Enhancement in Thermoelectric Figure of Merit in Nanostructured Bi2Te3 with Semimetal Nanoinclusions

The effect of Bi (semimetal) nanoinclusions in nanostructured Bi 2 Te 3 matrices is investigated. Bismuth nanoparticles synthesized by a low temperature solvothermal method are incorporated into Bi 2 Te 3 matrix phases, synthesized by planetary ball milling. High density pellets of the Bi nanoparticle/Bi 2 Te 3 nanocomposites are created by hot pressing the powders at 200 ° C and 100 MPa. The effect of different volume fractions (0–7%) of Bi semimetal nanoparticles on the Seebeck coeffi cient, electrical conductivity, thermal conductivity and carrier concentration is reported. Our results show that the incorporation of semimetal nanoparticles results in a reduction in the lattice thermal conductivity in all the samples. A signifi cant enhancement in power factor is observed for Bi nanoparticle volume fraction of 5% and 7%. We show that it is possible to reduce the lattice thermal conductivity and increase the power factor resulting in an increase in fiof merit by a factor of 2 (from ZT = 0.2 to 0.4). Seebeck coeffi cient and electrical conductivity as a function of carrier concentration data are consistent with the electron fi ltering effect, where lowenergy electrons are preferentially scattered by the barrier potentials set up at the semimetal nanoparticle/semiconductor interfaces.

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