In-situ and real-time studies of the influence of ion irradiation on glass corrosion kinetics and surface alteration layer formation by fluid-cell Raman spectroscopy

• Applicant: Professor Dr. Thorsten Geisler-Wierwille
• Subject Area: Mineralogy, Petrology and Geochemistry ; Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 457756859

Borosilicate glasses are used for various medical and technical applications, e.g., for the immobilization of high-level nuclear waste from spent fuel. A key challenge, especially for the permanent disposal of nuclear waste in glasses, is the development of predictive models of the effects of self-irradiation damage on the aqueous corrosion process. Borosilicate glasses undergo significant structural modifications due to self-irradiation processes involving ionization as well as electronical and nuclear collisions. Currently, there is only very limited knowledge and controversial data about the effect of self-irradiation damage on the aqueous stability of silicate glasses. Novel fluid-cell Raman spectroscopic corrosion experiments with a swift heavy ion irradiated glass at temperatures between 80 and 85°C, however, demonstrated a non-negligible impact of the damaged glass structure on the dissolution kinetics. The proposed research project aims to systematically study the missing link between the type and degree of radiation damage and the glass corrosion mechanism(s) and kinetics by fluid-cell Raman spectroscopy. Fluid-cell Raman spectroscopy enables the corrosion of glasses to be investigated in situ and in real time in a unique way without interrupting the reaction. A ternary borosilicate glass and the “International Simple Glass” shall be subjected to different heavy ion irradiation scenarios to simulate the different decay processes in glasses. The radiation damage shall be characterized and quantified by Raman spectroscopy. In-situ fluid-cell Raman corrosion experiments will then be performed at different temperatures and for different duration (up to several months) with the irradiated glasses and different silica-undersaturated solutions with different pH values. To study and quantify transport and re-equilibration processes, 2H- and 18O-labelled solutions will be used as isotope tracers. These experiments will deliver valuable kinetic data as well as information about still controversially discussed mechanistic aspects of the corrosion process, which are necessary to model the long-term stability of borosilicate glasses that are subjected to high-energy radiation and aqueous solutions.

• DFG Programme: Research Grants