Mapping the structural trends in zinc aluminosilicate glasses

• Published in: The Journal of chemical physics Vol. 159; no. 6
• Main Authors: Mendes Da Silva, Rita, Zeidler, Anita, Mohammadi, Hesameddin, Gammond, Lawrence V. D., Girón Lange, Esther, Youngman, Randall E., Aitken, Bruce G., Hannon, Alex C., Benmore, Chris J., Vaughan, Gavin B. M., Salmon, Philip S.
• Format: Journal Article
• Language: English
• Published: United States 14.08.2023
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/5.0157790

The structure of zinc aluminosilicate glasses with the composition (ZnO)x(Al2O3)y(SiO2)1−x−y, where 0 ≤ x < 1, 0 ≤ y < 1, and x + y < 1, was investigated over a wide composition range by combining neutron and high-energy x-ray diffraction with 27Al magic angle spinning nuclear magnetic resonance spectroscopy. The results were interpreted using an analytical model for the composition-dependent structure in which the zinc ions do not act as network formers. Four-coordinated aluminum atoms were found to be in the majority for all the investigated glasses, with five-coordinated aluminum atoms as the main minority species. Mean Al–O bond distances of 1.764(5) and 1.855(5) Å were obtained for the four- and five-coordinated aluminum atoms, respectively. The coordination environment of zinc was not observed to be invariant. Instead, it is dependent on whether zinc plays a predominantly network-modifying or charge-compensating role and, therefore, varies systematically with the glass composition. The Zn–O coordination number and bond distance were found to be 4.36(9) and 2.00(1) Å, respectively, for the network-modifying role vs 5.96(10) and 2.08(1) Å, respectively, for the charge-compensating role. The more open coordination environment of the charge-compensator is related to an enhanced probability of zinc finding bridging oxygen atoms as nearest-neighbors, reflecting a change in the connectivity of the glass network comprising four-coordinated silicon and aluminum atoms as the alumina content is increased.