High voltage electron microscope observations of UO2

Calculation of the threshold displacement energies in UO2 using ionic potentials

“…Consequently, eight characteristic crystallographic directions have been considered in UO 2 and the results are given in Table 5. The results for the oxygen compare well with the value estimated previously by Soullard et al [26,27], that is approximately E d [O] $ 20 eV. Conversely, for the uranium the calculations show that the mean threshold displacement energy is higher than the mean value estimated by Soullard et al, being rather close to E d [U] $ 50 eV.…”

“…Despite the fact that numerous experimental works have been carried out in order to investigate the behavior of uranium dioxide under irradiation, the threshold displacement energies have never been measured directly and have been rather deduced by indirect considerations which were supposed to match the final irradiation state obtained by theoretical calculations with that of the experimental observations. In fact, the very first theoretical work was done by Soullard et al [26,27] who established a computational code for studying single event displacement cascades in UO 2 . They evaluated the threshold displacement energies of oxygen and uranium, to be roughly 20 eV and 40 eV respectively, since, according to their calculations, these values permitted to obtain consistent results with the experimental observations.…”

TEM investigation of irradiation damage in single crystal CeO2

“…The results indicate CeO 2 remains crystalline without turning amorphous even with heavy overlapping of ion tracks [9], which is similar to the results shown on UO 2 [10,11]. The threshold displacement energy of the Ce-sublattice is found to be between 44 and 58 eV [7], and it is comparable to the value of 40 eV in the U-sublattice [12].…”

A molecular dynamics study of radiation induced diffusion in uranium dioxide

“…3. Each curve N(E) represents the number N of displaced atoms whose energy was 'initially' (just after the collision) at least E. As expected, the simulated curves are quasi flat below the displacement threshold (here 40 eV for U and 20 eV for O [15,16]). …”

“…Indeed an analysis of density of charges cartographies obtained from electronic structure calculations allows to roughly estimate Bader ionic radii of uranium and oxygen, respectively equal to 132 pm and 112 pm. a and b mean energy transfer coefficients calculated classically from the masses of atoms a ¼ 1 [15,16]). …”