Stability against reduction of fluorite-like rhombohedral La5.5MoO11.25 and Ho5.4Zr0.6MoO12.3 fluorite: conductivity and neutron diffraction study

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dc.contributor.authorSavvin, SNen_AU
dc.contributor.authorAvdeev, Men_AU
dc.contributor.authorKolbanev, IVen_AU
dc.contributor.authorKharitonova, EPen_AU
dc.contributor.authorShcherbakova, LGen_AU
dc.contributor.authorShlyakhtina, AVen_AU
dc.contributor.authorNuñez, Pen_AU
dc.date.accessioned2021-02-03T23:38:52Zen_AU
dc.date.available2021-02-03T23:38:52Zen_AU
dc.date.issued2018-06-01en_AU
dc.date.statistics2021-01-19en_AU
dc.description.abstractZr-substituted rare-earth molybdates Ho5.4Zr0.6MoO12.3 and unsubstituted La5.5MoO11.25 demonstrate appreciable mixed electron-proton conductivity in the 200–470 °C and 145–730 °C temperature range, respectively, under wet oxidizing and mild reducing conditions (air, Ar, Ar-5% H2). Rhombohedral fluorite-like La5.5MoO11.25 showed the highest bulk conductivity of about 1 × 10−5 S/cm at 400 °C in wet air and Ar. Its impedance spectra did not provide any evidence of the grain boundary contribution in wet atmosphere. Total conductivity of Ho5.4Zr0.6MoO12.3 fluorite is much lower and is 3 × 10−7 S/cm at 400 °C in wet air. Besides, it should be noted that there is a grain-boundary contribution of Ho5.4Zr0.6MoO12.3 in wet air and Ar. Thermogravimetry data demonstrate that the fraction of strong structurally bound water and interstitial protons in La5.5MoO11.25 and Ho5.4Zr0.6MoO12.3 is ~0.02–0.03% in the range ~600–900 °C. The stability of Ho5.4Zr0.6MoO12.3 fluorite structure and fluorite-like rhombohedral La5.5MoO11.25 structure in extremely dry conditions under dynamic vacuum of 10−6–10−7 mbar was investigated by in situ variable temperature neutron diffraction between 800 and 1400 °C to understand phase behaviour under mild reducing conditions in a wide temperature range. Rhombohedral fluorite-like La5.5MoO11.25 has been shown to be more resistant to reduction under vacuum below 1100 °С in heating–cooling cycles than is fluorite Ho5.4Zr0.6MoO12.3. Given the higher proton conductivity of Ln5.5MoO11.25, this suggests that rhombohedral fluorite-like La6MoO12 - based molybdates are suitable for long-term use under mild reducing conditions and 600–800 °С. © 2018 Elsevier B.V.en_AU
dc.identifier.citationSavvin, S. N., Avdeev, M., Kolbanev, I. V., Kharitonova, E. P., Shcherbakova, L. G., Shlyakhtina, A. V., & Nuñez, P. (2018). Stability against reduction of fluorite-like rhombohedral La5.5MoO11.25 and Ho5.4Zr0.6MoO12.3 fluorite: conductivity and neutron diffraction study. Solid State Ionics, 319, 148-155, doi:10.1016/j.ssi.2018.02.001en_AU
dc.identifier.issn0167-2738en_AU
dc.identifier.journaltitleSolid State Ionicsen_AU
dc.identifier.pagination148-155en_AU
dc.identifier.urihttps://doi.org/10.1016/j.ssi.2018.02.001en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/10301en_AU
dc.identifier.volume319en_AU
dc.language.isoenen_AU
dc.publisherElsevieren_AU
dc.subjectFluoriteen_AU
dc.subjectTrigonal latticesen_AU
dc.subjectProton conductivityen_AU
dc.subjectReductionen_AU
dc.subjectRare earthsen_AU
dc.subjectGrain boundariesen_AU
dc.subjectThermal gravimetric analysisen_AU
dc.subjectNeutron diffractionen_AU
dc.titleStability against reduction of fluorite-like rhombohedral La5.5MoO11.25 and Ho5.4Zr0.6MoO12.3 fluorite: conductivity and neutron diffraction studyen_AU
dc.typeJournal Articleen_AU
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