Structure and conductivity of Nd6MoO12-based potential electron–proton conductors under dry and wet redox conditions

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dc.contributor.authorShlyakhtina, AVen_AU
dc.contributor.authorAvdeev, Men_AU
dc.contributor.authorAbrantes, JCCen_AU
dc.contributor.authorGomes, EDen_AU
dc.contributor.authorLyskov, NVen_AU
dc.contributor.authorKharitonova, EPen_AU
dc.contributor.authorKolbanev, IVen_AU
dc.contributor.authorShcherbakova, LGen_AU
dc.date.accessioned2021-03-15T02:51:34Zen_AU
dc.date.available2021-03-15T02:51:34Zen_AU
dc.date.issued2019-01-09en_AU
dc.date.statistics2021-03-09en_AU
dc.description.abstractNominal compositions Nd6MoO12 (3[thin space (1/6-em)]:[thin space (1/6-em)]1) and Nd10Mo2O21 (5[thin space (1/6-em)]:[thin space (1/6-em)]2) were prepared by high-temperature synthesis in air from a mechanically activated mixture of Nd2O3 and MoO3. Phase-pure Nd6MoO12−δ and Nd6MoO12−α have been obtained at 1600 and 1650 °C, respectively. They are both slightly rhombohedrally distorted derivatives from the cubic fluorite structure. Nd10Mo2O21 with a lower content of Nd2O3 was shown to be a more complex phase based on the rhombohedral phase (R[3 with combining macron]) in the 1600–1650 °C temperature range. As a result of the formation of a more complex rhombohedral phase, the conductivity of Nd10Mo2O21 changes dramatically in comparison with Nd6MoO12−δ. In wet air Nd6MoO12−δ is a p-type electronic conductor, whereas proton conductivity dominates in Nd10Mo2O21 over the entire temperature range studied. The electrical conductivity dependence of Nd6MoO12−δ on the oxygen partial pressure shows a V-type behaviour typical of a transition from a p-type to n-type conductivity mechanism at 800 ≤ T ≤ 1000 °C. There is no p-type conductivity contribution in Nd10Mo2O21 in the same temperature range. The prevalence of electronic conductivity in the samples with nominal composition Nd6MoO12 in a wide temperature range is due to the fact that Nd and Mo in the fluorite materials are readily reduced. Predominantly Nd3+ and Mo6+ forms exist in more complex rhombohedral phase Nd10Mo2O21 and it has proton conductivity ∼8.5 × 10−3 S cm−1 at 800 °C. Thus, the loss of dimensional stability is more characteristic of fluorites and rhombohedral phases with small rhombohedral distortion (Nd5.4Zr0.6MoO12.3, Nd6MoO12−δ) than more complex rhombohedral phases based on (R[3 with combining macron]) (Nd10Mo2O21). A comparative high-temperature in situ neutron diffraction study under high vacuum of rhombohedral Nd6MoO12−δ and cubic fluorite Nd5.4Zr0.6MoO12.3 showed that the former transforms to the high-temperature cubic fluorite type above ∼1140 °C while the latter retains its cubic structure in the studied range up to 1350 °C. © the Partner Organisations 2019en_AU
dc.identifier.citationShlyakhtina, A. V., Avdeev, M., Abrantes, J. C. C., Gomes, E., Lyskov, N. V., Kharitonova, E. P., Kolbanev, I. V., & Shcherbakova, L. G. (2019). Structure and conductivity of Nd6MoO12-based potential electron–proton conductors under dry and wet redox conditions. Inorganic Chemistry Frontiers, 6(2), 566-575. doi:10.1039/C8QI01142Gen_AU
dc.identifier.issn2052-1553en_AU
dc.identifier.issue2en_AU
dc.identifier.journaltitleInorganic Chemistry Frontiersen_AU
dc.identifier.pagination566-575en_AU
dc.identifier.urihttp://dx.doi.org/10.1039/C8QI01142Gen_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/10537en_AU
dc.identifier.volume6en_AU
dc.language.isoenen_AU
dc.publisherRoyal Society of Chemistryen_AU
dc.subjectFluoriteen_AU
dc.subjectCubic latticesen_AU
dc.subjectTrigonal latticesen_AU
dc.subjectTemperature range 1000-4000 Ken_AU
dc.subjectElectric conductivityen_AU
dc.subjectOxygenen_AU
dc.subjectPartial pressureen_AU
dc.subjectProton conductivityen_AU
dc.subjectNeutron diffractionen_AU
dc.titleStructure and conductivity of Nd6MoO12-based potential electron–proton conductors under dry and wet redox conditionsen_AU
dc.typeJournal Articleen_AU
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