Enhanced thermoelectric performance of n-type PbTe bulk materials fabricated by semisolid powder processing

The introduction of mesoscale (∼0.1-1.0 μm) structures is one of effective approaches to reduce the thermal conductivity of thermoelectric materials. In this study, n-type PbTe bulk samples were fabricated by semisolid powder processing (SPP) using powders synthesized by melting. The field emission scanning electron microscope (FESEM) results showed that there were circular mesoscale pores in the grains of the samples fabricated by SPP. The mesoscale pores effectively reduced the lattice thermal conductivity by enhancing the scattering of phonons with long mean free paths. The samples fabricated by SPP had a figure of merit (ZT) value of 1.33 at 773 K, which showed an enhancement of 77% compared with that of their hot-pressed counterparts. This enhancement mainly resulted from the lower lattice thermal conductivity and higher power factor of the SPP samples.