Hydration and Ionic Conduction Mechanisms of Hexagonal Perovskite Derivatives

Sacha Fop* (Corresponding Author), James A. Dawson, A. Dominic Fortes, Clemens Ritter, Abbie McLaughlin* (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)
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Abstract

High ionic conductivity has been recently reported in hexagonal perovskite derivative materials. These systems constitute a promising class of novel electrolytes for application in hydrogen-based energy technologies. Herein, we performed the first in-situ hydration neutron diffraction experiments and atomistic calculations for the determination of the water absorption and ionic conduction mechanisms in the dual-ion conductor Ba7Nb4MoO20. Our results demonstrate a remarkable mechanism of water uptake and proton incorporation, assisted by the ability of the structure of accommodating substantial stacking and anion disorder. Simulations show high dynamic and rotational flexibility of the variable coordination MOx units, a crucial factor in enabling fast ionic transport along the palmierite-like layers. Such flexibility contributes to delocalisation of the proton defects and to the creation of a frustrated proton sub-lattice with high proton mobility and low energy diffusion pathways. These insights provide design principles for the discovery of innovative ionic conductors crystallizing in related hexagonal systems or disordered oxide structures.
Original languageEnglish
Pages (from-to)4651–4660
Number of pages10
JournalChemistry of Materials
Volume33
Issue number12
Early online date6 Jun 2021
DOIs
Publication statusPublished - 22 Jun 2021

Bibliographical note

Acknowledgements
S.F. and A.C.M. acknowledge STFC-GB for provision of beamtime at ISIS (DOI: 10.5286/ISIS.E.RB1920006) and the ILL. J.A.D. gratefully acknowledges the EPSRC and the MCC/Archer consortium (EP/L000202/1) for computational resources. J.A.D. also gratefully acknowledges Newcastle University for funding through a Newcastle Academic Track (NUAcT) Fellowship

Funding Sources
This research was supported by the Leverhulme-Trust (RPG2017-351).

Data Availability Statement

Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.chemmater.1c01141

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