Thermoelectric Properties of (fe1−xcox)2val Heusler-type Compounds

Polycrystalline (Fe1−xCox)2VAl (0≤x≤0.5) alloys were synthesized through a combined process of arc-melting, annealing and sintering. Thermoelectric properties were investigated from 300 to 850K. Stoichiometric Fe2VAl exhibited p-type conduction, however, it shifted to n-type with slight Co substitution for Fe site. After Co substitution, the electrical conductivity and absolute value of Seebeck coefficient at room temperature increased from 1.2×105 to 5×105Sm−1 and 30 to 112μV/K, respectively. Meanwhile, the lattice thermal conductivity dropped from 23 to 6W/mK because of the introduction of extra phonon scattering due to alloying effect. The highest dimensionless figure of merit ZT value for (Fe0.7Co0.3)2VAl is 0.09 at 650K.