Review Of Experimental Studies Conducted At CEA-SRMA
On Radiation Damage Induced In Insulating Oxides At
Different Spatial Scales By Charged Particle Irradiations

Jean-Marc Costantini

Université Paris-Saclay, CEA, Service de Recherche en Matériaux et procédés Avancés, 91191, Gif-sur Yvette, (FRANCE)

PAGE NO: 053-088

ABSTRACT – DOI: https://dx.doi.org/10.47204/EMSR.6.1.2024.053-088

This report reviews 50 papers on studies of radiation effects in oxides conducted at the SRMA from 2000 to 2023. The need to probe the damage at different length scales is emphasized as reported by these experimental results. For this purpose, various experimental techniques were applied, such as X-ray diffraction (XRD), Raman spectroscopy and Fourier transform Infrared (FTIR) spectroscopy, UV-vis absorption and diffuse reflectance spectroscopy, cathodo-luminescence (CL) spectroscopy, thermo-stimulated luminescence (TSL) spectroscopy, photoluminescence (PL) spectroscopy, and electron paramagnetic resonance (EPR) spectroscopy, starting from the long-range scale down to the atomic scale. Experimental data on non-amorphisable oxides, such as yttria-stabilized zirconia (YSZ, ZrO₂: Y) and ceria (CeO₂), are summarized in view to highlight the radiation resistance of dioxides with the same fluorite-like crystal structure as urania (UO₂). In this respect, the relevance of using these non-amorphisable oxides to mimic the behavior of actinide dioxides under radiation is discussed with respect to proper irradiation conditions. The comparison with other amorphisable complex oxides, such as fluorapatites (Ca₁₀(PO₄)₆)F₂), and iron garnets (Y₃Fe₅O₁₂), is also addressed in order to show the major spectroscopic features of amorphisation. For CeO₂, one of the major results is the reduction of Ce⁴⁺ to Ce³⁺ either by electron or heavy ion irradiations which is evidenced by EPR spectroscopy, CL spectroscopy, UV-vis absorption spectroscopy, and diffuse reflectance spectroscopy. The underlying processes of reduction by inelastic or elastic interactions and the potential impact for actinide dioxides such as UO₂ and PuO₂ are discussed. The formation of a polygonised structure in YSZ after swift heavy ion irradiations is also discussed with respect to the in-pile (U, Pu)O_2-x fuel behavior such as the RIM effect. Following these results, some recommendations are provided for further studies of radiation damage in actinide oxides. The use of the vibrational spectroscopies as well as electronic and magnetic spectroscopies is highlighted to probe the radiation damage from the medium range scale to the short atomic scale. This is mandatory for the benchmark of numerical simulations of the behavior of actinide oxides under fast neutron and fission fragment irradiations. Standard XRD and transmission electron microscopy techniques are not adequate to characterize in full the defect formation and radiation damage at the atomic scale in these non-amorphisable materials.