Coordination changes in crystalline and vitreous GeO2

Abstract
High pressure x ray absorption spectroscopy (XAS) has been performed up to 29 GPa on crystalline and amorphous GeO2. The modification of the x ray absorption near edge structure (XANES) as well as the variation of the Ge-O distance, indicate that the coordination of Ge changes from 4 to 6 above 6.5 GPa. The transition is confirmed by Raman spectroscopy.