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 UO2+x (x=0.3, 0.4, 0.8, 0.11) were performed at low temperatures (2-300 K). The thermal conductivity of UO2+x is significantly suppressed compared to UO2 except near the N\'eel 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 UO2+x are similar and that the suppressed thermal conductivity in UO2+x results from high phonon scattering rates. These new insights advance our fundamental understanding of thermal transport properties in advanced nuclear fuels.
@article{arxiv.2203.12371,
title = {High Phonon Scattering Rates Suppress Thermal Conductivity in Hyperstoichiometric Uranium Dioxide},
author = {Hao Ma and Matthew S. Bryan and Judy W. L. Pang and Douglas L. Abernathy and Daniel J. Antonio and Krzysztof Gofryk and Michael E. Manley},
journal= {arXiv preprint arXiv:2203.12371},
year = {2022}
}