High-temperature thermoelectric properties of late rare earth-doped Ca 3Co4O9+δ

N. V. Nong, Chia Jyi Liu, M. Ohtaki

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Abstract

Misfit-layered oxides Ca3-xLnxCo4O 9+δ with Ln = Dy, Er, Ho, and Lu were synthesized using solid state reactions. The resulting samples were hot-pressed (HP) at 1123 K in air for 2 h under a uniaxial pressure of 60 MPa. Thermoelectric properties of Ca3-xLnxCo4O9+δ were investigated up to 1200 K. Both the Seebeck coefficient and electrical resistivity increase upon Ln substitution for Ca. Among the Ln-doped samples, the magnitude of Seebeck coefficient tends to increase with decreasing ionic radius of Ln3+. The Ln-doped samples exhibit a lower thermal conductivity than the non-doped one due to a decrease of their lattice thermal conductivity. The dimensionless figure of merit, ZT, reaches 0.36 at 1073 K for the Ca2.8Lu0.2Co4O9+δ sample, which is about 1.6 times larger than that for the non-doped counterpart.

Original languageEnglish
Pages (from-to)977-981
Number of pages5
JournalJournal of Alloys and Compounds
Volume509
Issue number3
DOIs
Publication statusPublished - 2011 Jan 21

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All Science Journal Classification (ASJC) codes

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

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