Low-energy sputtering of UO₂

Abstract

A theoretical analysis of the sputtering of polycrystalline UO₂ under low-energy (˜10 keV) Ar⁺ bombardment is presented. The database against which the model is tested consists of twenty time-of-flight spectra and three angular distributions. An isotropic linear collision cascade mechanism appears to match the experimental data extremely well provided the bulk binding potential of the atoms in the lattice is included in the theory. The value of the bulk potential required to fit the time-of-flight data is 25—30 eV and the corresponding surface potential is 1-1•3 eV. An explanation of the observed decrease of the bulk binding potential for the lower bombarding-ion energies is offered and the increase of the surface potential with ion energy is also accounted for. Finally, a brief description of the behaviour of UO, under high-energy ion bombardment is proposed on the basis of an angular distribution obtained with 55 keV H⁺ ions.