Oxygen nonstoichiometry and defect equilibrium in La2 - xSrxNiO4 + δ

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Abstract

Nonstoichiometric variation of oxygen content in La2 - xSrxNiO4 + δ (x = 0, 0.1, 0.2, 0.3, 0.4) and decomposition P(O2) were determined by means of high temperature gravimetry and coulometric titration. The measurements were carried out in the temperature range between 873 and 1173 K and the P(O2) range between 10- 20 and 1 bar. La2 - xSrxNiO4 + δ showed the oxygen excess and the oxygen deficient compositions depending on P(O2), temperature, and the Sr content. The value of partial molar enthalpy of oxygen approaches zero as δ increases in the oxygen excess region, which indicate that the interstitial oxygen formation reaction is suppressed as δ increase. The relationship between δ and logP(O2) were analyzed by two types of defect equilibrium models. One is a localized electron model, and the other is a delocalized electron model. Both models can well explain the oxygen nonstoichiometry of La2 - xSrxNiO4 + δ with a regular solution approximation.

Original languageEnglish
Pages (from-to)368-376
Number of pages9
JournalSolid State Ionics
Volume180
Issue number4-5
DOIs
Publication statusPublished - 2009 Apr 27

Keywords

  • KNiF type oxides
  • LaNiO
  • Lanthanum nickelate
  • Layered perovskite
  • Oxygen nonstoichiometry

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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