Ternary chalcogenides NbIn<i>X</i>₂ (<i>X</i> = S, Se): A comprehensive investigation of mechanical, electronic, vibrational, optical and thermophysical properties

A comprehensive investigation of the unexplored mechanical, electronic, Mulliken bond population, vibrational, optical and thermophysical properties of the synthesized compounds NbIn[Formula: see text] (X = S, Se) have been made for the first time using the density functional theory. The chemical, mechanical and dynamical stabilities of the compounds are established in our calculations. Both compounds are soft, machinable and brittle. The anisotropic nature of the studied compounds is shown by 3D representations of elastic moduli. The density of states and electronic band structure demonstrate that the compounds are metallic. Fermi surfaces of both compounds are almost similar and contain both hole- and electron-like topologies. The characteristics of chemical bonding among different atoms of the compounds are studied via a charge density distribution map and bond population analysis. Both the compounds possess optical anisotropy. Reflectivity is high (above 44%) in the IR–visible–UV region indicating that the phases may be effective in reducing solar heat. Minimum thermal conductivity, [Formula: see text] (used to select appropriate material for thermal barrier coating) and its anisotropy are calculated for the first time. The results show that both compounds have [Formula: see text] much smaller than the reference value of 1.25[Formula: see text]W[Formula: see text]m[Formula: see text][Formula: see text]K[Formula: see text].