Hitoshi Gomi

Hitoshi Gomi
Tokyo Institute of Technology | TITech · Earth-Life Science Institute

PhD

About

27
Publications
3,939
Reads
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441
Citations
Citations since 2016
22 Research Items
382 Citations
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20162017201820192020202120220204060
20162017201820192020202120220204060
20162017201820192020202120220204060
Introduction
I am interested in the phase stability, elastic and transport properties (electrical resistivity and thermal conductivity) of planetary cores.
Additional affiliations
January 2020 - present
Tokyo Institute of Technology
Position
  • Laboratory Manager
January 2016 - December 2019
Okayama University
Position
  • PostDoc Position
September 2014 - December 2015
Carnegie Institution for Science
Position
  • PostDoc Position
Education
October 2010 - March 2014
Tokyo Institute of Technology
Field of study
  • Earth and Planetary Science
October 2008 - September 2010
Tokyo Institute of Technology
Field of study
  • Earth and Planetary Science
April 2003 - September 2008
Tokyo Institute of Technology
Field of study
  • Earth and Planetary Science

Publications

Publications (27)
Article
Full-text available
Plain Language Summary FeH is an important component in terrestrial planetary cores, and its equation of state (EoS) is useful to estimate their H concentrations from observed densities. The high‐T EoS of FeH has not been examined experimentally to the Earth's core pressure range (>136 GPa) because of difficulties in high P‐T experiments on H‐beari...
Article
Full-text available
Anelastic measurement by cyclic loading under high pressure has been developed by means of in situ X-ray observation at a synchrotron facility. In this method, the reference material is a key factor to precisely determine attenuation and moduli of unknown materials. We compared the performance of three types of reference materials (dense polycrysta...
Presentation
高校生向けのアウトリーチ活動でプレゼンテーションを行いました。 https://wpi-forum.jsps.go.jp/highschoolsympo2020/
Poster
Full-text available
This iPoster can be obtained at https://jpgu-agu2020.ipostersessions.com/Default.aspx?s=E9-85-CB-63-43-B6-DB-09-4E-EF-9C-00-93-3C-82-4E --- Abstract Many physical properties of semiconductors and insulators are characterized by their band gap energy, which is the energy difference between the valence band minimum (VBM) and the conduction band maxi...
Article
Full-text available
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...
Article
Full-text available
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 co...
Presentation
Electrical resistivity and thermal conductivity of face-centred cubic (fcc) Fe are calculated by the Korringa-Kohn-Rostoker (KKR) method with the Kubo-Greenwood formula. Phonon and magnetic scatterings are considered. The former is approximated by the alloy analogy model, and the latter is represented by the local magnetic disorder (LMD) approach....
Presentation
The Mercury’s magnetic fields are known to be weaker than that predicted by conventional dynamo models. In order to explain the Mercury’s weak magnetic field, several models are proposed (Stanley and Glatzmaier, 2010). One of them is the thermoelectric dynamo, which drive the dynamo via the thermoelectric force (Stevenson, 1987). The field strength...
Poster
The Mercury’s magnetic field may be sustained by the geodynamo motion in the liquid Fe core. However, its strength is about 1% of that of Earth. This weak magnetic field may implies a partly stratified core. Gomi et al. (2013) pointed out that the geometry of the thermal stratification depends critically on the depth dependency of the thermal condu...
Article
Phonon velocities and densities for Pt were measured based on inelastic X-ray scattering from ambient pressure to 20 GPa in order to independently determine its equation of state (EOS). Phonon velocities were determined with sine dispersion relations. Cij values were obtained by fitting phonon velocities and densities to the Christoffel equation. W...
Poster
Full-text available
The Mercury’s magnetic fields are known to be weaker than that predicted by conventional dynamo models. In order to explain the Mercury’s weak magnetic field, several models are proposed (Stanley and Glatzmaier, 2010). One of them is the thermoelectric dynamo, which drive the dynamo via the thermoelectric force (Stevenson, 1987). The field strength...
Poster
Full-text available
Pt is one of the most widely used functional material in high-pressure -temperature experiments. Despite the crucial importance of its transport properties, both experimental and theoretical studies are very limited. In this study, we conducted the density-functional theory (DFT) calculations on the electrical resistivity, Seebeck coefficient and t...
Article
Full-text available
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 (mach...
Article
Full-text available
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 = (VFeHx-VFe)/ΔVH, where x is the hydrogen content, ΔVH is the volume expansion caused by...
Article
Full-text available
We extended the attainable pressure of the Kawai-type multianvil apparatus to 71.3 GPa and 120.3 GPa at room temperature by equipping it with tungsten carbide (WC) and sintered diamond (SD) cubic anvils, respectively. In the experiments with WC anvils, pressure decreased largely, ΔP ∼−20 GPa, on heating from room temperature to 1500 K. In the exper...
Article
We measured the elasticity of single crystal gold (Au) and its lattice parameters under high pressure using inelastic X-ray scattering (IXS). The elastic moduli were obtained at five pressure points between 0 and 20 GPa. The pressure variation of the bulk modulus displays anomalous behavior, being nearly constant up to ∼5 GPa, and then steeply incr...
Article
The thermal conductivity of the Earth's core can be estimated from its electrical resistivity via the Wiedemann–Franz law. However, previously reported resistivity values are rather scattered, mainly due to the lack of knowledge with regard to resistivity saturation (violations of the Bloch–Grüneisen law and the Matthiessen's rule). Here we conduct...
Article
We measured the electrical resistivity of Fe-Ni alloys (iron with 5, 10, and 15 wt.% nickel) using four-terminal method in a diamond-anvil cell up to 70 GPa at 300 K. The results demonstrate that measured resistivity increases linearly with increasing nickel impurity concentration, as predicted by the Matthiessen’s rule. The impurity resistivity is...
Presentation
The existence of an intense magnetic field on Earth is thought to be important for the stability of the atmosphere. Understanding the early evolution of the geodynamo may be a key issue for the emergence of a habitable planet. A thermal convection-driven geodynamo can be maintained if the heat flow at the core mantle boundary (CMB) is larger than w...
Presentation
Core-mantle boundary (CMB) heat flow is determined by the pace of plate tectonics and propagation of mantle convection into the deep interior of the Earth, and is widely recognized as the most important dynamical quantity in the Earth's interior. The magnitude of present CMB heat flow (and heat flux variation) has been highly uncertain for decades,...
Presentation
The knowledge of the thermal conductivity of the core constrains the heat flow and the amount of radiogenic elements in the core [1]. The electrical conductivity of iron has been measured by shock compression experiments. The thermal conductivity can be then calculated using the Wiedemann-Franz law. Stacey and Loper [2] estimated the thermal conduc...

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