Electrical/thermal transport and electronic structure of the binary cobalt pnictides Co Pn <inf>2</inf> (Pn = As and Sb)

Yosuke Goto, Syuhei Miyao, Yoichi Kamihara, Masanori Matoba

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Abstract

We demonstrate the electrical and thermal transport properties of polycrystalline CoPn<inf>2</inf> (Pn = As and Sb) between 300 and 900 K. CoAs<inf>2</inf> shows semiconducting electrical transport up to 900 K, while CoSb<inf>2</inf> exhibits degenerate conduction. Sign inversion of the Seebeck coefficient is observed at ∼310 and ∼400 K for CoAs<inf>2</inf> and CoSb<inf>2</inf>, respectively. Thermal conductivity at 300 K is 11.7 Wm<sup>-1</sup>K<sup>-1</sup> for CoAs<inf>2</inf> and 9.4 Wm<sup>-1</sup>K<sup>-1</sup> for CoSb<inf>2</inf>. The thermoelectric power factor of CoAs<inf>2</inf> is ∼10 μWcm<sup>-1</sup>K<sup>-2</sup>, although the dimensionless figure of merit is limited to ∼0.1 due to relatively high thermal conductivity. Using electronic structure calculations, the band gap value is calculated to be 0.55 eV for CoAs<inf>2</inf> and 0.26 eV for CoSb<inf>2</inf>.

Original languageEnglish
Article number067147
JournalAIP Advances
Volume5
Issue number6
DOIs
Publication statusPublished - 2015 Jun 1

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ASJC Scopus subject areas

  • Physics and Astronomy(all)

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