Thermodynamics and superconductivity of S${}_x$Se${}_{1-x}$H${}_3$

Abstract

The compression of SH${}_2$ and its subsequent decomposition to SH${}_3$, presumably in a cubic Im$\overline{3}$m structure, has lead to the discovery of conventional superconductivity with the highest measured and confirmed $T_c$ to date, 203 K at 160 GPa. Recent theoretical studies suggest that a mixture of S with other elements of the chalcogen group could improve the superconducting temperature. Here, we present a detailed analysis of the thermodynamic properties of S and Se mixtures in the bcc lattice with Im$\overline{3}$m symmetry using a cluster expansion technique to explore the phase diagram of S${}_x$Se${}_{1-x}$H${}_3$. In contrast to earlier reports, we find that S${}_{0.5}$Se${}_{0.5}$H${}_3$ is not stable in the pressure range between 150-200 GPa. However, phases at compositions S${}_{0.2}$Se${}_{0.8}$H${}_3$, S${}_{0.\overline{3}}$Se${}_{0.\overline{6}}$H${}_3$, and S${}_{0.6}$Se${}_{0.4}$H${}_3$ are stable at 200 GPa, while additional phases at S${}_{0.25}$Se${}_{0.75}$H${}_3$ and S${}_{0.75}$Se${}_{0.25}$H${}_3$ are accessible at lower pressures. Electron-phonon calculations show that the values of $T_c$ are consistently lower for all ternary phases, indicating that mixtures of S and Se with H might not be a viable route towards compounds with improved superconducting properties.

References in corpus (17)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• The Alloy Theoretic Automated Toolkit: A User Guide
• Evidence for superconductivity above 260 K in lanthanum superhydride at megabar pressures
• Superconductive "sodalite"-like clathrate calcium hydride at high pressures
• Observation of the Wigner-Huntington Transition to Solid Metallic Hydrogen
• Hydrogen sulphide at high pressure: a strongly-anharmonic phonon-mediated superconductor
• What superconducts in sulfur hydrides under pressure, and why
• Spectroscopy of H${}_3$S: evidence of a new energy scale for superconductivity
• Anharmonic effects in atomic hydrogen: superconductivity and lattice dynamical stability
• A Bell-Evans-Polanyi principle for molecular dynamics trajectories and its implications for global optimization
• Comment on "Observation of the Wigner-Huntington transition to metallic hydrogen"
• High-pressure phase diagram of hydrogen and deuterium sulfides from first principles: structural and vibrational properties including quantum and anharmonic effects
• Superconductivity at 215 K in lanthanum hydride at high pressures
• Low-energy structures of zinc borohydride Zn(BH${}_4$)${}_2$
• Exploring the high-pressure materials genome
• Comments on the claimed observation of the Wigner-Huntington Transition to Metallic Hydrogen
• Dense superconducting phases of copper-bismuth at high pressure

Cited by in corpus (13)

• A Perspective on Conventional High-Temperature Superconductors at High Pressure: Methods and Materials
• Tuning Chemical Precompression: Theoretical Design and Crystal Chemistry of Novel Hydrides in the Quest for Warm and Light Superconductivity at Ambient Pressures
• Phase Diagram and Superconductivity of Calcium Borohyrides at Extreme Pressures
• En route to high Tc superconductivity via Rb substitution of guest metal atoms in SrB3C3 clathrate
• Potential high-$T_c$ superconductivity in YCeH${}_x$ and LaCeH${}_x$ under pressure
• Materials under high pressure: A chemical perspective
• FLAME: a library of atomistic modeling environments
• Structural Diversity and Superconductivity in S-P-H Ternary Hydrides Under Pressure
• High-T${}_c$ superconductivity in H${}_3$S: Pressure effects on superconducting critical temperature and Cooper-Pairs Distribution Function
• The higher superconducting transition temperature T${}_c$ and the functional derivative of T${}_c$ with ${\alpha }^{2}F(\omega )$ for electron-phonon superconductors
• Crystal Chemistry at High Pressure
• Pressure-induced high temperature superconductivity in H3X (X=As, Se, Br, Sb, Te and I)
• Photochemical Synthesis of P-S-H Ternary Hydride at High Pressures