Abstract
An analytical model is developed for the composition-dependent structure of the amorphous aluminosilicate materials (M2O)x(Al2O3)y(SiO2)1-x-y and (MO)x(Al2O3)y(SiO2)1-x-y, where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1. The model is based on a simple set of reactions and contains a single adjustable parameter p (0 ≤ p ≤ 1). The latter is found from 27Al solid-state nuclear magnetic resonance (NMR) experiments in the regime where R = x/y ≥ 1, aided by new experiments on the magnesium and zinc aluminosilicate systems. The parameter p decreases linearly as the cation field strength of M+ or M2+ increases, as per the observation previously made for the degree of aluminum avoidance [Lee et al., J. Phys. Chem. C 120, 737 (2016)]. The results indicate that as the cation field strength increases, there are less fourfold coordinated aluminum atoms to contribute toward the glass network, and Al-O-Al bonds become more prevalent in a progressive breakdown of Loewenstein's aluminum avoidance rule. The model gives a good account of the composition-dependent fraction of non-bridging oxygen (NBO) atoms for R ≥ 1, as assessed from the results obtained from solid-state NMR experiments. An extension of the model to (M2O3)x(Al2O3)y(SiO2)1-x-y glasses leads, however, to an excess of NBO atoms, the proportion of which can be reduced by invoking network-forming fivefold coordinated Al atoms and/or oxygen triclusters. The model provides a benchmark for predicting the structure-related properties of aluminosilicate materials and a starting point for predicting the evolution in the structure of these materials under the extreme conditions encountered in the Earth's interior or in processes such as sharp-contact loading.
Original language | English |
---|---|
Article number | 064503 |
Number of pages | 17 |
Journal | Journal of Chemical Physics |
Volume | 156 |
Issue number | 6 |
Early online date | 9 Feb 2022 |
DOIs | |
Publication status | Published - 14 Feb 2022 |
ASJC Scopus subject areas
- General Physics and Astronomy
- Physical and Theoretical Chemistry
Fingerprint
Dive into the research topics of 'Structural model for amorphous aluminosilicates'. Together they form a unique fingerprint.Datasets
-
Data sets for "Structural model for amorphous aluminosilicates"
Salmon, P. (Creator), Zeidler, A. (Creator) & Youngman, R. E. (Work Package Leader), University of Bath, 8 Feb 2022
DOI: 10.15125/BATH-01093
Dataset