| Under the thermodynamic conditions of 1.0-4.0 GPa, 1073-1473 K, and different oxygen fugacities controlled by solid oxygen buffers NNO (Ni+NiO), IM (Fe+Fe3O4), IW (Fe+FeO) and MMO (Mo+MoO2), YJ-3000t cubic-anvil high-pressure apparatus and Solartron-1260 Impedance/Gain-Phase analyzer were employed to conduct an in-situ measurement of the electrical conductivities of single crystal diopside, pyroxenite, single crystal olivine and lherzolite. The experimental results show that:1 , With the frequency of the input voltage signal ranging from 10-1 to 107 Hz, either as viewed from the IS Nyquist plot or from the IS Bode plot, the electrical conductivities of all the samples are of strong dependence on frequency. 2, The electrical conductivity (σ) increases with increasing temperature (T). Lg σversus 1/T is consistent with Arrhenius relationship.3, Under the oxygen fugacities controlled by IM and NNO, the electricalconductivities tend to decrease with rising pressure. Physical parameters, such asactivation energy, activation enthalpy, and activation volume, which describe theconductive behaviour of the main charge carriers, have been obtained.4, Under given pressure and temperature, the electrical conductivity tends to increasewith increased oxygen fugacities in the sample cell.5 , Under given pressure and temperature, the electrical conductivity and the pre-exponential factors in the Arrhenius relationship decrease according to the order of crystalloplanar directions of (001), (100) and (010) for diopside, while the activation enthalpy tends to increase in the same order. Therefore, there exists crystalloplanar anisotropy for the electrical properties of diopside at high temperature and high pressure.6, The mechanism of electrical conduction of small polaron in iron-bearing samples of this study could provide a reasonable explanation for the variations of the electrical conductivity the pre-exponential factor, and the activation enthalpy in...
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