Deciphering the structural evolution in irreversibly
densified
oxide glasses is crucial for fabricating functional glasses with tunable
properties and elucidating the nature of pressure-induced anomalous
plastic deformation in glasses. High-resolution NMR spectroscopy quantifies
atomic-level structural information on densified glasses; however,
its application is limited to the low-pressure range due to technical
challenges. Here, we report the first high-resolution NMR spectra
of oxide glass compressed by diamond anvil cells at room temperature,
extending the pressure record of such studies from 24 to 65 GPa. The
results constrain the densification path through coordination transformation
of Al cations. Based on a statistical thermodynamic model, the stepwise
changes in the Al fractions of oxide glasses and the effects of network
polymerization on the densification paths are quantified. These results
extend the knowledge on densification of the previously unattainable
pressure conditions and contribute to understanding the origin of
mechanical strengthening of the glasses.
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