Experimental study of chemical durability of fluorozirconate and fluoroindate glasses in deionized water

This paper investigates the chemical durability of a fluoroindate (IZSBGC) glass (developed by our previous research for low-loss fluoroindate fiber production) compared to the widely studied fluorozirconate (ZBLAN) system via leaching of glass samples in deionized water. The chemical stability of both glass systems is probed using a series of analytical techniques such as FTIR, XPS and SEM to study the sample surfaces (before and after leaching) and hydrated layer products, both of which reflected the nature of the leaching process. Our experimental results suggest that IZSBGC glass presented better chemical stability in water than ZBLAN. The absorption due to both OH^- stretching and HOH bending vibrations for both glass types increased with increasing amounts of hydrated layers formed during the leaching. The investigation of hydrated layers using SEM suggests that the NaF content in fluoride glass accelerated the leaching significantly. XPS analyses suggest that (hydr)oxyfluorides and hydroxides formed on both fluorozirconate and fluoroindate glass surfaces after leaching, respectively. The degradation of fiber breaking strain in NaF-free IZSBGC glass is less than that of NaF-containing ZBLAN glass.