Local structure of glassy GeO2 at Mbar pressure conditions

Understanding the structural response of network-forming glasses to pressure is of great interest for condensed matter physics, geoscience and materials science. Silica (SiO2) and germania (GeO2) are prototype network-forming glasses. Recently a large debate is emerging about atomic coordination of these glasses under extreme compression as some experimental and theoretical works have reported that the coordination in glassy phases could exceed that of their crystalline counterparts in the 40-100 GPa range. Therefore, we propose here to address this issue by investigating the local structure of glassy GeO2 by X-ray Absorption Spectroscopy up to the Mbar range (150 GPa) and compare it to that of rutile GeO2.