Thermoelectric properties of Heusler-type compound Fe2V1−xNbxAl

The transport properties are calculated within the full-potential linearized augmented plane-wave method and the semi-classical Boltzmann theory on the Heusler-type compound Fe2V1−xNbxAl. The obtained Seebeck coefficients are in reasonable agreement with experimental results. The majority carriers of stoichiometric Fe2VAl are holes. When V is slightly replaced by Nb, the Seebeck coefficient becomes negative rapidly resulting in the main carrier changing from hole to electron. σ/τ of stoichiometric Fe2VAl exhibits semiconductor behavior. However, it transits into semimetal when V is replaced by Nb at low temperature and all Nb-substituted samples exhibit semiconducting behavior above 100 K. The power factor S2σ/τ of stoichiometric Fe2VAl is relative small, and it increases greatly after Nb substitution below 360 K. The low temperature power factor of Fe2V1−xNbxAl (x ≠ 0) increases dramatically due to the enhanced Seebeck coefficient.