Elucidating the role of aluminium oxide on the atomic structure of magnesium and calcium aluminosilicate glasses through Neutron and X-ray diffraction experiments

Indentation-induced damage in oxide glasses results from complex interplay between plasticity and brittle fracture. Recent studies demonstrate that, aluminum oxide exhibits counterintuitive behavior: simultaneously promoting shear band formation while increasing indentation damage resistance. In aluminosilicate systems, aluminum coordination with oxygen is composition-dependent. Alkali-aluminosilicates show tetrahedral Al when R = [Al O ]/[Na O+Al O ] < 1, with higher coordinations at R > 1. Alkaline-earth systems differ significantly, with magnesium glasses forming substantial AlO species at R = 1 and exhibiting superior damage tolerance compared to Ca, Sr, or Ba analogues. Current semi-empirical potentials inadequately reproduce these structural trends, limiting mechanical property predictions. This research elucidates aluminum's role in glass plasticity through neutron/X-ray diffraction experiments. Building on successful measurements of aluminosilicate and aluminoborosilicate glasses with varying alkaline-earth ions will support validation through atomistic simulations and NMR spectroscopy. Preliminary SANDALS neutron diffraction results show satisfactory simulation agreement but reveal refinement opportunities. Outcomes will advance understanding of plasticity mechanisms in aluminum-containing glasses and enable accurate computational predictions of mechanical behavior.