Structure and related properties of amorphous magnesium aluminosilicates

What is it about?

Amorphous aluminosilicates are network-forming materials that are omnipresent in our lives, whether it be the glass touch screen on a smart phone or the magma erupting from a volcano. Here, magnesium is a ubiquitous ingredient, but little is known about the roles it can play in changing the glass structure. In this paper, we uncover two distinct coordination environments, which are related to the fragmentation of the glass network by the creation of non-bridging oxygen atoms. This fragmentation is related to the glass hardness, a key property of an amorphous material that reflects its response to sharp-contact loading by indentation or scratching.

Featured Image

Photo by Jilbert Ebrahimi on Unsplash

Photo by Jilbert Ebrahimi on Unsplash

Why is it important?

Magnesium can serve the purpose of either modifying a network by the removal of Si-O-Si bridges or compensating the charge on the aluminium ions. This duality is, however, disguised by magnesium’s ability to adopt configurations in which it is four-, five or six-fold coordinated. It is also notoriously difficult to probe because magnesium is largely spectroscopically silent. We therefore used diffraction and modelling to investigate the structure of magnesium aluminosilicates over a broad range of glass compositions, thus enabling the identification of magnesium in each of its extreme roles. The results provide a benchmark for quantifying the duality of other cations in amorphous aluminosilicates.

Perspectives