The research of several Notre Dame Physics faculty members and graduate students resulted in a recently published article in ACS Applied Materials & Interfaces Journal (Irradiation-Driven Restructuring of UO2 Thin Films: Amorphization and Crystallization Vol 13, pp. 35153–35164, 2021) on the preparation, characterization and irradiation stability of thin UO2 targets for nuclear science measurements. Collaborators were Freimann Professor Ani Aprahamian, Assistant Research Professor Khachatur Manukyan, Associate Research Professor Daniel Robertson, physics graduate students Ashabari Majumdar and Stefania Dede, along with with Massman Professor of Civil and Environmental Engineering and Earth Sciences Peter C. Burns and a graduate student Jordan Roach from Department of Chemistry and Biochemistry.
The work reports the use of a combustion synthesis process to deposit thin nanostructured UO2 films on aluminum substrates with precise control over the characteristics of films. Irradiation with an argon ion beam is utilized to generate a uniform distribution of atomic displacements within the films. Post-irradiation characterization shows that the films were stable and did not undergo sputtering degradation or change in stoichiometry. The high-resolution electron microscopy imaging demonstrates that irradiation UO2 films are subjected to complete amorphization and beam-induced densification at the early stages of irradiation. Prolonged irradiation is shown to trigger a crystallization process at the surface of the films that move toward the UO2/Al interface, converting the amorphous material into a highly crystalline film. This work reports on an entirely different radiation-induced restructuring of the nanoscale UO2 compared to the coarse-grained counterpart.
The preparation of thin UO2 films deposited on Al substrates fills an area of national need within the stockpile stewardship program of the National Nuclear Security Administration (NNSA) and fundamental research with actinides. This research was funded by the NNSA under Grant # DE-NA0003888.
Link to article: https://pubs.acs.org/doi/10.1021/acsami.1c08682