Effect of spark plasma sintering temperature on microstructure and thermoelectric properties of the cermet composites consisting of Bi2Te2.1Se0.9 matrix and Co@CoTe2 inclusions

Novel cermet Bi2Te2.1Se0.9+0.33 ​wt% Co composite has been prepared via spark plasma sintering (SPS) the starting Bi2Te2.1Se0.9 and powders at different SPS-temperatures (TS ​= ​598, 623, 648 673 ​K). During sintering, initial inclusions transform into final filler [email protected]2 (“core”-“shell”) inclusions, randomly distributed inside textured grained matrix. Forming these is originated from high-temperature chemical interaction between Co. Main features in microstructure thermoelectric properties of found with increasing TS are: (i) a texturing degree matrix gradually decreases that attributed to reducing ability nanometer particles act as lubricant; (ii) fraction core decreases, CoTe2 shell increases related acceleration Co→CoTe2 reaction higher temperatures; (iii) specific electrical resistivity Seebeck coefficient reduce, whereas total thermal conductivity can be growth electron concentration due local doping. Highest value figure-of-merit equal ∼0.8 was observed for composite, SPS-treated ​K.