Chemical Durability of Fluoride Glasses: II, Reaction of Barium‐Thorium‐Based Glasses with Water

The aqueous leaching behavior of three Ba‐Th‐based fluoride glasses was studied. Results of solution analysis, SEM, and IR spectroscopy are reported and compared with earlier studies on fluorozirconate‐based glasses. Leaching appears to be by matrix dissolution dominated by component solubility. No hy‐drated leach layer was seen to form on the surface. Only a mild drift In solution pH, resulting from a limited hydrolysis of, dissolved thorium fluoride, was observed. The reduced pH drift away from neutral, coupled with lower component solubilities, is credited with the 100‐fold improvement in chemical durability of the Ba‐Th‐based fluoride glasses over the fluorozirconate‐based glasses reported previously.