Mixed conductivity and stability of CaFe2O4−δ

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dc.contributor.authorKharton, VVen_AU
dc.contributor.authorTsipis, EVen_AU
dc.contributor.authorKolotygin, VAen_AU
dc.contributor.authorAvdeev, Men_AU
dc.contributor.authorViskup, APen_AU
dc.contributor.authorWaerenborgh, JCen_AU
dc.contributor.authorFrade, JRen_AU
dc.date.accessioned2008-04-04T01:30:34Zen_AU
dc.date.accessioned2010-04-30T05:02:33Zen_AU
dc.date.available2008-04-04T01:30:34Zen_AU
dc.date.available2010-04-30T05:02:33Zen_AU
dc.date.issued2008-03en_AU
dc.date.statistics2008-03en_AU
dc.description.abstractThe total conductivity of CaFe2O4-delta, studied in the oxygen partial pressure range from 10(-17) to 0.5 atm at 1023-1223 K, is predominantly p-type electronic under oxidizing conditions. The oxygen ion transference numbers determined by the steady-state oxygen permeation and faradaic efficiency measurements vary in the range of 0.2 to 7.2 x 10(-4) at 1123-1273 K, increasing with temperature. No evidence of any significant cationic contribution to the conductivity was found. The Mossbauer spectroscopy, thermogravimetry, and X-ray diffraction (XRD) showed that the orthorhombic lattice of calcium ferrite is essentially intolerant to the oxygen vacancy formation and to doping with lower-valence cations, such as Co and Ni. The oxygen nonstoichiometry (delta) is almost negligible, 0.0046-0.0059 at 973-1223 K and p(O-2) = 10(-5)-0.21 atm, providing a substantial dimensional stability of CaFe2O4-delta ceramics. The average linear thermal expansion coefficients, calculated from the controlled-atmosphere dilatometry and high-temperature XRD data, are (9.6-13.9) x 10(-6) K-1 in the oxygen pressure range from 10(-8) to 0.21 atm at 873-1373 K. Decreasing P(02) results in a modest lattice contraction and in the p-n transition indicated by the conductivity and Seebeck coefficient variations. The phase decomposition of CaFe2O4-delta occurs at oxygen chemical potentials between the low-p(O-2) stability limit of Ca2Fe2O5-delta brownmillerite and the hematite/magnetite boundary in binary Fe-O system. © 2008, Electrochemical Society Inc.en_AU
dc.identifier.citationKharton, V. V., Tsipis, E. V., Kolotygin, V. A., Avdeev, M., Viskup, A. P., Waerenborgh, J. C., & Frade, J. R. (2008). Mixed conductivity and stability of CaFe2O4-delta. Journal of the Electrochemical Society, 155(3), 13-20. doi:10.1149/1.2823458en_AU
dc.identifier.govdoc1159en_AU
dc.identifier.issn0013-4651en_AU
dc.identifier.issue3en_AU
dc.identifier.journaltitleJournal of the Electrochemical Societyen_AU
dc.identifier.pagination13-30en_AU
dc.identifier.urihttp://dx.doi.org/10.1149/1.2823458en_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/1030en_AU
dc.identifier.volume155en_AU
dc.language.isoenen_AU
dc.publisherElectrochemical Societyen_AU
dc.subjectThermal expansionen_AU
dc.subjectTransporten_AU
dc.subjectIonic conductivityen_AU
dc.subjectOxygenen_AU
dc.subjectPerovskitesen_AU
dc.subjectOxidesen_AU
dc.subjectCeramicsen_AU
dc.titleMixed conductivity and stability of CaFe2O4−δen_AU
dc.typeJournal Articleen_AU
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