Abstract
For energy applications, knowing the electronic nature of a material is essential. Materials for thermoelectric applications are generally small-gap semiconductors and should have a high figure of merit ZT. Even if the Fe2VAl Heusler compound has a decent ZT, its conductive nature (semimetal or semiconductor) is not yet clarified especially at low temperature. In this paper, we focus our DFT calculations on the effect of temperature on the bandgap of Fe2VAl. We show that both the temperature increase and the formation of experimentally observed high temperature Al/V inversions open the bandgap. Such an unusual behavior is the key for reconciling all the bandgap measurements performed on the Fe2VAl compound using a standard GGA functional and could be an efficient way for improving the thermoelectric properties of this family of materials.