Band Degeneracy and Anisotropic Transport Dynamics in the Nanolayered BaFMgSb Compound

ZrCuSiAs-type materials have garnered significant interest in thermoelectrics (TE). In the current study, the crystal structure, thermal and electronic transport properties, and TE performance of the nanolayered BaFMgSb compound are investigated using first-principles calculations in combination with Boltzmann transport theory. The nanolayered BaFMgSb compound exhibits a direct band gap of 1.21 eV, with pronounced band degeneracy and a convergence phenomenon in the valence band, which contributes to a high Seebeck coefficient. The weak interactions between the [Ba 2 F 2 ] 2+ and [Mg 2 Sb 2 ] 2– layers, coupled with strong intralayer interactions, facilitate favorable electronic transport properties. A lattice thermal conductivity of 0.78 W/mK is achieved for the BaFMgSb compound with the incorporation of four-phonon scattering at 900 K. Meanwhile, the BaFMgSb compound demonstrates an excellent Seebeck coefficient and high electrical conductivity. Based on multiple carrier scattering mechanisms, the p -type doped BaFMgSb compound achieves an optimal dimensionless figure of merit ( ZT ) of 2.41 at 900 K. This work not only provides multifaceted insights into the thermal and electronic transport performance of the nanolayered BaFMgSb compound but also offers theoretical guidance for the design of layered TE materials.