchi, S., Okuda, Y., Wakamatsu, T., Hirose, K., Ohishi, Y., Kodama, M., Hirai, S., & Azuma, S. Measuring the electrical resistivity of liquid iron to 1.4 Mbar. Physical Review Letters, 130, 266301.

[51] Nagaya, Y., Gomi, H., Ohta, K., & Hirose, K. Equations of state for B2 and bcc Fe1-xSix. Physics of the Earth and Planetary Interirors, 341, 107046.

[50] Ohta, K. Ammonia and the ice giants. Nature Physics, https://doi.org/10.1038/s41567-023-02081-9.

[49] Park, Y., Yonemitsu, K., Hirose, K., Kuwayama, Y., Azuma, S., & Ohta, K. Viscosity of Earth's inner core constrained by Fe-Ni interdiffusion in Fe-Si alloy in an internal-resistive-heated diamond anvil cell. American Mineralogist, 108, 1064–1071.

[48] Okuda, Y. & Ohta, K. Heat flow from the Earth's core inferred from experimentally determined thermal conductivity of the deep lower mantle. Core-manltle Co-evolution: An interdisciplinary Approarch AGU monograph, 133–144.

[47] Hasegawa, A., Ohta, K., Yagi, T., & Hirose, K. Thermal conductivity of platinum and periclase under extreme conditions of pressure and temperature. High Pressure Research, https://doi.org/10.1080/08957959.2023.2193892.


2022

[46] Okuda, Y., Oka, K., Kubota, Y., Inada, M., Kurita, N., Ohta, K., & Hirose, K. High P–T impedance measurements using a laser-heated diamond anvil cell. Review of Scientific Instruments, 93, 105103. https://doi.org/10.1063/5.0097883

[45] Wakamatsu, T., Ohta, K., Tagawa, S., Yagi, T., Hirose, K., & Ohishi, Y. Compressional wave velocity for iron hydrides to 100 gigapascals via picosecond acoustics. Physics and Chemistry of Minerals, 49, 17. https://doi.org/10.1007/s00269-022-01192-8

[44] Aoyama, T., Ohta, K., Shimizu, K., & Ohgushi, K. Persistent spin-orbit Mott insulating state in highly compressed post-perovskite CaIrO3. Journal of the Physical Society of Japan, 91, 045003. https://doi.org/10.7566/JPSJ.91.045003

2021

[43] Zhang, Z., Zhang, D. -B., Onga, K., Hasegawa, A., Ohta, K., Hirose, K., & Wentzcovitch, R. Thermal conductivity of CaSiO3 perovskite. Physical Review B, 104, 184101. https://doi.org/10.1103/PhysRevB.104.184101 

[42] Sakuraba, H., Kurokawa, Y., Genda, H., & Ohta, K. Numerous chondritic impactors and oxdized magma ocean set Earth's volatile depletion. Scietific Reports, 11, 20894. https://doi.org/10.1038/s41598-021-99240-w

[41] Okuda, Y., Ohta, K., Nishihara, Y., Hirao, N., Wakamatsu, T., Suehiro, S., Kawaguchi, I. S., & Ohishi, Y. Low-spin ferric iron in primordial bridgmanite crystallized from a deep magma ocean. Scientific Reports, 11, 19471. https://doi.org/10.1038/s41598-021-98991-w

[40] Ohta, K., & Hirose, K. The thermal conductivity of the Earth's core and implications for its therma and compositional evolution. National Science Review, 8, nwaa303.  https://doi.org/10.1093/nsr/nwaa303

[39] Okuda, Y., Kimura, S., Ohta, K., Park, Y., Wakamatsu, T., Mashino, I., & Hirose, K. A cylindrical SiC heater for an externally heated diamond anvil cell to 1500 K. Review of Scientific Instruments, 92, 015119. https://doi.org/10.1063/5.0036551

2020

[38] Ohta, K., Wakamatsu, T., Kodama, M., Kawamura, K., & Hirai, S. Laboratory-based X-ray computed tomography for 3D imaging of samples in a diamond anvil cell in situ at high pressures. Review of Scientific Instruments, 91, 093703 (2020). https://doi.org/10.1063/5.0014486

