Insights into the Effect of Particle Size on the Low Energy Radiation Response of Ceria

Abstract

Understanding the radiation tolerance of ceramics against low energy heavy ions is important for evaluating their stability against alpha recoils, which are a significant source of damage for their application as nuclear fuels and/or waste immobilization matrices. Radiation response of ceramics is significantly affected by the particle size and microstructure in addition to their crystalline structure. With this motivation, three different particle-sized CeO 2 samples were subjected to irradiation by 400 keV Kr ion at various fluences. The smaller particle-sized samples are found to be more radiation tolerant, which is attributed to the higher prevalence of grain boundaries that act as sinks for the (irradiation-induced) defects. The predominant defects generated in these systems are observed to be Ce 3+ and vacancy-related isolated clusters as investigated by Raman spectroscopy and corroborated by X-ray photoelectron spectroscopy and photoluminescence studies. However, in the micron-sized sample, a secondary fluorite-type defective phase appears upon irradiation, as seen from X-ray diffraction, which continually expands with an increase in fluence, unlike the smaller-sized samples. Interestingly, the relative content of reduced Ce (Ce 3+ /Ce 4+ ratio) is observed to be much higher in the smaller-sized samples post-irradiation, making it an important manifestation of irradiation effects in nanoceria. More importantly, the radiation tolerance as a function of particle size in the low energy regime is observed to have an opposite trend to that under high energy heavy ion irradiation, and this comparison has been discussed. CeO 2 is also widely employed as the surrogate for PuO 2 , and the present study thus has significance to self-irradiation of PuO 2 as well.

Study on damage of Gd2O3–CeO2 under electronic energy loss: comparison between bulk-like and nanostructure

“…The phase and crystalline behavior of both irradiated and unirradiated CeO 2 and Gd-doped ceria has already been much studied in previous research papers and it has been observed that up to 5 mol% Gd doping in ceria, there is no major structural change. 12 The lattice parameters and phase structure, reported by Kalita et al 13 for ceria in their paper, are B0.514 for GDC-S and B0.504 for GDC-L, which are more or less the same in the present case. Therefore, motivated by such results, we have presumed that doping of Gd in pure ceria will not cause any major structural or phase change.…”

“…Synthesis of 5 mol% (Gd 0.05 Ce 95 O 1.975 ) Gd-doped ceria nano-powders was carried out through the self-assisted gel-combustion method. 13 To obtain different grain sizes, the prepared nano-powder was divided into two equal parts, pelletized and sintered at two different temperatures: 800 °C for 2 hours and 1300 °C for 30 hours. Hereafter, the samples sintered at 800 °C and 1300 °C will be represented as GDC-S and GDC-L (S = smaller particle size, L = larger particle size), respectively.…”

“…This is consistent with the work reported by Bai et al 1 This is attributed to the large density of grain boundaries which act as sinks for the irradiation-induced defects (created via collision cascades), thereby leading to defect removal and hence the excellent radiation tolerance. 13 However, the opposite is the case against high-energy ( S e ) irradiations. It has been reported that a material with smaller grain size experiences higher thermal spike, and thus greater damage, due to enhanced grain boundary scattering of electrons and phonons, which leads to a higher electron–phonon coupling and lower thermal conductivity.…”

Grain size effect on the radiation damage tolerance of cubic zirconia against simultaneous low and high energy heavy ions: Nano triumphs bulk

“…downsizing of materials to nano-dimension, has received significant attention and is being considered as an effective strategy in the context of mitigating the radiation damage in materials. It has been observed that the nano-crystalline (NC) state exhibits enhanced radiation damage tolerance, against low energy ions (S n dominant), when compared to its bulk counterparts 5 , 10 – 20 . We have, however, very recently shown that the better radiation tolerance of NC materials is not always true and designing nano-scale materials in order to lower the irradiation induced damage is not advantageous against high energy ions (S e dominant) 21 .…”

Radiation response of Y3Al5O12 and Nd3+–Y3Al5O12 to Swift heavy ions: insight into structural damage and defect dynamics

“…The asymmetric XRD peaks in the irradiated samples denoting the presence of more than one phase has also been observed in low and high energy irradiation of ceria. 35,36 This implies that the passage of radiation through garnets (YAG and Nd-YAG) is creating compositional inhomogeneity within the material as the manifestation of irradiation damage and defect creation, which results in the appearance of more than one garnet phase. The exact nature of these could be determined by electron microscopy and selected area electron diffraction, which are the future scope of this work.…”