Uranium Dioxide (UO$_{2})$ 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 UO$_{2}$, determined with the knowledge of the dipole-allowed transitions. We obtained the crystal field parameters and the 5$f$ electron eigen functions for UO$_{2}$. The fourth- and sixth-degree crystal field parameters were found to be V$_{4}$= -116.24 and V$_{6}$=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 150-180 meV range, only three of which can be explained by the crystal-field model. Our experiments on a different UO$_{2}$ sample show that the previously observed peak at about 180 meV is a spurious one, thus it is not intrinsic to UO$_{2}$. [1] G. Amoretti et al., Phys. Rev. B 15 (1989) 1856
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Authors
P. DeChatel
New Mexico State University
European Commission, Joint Research Center, Institute for Transuranium Compounds
LANSCE, Los Alamos National Laboratory
Physics Department, Colorado State University
School of Electrical and Computer Engineering, Purdue University
R. Rajaram
New Mexico State University
P. DeChatel
New Mexico State University
European Commission, Joint Research Center, Institute for Transuranium Compounds
LANSCE, Los Alamos National Laboratory
Physics Department, Colorado State University
School of Electrical and Computer Engineering, Purdue University
P. DeChatel
New Mexico State University
European Commission, Joint Research Center, Institute for Transuranium Compounds
LANSCE, Los Alamos National Laboratory
Physics Department, Colorado State University
School of Electrical and Computer Engineering, Purdue University
P. DeChatel
New Mexico State University
European Commission, Joint Research Center, Institute for Transuranium Compounds
LANSCE, Los Alamos National Laboratory
Physics Department, Colorado State University
School of Electrical and Computer Engineering, Purdue University
