Theoretical Investigation of Mechanical, Electronic, 
and Thermal Properties of Fe2TiSi and Fe2TiSn Under Pressure
In this study, the structural, mechanical, electronic, and thermal properties for Fe2TiSi and Fe2TiSn Heusler compounds were successfully studied by using the first-principles calculations based on density functional theory for the first time. The lattice constants calculated from the theoretical calculations are consistent with the experimental results, and cell volume decreases uniformly with increasing pressure. The elastic constants and shear moduli, bulk moduli, Young’s moduli of these alloys satisfy the traditional mechanical stability restrictions and those are suggesting that ductility of these alloys gradually change for the better with increasing ambient pressure conditions up to the considered pressures. These Heusler materials have small band gaps with flat band at the bottom of the conduction band and the calculated band gaps increase between 0.472 eV and 0.646 eV in Fe2TiSi, 0.144 eV and 0.175 eV in Fe2TiSn for pressure ranging from 0 GPa to 50 GPa. Density of states landscapes are considered and predict a better transport properties at a lower pressure. In addition, we predicted the Debye temperatures, the isochoric heat capacities, minimum thermal conductivities of Fe2TiSn and Fe2TiSi by using first-principles calculations combined with the quasi-harmonic Debye model under pressure up to 50 GPa.