Proton Mobility in the In-Doped CaZrO3 Perovskite Oxide

First-principles calculations, based on density functional theory, are exploited to investigate the mechanisms and energetics of proton mobility in CaZrO3. The computations accurately reproduce the observed orthorhombic crystal structure of the material. Proton binding sites in the lattice are deter...

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Main Authors: Bilic, Ante, Gale, Julian
Format: Journal Article
Published: American Chemical Society 2007
Online Access:http://hdl.handle.net/20.500.11937/17791
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author Bilic, Ante
Gale, Julian
author_facet Bilic, Ante
Gale, Julian
author_sort Bilic, Ante
building Curtin Institutional Repository
collection Online Access
description First-principles calculations, based on density functional theory, are exploited to investigate the mechanisms and energetics of proton mobility in CaZrO3. The computations accurately reproduce the observed orthorhombic crystal structure of the material. Proton binding sites in the lattice are determined for a range of In dopant concentrations and the corresponding binding strengths are given on a relative energy scale. A proton is typically found to be more strongly bound by 0.1-0.2 eV to the sites at In octahedra than to equivalent sites far from the dopant, though binding energies for certain sites remote from the dopant can exceed those on adjacent octahedra. This suggests that dopant-proton trapping is relatively weak and short-ranged. A series of constrained optimizations is carried out to evaluate minimumenergy paths between the binding sites. A set of proton-transfer jumps and reorientations is identified and associated energy barriers for these proton steps are calculated. It is found that interoxygen transfer and rotation of the proton about a single oxygen have comparable barrier heights. The calculated lowest energy paths that lead to proton propagation in CaZrO3 exhibit energy barriers in excess of 0.6 eV. Lattice dynamics calculations are used to evaluate the normal modes relevant for proton mobility and the associated attempt frequencies. In this manner, a comprehensive set of data is provided from which the rates of proton migration in In:CaZrO3 may be determined.
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spelling curtin-20.500.11937-177912017-09-13T13:36:45Z Proton Mobility in the In-Doped CaZrO3 Perovskite Oxide Bilic, Ante Gale, Julian First-principles calculations, based on density functional theory, are exploited to investigate the mechanisms and energetics of proton mobility in CaZrO3. The computations accurately reproduce the observed orthorhombic crystal structure of the material. Proton binding sites in the lattice are determined for a range of In dopant concentrations and the corresponding binding strengths are given on a relative energy scale. A proton is typically found to be more strongly bound by 0.1-0.2 eV to the sites at In octahedra than to equivalent sites far from the dopant, though binding energies for certain sites remote from the dopant can exceed those on adjacent octahedra. This suggests that dopant-proton trapping is relatively weak and short-ranged. A series of constrained optimizations is carried out to evaluate minimumenergy paths between the binding sites. A set of proton-transfer jumps and reorientations is identified and associated energy barriers for these proton steps are calculated. It is found that interoxygen transfer and rotation of the proton about a single oxygen have comparable barrier heights. The calculated lowest energy paths that lead to proton propagation in CaZrO3 exhibit energy barriers in excess of 0.6 eV. Lattice dynamics calculations are used to evaluate the normal modes relevant for proton mobility and the associated attempt frequencies. In this manner, a comprehensive set of data is provided from which the rates of proton migration in In:CaZrO3 may be determined. 2007 Journal Article http://hdl.handle.net/20.500.11937/17791 10.1021/cm070291b American Chemical Society restricted
spellingShingle Bilic, Ante
Gale, Julian
Proton Mobility in the In-Doped CaZrO3 Perovskite Oxide
title Proton Mobility in the In-Doped CaZrO3 Perovskite Oxide
title_full Proton Mobility in the In-Doped CaZrO3 Perovskite Oxide
title_fullStr Proton Mobility in the In-Doped CaZrO3 Perovskite Oxide
title_full_unstemmed Proton Mobility in the In-Doped CaZrO3 Perovskite Oxide
title_short Proton Mobility in the In-Doped CaZrO3 Perovskite Oxide
title_sort proton mobility in the in-doped cazro3 perovskite oxide
url http://hdl.handle.net/20.500.11937/17791