Thermodynamics and superconductivity of SxSe1-xH3

Article

关键词: TOTAL-ENERGY CALCULATIONS;    PLANE-WAVE;    CRYSTAL-STRUCTURE;    HYDROGEN-SULFIDE;    PHASE-DIAGRAM;    TEMPERATURE;    SULFUR;    PSEUDOPOTENTIALS;    TRANSITION;    SELENIUM;   

DOI  :  10.1103/PhysRevB.99.060102

来源: SCIE

【 摘 要 】

The compression of SH2 and its subsequent decomposition to SH3, presumably in a cubic Im (3) over barm structure, has led 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 (3) over barm symmetry using a cluster expansion technique to explore the phase diagram of SxSe1-xH3. In contrast to earlier reports, we find that S0.5Se0.5H3 is not stable in the pressure range between 150 and 200 GPa. However, phases at compositions S0.2Se0.8H3, S0.(3) over barSe0.(6) over barH3, and S0.6Se0.4H3 are stable at 200 GPa, while additional phases at S0.25Se0.75H3 and S0.75Se0.25H3 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.

【 授权许可】

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