Lookup NU author(s): Dr Stevin Pramana
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Oxygen conduction at low temperatures in apatites make these materials potentially useful as electrolytes in solid-oxide fuel cells, but our understanding of the defect structures enabling ion migration is incomplete. While conduction along  channels is dominant, considerable inter-tunnel mobility has been recognized. Using neutron powder diffraction of stoichiometric La10(GeO4)6O3, it has been shown that this compound is more correctly described as an La10(GeO4)5(GeO5)O2 apatite, in which high concentrations of interstitial oxygen reside within the channel walls. It is suggested that these framework interstitial O atoms provide a reservoir of ions that can migrate into the conducting channels of apatite, via a mechanism of inter-tunnel oxygen diffusion that transiently converts GeO4 tetrahedra to GeO5 distorted trigonal bipyramids. This structural modification is consistent with known crystal chemistry and may occur generally in oxide apatites. © International Union of Crystallography 2007.
Author(s): Pramana SS, Klooster WT, White TJ
Publication type: Article
Publication status: Published
Journal: Acta Crystallographica Section B: Structural Science
Print publication date: 01/08/2007
ISSN (print): 0108-7681
ISSN (electronic): 0108-7681
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