Oxide ion distribution, vacancy ordering and electrical behaviour in the Bi3NbO7-Bi3YbO6 pseudo-binary system
Journal article, 2014

Oxide ion distribution, vacancy ordering and electrical conductivity has been examined in the Nb/Yb double substituted bismuth oxide based system Bi3Nb1-xYbxO7-x, using X-ray and neutron powder diffraction, reverse Monte Carlo modelling of total neutron scattering data and a. c. impedance spectroscopy. Transference number measurements confirm the system to be predominantly ionically conducting above ca. 450 degrees C. Niobium rich compositions show incommensurate ordering of the fluorite subcell, while increasing ytterbium content results in a commensurate fluorite, with fully disordered cation and anion sublattices. Oxide ion distribution shows both compositional and thermal dependencies. The latter is discussed with respect to its effect on the thermal variation of cubic lattice parameter. Substitution of bismuth by niobium and ytterbium in the cation sublattice of bismuth oxide leads to the creation of Frenkel interstitial oxide ions, which increase the tetrahedral vacancy concentration. The high vacancy concentration is confirmed in both Rietveld and RMC analyses of neutron data. Examination of vacancy ordering, in the x - 0.6 composition, indicates a favouring of < 100 > vacancy pair alignment.


M. Leszczynska

Warsaw University of Technology

X. Liu

Queen Mary University of London

W. Wrobel

Warsaw University of Technology

M. Malys

Warsaw University of Technology

J. R. Dygas

Warsaw University of Technology

Stefan Norberg

Chalmers, Chemical and Biological Engineering, Environmental Inorganic Chemistry

S. Hull

ISIS Facility

F. Krok

Warsaw University of Technology

I. Abrahams

Queen Mary University of London

Journal of Materials Chemistry A

20507488 (ISSN) 20507496 (eISSN)

Vol. 2 43 18624-18634

Subject Categories

Environmental Sciences



More information

Latest update