Molecular Dissociation in Deuterium Sulfide under High Pressure:  Infrared and Raman Study

Abstract

Experiments using a diamond-anvil cell show that deuterium sulfide (D 2 S) dissociates to form sulfur at pressures above 27 GPa and room temperature. Raman-scattering spectroscopy indicates the presence of S-S bonds of a high-pressure phase sulfur, helical sulfur, and eight-membered cyclic sulfur. On the other hand, infraredabsorption spectroscopy indicates the presence of S-D bonds of both polymeric and unreacted D 2 S. The formation of sulfur from D 2 S can be interpreted as reconstruction of chemical bonds at high pressures.

Hydrogen sulfide at high pressure: Change in stoichiometry

“…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.…”

Order-disorder phase transition and dissociation of hydrogen sulfide under high pressure: Ab initio molecular dynamics study

“…10 Further, the negative slope Ϫ0.11 GPa/K of the IV/V phase boundary indicates that the decomposition process should be induced thermally. 10 In Fujihisa's work, the decomposition pressure is found at 43 GPa at 150 K which is significantly higher than the value of 27 GPa at 300 K. 10 According to this, we performed a series of simulations at increasing temperature up to 400 K at the pressure of 15 GPa which is sufficiently low to avoid the orbital overlapping of sulfur in order to see how the thermal motion affects phase IV and hopefully get the unreacted phase V of hydrogen sulfide as Sakashita et al 13 suggested. The calculated x-ray diffraction pattern as obtained from the structure factor of the MD trajectory at 15 GPa and 300 K. Intensity ͑in arbitrary units͒ is plotted as a function of scattering angle 2 ͑ = 0.7107 Å͒.…”

“…Instead, an intermediate disordered crystalline structure of phase V was obtained which can solve the puzzles emerged in earlier experimental studies. 10,13 We found that the structural and dynamical properties of phase V can help understanding the dissociation and decomposition of hydrogen sulfide at high pressure.…”

“…17,18 For hydrogen sulfide, which is an analog of water at molecular level, the dissociation turns out to be an intermediate process of the decomposition. 10,13 Structural tools which are able to probe the H sublattice are obviously required to provides microscopic information and understanding of this process.…”

Perspective: Role of structure prediction in materials discovery and design

“…3 Compressed hydrogen sulfide has been studied experimentally over many years. [6][7][8][9][10][11][12][13][14] However, the superconductivity that was observed in hydrogen sulfide was generally thought to arise from metallic sulfur formed at high pressures. The enormous T c found by Drozdov et al 3 in hydrogen sulfide was therefore a great surprise.…”