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<p>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<sub>2</sub>O<sub>5</sub>), we identify a qualitatively different transport mechanism. Based on first-principles calculations, we propose that H-Ta<sub>2</sub>O<sub>5</sub> 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 &#xa0;~0.2 eV. These results provide a microscopic interpretation of the reported high and anisotropic oxygen conductivity in H-Ta<sub>2</sub>O<sub>5</sub>.</p>

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Crystal structure and collective oxygen transport in high-temperature Ta2O5

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年5月7日

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  • Sung-Hoon Lee,
  • Ki-Ha Hong

摘要

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-Ta2O5), we identify a qualitatively different transport mechanism. Based on first-principles calculations, we propose that H-Ta2O5 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  ~0.2 eV. These results provide a microscopic interpretation of the reported high and anisotropic oxygen conductivity in H-Ta2O5.