The Effect of Sintering on the Thermoelectric Properties of Chemically Synthesized Nano-Bulk Bi$_{2-x}$Sb$_{x}$Te$_{3}$

Considerable research effort has gone into improving the performance of traditional thermoelectric (TE) materials such as Bi$_{2-x}$Sb$_{x}$Te$_{3}$ through a variety of nanostructuring approaches. Bottom-up, chemical approaches have the potential of producing very small nanoparticles ($<$ 50 nm) with narrow size distributions and controlled shape. For this study, nanocrystalline powder of Bi$_{2-x}$Sb$_{x}$Te$_{3}$ with x = 0 -- 1.5 has been synthesized using a ligand- assisted chemical method, and consolidated into bulk pellets with cold pressing followed by sintering. These materials have the interesting property that a wide range of carrier concentrations are accessible through different Bi/Sb ratios, with low values of x being n-type and higher values becoming p-type. In this work, we present the thermoelectric transport measurements from 6 -- 300 K as a function of sintering temperature, and a beneficial effect is found. The samples are also characterized by Hall effect, XRD, and compositional analysis. We will present results on the structure-property relations, and discuss strategies for optimization of this class of TE materials for high performance.