Detrimental effect of powder processing on the thermoelectric properties of CoSi

Hui Sun, Xu Lu, Donald T. Morelli

    Research output: Contribution to journalArticle

    Abstract

    Cobalt monosilicide (CoSi) prepared by arc melting possesses a very high thermoelectric power factor of 60 μW cm−1 K−2 at room temperature. The high lattice thermal conductivity of CoSi, however, limits its thermoelectric efficiency. In this paper, powder processing technique was intentionally used to reduce the grain sizes of CoSi and thus suppress its lattice thermal conductivity. The effects on the thermoelectric properties of CoSi under various processing conditions were explored. The electrical resistivity is drastically increased, while the absolute Seebeck coefficient is decreased for the powder processed samples compared to the arc-melted one. The detrimental influence is attributed to the grain boundary defects produced during processing, which brings about an excessive energy filtering effect and hence induces a huge decrease in the absolute Seebeck coefficient. The lattice thermal conductivity of powder processed samples is reduced as expected. However, the reduction is always offset by the reduction in the mobility due to the similar mean free paths of electrons and phonons of CoSi. As a result, it may not be feasible to upgrade the thermoelectric performance of the CoSi system by powder processing.

    Original languageEnglish (US)
    Pages (from-to)1-7
    Number of pages7
    JournalJournal of Materials Science
    DOIs
    StateAccepted/In press - Mar 29 2017

    Profile

    Accessory Nerve
    Powders
    Joint Loose Bodies
    Thermal conductivity
    Seebeck coefficient
    Acetanilides
    Paroxysmal Dyspnea
    Accidental Falls
    Fusobacterium
    Adolescent Behavior
    Grain boundaries
    Defects
    Electrons
    Thermoelectric power
    Phonons
    Cobalt
    Melting
    Temperature

    ASJC Scopus subject areas

    • Materials Science(all)
    • Mechanics of Materials
    • Mechanical Engineering

    Cite this

    Detrimental effect of powder processing on the thermoelectric properties of CoSi. / Sun, Hui; Lu, Xu; Morelli, Donald T.

    In: Journal of Materials Science, 29.03.2017, p. 1-7.

    Research output: Contribution to journalArticle

    Sun, Hui; Lu, Xu; Morelli, Donald T. / Detrimental effect of powder processing on the thermoelectric properties of CoSi.

    In: Journal of Materials Science, 29.03.2017, p. 1-7.

    Research output: Contribution to journalArticle

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    abstract = "Cobalt monosilicide (CoSi) prepared by arc melting possesses a very high thermoelectric power factor of 60 μW cm−1 K−2 at room temperature. The high lattice thermal conductivity of CoSi, however, limits its thermoelectric efficiency. In this paper, powder processing technique was intentionally used to reduce the grain sizes of CoSi and thus suppress its lattice thermal conductivity. The effects on the thermoelectric properties of CoSi under various processing conditions were explored. The electrical resistivity is drastically increased, while the absolute Seebeck coefficient is decreased for the powder processed samples compared to the arc-melted one. The detrimental influence is attributed to the grain boundary defects produced during processing, which brings about an excessive energy filtering effect and hence induces a huge decrease in the absolute Seebeck coefficient. The lattice thermal conductivity of powder processed samples is reduced as expected. However, the reduction is always offset by the reduction in the mobility due to the similar mean free paths of electrons and phonons of CoSi. As a result, it may not be feasible to upgrade the thermoelectric performance of the CoSi system by powder processing.",
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