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Description:

Large lattice responses in dense inorganic oxides are typically driven by structural phase transitions or redox processes that alter crystal symmetry or composition. Here, we identify a distinct mechanism for such responses: giant lattice expansion through symmetry-preserving cation redistribution in a metastable, structurally frustrated dense oxide. High-pressure-quenched Ba4Ru3O12 undergoes an irreversible volumetric expansion of 4.4% between 450 and 650 K while retaining R-3m symmetry and oxygen stoichiometry. High-resolution synchrotron diffraction reveals cooperative redistribution of Ru within face-sharing RuO6 trimers, directly linking intratrimer cation configuration to lattice volume. Thermogravimetric, transport, and magnetic measurements exclude decomposition, redox processes, and electronic or magnetic phase transitions. First-principles calculations show that compression stabilizes a low-volume cation configuration, which is retained after recovery to ambient pressure and relaxes upon heating through intratrimer cation exchange. Together, these results establish symmetry-preserving cation redistribution as a mechanism for giant lattice responses in dense oxides and identify metastable frustrated configurations as a route to large structural responses without symmetry breaking or compositional change.

Rights:

• Creative Commons BY Attribution 4.0 International
  

Keyword: High-pressure synthesis, Irreversible expansion, Barium ruthenate, Atomic rearrangement, Thermal stress control

Date published: 2026-06-03

Publisher: American Chemical Society (ACS)

Journal:

• Journal of the American Chemical Society (ISSN: 00027863) vol. 148 issue. 21 p. 22380-22388

Funding:

• National Institute for Materials Science (NIMS)
• JSPS KAKENHI JP25K01507
• JSPS KAKENHI JP25K01657
• World Premier International Research Center Initiative (WPI), MEXT, Japan

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1021/jacs.6c07579

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Updated at: 2026-06-04 15:54:31 +0900

Published on MDR: 2026-06-04 18:32:33 +0900