Lattice anharmonicity effects in fluorite oxide single crystals and anomalous increase in phonon lifetime in ceria at elevated temperature

Journal Article · Tue Aug 19 00:00:00 EDT 2025 · Applied Physics Letters

DOI:https://doi.org/10.48550/arXiv.2508.14254· OSTI ID:3024424

Khanolkar, Amey Rajendra ^[1]; Adnan, Saqeeb ^[2]; Minaruzzaman, Md ^[2]; Malakkal, Linu ^[1]; Mann, J. Matthew ^[3]; Hurley, David H ^[1]; Khafizov, Marat ^[2]

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1. Idaho National Laboratory
2. The Ohio State University
3. Air Force Research Laboratory

We investigate the temperature dependence of the frequency and linewidth of the triply-degenerate T2g zone-centered optical phonon in flux-grown ceria and hydrothermally-synthesized thoria single crystals from room temperature to 1273 K using Raman spectroscopy. Both crystals exhibit an expected increase in the phonon linewidth with temperature due to enhanced phonon-phonon scattering. However, ceria displays an anomalous linewidth reduction in the temperature range of 1023–1123 K. First-principles phonon linewidth calculations considering cubic and quartic phonon interactions within temperature-independent phonon dispersion fail to describe this anomaly. A parameterization of the temperature-dependent second order interatomic force constants (IFCs) based on previously reported phonon dispersion measured at room and high temperatures, predicts a deviation from the monotonic linewidth increase, albeit at temperatures lower than those observed experimentally for ceria. The qualitative agreement in the trend of temperature-dependent linewidth suggests that lattice anharmonicity-induced phonon renormalization plays a role in phonon lifetime. Specifically, a local minimum in the overlap between acoustic and optical branches at the zone center in the dispersion curve reduces the available phonon scattering phase space, leading to an increased phonon lifetime within a narrow temperature interval. These findings provide new insights into higher-order anharmonic interactions in ceria and thoria, motivating further investigations into the role of anharmonicity-induced phonon renormalization on phonon lifetimes at high temperatures.

• Research Organization: Idaho National Laboratory (INL), Idaho Falls, ID (United States)
• Sponsoring Organization: USDOE Office of Nuclear Energy (NE)
• Grant/Contract Number: AC07-05ID14517
• OSTI ID: 3024424
• Report Number(s): INL/JOU-25-86247
• Journal Information: Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 125 Vol. 0
• Country of Publication: United States
• Language: English

Related Subjects

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS
36 - MATERIALS SCIENCE
75 - CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
Raman spectroscopy
actinide oxides
anharmonicity
first principles calculations
lanthanide oxides
oxide nuclear fuels
phonon linewidth
phonons