Structural modifications of GeO2 glass under high pressure and high temperature

Abstract

Vitreous GeO2 has been compressed at high temperature to investigate the effect of thermal activation on the structural reorganization during compression. The measurements were performed in-situ using micro Raman spectroscopy under pressure up to 6 GPa and temperature up to 400 °C. The evolution of the Raman shift of the main band (400–500 cm−1) with temperature during compression evidences a pressure window around 3 GPa within which temperature has a remarkable influence on the structure, in particular, the intermediate range order. We find that this change is well correlated with previous ex-situ density measurements from high pressure-high temperature densifications. Moreover, coordination changes from tetrahedrally (GeO4) to octahedrally (GeO6) coordinated GeO2 are accelerated with the heating during the compression.