Jump to main content
Jump to site search


Nonstoichiometric oxides as a continuous homologous series: linear free-energy relationship in oxygen exchange

Abstract

A novel methodology for the analysis of oxygen exchange in practically important nonstoichiometric oxides with mixed ionic electronic conductivity (MIEC) is suggested. It is based on the fact that kinetic and thermodynamic properties of such oxides vary continuously with the oxygen stoichiometry. This allows considering MIEC oxides in terms of homologous series, with the difference that traditional series are discrete in their chemical composition whereas the MIEC oxides are continuous in oxygen stoichiometry. Analysis of relations between Gibbs energies of reactions and activation barriers traditionally performed for homologous series can be useful in studies of oxygen exchange in MIEC oxides. To demonstrate the approach, thermodynamic and oxygen-exchange kinetics parameters are measured as functions of oxygen nonstoichiometry δ for two perovskites, SrCo0.8Fe0.2O3-δ and SrFeO3-δ, having metal-like and p-type semiconducting conductivities, respectively. Both oxides are shown to obey linear free energy relationships of the Brønsted-Evans-Polanyi form in spite of different type of electronic structure. The results open up new possibilities for understanding the mechanism of rate determining step of oxygen exchange in MIEC oxides.

Back to tab navigation

Supplementary files

Publication details

The article was received on 08 May 2018, accepted on 08 Jun 2018 and first published on 09 Jun 2018


Article type: Paper
DOI: 10.1039/C8CP02924E
Citation: Phys. Chem. Chem. Phys., 2018, Accepted Manuscript
  •   Request permissions

    Nonstoichiometric oxides as a continuous homologous series: linear free-energy relationship in oxygen exchange

    S. A. Chizhik and A. P. Nemudry, Phys. Chem. Chem. Phys., 2018, Accepted Manuscript , DOI: 10.1039/C8CP02924E

Search articles by author

Spotlight

Advertisements