Pb _1-x Sn _x Te alloys: Application considerations

The search for alternative energy sources is at the forefront of applied research. In this context, thermoelectricity, i.e., direct conversion of thermal into electrical energy, plays an important role, particularly for exploitation of waste heat. Materials for such applications should exhibit thermoelectric potential and mechanical stability. PbTe-based compounds include well-known n-type and p-type compounds for thermoelectric applications in the 50°C to 600°C temperature range. This paper is concerned with the mechanical and transport properties of p-type Pb _0.5Sn _0.5Te:Te and PbTe<Na> samples, both of which have a hole concentration of ∼1 × 10 ²⁰ cm ^-3. The ZT values of PbTe<Na> were found to be higher than those of Pb _0.5Sn _0.5Te:Te, and they exhibited a maximal value of 0.8 compared with 0.5 for Pb _0.5Sn _0.5Te:Te at 450°C. However, the microhardness value of 49 H _V found for Pb _0.5Sn _0.5Te:Te was closer to that of the mechanically stable n-type PbTe (30 H _V) than to that of PbTe<Na> (71 H _V). Thus, although lower ZT values were obtained, from a mechanical point of view Pb _0.5Sn _0.5Te:Te is preferable over PbTe<Na> for practical applications.