Gas Solubility and Diffusion in Oxide Glasses – Implications for Nuclear Wasteforms

Publication date: 2014 Source:Procedia Materials Science, Volume 7 Author(s): James F. Shackelford Gas solubility and diffusion in oxide glasses define the overall mechanisms of gas transport in these materials. There are numerous practical aspects of this transport with substantial commercial implications, e.g., gas separation, the outgassing and leak testing of vacuum systems, the thermal oxidation of silicon, and the focus of this conference: nuclear wasteforms. The fundamentals of gas transport are defined in regard to gas solubility and diffusion in rigid glasses below the glass transition temperature, including the case of nuclear wasteforms. Gas transport also provides an excellent tool for better understanding the atomic-scale structure of glasses, and, in turn, that understanding helps refine our understanding of the mechanisms of gas solubility and diffusion. This understanding has also had a significant influence on models of geological importance, such as volcanic eruptions and formation of the earth's atmosphere. Specifically, the statistical thermodynamics of gas solubility is analyzed in regard to the interstitial structure of the glass. The gas atoms or molecules serve as structural probes. The structural basis of gas solubility is best understood for vitreous silica, the most-studied noncrystalline solid that can be described reasonably well by the random network model. A detailed analysis of noble gas solubility has indicated that the distribution of in...
Source: Procedia Materials Science - Category: Materials Science Source Type: research