Effect of annealing on thermoelectric properties of eutectic PbTe–Sb2Te3 composite with self-assembled lamellar structure

The eutectic PbTe–Sb2Te3 composite with self-organized lamellar structure was synthesized using induction melting and the effects of annealing on the microstructure and thermoelectric properties were investigated. The PbTe and Sb2Te3 lamellae are crystallographically oriented with coherent interface, which are found to insignificantly affect the electronic flow. After annealed, the spheroidization of the lamellae occurs, and the carrier concentration decreases. Despite the increased phase boundaries, the lattice thermal conductivity increases with the annealing time. Largely due to the enhanced Seebeck coefficient, a maximum ZT ∼ 0.48 at 550 K for the sample annealed for 20 h at 573 K is achieved, showing a 60% improvement over that of the as-melted one.