Numerical and experimental determination of the thermal conductivity of pristine and substituted Fe2VAl

In this article, we investigate the lattice thermal conductivity in the thermoelectric Fe2VAl Heusler alloy by implementing a Green's function approach to describe phonon-defect scattering mechanisms in the pristine and substituted compounds. Former calculations for pristine Fe2VAl largely overestimated the lattice thermal conductivity compared to the experimental value (28 W m(-1) K-1). By considering a realistic con-centration (similar to 5%) of combined Al-V and V-Al antisite defects as an extra phonon scattering mechanism, calculated and experimental values could be reconciled. The same theoretical approach was applied to Ta- and Ta + Sn-substituted Fe2VAl. In agreement with experiments it shows that the dual Ta + Sn-substitution is more efficient in decreasing the lattice thermal conductivity of Fe2VAl than the single Ta-substitution. A strong decrease of 70% is theoretically obtained in Fe2V0.96Ta0.04Al0.96Sn0.04 which could thus lead to better global thermoelectric performances. (C) 2021 Elsevier B.V. All rights reserved.