This PhD project focuses on the long-term behavior of nuclear glasses used to confine long-lived radioactive waste.
In aqueous environments, these glasses generally undergo homogeneous alteration: the transformation into alteration products occurs at a uniform rate across the entire surface.
However, cases of heterogeneous alteration also exist, where the glass/gel interface becomes irregular, forming pits or cavities.
Two key questions arise: what are the mechanisms responsible for that behavior, and what are the consequences for the long-term durability of the glass?
Several hypotheses have been suggested in the literature, such as local fluctuations in solution composition or mechanical stress at the glass surface, but no definitive explanation has yet been established.
The proposed approach combines accelerated experiments with chemical, mechanical, and structural characterizations, as well as modeling (e.g., mesoscopic and Monte Carlo models).
Experiments will be conducted on glasses with various surface states (polished, irradiated, fractured, etc.) using analytical tools such as SEM, TEM, and nanoSIMS.
Once the mechanisms are identified, the long-term impact of these heterogeneous alteration patterns can be assessed.
The project seeks candidates with a background in chemistry or materials science, strong interest in modeling, and solid theoretical knowledge.