Wang Yu, Glazyrin Konstantin, Roizen Valery, Oganov Artem R, Chernyshov Ivan, Zhang Xiao, Greenberg Eran, Prakapenka Vitali B, Yang Xue, Jiang Shu-Qing, Goncharov Alexander F
Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China.
Photon Science, Deutsches Elektronen-Synchrotron, Notkestrasse 85, 22607 Hamburg, Germany.
Phys Rev Lett. 2020 Dec 18;125(25):255702. doi: 10.1103/PhysRevLett.125.255702.
We report a new hydrogen clathrate hydrate synthesized at 1.2 GPa and 298 K documented by single-crystal x-ray diffraction, Raman spectroscopy, and first-principles calculations. The oxygen sublattice of the new clathrate hydrate matches that of ice II, while hydrogen molecules are in the ring cavities, which results in the trigonal R3c or R3[over ¯]c space group (proton ordered or disordered, respectively) and the composition of (H_{2}O){6}H{2}. Raman spectroscopy and theoretical calculations reveal a hydrogen disordered nature of the new phase C_{1}^{'}, distinct from the well-known ordered C_{1} clathrate, to which this new structure transforms upon compression and/or cooling. This new clathrate phase can be viewed as a realization of a disordered ice II, unobserved before, in contrast to all other ordered ice structures.
我们报道了一种在1.2吉帕斯卡压力和298开尔文温度下合成的新型氢笼形水合物，通过单晶X射线衍射、拉曼光谱和第一性原理计算进行了记录。这种新型笼形水合物的氧亚晶格与冰II的氧亚晶格相匹配，而氢分子位于环形空腔中，这导致了三方R3c或R3[上划线]c空间群（分别为质子有序或无序）以及(H₂O)₆H₂的组成。拉曼光谱和理论计算揭示了新相C₁′的氢无序性质，这与著名的有序C₁笼形水合物不同，在压缩和/或冷却时，这种新结构会转变为有序C₁笼形水合物。与所有其他有序冰结构相比，这种新的笼形水合物相可以被视为一种前所未有的无序冰II的实现形式。
