Metallic liquid hydrogen and likely Al2O3 metallic glass

Dynamic compression has been used to synthesize liquid metallic hydrogen at 140GPa (1.4 million bar) and experimental data and theory predict Al2O3 might be a metallic glass at similar to 300GPa. The mechanism of metallization in both cases is probably a Mott-like transition. The strength of sapphire causes shock dissipation to be split differently in the strong solid and soft fluid. Once the 4.5-eV H-H and Al-O bonds are broken at sufficiently high pressures in liquid H-2 and in sapphire (single-crystal Al2O3), electrons are delocalized, which leads to formation of energy bands in fluid H and probably in amorphous Al2O3. The high strength of sapphire causes shock dissipation to be absorbed primarily in entropy up to similar to 400GPa, which also causes the 300-K isotherm and Hugoniot to be virtually coincident in this pressure range. Above similar to 400GPa shock dissipation must go primarily into temperature, which is observed experimentally as a rapid increase in shock pressure above similar to 400GPa. The metallization of glassy Al2O3, if verified, is expected to be general in strong oxide insulators. Implications for Super Earths are discussed.