Thermoelectric properties of tungsten-substituted Heusler Fe₂VAl alloy

A Heusler Fe₂V_1-xW_xAl sintered alloy was synthesized to evaluate the effect of W substitution on thermoelectric properties of the Heusler alloy. The Seebeck coefficient and the electrical conductivity are simultaneously enhanced through electron injection resulting from the W substitution. Comparison with the Si-substituted Fe₂VAl alloy reveals that the additional electronic states derived from W 5d orbital in the vicinity of pseudogap are likely to degrade the Seebeck coefficient. Thermal conductivity is effectively reduced by the W substitution because of the large atomic mass and volume of W compared to the constituent elements of Fe₂VAl alloy. The appreciable reduction of thermal conductivity, without a serious deterioration in electrical conduction, enhances the thermoelectric figure of merit in the Heusler alloy.