Laboratory studies of the electrical conductivity of silicate perovskites at high pressures and temperatures

The electrical conductivities of two silicate perovskites and a perovskite‐magnesiowüstite assemblage, all having an atomic ratio of Mg to Fe equal to 0.88/0.12, have been measured with alternating current and direct current (DC) techniques at simultaneously high pressures and temperatures. Measurements up to pressures of 80 GPa and temperatures of 3500 K using a laser‐heated diamond anvil cell demonstrate that the electrical conductivity of these materials remains below 10–3 S/m at lower mantle conditions. The activation energies for electrical conduction are between 0.1 and 0.4 eV (0.1–0.2 eV most probably) from our data, and we ascribe the conduction in these perovskites to an extrinsic electronic process. Our new measurements are in agreement with a bound that was previously obtained from DC measurements for the high PT conductivity of perovskite‐dominated assemblages. The results show that the electrical conductivity of (Mg 0.88 Fe 0.12 )SiO 3 perovskite differs significantly from that of Earth's deep mantle, as inferred from geophysical observations.