Shock-Ramp of SiO₂ Melt

SiO₂ is an endmember for all silicate materials. As such, having a robust equation of state for SiO₂ is of fundamental importance for planetary and materials sciences. We will present experimental shock-ramp data from the Z-machine at Sandia National Laboratories for two samples of SiO₂ melt at pressures >80 GPa. The starting materials are Corning SiO₂ glasses_: one sample is anhydrous containing <1ppm OH and the other is nominally hydrated with 1000ppm OH, typical of some industrially produced high-purity SiO₂ glasses. Initial results suggest that the nominally hydrated SiO₂ melt is stiffer on ramp compression than the anhydrous melt. Also, we find that the Los Alamos’ OpenSesame EOS SiO₂ models the initial shock for both melts well, but does not to reproduce the ramp path for either sample. We will combine experimental data and theoretical results from classical atomistic simulation and density-functional theory calculations to investigate the atomic origin of the observed physical properties.