Development of thermoelectric materials based on Fe2VAl Heusler compound for energy harvesting applications

The Heusler-type Fe2VAl compound is a nonmagnetic semimetal with a sharp pseudogap at the Fermi level. Doping of quaternary elements causes a large enhancement in the Seebeck coefficient, in parallel with a significant decrease in the electrical resistivity. Since the Seebeck coefficient varies systematically with the valence electron concentration (VEC), irrespective of doping elements, the net effect of doping is most likely to cause a rigid-bandlike shift of the Fermi level from the central region in the pseudogap. Further increase in the Seebeck coefficient can be expected for the off-stoichiometric Fe2-xV1+xAl alloys due to tuning of the Fermi level by doping. The Fe2VAl-based compounds are a promising candidate for thermoelectric power generation near room temperature, because of the possession of higher thermoelectric power factor than that of Bi-Te system.