High-temperature electrical conductivity and thermopower in nonstoichiometric La1-xSrxCoO3-δ (x = 0.6)

E. B. Mitberg, M. V. Patrakeev, I. A. Leonidov, V. L. Kozhevnikov, Kenneth R Poeppelmeier

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

From 650 to 900°C in situ conductivity and thermopower measurements it was determined that La1-xSrxCoO3-δ (x = 0.6) is a small polaron conductor over the range 0.12 <δ <0.38 with a hopping energy of approximately 0.08 eV. Cobalt's valence distribution was calculated from the thermopower data complemented with the site balance and electroneutrality relations. Three valence states of cobalt appear to be present with the equilibrium constant of disproportionation, 2Co3+ = Co2+ + Co4+ independent of temperature and dependent of oxygen content. As δ decreases, a p-to-n transition occurs indicating a near half-filling of the conductance band. It is concluded also that the simple polaronic description of conductance becomes insufficient when approaching the stoichiometric oxygen composition.

Original languageEnglish
Pages (from-to)325-330
Number of pages6
JournalSolid State Ionics
Volume130
Issue number3-4
Publication statusPublished - May 2 2000

Keywords

  • Cobaltite
  • Electron conductivity
  • Mixed conductor
  • Thermopower

ASJC Scopus subject areas

  • Electrochemistry
  • Physical and Theoretical Chemistry
  • Energy Engineering and Power Technology
  • Materials Chemistry
  • Condensed Matter Physics

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    Mitberg, E. B., Patrakeev, M. V., Leonidov, I. A., Kozhevnikov, V. L., & Poeppelmeier, K. R. (2000). High-temperature electrical conductivity and thermopower in nonstoichiometric La1-xSrxCoO3-δ (x = 0.6). Solid State Ionics, 130(3-4), 325-330.