Abstract: Rare-earth elements (Re) Sc and Y doped Mg₂Si thermoelectric materials were made via a field-activated and pressure-assisted synthesis (FAPAS) method at 1023-1073 K, 50 MPa for 15 min. The samples created using this method have uniform and compact structures. The average grain size was about 1.5-2 μm, the micro-content of Re did not change the matrix morphology. A sample with 2500 ppm Sc obtained the best Seebeck coefficient absolute value, about 1.93 times of that belonging to non-doped Mg₂Si at about 408 K. The electric conductivity of the sample doped with 2000 ppm Y becomes 1.69 times of that of pure Mg₂Si at 468 K, while the former had a better comprehensive electrical performance. Their thermal conductivity was reduced to 70% and 84% of that of non-doped Mg₂Si. Thus, the figure of merit and ZT of these two samples were enhanced visibly, which were 3.3 and 2.4 times of the non-doped samples at 408 K and 468 K, respectively. The maximal ZT belonging to samples doped with 2500 ppm Sc went up to 0.42 at about 498 K, higher than 0.40 of sample doped with 2000 ppm Y at 528 K and 0.25 of non-doped Mg₂Si at 678 K, and the samples doped with Sc seemed to get the best thermoelectric performances at lower temperature.

Key words: Mg₂Si, rare-earth element, thermoelectric material, FAPAS