A Study of Thermoelectric Properties of the Atypical Heusler Alloy Fe₂ (V_1-xW_x) Al

The Heusler system permits great flexibility in electronic, thermal, morphological, and structural attributes. A typical (full) Heusler compound has a composition XY₂Z; here X and Y are transition metals and Z is a p-block element. Due to nonstoichiometric composition the atypical alloy offers additional tunability; random atomic scale substitution concomitant with off-stoichiometric composition affects transport properties. In addition, thermal and electronic properties can be selectively targeted, viz., electrical response is sensitive to defects in valency whereas phonon properties are affected by atomic weight disorder. Consequently, thermal conductivity in the quaternary alloy Fe₂ (V_1-xW_x) Al, is impacted by the large variation in the atomic weights of Vanadium (51) and Tungsten (184). These materials offer great potential for thermoelectricity. Because, for efficient direct conversion of heat into electricity high electrical conductivity and low thermal conductivity is desirable. We investigated the influence of synthesis and annealing on transport properties and the thermoelectric figure of merit (ZT) of this material. We will describe, electrical resistivity, thermal conductivity, and Seebeck coefficient of bulk Fe₂(V_1-xW_0.2)Al solids, with x~0.2 . The implication of our findings will be discussed.