High Porosity in Nanostructured -Type BiTe Obtaining Ultralow Lattice Thermal Conductivity.

Porous structure possesses full potentials to develop high-performance thermoelectric materials with low lattice thermal conductivity. In this study, the -type porous nanostructured BiTe pellet is fabricated by sintering BiTe nanoplates synthesized with a facile solvothermal method. With adequate sublimations of BiTeO during the spark plasma sintering, homogeneously distributed pores and dense grain boundaries are successfully introduced into the BiTe matrix, causing strong phonon scatterings, from which an ultralow lattice thermal conductivity of <0.1 W m K is achieved in the porous nanostructured BiTe pellet. With the well-maintained decent electrical performance, a power factor of 10.57 μW cm K at 420 K, as well as the reduced lattice thermal conductivity, secured a promising value of 0.97 at 420 K, which is among the highest values reported for pure -type BiTe. This study provides the insight of realizing ultralow lattice thermal conductivity by synergistic phonon scatterings of pores and nanostructure in the -type BiTe-based thermoelectric materials.