College Park, Maryland      June 6 - 10 , 2004

ACNS Home Meeting Announcement Committees and Contacts Registration Abstract Submission Travel Reimbursement Dates to Remember

T2-D4 (2:30 PM): Crystal fields in UO₂ - revisited

H. Nakotte, R. Rajaram (Physics Department, New Mexico State University, Las Cruces NM 88003), R. McQueeney (Los Alamos Neutron Science Center, Los Alamos National Laboratory), S. Kern (Physics Department, Colorado State University, Fort Collins CO 80524), G.H. Lander (Institute for Transuranium Compounds, D-76125 Karlsuhe, Germany)

Uranium Dioxide (UO₂) is an important nuclear fuel material. We performed high-resolution inelastic neutron scattering using PHAROS at the Los Alamos spallation source LANSCE in order to re-investigate the crystal field splitting in UO₂, determined with the knowledge of the dipole-allowed transitions. We obtained the crystal field parameters and the 5f electron eigen functions for UO₂. The fourth- and sixth-degree crystal field parameters were found to be V₄= -116.24 and V₆=25.78, in good agreement with previously published results by Amoretti et al. [1]. On the other hand, these previous studies did reveal four crystal-field excitations in the 150 meV to 180 meV range, only three of which can be explained by the crystal-field model. Our experiments on a different UO₂ sample show that the previously observed peak at about 180 meV is a spurious one, thus it is not intrinsic to UO₂.

[1] G. Amoretti et al., Phys. Rev. B 15 (1989) 1856

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