First principle studies on electronic and thermoelectric properties of Fe2TiSn based multinary Heusler alloys

The alloys with 8/18/24 valence electron count (VEC) are promising candidates for efficient energy conversion and refrigeration applications at low as well high temperatures. Recently Fe-based Heusler attracted researchers due to their compelling electronic band structure i.e flat along one direction of the Brillouin zone highly dispersive bands other directions. Here we focus on thermoelectric (TE) transport properties isovalent/aliovalent substituted Fe2TiSn systems those may be potential TE materials. multinary substitution has been done in such a way that it preserves 24 VEC hence semiconducting nature. calculated total energies VASP-PAW within density functional theory PBE-GGA were used determine ground state equilibrium lattice parameters, bulk modulus etc. We have also investigated structural, electronic, dynamic by using TB-mBJ exchange–correlation functional. full linearized augmented plane wave method implemented WIEN2k code was investigate exchange potentials Boltzmann theory. single crystal elastic constants, phonon dispersion states confirm these mechanically dynamically stable. is including part thermal conductivity (κL) obtained from two methods calculation (κLelastic) curve (κLphonon). strong phonon–phonon scattering large mass difference/strain fluctuation Ti/Sn sites reduces which results figure-of-merit (ZT) value 0.81 900 K Fe2Sc0.25Ti0.5Ta0.25Al0.5Bi0.5. comparative analysis structures shows ZT scheme found significantly higher than based PBE-GGA. relatively values suggest medium temperature waste heat recovery.