[37] Okuda, Y., Ohta, K., Sinmyo, R., Hirose, K., & Ohishi, Y. Anomarous compressibility in (Fe,Al)-bearing bridgmanite: implications for the spin state of iron. Physics and Chemistry of Minerals, 47, 40 (2020). https://doi.org/10.1007/s00269-020-01109-3

[36] Okuda, Y., Ohta, K., Hasegawa, A., Yagi, T., Hirose, K., Kawaguchi, S. I., & Ohishi, Y. Thermal conductivity of Fe-bearing post-perovskite in the Earth's lowermost mantle. Earth and Planetary Science Letters, 547, 116466 (2020). https://doi.org/10.1016/j.epsl.2020.116466

[35] Inoue, H., Suehiro, S., Ohta, K., Hirose, K., & Ohishi, Y. Resistivity saturation of hcp Fe-Si alloys in an internally heated diamond anvil cell: A key to assessing the Earth's core conductivity. Earth and Planetary Science Letters 543, 116357 (2020). https://doi.org/10.1016/j.epsl.2020.116357

[34] Kato, C., Umemoto, K., Ohta, K., Tagawa, S., Hirose, K., & Ohishi, Y. Stability of fcc phase FeH to 137 GPa. American Mineralogist 105, 917-921 (2020). DOI: https://doi.org/10.2138/am-2020-7153

2019

[33] Suehiro, S., Wakamatsu, T., Ohta, K., Hirose, K., & Ohishi, Y. High-temperature electrical resistivity measurements of hcp iron to Mbar pressure in an internally resistive heated diamond anvil cell. High Pressure Research 39, 579-587 (2019). https://doi.org/10.1080/08957959.2019.1692008

[32] Matsuoka, T., Muraoka, S., Ishikawa, T., Niwa, K., Ohta, K., Hirao, N., Kawaguchi, S., Ohishi, Y., Shimizu, K., & Sasaki, S. Hydrogen-storing salt NaCl(H2) synthesized at high pressure and high temperature. The Journal of Physical Chemistry C 123, 25074-25080 (2019). https://doi.org/10.1021/acs.jpcc.9b06639

[31] Hasegawa, A., Yagi, T., & Ohta, K. Combination of pulsed light heating thermoreflectance and laser-heated diamond anvil cell for in-situ pressure-temperature thermal diffusivity measurements. Review of Scientific Instrum 90, 074901 (2019). https://doi.org/10.1063/1.5093343

[30] Okuda, Y., Ohta, K., Sinmyo, R., Hirose, K., Yagi, T, & Ohishi, Y. Effect of spin transition of iron on the thermal conductivity of (Fe,Al)-bearing bridgmanite. Earth and Planetary Science Letters 520, 188-198 (2019). https://doi.org/10.1016/j.epsl.2019.05.042

[29] Hasegawa, A., Ohta, K., Yagi, T., Hirose, K., Okuda, Y., & Kondo, T. Composition and pressure dependence of lattice thermal conductivity of (Mg,Fe)O solid solutions. Comptes Rendus Geoscience 351, 229-235 (2019). https://doi.org/10.1016/j.crte.2018.10.005

[28] Ohta, K., Suehiro, S., Hirose, K., & Ohishi, Y. Electrical resistivity of fcc phase iron hydrides at high pressures and temperatures. Comptes Rendus Geoscience 351, 147-153 (2019). https://doi.org/10.1016/j.crte.2018.05.004

2018

[27] Ohta, K., Nishihara, Y., Sato, Y., Hirose, K., Yagi, T., Kawaguchi, S., Hirao, N., & Ohishi Y. An experimental examinaion of thermal conductivity anisotropy in hcp iron. Frontiers in Earth Science 6, 176 (2018). https://doi.org/10.3389/feart.2018.00176

[26] Wakamatsu, T., Ohta, K., Yagi, T., Hirose, K., & Ohishi, Y. Measurements of sound velocity in iron-nickel alloys by femtosecond laser pulses in a diamond anvil cell. Physics and Chemistry of Minerals 45, 589-595, (2018). https://doi.org/10.1007/s00269-018-0944-3

