Local ordering, defect dynamics, and phase stability in Sc–Hf oxides under ion irradiation
Abstract
High-level radioactive waste requires long-term isolation, motivating the development of durable materials beyond conventional glass matrices, which are thermodynamically metastable. Crystalline ceramics, particularly fluorite-derived oxides, are promising due to their stability, radiation tolerance, and capacity to incorporate radionuclides. In this study, we performed swift heavy ion irradiation into β-Sc2Hf7O17, one of the fluorite structural derivatives in the Sc2O3–HfO2 pseudo-binary system, and investigated its order-to-disordered phase transformation by transmission electron microscopy (TEM). The rhombohedral ordered β-phase transformed into a cubic disordered phase due to damage accumulation. Electron diffraction experiments and dark-field TEM observations revealed the formation of an intermediate phase with an ordered structure distinct from both the β-phase and the other equilibrium phases present in the phase diagram. Irradiation-induced evolution in these materials is complex, involving not only disorder and amorphization but also the formation of intermediate ordered phases and nanoscale heterogeneity. Model systems such as β-Sc2Hf7O17 provide insight into these processes, revealing that local ordering can persist or re-emerge under irradiation, potentially enhancing defect accommodation and delaying structural degradation. This highlights the importance of understanding defect dynamics, local structure, and interfacial effects in designing radiation-resistant waste forms capable of maintaining integrity over geological timescales.
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BibTeX
@article{noguchi2026local,
title = {{Local ordering, defect dynamics, and phase stability in Sc–Hf oxides under ion irradiation}},
author = {Yugo Noguchi and Kohei Kawamura and Maulik Patel and Gianguido Baldinozzi and Clara Grygiel and Manabu Ishimaru},
journal = {Journal of Applied Physics},
year = {2026},
month = sep,
doi = {10.1063/5.0347406},
url = {https://hal.science/hal-05743142v1},
note = {CC BY-NC 4.0},
}
RIS
TY - JOUR
TI - Local ordering, defect dynamics, and phase stability in Sc–Hf oxides under ion irradiation
AU - Yugo Noguchi
AU - Kohei Kawamura
AU - Maulik Patel
AU - Gianguido Baldinozzi
AU - Clara Grygiel
AU - Manabu Ishimaru
PY - 2026
DA - 2026/09/08
JO - Journal of Applied Physics
DO - 10.1063/5.0347406
UR - https://hal.science/hal-05743142v1
AB - High-level radioactive waste requires long-term isolation, motivating the development of durable materials beyond conventional glass matrices, which are thermodynamically metastable. Crystalline ceramics, particularly fluorite-derived oxides, are promising due to their stability, radiation tolerance, and capacity to incorporate radionuclides. In this study, we performed swift heavy ion irradiation into β-Sc2Hf7O17, one of the fluorite structural derivatives in the Sc2O3–HfO2 pseudo-binary system, and investigated its order-to-disordered phase transformation by transmission electron microscopy (TEM). The rhombohedral ordered β-phase transformed into a cubic disordered phase due to damage accumulation. Electron diffraction experiments and dark-field TEM observations revealed the formation of an intermediate phase with an ordered structure distinct from both the β-phase and the other equilibrium phases present in the phase diagram. Irradiation-induced evolution in these materials is complex, involving not only disorder and amorphization but also the formation of intermediate ordered phases and nanoscale heterogeneity. Model systems such as β-Sc2Hf7O17 provide insight into these processes, revealing that local ordering can persist or re-emerge under irradiation, potentially enhancing defect accommodation and delaying structural degradation. This highlights the importance of understanding defect dynamics, local structure, and interfacial effects in designing radiation-resistant waste forms capable of maintaining integrity over geological timescales.
SN - 0021-8979
SN - 1089-7550
ER -