Thermoelectric Properties of Bi2Te3 Nanocrystals with Diverse Morphologies Obtained via Modified Hydrothermal Method

Single-phase Bi2Te3 nanostructures (spherical and flower-like) have been synthesized using a modified hydrothermal method at different reaction temperatures (70A degrees C, 100A degrees C, and 150A degrees C) and subsequently consolidated by spark plasma sintering. Their crystal structure, morphology, and thermoelectric and mechanical properties were investigated. The results suggest that the reaction temperature had a significant effect on the morphology and thermoelectric properties. The presence of nanostructures in bulk samples led to a remarkable decrease in thermal conductivity with a lesser effect on electrical conductivity. As a result, the figurea of pound merit (ZT) of the spark-plasma-sintered sample processed from spherical nanoparticles reached 0.54 at 400 K. The Vickers microhardness of the bulk sample processed from spherical nanoparticles was higher than the best results found in literature.