Solvothermal synthesis and growth mechanism of Ag and Sb co-doped PbTe heterogeneous thermoelectric nanorods and nanocubes

Nanostructuring may contribute to distinct enhancement in thermoelectric (TE) performance via increasing the phonon scattering and density of states. In the present study, AgPb18SbTe20 (LAST-18) powders with a heterostructure of nanorods and nanocubes are synthesized by a facile one-pot solvothermal method using cheap chemical reagent as starting materials and cetyltrimethyl ammonium bromide (CTAB) as a surfactant. The results show that CTAB is crucial for the formation of nanorods owing to the preferential growth on the {1 0 0} faces or along the [1 0 0] direction with high surface energy. However, the powders are characterized by nanoparticles in case no surfactant or mass equivalent SDBS are used under the same condition. In addition, a relatively high Seebeck coefficient of the hot-pressed bulk LAST-18 with 5 vol.% heterogeneous nanopowders was obtained at high temperature range.