Increase in the Figure of Merit by Cd-Substitution in Sn1-xPbxTe and Effect of Pb/Sn Ratio on Thermoelectric Properties

The effects of Cd-doping on the thermoelectric properties of Sn1xPbxTe are investigated and compared to the properties of the corresponding Sn1xPbxTe solid solutions. The addition of Cd results in a reduction in the carrier concentration and changes in the physical properties, as well as in the conduction type of Sn1xPbxTe. A significant increase in the power factor accompanied by a reduction in the thermal conductivity result in a higher figure of merit (ZT) for (Sn1xPbx)0.97Cd0.03Te than that of undoped Sn1xPbxTe. The maximum ZT (similar to 0.7) values are observed for p-type material with x = 0.36 at 560 K. Much higher values (ZT similar to 1.2 at 560 K for x = 0.73) are obtained on n-type samples.