Influence of pressure and temperature on the electrical conductivity of dolomite

The electrical conductivity of dolomite, (Mg, Ca)CO3, was investigated under conditions of 650-1000 K and 3-6 GPa with a multi-anvil press and an impedance spectroscopy analyzer with a frequency range of 0.05-10(6) Hz. As pressure increased, an increase in the electrical conductivity and a decrease in the calculated activation enthalpy were observed. The negative activation volume observed in this study suggests that the hopping of polarons is the dominant mechanism for the electrical conductivity across the pressure and temperature range investigated. This mechanism is the same as that of magnesite, MgCO3, which has the similar structure of dolomite. In contrast, the mechanism of the ionic conduction was reported in aragonite, CaCO3. These results indicate that the mechanism for the electrical conductivity of carbonate minerals varies because of a crystallographic difference between the calcite- and the aragonite-type structure.