Microstructure and thermoelectric properties of Bi1.9Lu0.1Te3 compound

Effect of fabrication conditions on microstructure and thermoelectric properties of the Bi 1.9 Lu 0.1 Te 3 compound was studied. Starting nanopowder with mean nanoparticle size of ~37 nm was synthesized by a microwave–solvothermal method. In order to prepare samples with various micro-grained structures, the synthesized nanopowder was compacted by two methods. The first method is cold isostatic pressing with further high-temperature annealing, while the second method is spark plasma sintering at various temperatures of process (653 and 683 K). It is found that mean grain size is equal to ~290, ~730 and ~1160 nm for cold isostatically pressed and spark plasma sintered at 653 and 683 K samples, respectively. The micro-grained sample with maximum mean grain size shows the best thermoelectric properties. This sample is structurally inhomogeneous and has the lowest thermal conductivity and the specific electrical resistivity. Maximum dimensionless figure of merit for this sample is equal to ~0.9 for temperature range of 450–500 K.