Temperature variation at constant pressures of the electrical conductivity of periclase and olivine

The electrical conductivity of periclase and olivine (10.4 and 17.5% fayalite) was measured under uniaxial pressures to 42 kb at temperatures to 1200°K. The activation energy of periclase is about 1 ev and does not change with pressure to 42 kb. Comparison of results from conductivity, thermoelectric-power, transport-number, ion-diffusion, and absorption studies demonstrates the difficulties in deducing the type of charge carriers in periclase. For olivine an increase in fayalite content results in an increase in conductivity, a decrease in activation energy, and a greater pressure dependence for the activation energy; the activation energy decreases with increasing pressure.