Lattice thermal conductivity of self-assembled PbTe-Sb2Te3 composites with nanometer lamellae

In the system of PbTe and Sb₂Te₃, a metastable compound Pb₂Sb₆Te₁₁ appears by solidification processing. It has been reported that heat treatments decomposes this compound into two immiscible thermoelectric materials forming nanosized lamellar structure. The fraction transformed and the inter-lamellar spacing was systematically investigated. In this work, the thermal conductivities and the electrical resistivities have been measured as functions of annealing time through the transformation and the coarsening processes to clarify the effect of the fraction transformed and the inter-lamellar spacing. The thermal conductivity of Pb₂Sb₆Te₁₁ is lower than that after the decomposition. The lattice part of the thermal conductivity of PbTe/Sb₂Te₃ lamellar samples decreases with decreasing inter-lamellar spacing. This is considered to be due to the coarsening of the microstructure.