Investigating Enhanced Electrical Conductivity in Ice VII

At ambient conditions, the electrical conductivity of H2O is around 0.01 S/m, whereas in the deep interiors of Neptune and Uranus (≈5000 K and ≈300 GPa), conductivity increases by three orders of magnitude. So far, few experimental studies have considered the conductivity properties of ice at high-P-T conditions. In this work, we evaluate how the conductivity of H2O changes upon compression at 300 K, and show that at 10 GPa, ice VII exhibits a maximum in conductivity of 1.43 ± 0.47 × 10−5 S/m. We propose that time is an important variable in impedance spectroscopy measurements during the pressure-induced transitions: fluid → phase VI → phase VII, between 0.5 and 4 GPa.