High pressure structures of disilane and their superconducting properties

Abstract

A systematic ab initio search for low enthalpy phases of disilane (Si_2H_6) at high pressures was performed based on the minima hopping method. We found a novel metallic phase of disilane with Cmcm symmetry, which is enthalpically more favorable than the recently proposed structures of disilane up to 280 GPa, but revealing compositional instability below 190 GPa. The Cmcm phase has a moderate electron-phonon coupling yielding a superconducting transition temperature T_c of around 20 K at 100 GPa, decreasing to 13 K at 220 GPa. These values are an order of magnitude smaller than previously predicted T_c for disilane, and cast strong doubts on the possibility of high-T_c superconductivity in these systems as well as in other hydrogen-rich compounds under moderate pressure.

References in corpus (6)

• High-pressure phases of silane
• Crystal structure prediction using the Minima Hopping method
• High-Temperature Superconductivity in Atomic Metallic Hydrogen
• Formation of transition metal hydrides at high pressures
• Predicted formation of superconducting platinum-hydride crystals under pressure in the presence of molecular hydrogen
• Structural Metastability of Endohedral Silicon Fullerenes

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