Variations of thermoelectric properties of Mg2.2Si1-ySny-0.013Sb0.013 materials with different Si/Sn ratios

Mg2Si-Mg2Sn solid solutions are a promising class of thermoelectric materials. Mg2.2Si1-ySny-0.013Sb0.013 compounds with different Si/Sn ratios were prepared by B2O3 "flux" method followed by hot-pressing. The effect of Si/Sn ratio on the thermoelectric properties of the Mg2Si-Mg2Sn solid solutions at a fixed Sb doping level were measured in the temperature range 300-760 K. With the increase of Sn content (0.3 <= y <= 0.7), power factors are improved and lattice thermal conductivity decreased. Band convergence induced by Si/Sn ratio leads to enhanced effective mass and the materials parameter beta which qualifies a kind of thermoelectric material is improved evidently. A maximum ZT of similar to 1.1 at similar to 760 K was achieved for the Mg2.2Si0.3Sn0.7-0.013Sb0.013 sample arising from a high power factor of similar to 4 x 10(-3) W m(-1) K-2 and a low lattice thermal conductivity of similar to 1.6 W m(-1) K-1 at similar to 760 K. (C) 2014 Elsevier Inc. All rights reserved.