It has been suggested that water ice under high pressure, such as inside planets, would be superionic, with liquid-like hydrogen ions moving inside a solid lattice of oxygen. Now, Marius Millot of Lawrence Livermore National Laboratory and colleagues report laser-driven shock-compression of ice VII and find melting near 5000 K at 190 GPa. A variety of measurements, including optical reflectivity and absorption measurements, show a low electronic conductivity, which, together with previous measurements, provides evidence for superionic ice under planetary-interior conditions, verifying a prediction dating back 30 years.

Further reading

M Millot et al. 2018 Nat. Phys. 14 297.