2017

[25] Suehiro, S., Ohta, K., Hirose, K., Morard, G., & Ohishi Y. The influence of sulfur on the electrical resistivity of hcp iron: implications for the core conductivity of Mars and Earth. Geophysical Research Letters 44, 8254-8259 (2017). https://doi.org/10.1002/2017GL074021

[24] Matsuoka, T., Kuno, K., Ohta, K., Sakata, M., Nakamoto, Y., Hirao, N., Ohishi, Y., Shimizu, K., Kume, T., & Sasaki, S. Lithium polyhydrides synthesized under high pressure and high temperature. Journal of Raman Spectroscopy 48, 1222-1228 (2017). https://doi.org/10.1002/jrs.5183

[23] Okuda, Y., Ohta, K., Yagi, T., Sinmyo, R., Wakamatsu, T., Hirose, K., & Ohishi, Y. The effect of iron and aluminum incorporation on lattice thermal conductivity of bridgmanite at the Earth's lower mantle. Earth and Planetary Science Letters 474, 25-31 (2017). https://doi.org/10.1016/j.epsl.2017.06.022

[22] Ohta, K., Yagi, T., Hirose, K., & Ohishi, Y. Thermal conducitivity of ferropericlase in the Earth's lower mantle. Earth and Planetary Science Letters 465, 29-37 (2017). https://doi.org/10.1016/j.epsl.2017.02.030

2016

[21] Ohta, K., Kuwayama, Y., Hirose, K., Shimizu, K., & Ohishi, Y. Experimental determination of the electrical resistivity of iron at Earth's core conditions. Nature 534, 95-98 (2016). https://doi.org/10.1038/nature17957

[20] Tagawa, S., Ohta, K., Hirose, K., Kato, C., & Ohishi, Y. Compression of Fe-Si-H alloys to core pressures. Geophysical Research Letters 43, 3686-3692 (2016). https://doi.org/10.1002/2016GL068848

2015

[19] Ohta, K., Ichimaru, K., Einaga, M., Kawaguchi, S., Shimizu, K., Matsuoka, T., Hirao, N., & Ohishi, Y. Phase boundary of hot dense fluid hydrogen. Scientific Reports 5, 16560 (2015). https://doi.org/10.1038/srep16560

[18] Kuno, K., Matsuoka, T., Nakagawa, T., Hirao, N., Ohishi, Y., Shimizu, K., Takahama, K., Ohta, K., Sakata, M., Nakamoto, Y., Kume, T., & Sasaki, S. Heating of Li in hydrogen: Possible synthesis of LiHx. High Pressure Research 35, 16-21 (2015). https://doi.org/10.1080/08957959.2014.999677

2014

[17] Imada, S., Ohta, K., Yagi, T., Hirose, K., Yoshida, H., & Nagahara, H. Measurements of lattice thermal conductivity of MgO to core-mantle boundary pressures. Geophysical Research Letters 41, 4542-4547 (2014). https://doi.org/10.1002/2014GL060423

[16] Ohta, K., Fujino, K., Kuwayama, Y., Kondo, T., Shimizu, K., & Ohishi, Y. Highly conductive iron-rich (Mg,Fe)O magnesiowustite and its stability in the Earth's lower mantle. Journal of Geophysical Research Solid Earth 119, 4656-4665 (2014). https://doi.org/10.1002/2014JB010972

[15] Matsuoka, T., Sakata, M., Nakamoto, Y., Takahama, K., Ichimaru, K., Mukai, K., Ohta, K., Hirao, N., Ohishi, Y., & Shimizu, K. Pressure-induced re-entrant of metallic phase of lithium. Physical Review B 89, 144103 (2014). https://doi.org/10.1103/PhysRevB.89.144103

[14] Ohta, K., Yagi, T., & Hirose, K. Thermal diffusivities of MgSiO3 and Al-bearing MgSiO3 perovskites. American Mineralogist 99, 94-97 (2014). http://dx.doi.org/10.2138/am.2014.4598

2013

[13] Gomi, H., Ohta, K., Hirose, K., Labrosse, S., Caracas, R., Verstraete, M. J., & Hernlund, J. The high conductivity of iron and thermal evolution of the Earth's core. Physics of the Earth and Planetary Interiors 224, 88-103 (2013). https://doi.org/10.1016/j.pepi.2013.07.010

