Enhanced thermoelectric performance in Fe<sub>2</sub>V<sub>0.8</sub>W<sub>0.2</sub>Al thin films: synergistic effects of chemical ordering and tungsten substitution.

Abstract

We systematically investigate the combined effect of chemical ordering and W substitution on the thermoelectric properties of Fe₂V_0.8W_0.2Al thin films. Through controlled sputter deposition on MgO (100) and Al₂O₃ (112̄0) substrates at temperatures ranging from 350 °C to 950 °C, we achieve varying degrees of crystalline and chemical order. Films deposited between 750 °C and 950 °C adopt the highly ordered L2₁ phase, exhibiting a dramatic enhancement in Seebeck coefficient and substantial reduction in thermal conductivity compared to isostructural Fe₂VAl thin films without tungsten substitution. These synergistic improvements, attributed to electronic structure modifications and enhanced phonon scattering mechanisms, yield exceptional thermoelectric performance with maximum power factors of 730 ± 70 µW m^-1 K^-2 and figure of merit <i>zT</i> = 0.12 ± 0.03 at room temperature, representing a more than four-fold enhancement over undoped Fe₂VAl and demonstrating the potential for sustainable energy harvesting applications.