2026-02-20 静岡大学
図１：3次元氷と2次元氷のハニカム格子(水分子の蜂の巣状配列)。
マーティアイト中で回転する水分子がどう整列するかは非自明
＜関連情報＞
マルティアイトにおける単層氷の強軸秩序 Ferroaxial Order of the Monolayer Ice in Martyite
Toshihiro Nomura,Shunsuke Kitou,Junichi Komatsu,Jun Kimura,Kenichiro Koga,Takumi Hasegawa,Norio Ogita,Yuiga Nakamura,Hajime Ishikawa,Takeshi Yajima,Akira Matsuo,Maiko Kofu,Osamu Yamamuro,Zenji Hiroi,Yusuke Tomita,Taka-hisa Arima,and Takasuke Matsuo
Journal of the American Chemical Society Published: February 13, 2026
DOI:https://doi.org/10.1021/jacs.5c19407
Abstract
Ice Ih, the most stable phase of water at ambient pressure, is a stacking of the honeycomb network of water molecules H2O. What if one layer of ice is exfoliated and confined to a two-dimensional (2D) sheet? Martyite Zn3(V2O7)(OH)2·2H2O, a mineral with the honeycomb lattice of H2O in the porous framework, is an ideal system for studying such monolayer ice. Due to the geometrical frustration and 2D nature, H2O molecules are dynamically disordered at room temperature. In this study, we reveal disorder–order transitions of H2O in martyite using single-crystal X-ray diffraction (XRD). The XRD results visualize the formation of hydrogen-bonded toroidal H2O hexamers, leading to the ferroaxial order below 200 K. Combined with the molecular dynamics simulations, we discuss the formation process of the H2O hexamers and how they compromise the molecular arrangement toward lower temperatures. Our results demonstrate that martyite is a model system for studying 2D ice, which may give a clue for understanding the polymorphism of H2O.
