PbTe-PbS materials are promising for thermoelectric power generation applications. For the composition of (Pb0.95Sn0.05Te)0.92(PbS)0.08 nanostructuring from nucleation and growth and spinodal decomposition has been reported along with thermal conductivity of approximately 1.1 W/m·K at 650 K [1]. Based on temperature-dependent measurements of electrical conductivity, thermopower, and thermal conductivity, the thermoelectric figure of merit, ZT, are ~1.5 at 650 K for cast ingots.

To develop larger quantities of material for device fabrication, advancement in the synthesis, processing and production of (Pb0.95Sn0.05Te)0.92(PbS)0.08 is necessary. Powder processing of samples is a well-known technique for increasing sample strength, and uniformity. In this presentation, we show sample fabrication and processing details of pulsed electric current sintering (PECS) processed (Pb0.95Sn0.05Te)0.92(PbS)0.08 materials and their thermoelectric properties along with the latest advancements in the preparation of these materials.

In this work we report on the infrared properties of the thermoelectric (1-x)PbTe-xPbSnS2 system with x=0.03, 0.06, 0.11 and 0.33. The results obtained by the analysis of the reflectivity spectra are discussed together with the structural and morphological characteristics obtained by XRD and SEM-EDS measurements. The system was found macroscopically homogeneous for x=0.03 and x=0.06 and phase separated for x=0.11 and x=0.33. The analyzed ~150cm-1 PbS impurity mode demonstrated a composition close to the PbTe0.98S0.02 for the major phase. The incorporation of PbSnS2 causes a reduction in plasma frequency (decrease in carrier frequency concentration) and an increase in carrier mobility.

The synthesis and properties characterization of several PbS1-xTexx = 0-0.16 samples are presented. Notably it is shown how a local minimum occurs in the thermal diffusivity for the PbS1-xTex samples at x ≈ 0.03. The thermoelectric properties of doped PbS1-xTex with x = 0.03 are reported and the properties are compared to the pure PbS and PbTe end members. The electronic contribution to the total thermal conductivity is analyzed for PbS1-xTexx = 0.03 and it is shown how the lattice thermal conductivity is significantly lowered compared to single crystalline PbS.

The thermoelectric (Pb1-mSnmTe)1-x(PbS)x where m = 0.05 and x = 0.08 has been shown to produce PbS nanostructures that effectively scatter phonons, enhancing ZT. As Sn substitution is increased, a new phase of PbSnS2 precipitates. We find that incorporation of PbSnS2 in PbTe results in a significant reduction in lattice thermal conductivity around 0.6 W/mK at room temperature. We present preliminary characterization and thermoelectric properties.

We have shown that (Pb1-mSnmTe)1-x(PbS)x where m = 0.05 and x = 0.08 exhibits a ZT of ˜1.4 at 700 K. This system incorporates two thermoelectric systems: PbSxTe1-x and Pb1-xSnxTe. Here we report the thermoelectric properties of PbSxTe1-x (x = 0.08 and 0.30). The material PbS0.08Te0.92 exhibits nucleation and growth of PbS precipitates, while PbS0.30Te0.70 exhibits PbS precipitation through spinodal decomposition phase separation. We report the thermoelectric properties of this system as a result of the differing precipitation phenomena.

For the material (Pb0.95Sn0.05Te)1-x(PbS)x nanostructuring from nucleation and growth and spinodal decomposition were reported to enhance the thermoelectric figure of merit over bulk PbTe, producing ZT of 1.1 - 1.4 at 650 K for x = 0.08[1]. Thermoelectric modules made from (Pb0.95Sn0.05Te)1-x(PbS)x materials with various hot-side metal electrodes were fabricated and tested. Short circuit current was measured on unicouples of Pb0.95Sn0.05Te – PbS 8% (n-type) legs and Ag0.9Pb9Sn9Sb0.6Te20 (p-type) legs over 10 (A) for a hot side temperature of 870K, and a cold side of 300K. Hot pressed (Pb0.95Sn0.05Te)1-x(PbS)x materials were also investigated for module fabrication. Investigations of the electrical properties of hot-pressed (Pb0.95Sn0.05Te)1-x(PbS)x materials are presented along with the latest advancements in the fabrication and characteristics of modules based on the processing of these materials.

We report the physical characterization and thermoelectric properties of (Pb0.95Sn0.05Te)0.92(PbS)0.08 containing excess Pb and Sb prepared using the matrix encapsulation technique. Samples of (Pb0.95Sn0.05Te)0.92(PbS)0.08 : Pb 0.5 - 4 at. % rapidly quenched from the melt show microscale Pb inclusions that increase the thermal conductivity while slightly increasing the power factor, compared to (Pb0.95Sn0.05Te)0.92(PbS)0.08. Samples of (Pb0.95Sn0.05Te)0.92(PbS)0.08 : Pb 0.5%, Sb 2% prepared using the same technique show microscale Sb and Pb inclusions that upon heating cause rapid PbS and Sb segregation from the PbTe matrix. This behavior significantly alters the microstructure and degrades the transport properties of the material.