The metallization and superconductivity of dense hydrogen sulfide

Abstract

Hydrogen sulfide (H2S) is a prototype molecular system and a sister molecule of water (H2O). The phase diagram of solid H2S at high pressures remains largely unexplored arising from the challenges in dealing with the pressure-induced weakening of S-H bond and larger atomic core difference between H and S. Metallization is yet achieved for H2O, but it was observed for H2S above 96 GPa. However, the metallic structure of H2S remains elusive, greatly impeding the understanding of its metallicity and the potential superconductivity. We have performed an extensive structural study on solid H2S at pressure ranges of 10-200 GPa through an unbiased structure prediction method based on particle swarm optimization algorithm. Besides the findings of candidate structures for nonmetallic phases IV and V, we are able to establish stable metallic structures violating an earlier proposal of elemental decomposition into sulfur and hydrogen [R. Rousseau, M. Boero, M. Bernasconi, M. Parrinello, and K. Terakura, Phys. Rev. Lett. 85, 1254 (2000)]. Our study unravels a superconductive potential of metallic H2S with an estimated maximal transition temperature of ∼80 K at 160 GPa, higher than those predicted for most archetypal hydrogen-containing compounds (e.g., SiH4, GeH4, etc.).

High-pressure studies with x-rays using diamond anvil cells

“…The superconductivity of a large number of elements and compounds including cuprates [633,634], fullerides [635], intermetallic boron carbides [636], layered nitrides [637], magnesium diboride [638], iron pnictides [639], and recently hydrides [640,641], can be strongly altered and tuned by pressure [642,643]. Many elements, although not superconducting at ambient pressure, become superconductors at HP.…”

Near-room-temperature superconductivity in hydrogen sulfide

“…Recent theoretical work 4 indicated that such dissociation would not occur and predicted that H 2 S pressurized at 1.6 million atmospheres would show superconductivity at temperatures above 80 K. This led to the practical work of Drozdov et al, 1 who found that H 2 S compressed in a diamond anvil cell exhibited two astonishing superconductive states at pressures above 1 million atmospheres: the superconductivity ranging from 30 to 150 K measured in the lowtemperature runs (Fig. 1) 1 relates to H 2 S, as it is consistent with calculations; 4 the highest superconductivity of 203 K was achieved in samples annealed at the room temperature (Fig.…”

Perspective: Role of structure prediction in materials discovery and design

“…A DFT study by Li et al 15 was the first to suggest that metallic H 2 S could become a high-temperature superconductor, which they predicted to have a T c of 80 K at 160 GPa. In the same study Li et al 15 also showed that pressure-induced decomposition of H 2 S into its elements was thermodynamically unfavorable.…”

“…A DFT study by Li et al 15 was the first to suggest that metallic H 2 S could become a high-temperature superconductor, which they predicted to have a T c of 80 K at 160 GPa. In the same study Li et al 15 also showed that pressure-induced decomposition of H 2 S into its elements was thermodynamically unfavorable. This result overturned the conclusion from a DFT study 28 that pressure-induced decomposition into the elements might occur, and suggested that new H/S compounds could be formed.…”

“…The number of papers published on the theory and modelling of high T c superconductivity in hydrogen sulfide has increased rapidly since 2014, see for example Refs. [15][16][17][18][19][20][21][22][23][24][25][26][27].…”