195 citations · 536 across the 11 of their papers we have counts for
11 papers
Ab initio investigation of H-bond disordering in -AlOOH
Chenxing Luo, Koichiro Umemoto, Renata M. Wentzcovitch
-AlOOH () is a high-pressure hydrous phase that participates in the deep geological water cycle. At 0 GPa, has asymmetric hydrogen bonds (H-bonds). Under pressure, it exh…
Ab initio prediction of an order-disorder transition in MgGeO: implication for the nature of super-Earth's mantles
Koichiro Umemoto, Renata M. Wentzcovitch
Here we present an ab initio prediction of an order-disorder transition (ODT) from -type to a ThP-type phase in the cation sublattices of MgGeO, a post-…
Structural transition and re-emergence of iron's total electron spin in (Mg,Fe)O at ultrahigh pressure
Han Hsu, Koichiro Umemoto
Fe-bearing MgO [(MgFe)O] is considered a major constituent of terrestrial exoplanets. Crystallizing in the B1 structure in the Earth's lower mantle, (MgFe)O…
Light and Slow-Neutron Diffraction by Nanodiamond-Dispersed Nanocomposite Holographic Gratings
Y. Tomita, A. Kageyama, Y. Iso +9
We demonstrate the use of nanodiamond in constructing holographic nanoparticle-polymer composite transmission gratings with large saturated refractive index modulation amplitudes a…
Phase transitions in MgSiO3 post-perovskite in super-Earth mantles
Koichiro Umemoto, Renata M. Wentzcovitch, Shunqing Wu +3
The highest pressure form of the major Earth-forming mantle silicate is MgSiO3 post-perovskite (PPv). Understanding the fate of PPv at TPa pressures is the first step for understan…
Post-stishovite transition in hydrous aluminous SiO2
Koichiro Umemoto, Katsuyuki Kawamura, Kei Hirose +1
Lakshtanov et al. (2007) showed that incorporation of aluminum and some water into SiO2 significantly reduces the post-stishovite transition pressure in SiO2. This discovery sugges…