The Compression Behavior of Copper Hydroxyfluoride CuOHF as a Case Study of the High Pressure Responses of the Hydrogen Bonded Two Dimensional Layered Materials

Combined experimental and theoretical investigations on the compression behavior of CuOHF, as a case study of the high-pressure responses of hydrogen-bonded two-dimensional layered materials, are presented. The characteristics of hydrogen bonds endow these materials with more complicated physics and chemistry under high pressures. CuOHF undergoes two pressure-induced structural phase transitions below 38.2 GPa. The first one occurs isostructurally at 7.8 GPa, evidenced by subtle changes of interlayer spacing due to layer sliding along the a–b basal plane. A further dimensionality transition from the 2D layered structure to a 3D amorphous one takes place at 22.5 GPa. Both transitions are accompanied with variations of the spatial configurations of hydrogen bonds and attributed to competition and collaboration between the interlayer hydrogen bonds and intralayer strong chemical bonds. Theoretical simulations confirm the phase transitions and present deeper insights into the structure–property correlations.