Abstract
Experimental investigations of silica under high pressure and
temperature offer crucial insights into modeling of Earth and
super-Earth’s interiors. Despite extensive studies on Hugoniots of
silica polymorphs like fused-silica (2.20 g/cm3), quartz (2.65 g/cm3)
and stishovite (4.29 g/cm3) up to tera-pascal, the initial density
dependent Hugoniots leave an unexplored region of melting and liquid of
silica at high pressures. This emphasizes the urgence to supplementing
the phase diagram to constrain silica properties under extreme
conditions. Here, the Hugoniot and shock temperature of coesite (2.92
g/cm3), were studied by laser shock compressions up to 950 GPa. Our
findings confirm the shock-induced superheating in coesite, reveals a
higher Grüneisen parameter and lower electrical conductivity compared to
those of fused-silica and quartz along an isothermal line (<
2×104 K). These results suggest unique properties of shocked coesite,
and implys a warmer and longer survival silica magma ocean in earlier
rocky-planetary interior.