Effect of Co-Doping on Thermoelectric Properties of <i>n</i>-Type Bi₂Te₃ Nanostructures Fabricated Using a Low-Temperature Sol-Gel Method

In this work, a novel low-temperature double solvent sol-gel method was used to fabricate (Sm, Ce, Gd) and (Sn, Se, I) co-doped at Bi and Te-sites, respectively, for Bi2Te3 nanostructures. The phase-purity and high crystallinity of as-synthesized nanostructures were confirmed using X-ray diffraction and high-resolution transmission electron microscopy. The nanopowders were hot-pressed by spark plasma sintering into bulk pellets for thermoelectric properties. The spark plasma sintering temperature significantly affects the Seebeck coefficient and electrical conductivity of bulk Bi2Te3 pellets. The electrical conductivities of co-doped samples decrease with an increase in the temperature, but conversely, the Seebeck coefficient is linearly increasing. The power factor showed that the co-dopants enhanced the thermoelectric properties of Bi2Te3 nanopowders