Enhanced thermoelectric performance of nanostructured ZnO: A possibility of selective phonon scattering and carrier energy filtering by nanovoid structure

Michitaka Ohtaki, Ryosuke Hayashi

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    24 Citations (Scopus)

    Abstract

    Highly dispersed nanosized closed pores (nanoviods) are revealed to be effective to substantially enhance the thermoelectric performance of bulk sintered body of n-type Al-doped ZnO oxide, resulting in a dimensionless figure-of-merit of ZT - 0.65 at 1250 K. The nanovoid structure is built in a densely sintered Al-doped ZnO matrix by using combustible nanosized polymer particles as a void forming agent (VFA), the uniformity of the WA distribution in the sintering mixture being greatly improved by employing planetary-type ball milling with high pulverizing capability. A combination of shortened mixing period and liquid mixing media enables us to prevent formation of oxygen-related defects in ZnO, and sintered samples thus obtained show the electrical conductivity (σ) higher than that of those prepared with conventional ball milling. The sintered samples obtained in the present study also show the Seebeck coefficient (S). considerably larger than that of the control sample over the whole temperature range from 300 K to 1273 K, implying an enhancement of the thermopower possibly due to a carrier energy filtering effect by low-energy nanosized defects. Although a decrease in the thermal conductivity (κ) is only of the same magnitude to that of the σ values, the marked increase in both σ and S gives rise to a significant enhancement of the power factor. With fairly suppressed κ values, the nanovoid ZnO samples successfully attain a largest ZT value so far observed for n-type bulk oxide materials.

    Original languageEnglish
    Title of host publicationProceedings ICT'06 - 25th International Conference on Thermoelectrics
    Pages276-279
    Number of pages4
    DOIs
    Publication statusPublished - Dec 1 2006
    EventICT'06 - 25th International Conference on Thermoelectrics - Vienna, Austria
    Duration: Aug 6 2006Aug 10 2006

    Publication series

    NameInternational Conference on Thermoelectrics, ICT, Proceedings

    Other

    OtherICT'06 - 25th International Conference on Thermoelectrics
    CountryAustria
    CityVienna
    Period8/6/068/10/06

    Fingerprint

    Phonon scattering
    Ball milling
    Defects
    Oxides
    Seebeck coefficient
    Thermoelectric power
    Thermal conductivity
    Sintering
    Oxygen
    Liquids
    Polymers
    Temperature
    Electric Conductivity

    All Science Journal Classification (ASJC) codes

    • Engineering(all)

    Cite this

    Ohtaki, M., & Hayashi, R. (2006). Enhanced thermoelectric performance of nanostructured ZnO: A possibility of selective phonon scattering and carrier energy filtering by nanovoid structure. In Proceedings ICT'06 - 25th International Conference on Thermoelectrics (pp. 276-279). [4133287] (International Conference on Thermoelectrics, ICT, Proceedings). https://doi.org/10.1109/ICT.2006.331368

    Enhanced thermoelectric performance of nanostructured ZnO : A possibility of selective phonon scattering and carrier energy filtering by nanovoid structure. / Ohtaki, Michitaka; Hayashi, Ryosuke.

    Proceedings ICT'06 - 25th International Conference on Thermoelectrics. 2006. p. 276-279 4133287 (International Conference on Thermoelectrics, ICT, Proceedings).

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Ohtaki, M & Hayashi, R 2006, Enhanced thermoelectric performance of nanostructured ZnO: A possibility of selective phonon scattering and carrier energy filtering by nanovoid structure. in Proceedings ICT'06 - 25th International Conference on Thermoelectrics., 4133287, International Conference on Thermoelectrics, ICT, Proceedings, pp. 276-279, ICT'06 - 25th International Conference on Thermoelectrics, Vienna, Austria, 8/6/06. https://doi.org/10.1109/ICT.2006.331368
    Ohtaki M, Hayashi R. Enhanced thermoelectric performance of nanostructured ZnO: A possibility of selective phonon scattering and carrier energy filtering by nanovoid structure. In Proceedings ICT'06 - 25th International Conference on Thermoelectrics. 2006. p. 276-279. 4133287. (International Conference on Thermoelectrics, ICT, Proceedings). https://doi.org/10.1109/ICT.2006.331368
    Ohtaki, Michitaka ; Hayashi, Ryosuke. / Enhanced thermoelectric performance of nanostructured ZnO : A possibility of selective phonon scattering and carrier energy filtering by nanovoid structure. Proceedings ICT'06 - 25th International Conference on Thermoelectrics. 2006. pp. 276-279 (International Conference on Thermoelectrics, ICT, Proceedings).
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