Abstract
In this work, first-principles calculations have been used to investigate the electronic structure, phonon scattering, and Debye temperature of Mg3Sb2-xBix alloys. The electronic transport properties were predicted by solving the Boltzmann equations. Additionally, thermoelectric properties of alloys with corresponding compositions prepared using directional solidification were analyzed and compared with the predicted results. The research findings reveal that the increase in Bi content is accompanied by an increase in carrier concentration and mobility, and a decrease in carrier effective mass. The Mg3Sb1.5Bi0.5 alloy showed the highest power factor value of 0.49 mWm−1K−2 due to the synergistic effect between the electrical conductivity and the Seebeck coefficient. As the Bi atoms replace Sb sites, the scattering rates of low-frequency phonons become stronger, significantly reducing the lattice thermal conductivity. The Mg3Sb0.5Bi1.5 alloy reaches the lowest thermal conductivity, especially in the low and medium temperature range. Mg3Sb1.5Bi0.5 alloy provides the maximum ZT value of 0.29 at 630 K. This study systematically analyzes the impact of Bi on electronic transport and phonon scattering in Mg3Sb2-xBix alloys，and extensively discusses the dependence of thermoelectric performance parameters on Bi content. This work also provides a theoretical reference for the subsequent research on doping modification of Mg3Sb2-xBix alloys.
Published Version
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