Thermoelectric properties of Sb-doped Heusler Fe2VAl alloy

A Heusler Fe2VAl1−xSbx sintered alloy was synthesized to evaluate the effect of Sb substitution on thermoelectric properties of the Heusler alloy. Thermal conductivity was effectively reduced by a small amount of the substitution because of the large atomic mass of Sb compared to the constituent elements of Fe2VAl alloy. The Seebeck coefficient was enhanced through electron injection resulting from the Sb substitution and reached −130 μV/K. Although the Sb substitution also increased electrical conductivity because of the increase in the number of electron carriers, the low substitution limit of Sb left room for improvement. Additional electron injection by the Si substitution for the Al site further increased the electrical conductivity while maintaining the large Seebeck coefficient and the low thermal conductivity. The thermoelectric figure of merit of 5.1 × 10−4 K−1 was then obtained at room temperature for Fe2VAl0.9Sb0.03Si0.07.