Vitreous GeO2 response to shock loading

Shock wave profiles in vitreous GeO2 (6.56 Mg/m(3)) under planar loading were measured using stress gauges to 14 GPa. New and previous data yield Hugoniot: D = 0.974 (km/s) + 1.711 u for shocks of 6 to 40 GPa. We show that the phase change from 4- to 6-fold coordination of Ge+4 with O-2 in vitreous GeO2 occurs from 4 to 15 GPa. Hugoniots of vitreous GeO2 and SiO2 are found to approximately coincide if the pressure in SiO2 is scaled by the ratio of SiO2 to GeO2 initial density.