Pressure-induced decomposition of solid hydrogen sulfide

Abstract

Solid hydrogen sulfide is well known as a typical molecular crystal but its stability under pressure is still under debate. Particularly, Eremets et al. found the high pressure superconductivity with $T_{c}\approx$ 190 K in a H$_{2}$S sample [arXiv: 1412.0460 (2014)] which is associates with the elemental decomposition into H$_{3}$S [Sci. Rep. 4, 6968 (2014)]. Therefore, on what pressure H$_{2}$S can decompose and which kind of the products of decomposition urgent need to be solved. In this paper, we have performed an extensive structural study on different stoichiometries H$_{n}$S with ${n> 1}$ under high pressure using $ab$ $initio$ calculations. Our results show that H$_{2}$S is stable below 50 GPa and decomposes into H$_3$S and sulfur at high pressure, while H$_{3}$S is stable at least up to 300 GPa. The other hydrogen-rich H$_{4}$S, H$_{5}$S, and H$_{6}$S are unstable in the pressure range from 20 to 300 GPa

Structure and Composition of the 200 K‐Superconducting Phase of H2S at Ultrahigh Pressure: The Perovskite (SH−)(H3S+)

“…[ 2 , 3 , 4 ] The obtained XRD patterns can be indexed based on a mixture of two phases, namely, the bcc m Im3 structure ascribed to H3S with cell parameter a = 3.089 Å and the -Po structure of sulfur. [3,5 ] Another XRD study under high pressure reported a more complex decomposition mixture that includes H3S and H4S3 phases. [6] DFT calculations confirmed the proposed m Im3 structure of H3S as the lowest energy one.…”

Superconductivity in Hydrides Doped with Main Group Elements Under Pressure

“…Theoretical studies, which have shown that the superconductivity observed in Ref. [38] arises primarily from an H 3 S phase [40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55] whose structure has been recently confirmed experimentally [56], will not be described within this short review. We will, however, discuss the results of first principles calculations carried out for the hydrides of phosphorus [57][58][59].…”

Corrigendum: Structure and Composition of the 200 K‐Superconducting Phase of H2S at Ultrahigh Pressure: The Perovskite (SH−)(H3S+)

“…In their estimation of the enthalpy change DH for the reaction (1), ½ð1Þ2H 3 S ðsÞ!ðSH À ÞðH 3 S þ Þð sÞþH 2 ðgÞ, where the sulfur frameworks of H 3 S(s) and (SH À )(H 3 S + + )(s) have the bcc structure (space group Im3m with a = 3.089 ), [1,2] the authors of this Communication made an inadvertent error of using half the energy of H 2 instead of the full energy.For the P4mm, Cmmm, Cmc21,and Ima2s tructures of (SH À )(H 3 S + + )( s), the correct DH values are À3.200, À3.511, À3.559, and À3.582 eV,respectively.Thus, at 200 K, the correct DG values are À3.219, À3.529, À3.578, and À3.601 eV,respectively.Ina rriving at these estimates, the energy of H 2 calculated for its structure at ambient pressure was employed. To estimate the DH values at ultrahigh pressure P,itisnecessary to consider the VP term, where V is the cell volume.…”