A Study 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. Interestingly random atomic scale substitution concomitant with off-stoichiometric composition affects transport properties. In addition, both thermal and electronic properties can be selectively targeted. For instance, 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 likely to be impacted by the large variation in the atomic weights of Vanadium (51) and Tungsten (184).

Thermoelectric materials offer a great potential for directly converting heat into electricity and are essential for wide-scale renewable energy application. For efficient conversion high electrical conductivity and low thermal conductivity is desirable. In this work we investigate the influence of synthesis and annealing on transport properties and the thermoelectric figure of merit (ZT) of this material. We will describe experimental details and numerical results on thermal and electrical properties of bulk Fe₂V_0.8W_0.2Al. Briefly, both electrical resistivity and thermal conductivity, and Seebeck coefficient are measured. The implication of our findings will be discussed.