Oxygen non-stoichiometry and oxygen diffusivity of mixed conducting perovskites

Martijn H.R. Lankhorst, H.J.M. Bouwmeester, B.A. Boukamp, H. Verweij

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An oxygen coulometric titration cell has been designed to measure non-stoichiometry and oxygen diffusivity of mixed oxygen ion and electronic conducting, La0.8Sr0.2CoO3-δ. Chemical diffusion data, combined with oxygen non-stoichiometry data, δ, show that the oxygen vacancy diffusion coefficient is 5.25*e -(132±7 KJ/mol)RTcm2/s, and independent of the oxygen partial pressure, P01. In addition, it is found that log(δ) is linearly related to log(P01) with slope of -0.23±0.02. The entropy associated with oxygen incorporation can be modelled with the configurational entropy of the oxygen vacancies. No electronic entropy contribution is observed. The energy of oxygen incorporation decreases almost linearly with increasing oxygen stoichiometry. Both energy and entropy data agree with a model in which electrons gradually fill electron states in a broad electron band. From the data an empirical relation between vacancy-concentration, temperature and oxygen partial pressure can be formulated, which deviates from mass action behavior.
Original languageEnglish
Title of host publicationCeramic Membranes I
Subtitle of host publicationProceedings of the First International Symposium on Ceramic Membranes
EditorsH.U. Anderson, A.C. Khandkar, M. Liu
Place of PublicationPennington, NJ
PublisherElectrochemical Society
ISBN (Print)9781566771191
Publication statusPublished - 1997
Event1st International Symposium on Ceramic Membranes 1995 - Chicago, United States
Duration: 8 Oct 199513 Oct 1995
Conference number: 1

Publication series

PublisherThe Electrochemical Society, Inc.
ISSN (Print)0161-6374


Conference1st International Symposium on Ceramic Membranes 1995
Country/TerritoryUnited States


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