Helium Bubbles in Gd2Ti2O7 Borosilicate Glass-Ceramic Composites

Glass-ceramics have the potential to be the advanced nuclear wasteforms that can incorporate radioac-tive nuclides for a long-term geological disposal. In order to understand the He accumulation arising from long-term alpha-decay events, 10 keV in-situ TEM helium implantation experiments were carried out to ex-amine the accumulation of helium bubbles in Gd2Ti2O7 borosilicate glass-ceramics. STEM analysis shows He accumulation in amorphous/crystalline ceramic matrix. Helium bubbles with an average bubble size of 1.2 nm were formed at a fluence of 1 . 1 x 10 17 He/cm2 within the ceramic matrix. No helium bubbles were observed in either the glass matrix or glass-ceramic interfaces due to the higher He diffusion co-efficient in glass. The helium bubbles preferred to accumulate near glass-ceramic interfaces and nucleate along ceramic grain boundaries.(c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )