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Title: Combined experimental and computational study of oxide ion conduction dynamics in Sr2Fe2O5 brownmillerite
Authors: Auckett, JE
Studer, AJ
Pellegrini, E
Ollivier, J
Johnson, MR
Schober, H
Miiller, W
Ling, CD
Keywords: Oxides
Ionic conductivity
Issue Date: 13-Aug-2013
Publisher: American Chemical Society
Citation: Auckett, J.E., Studer, A.J., Pellegrini, E., Ollivier, J., Johnson, M.R., Schober, H., Miiller, W., & Ling, C.D. Combined experimental and computational study of oxide ion conduction dynamics in Sr2Fe2O5 brownmillerite. Chemistry of Materials, 2013. 25(15), 3080-3087. doi:10.1021/cm401278m
Abstract: We report a detailed study of the dynamics of oxide ionic conduction in brownmillerite-type Sr2Fe2O5, including lattice anisotropy, based on neutron scattering studies of a large (partially twinned) single crystal in combination with ab initio molecular dynamics simulations. Single-crystal diffraction reveals supercell peaks due to long-range ordering among chains of corner-sharing FeO4 tetrahedra, which disappears on heating above 540 °C due to confined local rotations of tetrahedra. Our simulations show that these rotations are essentially isotropic, but are a precondition for the anisotropic motion that moves oxide ions into the tetrahedral layers from the octahedral layers, which we observe experimentally as a Lorentzian broadening of the quasielastic neutron scattering spectrum. This continual but incoherent movement of oxide ions in turn creates conduction pathways and activates long-range diffusion at the interface between layers, which appears to be largely isotropic in two dimensions, in contrast with previously proposed mechanisms that suggest diffusion occurs preferentially along the c axis.© 2013, American Chemical Society.
Gov't Doc #: 5448
ISSN: 0897-4756
Appears in Collections:Journal Articles

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