IBA and SIMS coupling to study glass alteration mechanisms

Alkali-alumino-borosilicate glasses have been synthesized by melting the stoichiometric corresponding powder mixtures and heating at 1100 °C in a platinum crucible. Electron microprobe analyses were then carried out in order to determine their initial composition. Glass samples were submitted to static aqueous leaching tests in deionized water during 1 month (surface/ratio = 0.3 cm−1) at temperature of 96 °C. The leachates were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The leached samples were then characterized by ion beam analytical (IBA) methods: Rutherford backscattering and elastic recoil spectrometries (RBS and ERDA), proton-induced X-ray or gamma ray emission (PIXE and PIGE) and secondary ion mass spectrometry (SIMS). The role of the presence of one or several contained transition elements (Fe, Mo, and Nd) and the effect of their respective contents on the chemical durability of alkali-borosilicate glasses were investigated. This work outlines the fact that a competition may occur between congruent and selective dissolution. Both surface hydration thickness and mobile element depletion amplitude cannot be considered as the unique reliable glass durability indicators.