Study of phonons in irradiated epitaxial thin films of UO 2

Sophie Rennie, Eleanor Lawrence Bright, James E. Darnbrough, Luigi Paolasini, Alexei Bosak, Andrew Smith, Nicholas J.S. Mason, Gerard H. Lander, Ross Springell

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Abstract

We report experiments to determine the effect of radiation damage on the phonon spectra of the most common nuclear fuel, UO2. We irradiated thin (∼300 nm) epitaxial films of UO2 with 2.1 MeV He2+ ions to 0.15 displacements per atom and a lattice swelling of Δa/a∼0.6% and then used grazing-incidence inelastic x-ray scattering to measure the phonon spectrum. We succeeded in observing the acoustic modes, both transverse and longitudinal, across the Brillouin zone. The phonon energies, in both the pristine and irradiated samples, are unchanged from those observed in bulk material. On the other hand, the phonon linewidths (inversely proportional to the phonon lifetimes) show a significant broadening when comparing the pristine and irradiated samples. This effect is shown to increase with phonon energy across the Brillouin zone. The decreases in the phonon lifetimes of the acoustic modes are roughly consistent with a 50% reduction in the thermal conductivity
Original languageEnglish
Article number224303
Number of pages9
JournalPhysical Review B
Volume97
Issue number22
Early online date8 Jun 2018
DOIs
Publication statusPublished - 8 Jun 2018

Keywords

  • Phonons
  • UO2
  • Irradiation Damage
  • Thermal conductivity
  • Brillouin Zone

Research Beacons, Institutes and Platforms

  • Advanced materials
  • Dalton Nuclear Institute

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