Effective modelling of the Seebeck coefficient of Fe2VAl.

ABSTRACT

Previous first-principles calculations have failed to reproduce many of the key thermoelectric features of Fe2VAl, e.g. the maximum values of the Seebeck coefficient S and its asymmetry with respect to the chemical potential. Also, previous theoretical predictions suggested that the pseudo band gap of Fe2VAl switches from indirect to direct upon doping. In this work, we report first-principles calculations that correctly reproduce the experimentally measured thermoelectric properties of Fe2VAl. This is achieved by adding a larger Hubbard U term to V atoms than to Fe atoms and including a scissors operator afterwards. As a result, bulk Fe2VAl is modelled as a gapless semiconductor with maximum S values of 76 and -158 [Formula see text]V K-1 for p - and n-type, respectively, which agree well with the experimental measurements.