高温高压下蛇纹岩电导率的初步研究

 在压力为2.0和4.0 GPa、温度为373～933 K的条件下，利用交流阻抗谱仪，在0.1～10⁶ Hz的频率范围内测量了蛇纹岩的电导率。实验结果表明：蛇纹岩的复阻抗对频率有明显的依赖性，电导率受温度的影响较大，压力对电导率的影响相对较弱；当温度为690～761 K时，蛇纹岩发生脱水，致使电导率发生突变；脱水前，蛇纹岩的活化能约为0.6 eV，脱水后则高达2 eV。根据测得的电导率和活化能，分析了蛇纹岩脱水前、后的微观导电机制。分析认为，脱水前蛇纹岩的微观导电机制可能与内部二价铁和三价铁之间的电子移动有关，脱水后则可能是离子导电。

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.