Enhanced Thermoelectric Performance of BiSbTe Nanostructured with CdTe.

Cd-containing polycrystalline BiSbTe samples with precisely controlled phase composition were synthesized by conventional melting-quenching-annealing technique and a melt-spinning method. The pseudo ternary phase diagram for Cd-Bi/Sb-Te in the region near BiSbTe was systematically studied. Cd serves as an acceptor dopant contributing holes, whereas for samples doped with CdTe, the combined effects of the substitution of Sb/Bi with Cd and the formation of Sb/Bi antisite defects leads to the increase in hole concentration. Moreover, upon doping with Cd, the lattice thermal conductivity decreases significantly owing to the intensified point defect phonon scattering. The sample with Cd content of 0.01 attains the maximum of 1.15 at 425 K. The utilization of melt-spinning method brings about the in situ nanostructured CdTe and grain size refinement, which further reduce the lattice thermal conductivity while preserving excellent electrical performance. As a result, a higher of 1.30 at 425 K is realized with CdTe content = 0.005.