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Local Distortions and Dynamics in Hydrated Y-Doped BaZrO3

Torayev, Amangeldi and Sperrin, Luke and Gomez, Maria A. and Kattirtzi, John A. and Merlet, Céline and Grey, Clare P. Local Distortions and Dynamics in Hydrated Y-Doped BaZrO3. (2020) Journal of Physical Chemistry C, 124 (30). 16689-16701. ISSN 1932-7447

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Official URL: https://doi.org/10.1021/acs.jpcc.0c04594

Abstract

Y-doped BaZrO3 is a promising proton conductor for intermediate temperature solid oxide fuel cells. In this work, a combination of static DFT calculations and DFT based molecular dynamics (DFT-MD) was used to study proton conduction in such a material. Geometry optimisations of 100 structures with a 12.5% dopant concentration allowed us to identify a clear correlation between the bending of the metal-oxygen-metal angle and the energies of the simulated cells. Depending on the type of bending, two configurations, designated as inwards bending and outwards bending, were defined. The results demonstrate that a larger bending decreases the energy and that the lowest energies are observed for structures combining inwards bending with 2 protons being close to the dopant atoms. These lowest energy structures are the ones with the strongest hydrogen bonds. DFT-MD simulations in cells with different yttrium distributions provide complementary microscopic information on proton diffusion as they capture the dynamic distortions of the lattice caused by thermal motion. A careful analysis of the proton jumps between different environments confirmed that the inwards and outwards bending states are relevant for the understanding of proton diffusion. Indeed, intra-octahedral jumps were shown to only occur starting from an outwards configuration while the inwards configuration seems to favor rotations around the oxygen. On average, in the DFT-MD simulations, the hydrogen bond lengths are shorter for the outwards configuration which facilitates the intra-octahedral jumps. Diffusion coefficients and activation energies were also determined and compared to previous theoretical and experimental data showing a good agreement with previous data corresponding to local proton motion.

Item Type:Article
HAL Id:hal-03033083
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Other partners > Mount Holyoke College (USA)
Other partners > University of Cambridge (UNITED KINGDOM)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
Laboratory name:
Funders:
European Research Council (ERC) - ARCHER UK National Supercomputing Service. M.A.G.’s - Mount Holyoke College Department of Chemistry
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Deposited On:23 Oct 2020 11:49

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