Influence of Antisite Defects on the Thermoelectric Properties of Fe2VAl

Fe2VAl is well known as a promising candidate for thermoelectric applications due to its sharp pseudogap at the Fermi level. However, its energy conversion performance is compromised by its high thermal conductivity. Our previous studies revealed that antisite defects like AlV, AlFe, and VAl are the most likely imperfections in Fe2VAl [1]. It is thus important to understand the electron and phonon transport properties in these defective crystals to estimate their thermoelectric efficiency. Here we analyze the electronic transport properties of Fe2VAl solid solutions based on Boltzmann transport theory within the constant relaxation time approximation. We then calculate the lattice thermal conductivity of Fe2VAl containing AlV antisite defects by solving the linearized Boltzmann transport equation based on an ab initio model for defects. We find a significant increase of around an order of magnitude in ZT at 300 K compared to the stoichiometric compound.