Electrical resistivity and Seebeck coefficient of Sr6Co 5O15

Kouta Iwasaki, Masahiko Shimada, Hisanori Yamane, Junichi Takahashi, Shunichi Kubota, Takanori Nagasaki, Yuji Arita, Junji Yuhara, Yoshimasa Nishi, Tsuneo Matsui

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)

Abstract

Polycrystalline samples of Sr6Co5O15 (m = 1,n = 1) and Ca3Co2O6 (m = 1,n = 0), which are the members of homologous series (A3Co2O6) m(A′3Co3O9)n (A, A′ = Ca, Sr, Ba), were prepared by solid state reaction in air. The theoretical density ratios of obtained pellets, 89% for Sr6Co 5O15 and 95% for Ca3Co2O 6, sintered by the spark plasma sintering (SPS) method increased compared to those of Sr6Co5O15 (60%) and Ca3Co2O6 (67%) prepared by solid state reaction, respectively. Electrical resistivity (ρ) of Sr6Co 5O15 and Ca3Co2O6 exhibited semiconducting behavior in 300-1120K. The temperature dependence of electrical resistivity for Sr6Co5O15 showed a hysteresis-like behavior. Electrical resistivity of Sr6Co 5O15 (6.1 × 10-2 to 4.6Ωcm) and Ca3Co2O6 (4.1 × 10-2 to 1.2 × 103Ωcm) sintered by the SPS method were lower than those of Sr6Co5O15 (1.3 × 10 -1 to 8.0Ωcm) and Ca3Co2O6 (1.5 × 10-1 to 4.5 × 103Ωcm) prepared by solid state reaction, respectively. Seebeck coefficient (S) of Sr 6Co5O15 and Ca3Co2O 6 were positive and more than 100μV/K in 300-1120K, and both compounds showed the different temperature dependences, respectively. The power factor (S2/ρ) tended to increase with increasing temperature; the maximum values of the power factor were 1.4 × 10 -5W/(mK2) for Sr6Co5O15 and 1.6 × 10-5W/(mK2) for Ca3Co 2O6 prepared by solid state reaction, and 3.0 × 10-5W/(mK2) for Sr6Co5O 15 and 5.2 × 10-5W/(mK2) for Ca 3Co2O6 sintered by the SPS method.

Original languageEnglish
Pages (from-to)272-276
Number of pages5
JournalJournal of Alloys and Compounds
Volume377
Issue number1-2
DOIs
Publication statusPublished - 2004 Sep 8

Keywords

  • Other: thermoelectric, SrCoO , CaCoO
  • X-ray diffraction

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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