Thermoelectric performance boost by chemical order in epitaxial L21 (100) and (110) oriented undoped Fe2VAl thin films: an experimental and theoretical study†

This study demonstrates the direct correlation between the presence of the L2₁ ordered phase and the significant enhancement in the thermoelectric performance of Fe₂VAl thin films deposited on MgO and Al₂O₃ substrates at temperatures varying between room temperature and 950 °C. We employ both experimental techniques and computational modeling to analyze the influence of crystallographic orientation and deposition temperature on the thermoelectric properties, including the Seebeck coefficient, electrical conductivity, and thermal conductivity. Our findings indicate that the presence of the L2₁ phase significantly enhances the power factor (PF) and figure of merit (zT), surpassing previously reported values for both bulk and thin film forms of Fe₂VAl, achieving a PF of 480 μW m⁻¹ K⁻² and a zT of 0.025.