Raman spectra analysis of ZrO2 thermally grown on Zircaloy substrates irradiated with heavy ion: Effects of oxygen isotopic substitution

Recently, unusual Raman signals were observed in different works conducted on thin zirconia layers grown on zirconium alloys simulating in-reactor materials after high fluence ion irradiation or for samples cut from fuel rods irradiated in nuclear plants. As such, these spectra clearly do not correspond to any known spectrum of a pure standard zirconia phase. Therefore, the analysis conducted in this paper aims to provide a better understanding of these peculiar Raman features. For that purpose, specific ion-irradiated samples were analysed. In situ Raman spectroscopy was first used to follow the irradiation process. Then, samples were characterized using different excitation wavelengths. Finally, the effects of oxygen isotopic substitution were examined in details. Results are discussed in terms of disorder and size-related effects.