An Investigation of the Crystal Structure and Ionic Pathways of the Hexagonal Perovskite Derivative Ba3-xVMoO8.5

Dylan Tawse, Asma Gilane, Sacha Fop, Alfonso Martinez-Felipe, Falak Sher, Ronald I. Smith, Abbie McLaughlin* (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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The hexagonal perovskite derivatives Ba3NbMoO8.5, Ba3NbWO8.5 and Ba3VWO8.5 have recently been reported to exhibit significant oxide ion conductivity. Here we report the synthesis and crystal structure of the hexagonal perovskite derivative Ba3-xVMoO8.5-x. Rietveld refinement from neutron and
X-ray diffraction data show that the cation vacancies are ordered on the M2 site leading to a structure consisting of palmierite-like layers of M1Ox polyhedra separated by vacant octahedral layers. In contrast to other members of the Ba3M’M’’O8.5 family, Ba3-xVMoO8.5-x is not stoichiometric and both
barium and oxygen vacancies are present. Although synthesised in air at elevated temperatures, Ba3-xVMoO8.5-x is unstable at lower temperatures, as illustrated by the formation of BaCO3 and BaMoO4 by heat treatment in air at 400 °C. This precludes measurement of the electrical properties. However,
bond-valence site energy (BVSE) calculations strongly suggest that oxide ion conductivity is present in Ba3-xVMoO8.5-x.
Original languageEnglish
Pages (from-to)13550-13556
Number of pages7
JournalInorganic Chemistry
Early online date18 Aug 2021
Publication statusPublished - 6 Sept 2021

Bibliographical note

We thank the UK Science and Technology Facilities Council (STFC) for provision of Xpress Access neutron beamtime at ISIS. This research was supported by the Leverhulme trust (RPG-2017-351 and DS-2017-073). DNT, a Leverhulme Trust Doctoral Scholar, is part of the PhD scholarships of the “Leverhulme Centre for Doctoral Training in Sustainable Production of Chemicals and Materials” at
the University of Aberdeen (Scotland, United Kingdom). AG is supported by the Commonwealth Scholarship Commission.

Data Availability Statement

The Supporting Information is available free of charge at


  • Oxides
  • Crystal structure
  • Ions
  • Oxygen
  • Perovskites


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