Structure of Oxide Glasses

Non-crystalline or glassy materials are ubiquitous in our society. From shards of naturally occurring obsidian glass used as simple tools and art objects in early human history to fiber optics used in high speed data communication or metallic glasses used for their superior strength and hardness, glasses today continue to play a diverse and vital role in many aspects of our daily lives. Even today, there is significant room for improving our understanding of their atomic level structure and subsequently improve our ability to tailor their properties to our needs.

Surprisingly, even the structure of vitreous silica, probably one of the most extensively studied glasses, is still not well understood beyond the basic [SiO₄]; tetrahedral structural unit. Despite the use of titles such as random network model, modified random network, etc., we generally know very little about what random truly means. It is often said that disorder is what makes a glass a glass, but what does this really mean?

Over the last ten years, our research group has been developing two-dimensional solid-state nuclear magnetic resonance (NMR) methods and analyses for answering just this question. In our recent work , we've applied these and other advances to obtain, for the first time, quantitative measurements of the two-dimensional distribution of Si-O distances and Si-O-Si angles in the glass. This new advance opens the door for measuring previously inaccessible structural details in a variety of silicate based materials, and obtaining new insights into structure/property relationships.