Thermoelectric Performance of Sb-doped Mg2-xZnxSi (0≤x≤0.1) Solid Solutions

Mg2-xZnxSi0.99Sb0.01 (0≤x≤0.1) solid solutions were prepared by a B2O3 flux method combined with a spark plasma sintering (SPS) technique. The electrical conductivity, Seebeck coefficient and thermal conductivity were measured as a function of temperature from 300 K to 780 K. It is found that the lattice thermal conductivity reduces with Zn content increasing; however, the electrical conductivity first decreases and then increases. The underlying mechanism was discussed. Results show that among the samples, the maximum PF (power factor) of 1.76 mW·m−1·K−2 at x=0.075 is obtained at 780 K, about 18% higher than that of Mg2Si0.99Sb0.01. The lowest lattice thermal conductivity of 2.86 W·m−1·K−1 is obtained at 770 K for the x=0.1 sample. As a result, a maximum dimensionless figure of merit of 0.37 is obtained for Mg1.9Zn0.1Si0.99Sb0.01 at 780 K.