Thermoelectric properties of Bi2Te3-based prepared by directional solidification under a high magnetic field

This study reports a significant enhancement of the thermoelectric properties of Bi₂Te₃-based materials achieved by modifying their internal microstructure via the high magnetic field-directed solidification method. The magnetic moment generated by the magnetic field leads to an optimal crystal orientation, drastically reducing the resistivity while maintaining the stability of the Seebeck coefficient. Consequently, the power factors of P-type Bi_0.5Sb_1.5Te₃ and N-type Bi₂Te₃ samples were improved by 29.2 and 23.2 %, respectively. Furthermore, the thermoelectric magnetic force by the high magnetic field serves to refine the grain size and augment the source of phonon scatting, which effectively reduces the lattice thermal conductivity. Eventually, the zT_Max of the P-type Bi_0.5Sb_1.5Te₃ sample reaches 1.12, while that of the N-type Bi₂Te₃ sample is 0.24, both higher than the value without the high magnetic field.