title: Oxide Ion Conductivity in the Hexagonal Perovskite Derivative Ba3MoNbO8.5.
abstract: Oxide ion conductors are important materials with a range of technological applications and are currently used as electrolytes for solid oxide fuel cells and solid oxide electrolyzer cells. Here we report the crystal structure and electrical properties of the hexagonal perovskite derivative Ba3MoNbO8.5. Ba3MoNbO8.5crystallizes in a hybrid of the 9R hexagonal perovskite and palmierite structures. This is a new and so far unique crystal structure that contains a disordered distribution of (Mo/Nb)O6octahedra and (Mo/Nb)O4tetrahedra. Ba3MoNbO8.5shows a wide stability range and exhibits predominantly oxide ion conduction over a pO2range from 10-20to 1 atm with a bulk conductivity of 2.2 × 10-3S cm-1at 600 °C. The high level of conductivity in a new structure family suggests that further study of hexagonal perovskite derivatives containing mixed tetrahedral and octahedral geometry could open up new horizons in the design of oxygen conducting electrolytes.
authors.affiliation: The Chemistry Department, University of Aberdeen , Meston Walk, Aberdeen AB24 3UE, U.K.
authors.forename: Sacha
authors.initials: S
authors.lastname: Fop
authors.affiliation: The Chemistry Department, University of Aberdeen , Meston Walk, Aberdeen AB24 3UE, U.K.
authors.forename: Janet M S
authors.initials: JM
authors.lastname: Skakle
authors.affiliation: The Chemistry Department, University of Aberdeen , Meston Walk, Aberdeen AB24 3UE, U.K.
authors.forename: Abbie C
authors.identifier: 0000-0001-9960-723X
authors.initials: AC
authors.lastname: McLaughlin
authors.affiliation: School of Chemistry, University of St Andrews , St Andrews, Fife KY16 9ST, U.K.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Connor
authors.affiliation: School of Chemistry, University of St Andrews , St Andrews, Fife KY16 9ST, U.K.
authors.forename: John T S
authors.initials: JT
authors.lastname: Irvine
authors.affiliation: ISIS Facility, Rutherford Appleton Laboratory , Harwell, Didcot OX11 0DE, U.K.
authors.forename: Ronald I
authors.initials: RI
authors.lastname: Smith
authors.affiliation: The Chemistry Department, University of Aberdeen , Meston Walk, Aberdeen AB24 3UE, U.K.
authors.forename: Eve J
authors.initials: EJ
authors.lastname: Wildman