Wed 3rd April @ noon, Rm 312.222

Abstract:

Borosilicate glass is an important material used in various industries due to its chemical durability, such as for the immobilization of high-level nuclear waste. However, it is susceptible to aqueous corrosion, recognizable by the formation of surface alteration layers (SALs). In the talk, I will present results of novel in situ fluid-cell Raman spectroscopic experiments providing unprecedented real-time insights into reaction and transport processes during the aqueous corrosion of a borosilicate glass. The formation of a several micrometre-thick water-rich zone between the SAL and the glass, interpreted as an interface solution, is detected, as well as pH gradients at the glass surface and within the SAL. By replacing the solution with a deuterated solution, it is observed that water transport through the SAL is not rate-limiting. The data supports an interface-coupled dissolution-reprecipitation process for SAL formation. Fluid-cell Raman spectroscopic experiments open up new avenues for studying solid-water reactions, with the ability to in situ trace specific sub-processes in real time by using stable isotopes.

Short bio:

Thorsten Geisler-Wierwille studied Mineralogy at the University of Hamburg (Germany), where he also received his doctoral degree. After various postdoc periods in Hamburg, Cambridge (UK), Münster (Germany), and Perth (Australia) he became a professor at the University of Bonn (Germany). His main interest is to understand the mechanisms and kinetics of solid-fluid interactions and the application of Raman spectroscopy to various problems in Materials Research and Geosciences.