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

The effect of Bi (semimetal) nanoinclusions in nanostructured Bi2Te3 matrices is investigated. Bismuth nanoparticles synthesized by a low temperature solvothermal method are incorporated into Bi2Te3 matrix phases, synthesized by planetary ball milling. High density pellets of the Bi nanoparticle/Bi2...

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Bibliographic Details
Published in:Advanced energy materials 2011-11, Vol.1 (6), p.1141-1147
Main Authors: Sumithra, S., Takas, Nathan J., Misra, Dinesh K., Nolting, Westly M., Poudeu, P.F.P., Stokes, Kevin L.
Format: Article
Language:English
Subjects:
electron filtering
Seebeck coefficient
thermoelectricity
thermopower
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Summary:The effect of Bi (semimetal) nanoinclusions in nanostructured Bi2Te3 matrices is investigated. Bismuth nanoparticles synthesized by a low temperature solvothermal method are incorporated into Bi2Te3 matrix phases, synthesized by planetary ball milling. High density pellets of the Bi nanoparticle/Bi2Te3 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 coefficient, 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 significant 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 figure of merit by a factor of 2 (from ZT = 0.2 to 0.4). Seebeck coefficient and electrical conductivity as a function of carrier concentration data are consistent with the electron filtering effect, where low‐energy electrons are preferentially scattered by the barrier potentials set up at the semimetal nanoparticle/semiconductor interfaces. Nanocomposites are fabricated by combining chemically synthesized bismuth nanoparticles with mechanically‐alloyed Bi2Te3. The resulting material displays electronic transport properties consistent with energy‐dependent electronic scattering from the potential barrier established at the semimetal/semiconductor interface. This general synthetic approach can be used to create nanocomposite materials with transport properties engineered for direct thermal to electrical energy conversion applications by appropriate selection of the matrix and nanoparticle inclusions.
ISSN:1614-6832
1614-6840
DOI:10.1002/aenm.201100338