Leaching of Glasses with Molar Composition 20Na₂O · 10RO ·x Al₂O₃· (70‐x)SiO₂

Abstract

as a Microwave Dielectric Resonator," J . Am. Ceram. Soc., 58 19-10] 418-20 (1975). 'S. Kawashima, M. Nishida, I. Ueda, and H. Ouchi, "Dielectnc Properties of Ba(Zn,,,Nb2,,)0,-Ba(Zn ,,3Ta,,)0, Ceramics at Microwave Frequency": pp. 293-96 in ,)O, Ceramics with Temperature-Stable High Dielectric Constant and Low Microwave Loss," Jpn. J. Appl. Phys., 21 [lo] L624-26 (1982). Sodium depth profiles were determined in water-leached glass samples with molar composition 20Na20 * lORO *xA1203* (70x)Si02 (RO = CaO, MgO, and ZnO) using secondary ion mass spectrometry. The leaching of sodium ions decreases with increasing Alz03 content in all three glass systems. For x = 0 the leaching is hardly affected by the nature of the divalent cation. For x = 5 and 10 the corrosion resistance is highest for the glass containing ZnO, and for the glasses containing ZnO and MgO, respectively. These glasses correspond to those with the smallest fraction of NBOs. From all these results it is concluded that the nonbridging oxygen atoms play an important role in promoting the leaching of a glass.Presented as part of the Woldemar A. Weyl Award Lecture during the 13th Inter-

Effects of Al:Si and (Al+Na):Si ratios on the static corrosion of sodium‐boroaluminosilicate glasses

“…12 For glasses with low concentrations of Al 2 O 3 (<3.5 mol%), they suggest 7-day PCT measurements are dominated by Stage I behavior as ion-exchange processes are faster leading to increased pH, higher Si solubility, and delayed transition to stage II. [44][45][46] For intermediate concentrations (3.5 to 19 mol%), relatively low NL(α) values indicate that the glass dissolution rate slowed (which may be an indication of a transition to Stage II behavior). High NL(α) values observed with glasses with high Al 2 O 3 concentrations (>19 mol%) may be evidence that they are already undergoing Stage III behavior.…”

Photoinduced Electron Transfer Based Ion Sensing within an Optical Fiber

“…The differences in fluorescence enhancement due to the PET-effect for the bulk sample (5-fold as shown in Figure 3) compared to the MOF experiments (21.4–36.4% as in Figure 4) may be due to leaching of Na + or K + ions from the lead-silicate glass, resulting in a raised background fluorescence signal as the FI responds to the increased alkali cation concentration and consequently limiting the fluorescence enhancement when measuring spiked sodium solutions. Leaching under relatively benign conditions has been reported [36]. Future mitigation strategies include the use of coatings on the MOF surfaces or the use of alternative glass compositions.…”

Recent Advances in Corrosion Science Applicable To Disposal of High-Level Nuclear Waste

“…In the second mechanism, alumina increased the glass network connectivity and resulted in a decrease of water diffusivity. 83 By using secondary ion mass spectrometry (SIMS), Smets and Tholen found that alumina also stabilized 4-fold coordinated Mg and Zn, hence further improving the glass durability. 83 Corrosion of SLS glass with alumina was studied by Wassick et al 85 using nuclear reaction and Rutherford backscattering to determine the hydrogen and sodium profiles, respectively, of the corroded glass surfaces.…”

“…83 By using secondary ion mass spectrometry (SIMS), Smets and Tholen found that alumina also stabilized 4-fold coordinated Mg and Zn, hence further improving the glass durability. 83 Corrosion of SLS glass with alumina was studied by Wassick et al 85 using nuclear reaction and Rutherford backscattering to determine the hydrogen and sodium profiles, respectively, of the corroded glass surfaces. It was found that the addition of a small amount of Al 2 O 3 could improve the chemical durability, which was explained by the suppression of the formation of a surface alteration layer that has high ion mobility.…”

“…The effects of Al 2 O 3 concentration on silicate and borosilicate glass corrosion have been extensively investigated. − The improvement of chemical durability of silicate glasses with alumina addition was explained by two mechanisms, both increasing the chemical durability. First, the introduction of alumina decreased the amount of sodium ions bonded to NBOs by increasing the sodium ions for charge compensation of [AlO 4 ] − tetrahedra, and these sodium ions were less readily leached than those bonded to NBOs.…”