The high-pressure behaviour of caesium hydroxide monohydrate.
4 affiliations
- 1SUPA, School of Physics and Astronomy and Centre for Science at Extreme Conditions, University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh EH9 3FD, UK. [email protected].
- 2Geochemical Research Center, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
- 3J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Naka, Ibaraki 319-1195, Japan.
- 4Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS), IQBRC Building, 162-1 Shirakata, Tokai, Naka, Ibaraki 319-1106, Japan.
Abstract
Although the anhydrous alkali hydroxides have been extensively studied, their hydrates have been much less explored despite the common nature of the combination of ionic interactions and hydrogen bonding. In this study, we characterised the compression behaviour of CsOH·H₂O, which contains a quasi-2D hydrogen-bonded network exhibiting high solid-state proton conductivity via the Grotthuss mechanism. No clear structural transition was observed up to 9 GPa, whilst Raman scattering exhibits slight changes in the spectrum at 3 GPa. X-ray and neutron diffraction revealed anisotropic compression of CsOH·H₂O with the largest compressibility along the c-axis, reducing the interlayer distances like the other layered materials. Accordingly, the quasi-2D hydrogen-bonded network becomes flattened. In Raman spectroscopy, a typical pressure response was found for hydrogen-bonded crystals, such as pressure-induced strengthening of hydrogen bonds characterised by the downshift of OH stretching modes as well as the upshift of other optical modes of translations and librational movements. On the other hand, some of the low-frequency bands became indistinguishable above 3 GPa, where the pressure dependence of the OH stretching mode has a kink as well. The anisotropic compression behaviour reduces the free volume, which will affect the peculiar phase behaviour and proton dynamics in the quasi-2D hydrogen-bonded network of CsOH·H₂O present at ambient pressure.
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BibTeX
@article{yamashita2026highpressure,
title = {{The high-pressure behaviour of caesium hydroxide monohydrate.}},
author = {Keishiro Yamashita and Ciprian G Pruteanu and Graeme J Ackland and Kazuki Komatsu and Takanori Hattori and Shinichi Machida and John S Loveday},
journal = {Physical chemistry chemical physics : PCCP},
year = {2026},
month = oct,
doi = {10.1039/d6cp03154d},
url = {https://europepmc.org/article/MED/42929677},
note = {CC BY},
}
RIS
TY - JOUR
TI - The high-pressure behaviour of caesium hydroxide monohydrate.
AU - Keishiro Yamashita
AU - Ciprian G Pruteanu
AU - Graeme J Ackland
AU - Kazuki Komatsu
AU - Takanori Hattori
AU - Shinichi Machida
AU - John S Loveday
PY - 2026
DA - 2026/10/26
JO - Physical chemistry chemical physics : PCCP
DO - 10.1039/d6cp03154d
UR - https://europepmc.org/article/MED/42929677
AB - Although the anhydrous alkali hydroxides have been extensively studied, their hydrates have been much less explored despite the common nature of the combination of ionic interactions and hydrogen bonding. In this study, we characterised the compression behaviour of CsOH·H₂O, which contains a quasi-2D hydrogen-bonded network exhibiting high solid-state proton conductivity via the Grotthuss mechanism. No clear structural transition was observed up to 9 GPa, whilst Raman scattering exhibits slight changes in the spectrum at 3 GPa. X-ray and neutron diffraction revealed anisotropic compression of CsOH·H₂O with the largest compressibility along the c-axis, reducing the interlayer distances like the other layered materials. Accordingly, the quasi-2D hydrogen-bonded network becomes flattened. In Raman spectroscopy, a typical pressure response was found for hydrogen-bonded crystals, such as pressure-induced strengthening of hydrogen bonds characterised by the downshift of OH stretching modes as well as the upshift of other optical modes of translations and librational movements. On the other hand, some of the low-frequency bands became indistinguishable above 3 GPa, where the pressure dependence of the OH stretching mode has a kink as well. The anisotropic compression behaviour reduces the free volume, which will affect the peculiar phase behaviour and proton dynamics in the quasi-2D hydrogen-bonded network of CsOH·H₂O present at ambient pressure.
SN - 1463-9076
SN - 1463-9084
ER -