Topological Origins of the Mixed Alkali Effect in Glass
| Autor: | Arron R. Potter, Mathieu Bauchy, Rebecca S. Welch, John C. Mauro, Mario Affatigato, Collin J. Wilkinson, Qiuju Zheng, Caio Barca Bragatto, Steven A. Feller |
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| Rok vydání: | 2019 |
| Předmět: |
Alkali ions
Materials science Constraint theory 010304 chemical physics Ionic bonding 010402 general chemistry Alkali metal Topology 01 natural sciences 0104 chemical sciences Surfaces Coatings and Films Stress (mechanics) Viscosity Molecular dynamics 0103 physical sciences Physics::Atomic and Molecular Clusters Materials Chemistry Mixed alkali effect Physical and Theoretical Chemistry |
| Zdroj: | The journal of physical chemistry. B. 123(34) |
| ISSN: | 1520-5207 |
| Popis: | The mixed alkali effect, the deviation from expected linear property changes when alkali ions are mixed in a glass, remains a point of contention in the glass community. While several earlier models have been proposed to explain mixed alkali effects on ionic motion, models based on or containing discussion of structural aspects of mixed-alkali glasses remain rare by comparison. However, the transition-range viscosity depression effect is many orders in magnitude for mixed-alkali glasses, and the original observation of the effect (then known as the Thermometer Effect) concerned the highly anomalous temperature dependence of stress and structural relaxation time constants. With this in mind, a new structural model based on topological constraint theory is proposed herein which elucidates the origin of the mixed alkali effect as a consequence of network strain due to differing cation radii. Discussion of literature models and data alongside new molecular dynamics simulations and experimental data are presented in support of the model, with good agreement. |
| Databáze: | OpenAIRE |
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