Diminished Diffusion in the Aged Hydrated Gels of Irradiated Borosilicate Glasses
AM Jan and NMA Krishnan, JOURNAL OF PHYSICAL CHEMISTRY C (2022).
Under aqueous conditions, borosilicate glass, which is used as a matrix to store nuclear waste, forms a hydrated gel layer which plays a significant role in the durability of the glass matrix. However, the properties of this gel layer remain poorly understood. Here, we study the effect of irradiation on the structure and transport properties of the hydrated gels in a series of borosilicate glasses. By analyzing the gel structure of pristine and irradiated glasses, we observe that, indeed, there is a difference in the structure (connectivity and short- and medium-range order) of aged gels formed from pristine and irradiated glass. Particularly, aging has a pronounced effect on the irradiated gels as compared to gels obtained from pristine glasses. Furthermore, we observe that irradiated gels exhibit larger ring sizes in comparison to pristine gels. In contrast to the conventional hypothesis, we observe that diffusion of H decreases in gels from irradiated glasses in comparison to their pristine counterparts. We suggest that the topology of the ring plays a major role, in addition to their size, in governing the dynamics.
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