Oxygen Speciation in Multicomponent Silicate Glasses Using Through Bond Double Resonance NMR Spectroscopy

The description of the structure of aluminosilicate glasses is more often centered on its cationic constituents, and oxygen ions determine their connectivity, directly impacting the physical properties of those disordered materials. A very powerful approach to ascertain this short- to medium-range order is to use ¹⁷O NMR, but up to now the speciation of the chemical bonds was only ambiguously achieved for multicomponent glasses. Here, we propose to directly probe the very scarcely explored through-bond correlations using ¹⁷O{²⁷Al} and ¹⁷O{²³Na} solid-state nuclear magnetic resonance (NMR) double-resonance experiments. Our approach allows quantifying the strongly overlapping components of the ¹⁷O NMR spectra of a quaternary aluminosilicate glass. We observe a cooperative location of alkali and aluminum ions in the neighborhood of bridging oxygens, which is consistent with the modified random network model where the glass structure is composed of two regions: network structure and breakage region (i.e., channel).