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Durham University

Department of Chemistry

Publication details for Prof. Ivana Evans

Chambers, Matthew S., McCombie, Kirstie S., Auckett, Josie E., McLaughlin, Abbie C., Irvine, John T. S., Chater, Philip A., Evans, John S. O. & Evans, Ivana Radosavljevic (2019). Hexagonal perovskite related oxide ion conductor Ba3NbMoO8.5: phase transition, temperature evolution of the local structure and properties. Journal of Materials Chemistry A 7(44): 25503-25510.

Author(s) from Durham

Abstract

Ba3NbMoO8.5 has recently been demonstrated to exhibit competitive oxide ion conductivity and to be
stable under reducing conditions, making it an excellent potential electrolyte for solid oxide fuel cells.
We report here the first investigation of the local structure in Ba3NbMoO8.5, carried out using variabletemperature
neutron total scattering and pair distribution function (PDF) analysis. This work reveals
a significant degree of disorder in the material, even at ambient conditions, in both the cation and the
anion arrangements and suggests the prevalence of the five-fold Nb/Mo coordination. In addition, high
resolution powder X-ray diffraction data indicate that the temperature-dependent structural changes in
Ba3NbMoO8.5 are due to a first order phase transition, and reveal a previously unreported effect of
thermal history on the room-temperature form of the material. PDF modelling shows that Ba3NbMoO8.5
has an essentially continuous oxygen distribution in the ab plane at 600 C which leads to its high oxideion
conductivity.