Development of Nanostructures in Thermoelectric Pb-Te-Sb Alloys

Abstract

In analogy to recent demonstrations of enhanced thermoelectric properties in superlattice materials, composite structures with nanoscale features promise dramatic improvements in the figure of merit of thermoelectric materials. Fabrication of nanostructured thermoelectric materials via bulk synthesis is an attractive route for commercial applications. Nanometer scale lamellae of PbTe and Sb 2 Te 3 form when quenched eutectic PbTe-Sb 2 Te 3 melt is subsequently annealed. The lamellar spacing depends on the temperature and time of the anneal. The mechanism for the development of the nanostructures can be characterized by examining the fraction of material transformed as a function of anneal time. Preliminary analysis of the shape factor exponent reveals that the evolution of the nanostructured lamellae is likened to the thickening of very large plates. The coarsening of the lamellar spacing is also examined as a function of time.

Self-Assembled Nanometer Lamellae of Thermoelectric PbTe and Sb2Te3 with Epitaxy-like Interfaces

“…Here, γ is the surface energy, T E is the eutectoid invariant temperature, Δ T and Δ H are the temperature and enthalpy difference of the supercooled material at the point of nucleation compared to T E , and V m is the molar volume. The increase in interlamellar spacing with time evident in Figure is clearly expected from these relationships, although the linear dependence with time cannot be verified . Its increase with temperature suggests that λ 0 strongly depends on temperature, most likely via its dependence on Δ T .…”

Thermal and electrical transport properties of VA-element doped Pb9.6M0.2Te10−xSex (M = Sb, Bi) thermoelectric materials

“…It was also found that with excess Pb and/or Sb precipitated phases in PbTe the thermal conductivity was suppressed and power factor was effectively enhanced [4,20]. Utilizing the eutectic decomposition in the pseudo-binary PbTe-Sb 2 Te 3 system Snyder et al successfully produced a layer-by-layer self-assembled nanostructure [21][22][23]. Poudeu et al [24] found that the introduction of Sb into Pb 9.6 Te 10−x Se x solid solutions which are rich in chalcogen elements caused an extremely low thermal conductivity and hence good TE performance due to the formation of Sb-rich nanocrystals.…”