Stability and Elastic, Electronic, and Thermodynamic Properties of Fe ₂ TiSi _1−x Sn _x Compounds

We have systematically studied the structural, phase, and mechanical stability and elastic, electronic, and thermodynamic properties of Fe ₂ TiSi _1−x Sn _x (x = 0, 0.25, 0.5, 0.75, 1) compounds using first-principles calculations. The structural and phase stability and elastic properties of Fe ₂ TiSi _1−x Sn _x (x = 0, 0.25, 0.5, 0.75, 1) indicated that all of the compounds are thermodynamically and mechanically stable. The shear modulus, bulk modulus, Young’s modulus, Poisson’s ratio, electronic band structure, density of states, Debye temperature, and Grüneisen parameter of all the substituted compounds were studied. The results show that Sn substitution in Fe ₂ TiSi enhances its stability and mechanical and thermoelectric properties. The Fe ₂ TiSi _1−x Sn _x compounds have narrow bandgap from 0.144 eV and 0.472 eV for Sn substitution from 0 to 1. The calculated band structure and density of states (DOS) of Fe ₂ TiSi _1−x Sn _x show that the thermoelectric properties can be improved at substituent concentration x of 0.75. The lattice thermal conductivity was significantly decreased in the Sn-substituted compounds, and all the results indicate that Fe ₂ TiSi _0.25 Sn _0.75 could be a new candidate high-performance thermoelectric material.