Conductivity and water uptake of Sr-4(Sr2Nb2)O-11 center dot nH(2)O and Sr-4(Sr2Ta2)O-11 center dot nH(2)O

Publication: Research - peer-reviewJournal article – Annual report year: 2009

Without internal affiliation

  • Author: Jalarvo, Niina

    University of Oslo

  • Author: Haavik, Camilla

    University of Oslo

  • Author: Kongshaug, Camilla

    University of Oslo

  • Author: Norby, Poul

    Unknown

  • Author: Norby, Truls

    University of Oslo

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The hydrated oxygen deficient complex perovskite-related materials Sr-4(Sr2Nb2)O-11 center dot nH(2)O and Sr-4(Sr2Ta2)O-11 center dot nH(2)O were studied at high water vapour pressures over a large temperature range by electrical conductivity measurements, thermogravimetry (TG), and X-ray powder diffraction (XRPD). In humid atmospheres both materials are known to exhibit protonic conductivity below dehydration temperatures, with peak-shaped maxima at about 500 degrees C. In this work we show that the peaks expand to plateaus of high conductivity from 500 to 700 degrees C at a water vapour pressure of 1 atm. However, in situ synchrotron XRPD of Sr-4(Sr2Nb2)O-11 center dot nH(2)O as a function of temperature shows that these observations are in fact coincident with melting and dehydration of a secondary phase Sr(OH)(2). The stability of Sr-4(Sr2Nb2)O-11 center dot nH(2)O and Sr-4(Sr2Ta2)O-11 center dot nH(2)O in humid atmospheres is thus insufficient, causing decomposition into perovskites with lower Sr content and Sro/Sr(OH)(2) secondary phases. This, in turn, rationalizes the observation of peaks and plateaus in the conductivity of these materials. (C) 2009 Elsevier B.V. All rights reserved.
Original languageEnglish
JournalSolid State Ionics
Publication date2009
Volume180
Issue20-22
Pages1151-1156
ISSN0167-2738
DOIs
StatePublished
CitationsWeb of Science® Times Cited: 11
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