Polarization currents in illite at various temperatures

Polarization effects, which take place when an external electrical field is applied, play an important role in ceramics. The polarization currents were measured in illite samples in the temperature range 450 °C-1200 °C, for 150-300 min. Since the polarization current does not reach a zero value even after a long time, it was deduced that both the ions and electrons are the charge carriers. However, the ionic component is dominant in polarization currents in illite. Power functions, which describe the time dependence of the currents, suggest several polarization mechanisms. They are ascribed to local hopping or migration of K+, H+, and OH- ions which are dominant charge carriers in various temperature ranges. The polarization is a long-lasting process also at high temperatures.