Electrical conductivity measurements of periclase under high pressure and high temperature

The electrical conductivity of sintered polycrystalline periclase has been measured at 20 GPa and temperatures up to 1700 K with a KAWAI-type multi-anvil apparatus. Arrhenius plot of the electrical conductivity shows two linear regions, implying a change of charge transport mechanism with temperature in this experiment. At temperatures below 700 K small polaron conduction dominates, with an activation energy of 0.2 eV. At higher temperatures, the activation energy is determined to be 1.18 eV, which is much higher than 0.2 eV at low temperature. Our observations suggest the high-temperature conduction is attributed to a large polaron process with magnesium vacancy trapping hole on oxygen.