Pressure-dependent semiconductor–metal transition and elastic, electronic, optical, and thermophysical properties of orthorhombic SnS binary chalcogenide

Abstract

Pressure dependent physical properties of binary SnS compound have been studied using the density functional theory based methodology. The computed elastic constants reveal that SnS is stable mechanically and is brittle under ambient conditions. With increasing pressure, the compound becomes ductile. The Poisson’s ratio and Cauchy pressure also indicate brittle-ductile transition when pressure increases. The hardness of SnS increases significantly with pressure. The compound possesses elastic anisotropy. The ground state electronic band structure is semiconducting with a small band gap. The band structure becomes metallic under pressure. The bands crossing the Fermi level become more and more dispersive with the increase in pressure while the electronic correlations decrease as pressure is raised. Both the Debye temperature and the phonon thermal conductivity of SnS increase sharply with pressure. The melting temperature of the compound is low. Mixed bonding characteristics are found with ionic and moderate covalent contributions. SnS is a good absorber of ultraviolet light. The reflectivity of the material increases with the increase in the pressure. The reflectivity is nonselective over a wide spectral range. The low energy refractive index is high. The low band gap energy under ambient conditions makes SnS suitable for photovoltaic applications. Non-selective and high reflectivity of SnS indicates that this compound can be used as a coating material to reduce solar heating. Unlike structural anisotropy, the optical anisotropy of SnS is low.