Theoretical investigation of stabilities and physical properties of low cost Fe-based full-Heusler materials

In this study, structural, phase and mechanical stabilities as well as elastic, electronic and thermal properties of low cost Fe-based full-Heusler materials Fe ₂ XY (X = Ti, Zr, Y = Si, Sn) were successfully studied by using the first−principles calculations based on density functional theory(DFT). The structural, phase and mechanical stabilities of all the investigated compounds have been verified for the first time. The optimized lattice constants for Fe ₂ TiSi, Fe ₂ TiSn, Fe ₂ ZrSi and Fe ₂ ZrSn are 5.658, 6.033, 5.899 and 6.227 Å respectively and the elastic constants C _ij , shear moduli G, bulk moduli B, Young's moduli E, B/G and poission ratios have been calculated. These heusler materials have small band gaps with flat band at the bottom of the conduction band and the calculated electronic properties imply that these alloys could be the very promising candidates of thermoelectric materials. Debye temperatures(Θ _D ), isochoric heat capacities(C _V ), minimum thermal conductivities (κ _min ) of Fe ₂ XY (X = Ti, Zr, Y = Si, Sn) were predicted. Our result of study is interesting from the fundamental point of view, and it has a great significance when these materials are used in practical fabrications and applications.