In situ electrical conductivity measurements of H2O under static pressure up to 28 GPa

• We conduct in situ electrical conductivity measurements on water in a diamond anvil cell (DAC) under high pressure up to 28 GPa and study the electrical transport properties of water and ices.
• In liquid state, the increasing rate of electrical conductivity with pressure is slower than that obtained in shock-waves measurements.
• In solid phase, the relationship between electrical conductivity and pressure is discontinuous, which is corresponding to phase transformation from ice VIII to ice VII.
• The difference in electrical conductivity of VI, VII, and VIII may associate with different orientational ordering in these ices.
• The electrical conduction in these ices is dominated by already existing ions and Bjerrum defects, which play an important role in electrical transport properties of ices.

The in situ electrical conductivity measurements on water in both solid state and liquid state were performed under pressure up to 28 GPa and temperature from 77 K to 300 K using a microcircuit fabricated on a diamond anvil cell (DAC). Water chemically ionization mainly contributes to electrical conduction in liquid state, which is in accord with the results obtained under dynamic pressure. Energy band theory of liquid water was used to understand effect of static pressure on electrical conduction of water. The electric conductivity of H2O decreased discontinuously by four orders of magnitude at 0.7–0.96 GPa, indicating water frozen at this P–T condition. Correspondingly, the conduction of H2O in solid state is determined by arrangement and bending of H-bond in ice VI and ice VII. Based on Jaccard theory, we have concluded that the charge carriers of ice are already existing ions and Bjerrum defects.