dc.contributor.authorLi, Henan
dc.contributor.authorBaikie, Tom
dc.contributor.authorPramana, Stevin S.
dc.contributor.authorShin, J. Felix
dc.contributor.authorSlater, Peter R.
dc.contributor.authorBrink, Frank
dc.contributor.authorHester, James
dc.contributor.authorWallwork, Kia
dc.contributor.authorWhite, Timothy John
dc.identifier.citationLi, H., Baikie, T., Pramana, S. S., Shin, J. F., Slater, P. R., Brink, F., et al. (2012). Synthesis and characterisation of vanadium doped alkaline earth lanthanum germanate oxyapatite electrolyte. Journal of Materials Chemistry, 22(6), 2658-2669.en_US
dc.description.abstractThe crystal chemistry and oxygen conductivity of vanadium-doped apatites of nominal composition [La8AE2][Ge6−xVx]O26+x/2 (AE = Ca, Sr, Ba; 0 ≤ x ≤ 1.5) were studied to establish their potential as intermediate temperature solid oxide fuel cell (SOFC) electrolytes. Single-phase products obtained for x ≤ 0.5 were found, using a combination of powder synchrotron X-ray and neutron diffraction, to be P63/m apatites. The ionic conductivities extracted by complex impedance spectroscopy showed that small vanadium amendments enhanced oxygen mobility at intermediate temperatures (500–700 °C) by more than one order of magnitude, as the incorporation of V5+ through displacement of Ge4+ is charge balanced with interstitial O2− that improves ionic conduction. The most promising composition was La7.88Ca2Ge5.35V0.65O26.15 that delivered σ = 3.44 × 10−4 S cm−1 at 500 °C. The superstoichiometric oxygen was delocalised, without fixed X-ray or neutron scattering centres. Crystal chemistry systematics demonstrate that the Ca-apatite was superior because the relatively small framework expanded the tunnel through reduced (La/AE)O6 metaprism twisting (φ), ensuring the P63/m symmetry was adopted, which favours the passage of O2− with lower activation energy.en_US
dc.relation.ispartofseriesJournal of materials chemistryen_US
dc.rights© 2012 The Royal Society of Chemistry. This is the author created version of a work that has been peer reviewed and accepted for publication by Journal of materials chemistry, The Royal Society of Chemistry. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [http://dx.doi.org/10.1039/c1jm13752b].en_US
dc.subjectSolid oxide fuel cell
dc.subjectCrystal chemistry
dc.subjectMicroscopic structure
dc.titleSynthesis and characterisation of vanadium doped alkaline earth lanthanum germanate oxyapatite electrolyteen_US
dc.typeJournal Article
dc.contributor.schoolSchool of Materials Science and Engineeringen_US
dc.description.versionAccepted version

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