High-pressure phase transitions of solidH2S probed by Fourier-transform infrared spectroscopy

Hydrogen sulfide at high pressure: Change in stoichiometry

“…The room temperature experiment (A) showed changes in RS, which are consistent with previously detected phase changes [23] to orientionally ordered phase IV, and then to phases V and VI, where the molecular character is diminished [16,18] (Fig. 2).…”

“…In the absence of experimental data on the structure and composition of the superconducting phase, the insights were offered by several theoretical calculations [3,[9][10][11][12][13][14] suggesting that it is a new polyhydride H 3 S which possesses such unusually high T c due to the strong electron-phonon coupling and high hydrogen (H) phonon frequencies. This called for more detailed experimental investigation of high-pressure behavior of H 2 S as the existing structural and experimental data are scarce and partially inconsistent [15][16][17][18] concerning the structure, physical properties, and possible chemical reactivity of this system at high pressure.…”

Pressure-Induced Molecular Dissociation and Metallization in Hydrogen-BondedH2SSolid

“…However, both the intensity and width of this peak change across the phase boundary. The n 2 mode of the molecular phase is very weak and narrow [9], while the lattice mode of the dissociated phase is broad and strong.…”

“…Phase transitions in solid H 2 S have been studied by Raman [5,6] and Brillouin scattering [7], x-ray diffraction [8], and infrared absorption [9] to 50 GPa from 30 to 300 K. All of the phases studied are molecular, differing by arrangements of molecular orientations. No experimental evidence for molecular dissociation has been reported.…”

Static Structure and Dynamical Correlations in High PressureH2S

“…Our simulated structure, compatible with experimental scattering data, differs from the previous static models: dynamical correlations in the S positions are essential for a correct description of H 2 S phase IV. The high pressure behavior of solid H 2 S has recently drawn considerable attention [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Although the structure of the molecule is similar to H 2 O, its phase diagram is remarkably different.…”