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

• Published in: Journal of phase equilibria and diffusion 2024, Vol.45 (3), p.397-415
• Main Authors: Sato, H., Miyazaki, H., Nishino, Y., Mizutani, U.
• Format: Article
• Language: English
• Subjects: Boltzmann transport equation; Ceramics; Composites; Crystallography and Scattering Methods; Defects; Energy spectra; Engineering Thermodynamics; Fourier transforms; Glass; Group velocity; Heat and Mass Transfer; Linearization; Metallic Materials; Natural Materials; Original Research Article; Physics; Physics and Astronomy; Relaxation time; Seebeck effect; Software; Temperature dependence; Temperature gradients; Thermodynamics
• ISSN: 1547-7037; 1863-7345; 1934-7243
• DOI: 10.1007/s11669-024-01086-y

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 Fe 2 VAl (cF16) and its quaternary compounds for the range from − 263 °C (10 K) to 727 °C (1000 K). We revealed that Fe 2 VAl 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 Fe 2 VAl. 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 v x 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 Fe 2 VAl 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 ε in the LBT-CRT equation.