2012

[12] Sugimura, E., Komabayashi, T., Ohta, K., Hirose, K., Ohishi, Y., & Dubrovinsky, L. Experimental evidence of superionic conduction in H2O ice. Journal of Chemical Physics 137, 194505 (2012). https://doi.org/10.1063/1.4766816

[11] Ohta, K., Yagi, T., Taketoshi, N., Hirose, K., Komabayshi, T., Baba, T., Ohishi, Y., & Hernlund, J. Lattice thermal conductivity of MgSiO3 perovskite and post-perovskite at the core-mantle boundary. Earth and Planetary Science Letters 349-350, 109-115 (2012). https://doi.org/10.1016/j.epsl.2012.06.043

[10] Ohta, K., Cohen, R. E., Hirose, K., Haule, K., Shimizu, K., & Ohishi, Y. Experimental and theoretical evidence for pressure-induced metallization in FeO with the rock-salt type structure. Physical Review Letters 108, 026403 (2012). https://doi.org/10.1103/PhysRevLett.108.026403

2011

[9] Ozawa, H., Hirose, K., Ohta, K., Ishii, H., Hiaoka, N., Ohishi, Y., & Seto, Y, Spin crossover, structural change, and metallization in NiAs-type FeO at high pressure. Physical Review B 84, 134417 (2011). https://doi.org/10.1103/PhysRevB.84.134417

[8] Yagi, T., Ohta, K., Kobayashi, K., Taketoshi, N., Hirose, K., & Baba, T. Thermal diffusivity measurement in diamond anvil cell using light pulse thermoreflectance technique. Measurement Science and Technology 22, 024011 (2011). https://doi.org/10.1088/0957-0233/22/2/024011

2010

[7] Iizuka, T., McCulloch, M.T., Komiya, T., Shibuya, T., Ohta, K., Ozawa, H., Sugimura, E., & Collerson, K.D. Monazite geochronology and geochemistry of meta-sediments in the Narryer Gneiss Complex, Western Australia: constraints on the tectonothermal history and provenance. Contributions to Mineralogy and Petrology 160, 803-823 (2010). https://doi.org/10.1007/s00410-010-0508-0

[6] Ohta, K., Hirose, K., Shimizu, K., & Ohishi, Y. High-pressure experimental evidence for metal FeO with normal NiAs-type structure. Physical Review B 82, 174120 (2010). https://doi.org/10.1103/PhysRevB.82.174120

[5] Ohta, K., Hirose, K., Shimizu, K., Sata, N., & Ohishi, Y. The electrical resistance measurements of (Mg,Fe)SiO3 perovskite at high pressures and implications for electronic spin transition of iron. Physics of the Earth and Planetary Interiors 180, 154-158 (2010). https://doi.org/10.1016/j.pepi.2009.11.002

[4] Ohta, K., Hirose, K., Ichiki, M., Shimizu, K., Sata, N., & Ohishi, Y. Electrical conductivities of pyrolitic mantle and MORB materials up to the lowermost mantle conditions. Earth and Planetary Science Letters 289, 497-502 (2010). https://doi.org/10.1016/j.epsl.2009.11.042

2008

[3] Ohta, K., Onoda, S., Hirose, K., Sinmyo, R., Shimizu, K., Sata, N., Ohishi, Y., & Yasuhara, A. The electrical conductivity of post-perovskite in Earth’s D” layer. Science 320, 89-91 (2008). DOI: 10.1126/science.1155148

[2] Ohta, K., Hirose, K., Lay, T., Sata, N., & Ohishi, Y. Phase transitions in pyrolite and MORB at lowermost mantle conditions: Implications for a MORB-rich pile above the core-mantle boundary. Earth and Planetary Science Letters 267, 107-117 (2008). https://doi.org/10.1016/j.epsl.2007.11.037

2007

[1] Ohta, K., Hirose, K., Onoda, S., & Shimizu, K. The effect of iron spin transition on electrical conductivity of (Mg,Fe)O magnesiowüstite. Proceedings of the Japan Academy Ser. B 83, 97-100 (2007). https://doi.org/10.2183/pjab.83.97

Proceedings and articles written in Japanese