Effect of thermally induced structural disorder on the chemical durability of International Simple Glass

Abstract

While the influence of silicate oxide glass composition on its chemical durability is increasingly known, the contribution of structure only is less well understood, yet is crucial for an accurate description of aqueous alteration mechanisms. The effect of structural disorder can be investigated by varying the thermal history of the glass. Furthermore, the structural changes generated by selfirradiation in nuclear glasses can be compared with those induced by fast quenching. In the context of deep geological disposal of vitreous matrices, it is then challenging to address the structural impact on glass durability. Here, a borosilicate glass, the International Simple Glass, was fiberized to obtain a rapidly quenched sample. The quenching rate and fictive temperature were evaluated from in situ Raman and Brillouin spectroscopies. Multinuclear nuclear magnetic resonance was used to obtain insight into the effect of quenching on the pristine and altered glass structure. Higher bond angle distribution and lower mixing of alkalis were observed in the fast quenched glass. Some of AlO 4 groups are then Ca-compensated, while a part of BO 4 is transformed into BO 3 units. The structural modifications increase the hydrolysis of the silicate network occurring in the forward rate regime at 90°C by a factor of 1.4-1.8 depending on the pH value. Residual rate regime is similarly affected, more significantly at the beginning of the experiments conducted in silica saturated solutions. These findings prove that the reactivity of glass remains controlled by its structure under the various alteration regimes.

Impact of magnesium on the structure of aluminoborosilicate glasses: A solid‐state NMR and Raman spectroscopy study

“…Similar to B[III], the two components can be interpreted in terms of connectivity with the silicate network (i.e. B[IV] connected to 3 or 4 SiO 2 units): an increase of Si connectivity leads to more negative isotropic chemical shifts 28,74,76 . was also observed when substituting magnesium for calcium in the N19C8 and N19M8 glasses (from 54% to 63%, respectively), as shown in Figure 4 (b).…”

New Insights about the Importance of the Alteration Layer/Glass Interface

“…In addition, NMR spectroscopy of altered ISG glass leached at pH 7 for 100 days at 90 o C has shown that the altered glass was slightly enriched in B (IV) compared to the nonaltered one. This can be understood as a preferential release of B (III) during alteration 40 . In any case, one of the consequences of the irradiation-induced transformation of BO4 to BO3 is to free up the Na atoms.…”

Effects of Al:Si and (Al + Na):Si ratios on the properties of the international simple glass, part I: Physical properties

“…A simplified representation of borosilicate waste glasses known as the international simple glass (ISG) was designed and developed by the nuclear waste glass community to synergize efforts towards understanding waste glass properties and corrosion behavior. 15 ISG has been intensively researched with studies focusing on its physical 16 and mechanical properties, [17][18][19] structural insights obtained experimentally 20 and via computer simulations, [21][22][23][24] surface quality, 19,25 waste loading, 26 radiation effects, [27][28][29][30] dissolution behavior under different testing conditions, [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49] dissolution kinetic models, 50,51 as well as characterization of alteration layers using advanced techniques. 34,[52][53][54][55][56] The wealth of data associated with this glass made it a logical choice to study the impact of Al 2 O 3 concentrat...…”