Pressure-Driven Changes in the Coordination Environment of Aluminate and Aluminosilicate Glass up to Lower-Mantle Pressures

Shujia Li¹*, Jin Jun Kweon¹, Seoyoung Lee¹, A Chim Lee¹, Sung Keun Lee^1,2

¹Laboratory of Physics and Chemistry of Earth Materials, School of Earth and Environmental Sciences, Seoul National University, Seoul 08826 South Korea

²College of Natural Sciences, Institute of Applied Physics, Seoul National University, Seoul 08826 South Korea

Abstract

Oxide glasses undergo irreversible deformation upon extreme compression, permanently improving hardness and fracture toughness after pressure release. 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. The experimental studies on electronic bonding and coordination of non-network-former cations are limited to ambient pressure.

Here, we report the first high-resolution solid-state NMR spectra of oxide glass compressed by diamond anvil cells, extending the pressure record of such studies from 24 to 65 GPa, corresponding to the Earth’s lower mantle region.^1-2 The results constrain the densification path of Al cations in the room-temperature compressions of aluminate and aluminosilicate glass through Al coordination transformation. Based on a statistical thermodynamic model, the stepwise changes in the Al fractions of oxide glasses and the effects of compositions and network polymerization on the Al densification paths are quantified. These results extend the knowledge on short-range order of aluminate and aluminosilicate glass to previously unattainable pressure conditions and contribute to understanding the atomic origin of mechanical strengthening of the glasses and rebuilding relative geological processes in planetary interiors.

[1] Li, S. J., Kweon, J. J., Lee, A. C and Lee, S. K., Journal of Physical Chemistry Letter, 14 2078-2086 (2023).

[2] Lee, S. K., Lee, A. C., Kweon, J. J., Journal of Physical Chemistry Letter, 12 1330-1338 (2021).