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Correlated motion of anions and cations in fast cation conducting rotor phases
Ist Teil von
Solid state ionics, 2004-11, Vol.175 (1), p.463-466
Ort / Verlag
Elsevier B.V
Erscheinungsjahr
2004
Link zum Volltext
Quelle
Elsevier ScienceDirect Journals Complete
Beschreibungen/Notizen
A set of quasielastic neutron scattering experiments on solid solutions of sodium orthophosphate and sodium sulfate is reported. These materials are not only fast-ion conductors in their high-temperature cubic phases but also show considerable dynamic reorientation disorder of their tetrahedral anions.
High resolution backscattering experiments were used to examine sodium diffusion in
xNa
2SO
4·(1−
x)Na
3PO
4, which was found to be dominated by thermally activated jumps between tetrahedrally coordinated sites, the activation energies ranging from 0.64 eV for
x=0.0 to 0.30 eV for
x=0.5.
Time-of-flight scattering proved to be mainly sensitive to oxygen scattering and thus to anion reorientation. This thermally activated motion exhibits activation energies between 0.184 eV (
x=0.0) and 0.052 eV (
x=0.5). Analysis of the quasielastic intensities as a function of scattering vector
Q gives clear evidence of the involvement of cations in the anion motion.