Quantitative Evaluation of Seebeck Coefficient using Linearized Boltzmann Transport Equation for Fe2VAl-Based Compounds

Abstract

Using our new program code, we have calculated the temperature dependence of the Seebeck coefficient (\(S-T\)) in the linearized Boltzmann transport equation with a constant relaxation time (LBT-CRT) for Fe₂VAl (cF16) and its quaternary compounds for the range from − 263 °C (10 K) to 727 °C (1000 K). We revealed that Fe₂VAl compound free from any defects exhibited the Seebeck coefficient with a negative sign at odds with experimental data with a positive sign. However, this dilemma could be removed after the introduction of Al/V near neighbor inversion defects into the perfect Fe₂VAl. A key point in developing a reliable temperature-dependent Seebeck coefficient software lies in how precisely we calculate the density of states times square of the group velocity \({\left|{{\text{v}}}_{x}\right|}^{2}\) along the direction \(x\) of thermal gradient. The present method is contrasted to the Fourier Transform Interpolation method in BoltzTraP developed by Madsen and Singh (2006). Nevertheless, both could reproduce the experimental data of Fe₂VAl once the inversion effect was taken into account. Our new software allows us to seek the origin of characteristic behaviors in the \(S-T\) curve by decomposing the electronic parameter above into sub-bands and analyzing the sub-band dependence of the energy spectrum \(A\left(\varepsilon \right)\) in the LBT-CRT equation.