He irradiation‐induced lattice distortion and surface blistering of Gd₂Zr₂O₇ defect‐fluorite ceramics

Abstract

Gd2Zr2O7 ceramics with different grain sizes ranging from nanoscale to submicron scale (91, 204, and 634 nm) were irradiated at room temperature using 190 keV He ions with doses ranging from 5 × 1016 to 5 × 1017 ions/cm2. We fully characterized the pre‐ and post‐irradiation samples using grazing‐incidence X‐ray diffraction (GIXRD), scanning electron microscope (SEM), and atomic force microscope (AFM) as the grain size and degree of irradiation vary. The results suggested that all three Gd2Zr2O7 samples demonstrate outstanding radiation tolerance to displacement damage by retaining their crystallinity after irradiation at 5 × 1017 ions/cm2. which is equal to 16 displacement per atom (dpa) at peak positions. Although lattice expansion was observed at a He irradiation at 5 × 1016 ions/cm2 and beyond, the lattice remained stable for the nanograin ceramic, while the degree of distortion for the sample with the largest grain size (634 nm) continuously increased. Moreover, a delayed He bubble evolution process was seen for the nanograin ceramic, which did not appear for the submicron‐grained sample. Interestingly, the grain size‐dependent surface blistering was also found to be a function of ion fluence. After He irradiation at 5 × 1017 ions/cm2 the AFM root‐mean‐square(RMS) roughness variation for Gd2Zr2O7 ceramics of 91, 204, and 634 nm were 4.8, 7.0, and 11.1 nm, respectively.

Recent Progress on Interfaces in Nanomaterials for Nuclear Radiation Resistance

“…The further experiments indicate that Gd 2 Zr 2 O 7 samples with different grain sizes of 91, 204, and 634 nm all demonstrate outstanding radiation tolerance to displacement damage by retaining their crystallinity after irradiation at 5 × 10 17 ions/cm 2 , equally to 16 dpa at peak positions. [81] The lattice of nanograin ceramic is much more stable compared to the sample with largest grain size (634 nm) sample in which the distortion continuously increased. The similar observation could be found in the nano-and coarse-grain size Lithium titanium oxide (Li 2 TiO 3 ) tritium breeder ceramic plates.…”

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“…In this regard, it is necessary to have a clear understanding of the processes that occur during the accumulation of helium, as well as the consequences they have on changes in the structural, strength, or mechanical properties of structural materials. In the last few years, much attention has been paid to the study of the mechanisms of helium swelling, as well as the conditions and critical doses under which the formation of helium bubbles in the structure is observed, their further evolution, and the consequences they cause [31][32][33]. At the same time, special attention is paid to this issue when studying these processes of radiation damage and helium swelling in high-temperature ceramics, the interest in which, as mentioned above, is due to the possibility of using them as structural materials for new generation reactors [34,35].…”

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