Abstract
Aluminum and sulfur, as abundant elements in earth, only form Al2S3 in nature at ambient pressure. It has been realized that the stoichiometry of compounds may change under high pressure, which is crucial in the discovery of novel materials. In this work, we systematically perform structure search for Al–S system under pressure. Four binary compounds of Al–S with exotic stoichiometries of AlS, Al2S, Al3S4, and AlS2 are found at high pressure and show exciting physical properties. In particular, Al3S4 becomes a superconductor with a predicted superconducting transition temperature Tc of 20.9 K at 100 GPa, while the pressure-induced Al2S becomes an electride, where the valence electrons of aluminum strongly localize in the interstices, acting as anions, at a pressure of 70 GPa. This work provides a viable direction for further experimental study of the properties of Al–S system.
Highlights
Aluminum and sulfur are among abundant elements in earth and have broad applications in industry.[1,2]
A recent investigation indicates that Al–S battery is a promising candidate for use in high-performance low-cost energy-storage systems.[9]
All the candidate structures are relaxed by Vienna ab initio Simulation Package (VASP) code,[25] and the thermodynamic stabilities of Al–S system with variable stoichiometries are systematically investigated by means of calculating the formation enthalpies relative to Al and S at corresponding pressure
Summary
Aluminum and sulfur are among abundant elements in earth and have broad applications in industry.[1,2] For instance, they have been used extensively in batteries for high energy density and acceptable voltage in recent years.[3,4] As aluminum and sulfur have +3 and −2 oxidation states, respectively, only Al2S3 has been observed in nature.
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