Zobrazeno 1 - 10
of 87
pro vyhledávání: '"Koichiro Umemoto"'
Autor:
Koutaro Hikosaka, Shoh Tagawa, Kei Hirose, Yoshiyuki Okuda, Kenta Oka, Koichiro Umemoto, Yasuo Ohishi
Publikováno v:
Scientific Reports, Vol 12, Iss 1, Pp 1-8 (2022)
Abstract Hydrogen could be an important light element in planetary cores, but its effect on phase diagrams of iron alloys is not well known because the solubility of H in Fe is minimal at ambient pressure and high-pressure experiments on H-bearing sy
Externí odkaz:
https://doaj.org/article/c2b6301c6a2d4c76bfe6e436a44ae7a0
Autor:
Han Hsu, Koichiro Umemoto
Publikováno v:
Nature Communications, Vol 13, Iss 1, Pp 1-8 (2022)
Iron spin transition occurs at ultrahigh pressure. The total electron spin increases from 0 to 1 as the structural transition of (Mg,Fe)O occurs (~0.6 TPa) and drops back to 0 at higher pressure. Its effects on exoplanet interiors are anticipated.
Externí odkaz:
https://doaj.org/article/5e485b380043417797961f2bf0d4bcd7
Publikováno v:
Physical Review Research, Vol 4, Iss 2, p 023223 (2022)
δ-AlOOH (δ) is a high-pressure hydrous phase that participates in the deep geological water cycle. At 0 GPa, δ has asymmetric hydrogen bonds (H bonds). Under pressure, it exhibits H-bond disordering, tunneling, and finally, H-bond symmetrization a
Externí odkaz:
https://doaj.org/article/303d870e5e774b2cb91b86a1046e9626
Autor:
Ilias Efthimiopoulos, Elissaios Stavrou, Koichiro Umemoto, Sathish Mayanna, Antonius Torode, Jesse S. Smith, Stella Chariton, Vitali B. Prakapenka, Alexander F. Goncharov, Yuejian Wang
Publikováno v:
Physical Review B
We have studied the high-pressure vibrational and structural behavior of bulk graphite and graphene nanoplatelets at room temperature by means of high-pressure Raman spectroscopic and x-ray diffraction probes. We have detected a clear pressure-induce
Autor:
Koutaro Hikosaka, Shoh Tagawa, Kei Hirose, Yoshiyuki Okuda, Kenta Oka, Koichiro Umemoto, Yasuo Ohishi
Hydrogen could be an important light element in planetary cores, but its effect on phase diagrams of iron alloys is not well known because the solubility of H in Fe is minimal at ambient pressure and high-pressure experiments on H-bearing systems hav
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::2abf4d515bddc29cd796010f62dbe7f9
https://doi.org/10.21203/rs.3.rs-1326566/v1
https://doi.org/10.21203/rs.3.rs-1326566/v1
$\delta$-AlOOH ($\delta$) is a high-pressure hydrous phase that participates in the deep geological water cycle. At 0 GPa, $\delta$ has asymmetric hydrogen bonds (H-bonds). Under pressure, it exhibits H-bond disordering, tunneling, and finally, H-bon
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::1e161e4f09b3c6507bba7a0f819f16a8
http://arxiv.org/abs/2112.11369
http://arxiv.org/abs/2112.11369
Publikováno v:
Physical Review Materials. 5
Here we present an ab initio prediction of an order-disorder transition (ODT) from a $I\overline{4}2d$-type to ${\mathrm{Th}}_{3}{\mathrm{P}}_{4}$-type phase in the cation sublattices of ${\mathrm{Mg}}_{2}\mathrm{Ge}{\mathrm{O}}_{4}$, a post-post-per
Autor:
Koichiro Umemoto, Jun Tsuchiya
Publikováno v:
Geophysical Research Letters. 46:7333-7336
Publikováno v:
Computer Physics Communications. 237:199-207
In this work, we present a Python package, qha , which can calculate the equation of state and various thermodynamic properties of both single- and multi-configuration crystalline materials within a user-specified pressure and temperature range in th
Publikováno v:
American Mineralogist. 105(2)
We examined the crystal structure of FeHX (X~1) (FeH hereafter) at high pressure and temperature by X-ray diffraction up to 137 GPa. Results show that FeH adopts a face-centered cubic (fcc) structure at pressures of 43 to 137 GPa and temperatures of