Multiscale Experimental Evidence of a Transitory State in the HDA-LDA Transition in Alumino-sodo-silicate Glasses

TL;DR

This study provides experimental evidence of a transitory state during the HDA-LDA transition in alumino-sodo-silicate glasses, supporting the existence of glass polyamorphism linked to a liquid-liquid transition.

Contribution

It introduces multiscale x-ray scattering experiments revealing a transient state, advancing understanding of polyamorphism in silicate glasses.

Findings

Identification of a transient scattering maximum indicating a transitory state.

Observation of a nucleation-like peak in small angle scattering.

Evidence supporting a thermodynamic liquid-liquid transition underlying polyamorphism.

Abstract

The structural evolution with temperature of pure silica (SiO2), sodium-silicate (5Na2O-95SiO2, 10Na2O-90SiO2 and 25Na2O-75SiO2) and albite (15Na2O-15Al2O3-75SiO2) glasses previously densified from hot compression is monitored with a combination of small and wide angle x-ray scattering. Transient scattering maxima in the length scales associated with both techniques indicate the presence of a transitory state, suggesting the classification of the initial and final states as distinct glass states in the context of polyamorphism. In all glasses, a transient intensity peak in the small angle scattering is observed, consistent with the nucleation of a new amorphous state. Based on a comparison with the phenomenology observed in supercooled and glassy water, we propose that this structural evolution provide a strong evidence of the glass polyamorphism as the consequence of the existence of an underlying but thermodynamically defined liquid-liquid transition, independent on the polymerization degree of the system.