Property-processing relations in developing thermoelectric ceramics: Na1-x Co2O4

Hiroo Yamakawa, Soonil Lee, Hiroshi Takagi, Clive A. Randall

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Polycrystalline Na1-x Co2O4 is a promising p-type oxide thermoelectric, and it was investigated in a property-processing study to enhance the thermoelectric properties for high temperature applications. The density of the ceramics was improved by a post-milling process, and consequently, we obtained better thermoelectric power factors (PF) due to an associated improvement in electrical conductivity. Through a milling process, and sintering at 1203 K, we obtained an enhanced thermoelectric power factor of ~4 μW/cm K2 at 500 K for randomly orientated polycrystalline ceramics. The Seebeck coefficient variation with temperature demonstrates through modeling that the conduction mechanism changed from metallic to a semiconducting behavior between temperatures 300 to 400 K.

Original languageEnglish (US)
Pages (from-to)2064-2070
Number of pages7
JournalJournal of Materials Science
Issue number7
StatePublished - Apr 2011

All Science Journal Classification (ASJC) codes

  • Mechanics of Materials
  • Ceramics and Composites
  • Mechanical Engineering
  • Polymers and Plastics
  • General Materials Science
  • Materials Science (miscellaneous)


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