Investigating the Structure-Property Relationships of Ionic Glasses

• Applicant: Dr. Courtney Calahoo
• Subject Area: Synthesis and Properties of Functional Materials
• Term: from 2019 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 421037427

Ionic glasses offer a unique opportunity for glass scientists to design materials with desirable properties. Rather than directional, covalent bonds found in conventional network glasses, the structure of ionic glasses is dominated by Coulombic cation-anion interactions. In a paradigm shift, cations are now the only cross-linkers between network formers (such as phosphate) and are deterministic of glass structure, topology and macroscopic properties. Despite many stable ionic glass compositions being reported, the connectivity is more difficult to analyze due to routine structure analysis techniques such as Raman and NMR spectroscopy being only useful for the covalent backbone. Oxygen-17 NMR overcomes many of these problems, making it an ideal analysis technique; it is sensitive to bonding environment, identity of neighbours and capable of observing preferential cation-anion bonding. The main motivation of the proposed work is to structurally characterize the intermediate-range order of ionic glasses and relate the structure to macroscopic properties. Due to their unique structure, our goal is to understand the driving forces which dictate preferred bonding in ionic glasses, thereby providing the insight for us to choose a composition for a specific application. To gain further structural understanding of glass formation, we will compare the experimental structure to that predicted from thermodynamic and statistical calculations. We aim to determine whether the structure and topology of ionic glasses can be explained with this combination of statistical and thermodynamic inputs, thereby leading to the prediction of properties based on glass composition. Given the lack of polymerization in ionic glasses, the thermodynamics of bonding may play more of a role in determination of structure and lead to unique structure-property relationships compared to network glasses.

• DFG Programme: Research Grants
• International Connection: Canada
• Cooperation Partners: Professorin Dr. Ulrike Werner-Zwanziger; Professor Josef Zwanziger