Effect of GaSb Addition and Sb Doping on the Thermoelectric Properties of Mg2Si0.5Sn0.5 Solid Solutions

Abstract Mg 2 Si 0.487-2 x Sn 0.5 (GaSb) x Sb 0.013 (0.04 ≤ x ≤ 0.10) solid solutions were synthesized by a B 2 O 3 flux method followed by hot pressing. X-ray power diffraction analysis confirms that single-phased samples are obtained. It is found that the Sb-doping effectively enhances the electrical conductivity. The Seebeck coefficients increase while the electrical conductivity decreases for Mg 2 Si 0.487-2 x Sn 0.5 (GaSb) x Sb 0.013 with the increase of temperature. With increasing of GaSb content the electrical conductivity first increases and then decreases. Among all the samples, Mg 2 Si 0.287 Sn 0.5 (GaSb) 0.1 Sb 0.013 sample has the lowest lattice thermal conductivity which is about 15% lower than that of Mg 2 Si 0.5 Sn 0.5 [11] at room temperature. A maximum dimensionless figure of merit of 0.61 at 720 K has been obtained for Mg 2 Si 0.327 Sn 0.5 (GaSb) 0.08 Sb 0.013 mainly due to its high electrical conductivity, which is obviously higher than that (0.019 at 540 K) of Mg 2 Si 0.5 Sn 0.5 [11] .