AVS 58th Annual International Symposium and Exhibition
    Energy Frontiers Focus Topic Friday Sessions
       Session EN+AC-FrM

Invited Paper EN+AC-FrM4
Proof that UO2 is an f-f Electron Correlated System

Friday, November 4, 2011, 9:20 am, Room 203

Session: Materials Challenges for Nuclear Energy
Presenter: Sung Woo Yu, Lawrence Livermore National Laboratory
Authors: S.W. Yu, Lawrence Livermore National Laboratory
J.G. Tobin, Lawrence Livermore National Laboratory
J.C. Crowhurst, Lawrence Livermore National Laboratory
S. Sharma, Max Planck Institute, Halle, Germany
J.K. Dewhurst, Max Planck Institute, Halle, Germany
P. Olalde-Velasco, Lawrence Berkeley National Laboratory
W.L. Yang, Lawrence Berkeley National Laboratory
W.J. Siekhaus, Lawrence Livermore National Laboratory
Correspondent: Click to Email
We have performed x-ray absorption experiments on uranium dioxide (UO2) at the O 1s, U 4d, U 4f, and U 5d edges. After comprehensive energy calibrations for O 1s, U 4d, and U 4f spectra, we have used the U 4d and 4f spectra to sort the energetic positions of the 5f and the 6d states in the unoccupied band unambiguously. This demonstrates conclusively that UO2 is an f-f Mott-Hubbard insulator, where the electronic repulsion between f electrons is responsible for the insulating state. Calculations performed within the U-corrected generalized gradient approximation of the optical response of UO2 permit direct comparison with the absorption spectra and confirm the experimental results.

Lawrence Livermore National Laboratory is operated by Lawrence Livermore National Security, LLC, for the U.S. Department of Energy, National Nuclear Security Administration under Contract DE-AC52-07NA27344. This work is funded in part by the DOE Office of Science, Office of Basic Energy Science, Division of Materials Sciences and Engineering. This work is also funded in part by Laboratory Directed Research and Development (LDRD) Program (10-SI-016) of Lawrence Livermore National Laboratory. The Advanced Light Source (ALS) is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. We would like to thank Ian Hutcheon, Patrick Allen, Anthony Van Buuren, Trevor Wiley, and Joseph Zaug for valuable discussions. POV would like to acknowledge CONACyT Mexico.