Structural Analysis of Amorphous GeO$_2$ under High Pressure Using Reverse Monte Carlo Simulations

Abstract

The structural properties of amorphous GeO$_2$, a prototypical network glass, were investigated under ambient to high pressure using reverse Monte Carlo simulations based on reported structure factors from in situ high-pressure neutron diffraction experiments with isotopic substitution. The results indicate the retention of the topological structure containing predominantly tetrahedral GeO$_4$ units up to ca.~\SI{4}{\giga\pascal} ($\rho/\rho_0 = 1.15$), which is explained by the reduction of cavity volumes. With further application of pressure, an increase in the number of GeO$_5$ units is first observed, which is then followed more gradually by an increase in the number of GeO$_6$ units.