The structures and properties of yttrium aluminosilicate glasses with low, medium, and high silica contents

Yttrium aluminosilicate glasses with 25-78 mol% silica were studied using molecular dynamics simulations to understand their structural and property changes. The results show that Al3+ ions primarily exist as four-fold coordinated, with <5% in higher-coordinated states that increase with decreasing silica content. The forma-tion of significant concentrations (4-9%) of oxygen tri-clusters and small amounts of free oxygen were also observed, suggesting a perturbed glass network structure. An average Y-O bond distance of 2.26 angstrom and Y co-ordination number of 6.3 were found. The glass transition temperatures are relatively insensitive to composition, agreeing with experiments. A 16% and 30% increase in Young's and bulk moduli, respectively, was observed with decreasing silica contents which was explained by the strong Y-O bond and formation of oxygen tri-clusters that aggregate higher coordinated Al species. These results were discussed in the context of optical and acoustic properties of YAS optical fibers that exhibit reduced nonlinearities.

Automated summary

Molecular dynamics simulations were used to study the structural and property changes in yttrium aluminosilicate glasses with varying silica contents. The results showed that the majority of Al3+ ions had a coordination number of four, with a small percentage in higher coordination states that increased with decreasing silica content. Significant concentrations of oxygen tri-clusters and small amounts of free oxygen were also observed, indicating a perturbed glass network structure. The glass transition temperatures were relatively unaffected by composition, consistent with experimental findings. A decrease in silica content resulted in an increase in Young's and bulk moduli, attributed to the strong Y-O bond and the formation of oxygen tri-clusters aggregating higher coordinated Al species. These findings were relevant to the optical and acoustic properties of YAS optical fibers with reduced nonlinearities.