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| Main Authors: | , |
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| Format: | Preprint |
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2024
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2410.22017 |
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| _version_ | 1866914555976744960 |
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| author | Lee, Sung-Hoon Hong, Ki-Ha |
| author_facet | Lee, Sung-Hoon Hong, Ki-Ha |
| contents | Ionic conduction in crystalline solids is conventionally understood to proceed via atomic-scale defects such as vacancies or interstitials. Here, by addressing the long-standing structural ambiguity of high-temperature tetragonal tantalum pentoxide (H-Ta$_2$O$_5$), we identify a qualitatively different transport mechanism. Based on first-principles calculations, we propose that H-Ta$_2$O$_5$ adopts a chiral framework composed of orthorhombic building units interconnected by screw-rotation planes, with a tantalum sublattice consistent with available transmission electron microscopy observations. Our ab initio molecular dynamics simulations reveal collective, one-dimensional oxygen migration within this stoichiometric lattice at temperatures of a few hundred degrees Celsius. This cooperative transport is enabled by the structural flexibility of octahedral coordination at the screw-rotation planes, which allows extensive lattice relaxation and dynamic charge redistribution, yielding a migration barrier of $\sim$0.2 eV. These results provide a microscopic interpretation of the reported high and anisotropic oxygen conductivity in H-Ta$_2$O$_5$. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2410_22017 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Crystal structure and collective oxygen transport in high-temperature Ta$_{2}$O$_{5}$ Lee, Sung-Hoon Hong, Ki-Ha Materials Science Ionic conduction in crystalline solids is conventionally understood to proceed via atomic-scale defects such as vacancies or interstitials. Here, by addressing the long-standing structural ambiguity of high-temperature tetragonal tantalum pentoxide (H-Ta$_2$O$_5$), we identify a qualitatively different transport mechanism. Based on first-principles calculations, we propose that H-Ta$_2$O$_5$ adopts a chiral framework composed of orthorhombic building units interconnected by screw-rotation planes, with a tantalum sublattice consistent with available transmission electron microscopy observations. Our ab initio molecular dynamics simulations reveal collective, one-dimensional oxygen migration within this stoichiometric lattice at temperatures of a few hundred degrees Celsius. This cooperative transport is enabled by the structural flexibility of octahedral coordination at the screw-rotation planes, which allows extensive lattice relaxation and dynamic charge redistribution, yielding a migration barrier of $\sim$0.2 eV. These results provide a microscopic interpretation of the reported high and anisotropic oxygen conductivity in H-Ta$_2$O$_5$. |
| title | Crystal structure and collective oxygen transport in high-temperature Ta$_{2}$O$_{5}$ |
| topic | Materials Science |
| url | https://arxiv.org/abs/2410.22017 |