A Preliminary Study on Conductivity of Serpentinite at High Pressure and High Temperature

Using an AC impedance spectroscopy within the frequency ranges of 0.1～106 Hz, the electrical conductivities of serpentinite were determined from 373 K to 933 K and at 2.0 GPa and 4.0 GPa respectively. The conduction mechanisms of serpentinite before and after dehydration were also analyzed. The experimental results show that complex impedance depends on the variation of frequency, and the electrical conductivity of serpentinite is highly dependant on temperature but only slightly on pressure. The activation enthalpies derived are ~0.6 eV before dehydration and up to 2.0 eV after dehydration. The dehydration of serpentinite, occurred at 690～761 K, causes the jump of the electrical conductivity and alters conduction mechanism. The analysis results indicate that the charge carriers in serpentinite are probably electrons transferred between Fe2+ and Fe3+ before dehydration and are dominated by ions after dehydration.