High Phonon Scattering Rates Suppress Thermal Conductivity in Hyperstoichiometric Uranium Dioxide

2022/03/23 by Hao Ma, Ma, Hao, Matthew S. Bryan +11
Chemistry · Engineering · Materials Science · #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Nuclear Materials and Properties #Nuclear reactor physics and engineering #Radioactive element chemistry and processing

paper · pdf · doi:10.48550/arxiv.2203.12371

openalex publication_date 2022/03/23 · openalex created_date 2022/04/03 · openalex updated_date 2026/07/28

Abstract

Uranium dioxide (UO₂), one of the most important nuclear fuels, can accumulate excess oxygen atoms as interstitial defects, which significantly impacts thermal properties. In this study, thermal conductivities and inelastic neutron scattering measurements on UO₂ and UO_2+x (x=0.3, 0.4, 0.8, 0.11) were performed at low temperatures (2-300 K). The thermal conductivity of UO_2+x is significantly suppressed compared to UO₂ except near the Néel temperature TN= 30.8 K, where it is independent of x. Phonon measurements demonstrate that the heat capacities and phonon group velocities of UO₂ and UO_2+x are similar and that the suppressed thermal conductivity in UO_2+x results from high phonon scattering rates. These new insights advance our fundamental understanding of thermal transport properties in advanced nuclear fuels.

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