Study of uranium oxide milling in order to obtain nanostructured UCx target

TL;DR

This study investigates the grinding processes of uranium dioxide to produce nanostructured targets for neutron-rich nuclei beams, analyzing effects on particle size, oxidation, and morphology.

Contribution

It compares dry and wet grinding methods for uranium dioxide to optimize nanostructure formation and control oxidation during target preparation.

Findings

Dry grinding is more efficient than wet grinding.

Oxidation of UO2 occurs during grinding, forming U4O9 and U3O7.

Particle size decreases with grinding time.

Abstract

A R&D program is developed at the ALTO facility to provide new beams of exotic neutron-rich nuclei, as intense as possible. In the framework of European projects, it has been shown that the use of refractory targets with nanometric structure allows us to obtain beams of nuclei unreachable until now. The first parameter to be controlled in the processing to obtain targets with a homogeneous nanostructure is the grinding of uranium dioxide, down to 100 nm grain size. In this study, dry and wet grinding routes are studied and the powders are analyzed in terms of phase stabilization, specific surface area and grain morphology. It appears that the grinding, as well dry as wet, leads to the decrease of the particle size. The oxidation of UO2 is observed whatever the grinding. However, the dry grinding is the most efficient and leads to the oxidation of UO2 into U4O9 and U3O7 whose quantities increase with the grinding time while crystallite sizes decrease.