| In this dissertation, a novel method using four electrodes perpendicular to shock front was proposed to measure the electrical conductivity of metals under shock compression up to megabar pressures. The electrical conductivities of iron under shock compression in the final equilibrium pressures ranging from 101 to 208GPa were obtained by using the two-stage light gas gun techniques. The measurements for the electrical conductivity of iron were first expanded experimentally to pressures beyond 200 GPa, entering into the solid-liquid mixed phase region of iron. The Bloch-Griineisen equation describing the high-pressure electrical conductivity of metals was found still hold true up to 200 GPa for e-iron (hep structure), even in its solid-liquid mixed phase region. By using the Bloch-Griineisen equation, the distribution of electrical conductivity in the earth's core was calculated, based on which a new model that there exists a discontinuity in the conductivity at the Inner Core Boundary (ICB) was proposed. The main results and conclusions of this dissertation are as follows:(1) A new method by using the four electrodes perpendicular to shock front and the drilled sapphire disk with a rectangular cell as the insulated layer was proposed, which was used in measuring the electrical conductivity of metals under strong shock compression, (a) A new configuration by enclosure the sample in the rectangular cell of the sapphire disk was used to replace the "sandwich" configuration (insulated layer / sample / insulated block) previously used by the other investigators. The shunting effect in the sandwich configuration due to the electric conducting of the epoxy resin surrounding the sample under high pressures, which will result in a high conductivity data, was eliminated. The pressure limit in the measurements was improved, (b) Several technical problems including the machining of the cell in the sapphire disk and the assembling of the experimental set-up were solved, and the high-power pulsed constant current device was developed, (c) A special experiment was designed to exam the effect of the ohm heating on the conductivity of the sample because of the large current in the experiment measurements. Results show that this effect is negligible, (d) The pressure-history of the metal sample during the shock reverberating processes between the two sapphire disks was calculated by using the one-dimensional fluid dynamics method which is very helpful in the data analyzing. The experimental records of the conductivity signalprofile were reasonably consistent with the above model calculations.(2) The electrical conductivities (from 1.45 x 104 Q-1cm"1 to 7.65x 103 Q-1cm-1) for iron at the final equilibrium shock compression states from 101 to 208GPa were obtained by using the two-stage light gas gun techniques. The measurement for the electrical conductivity of iron was expanded, for the first time, to the pressure range over 200 GPa, and entered the solid-liquid mixed phase region of iron. Experimental results indicated that there existed systematically differences between our results and those of Keeler's. By analyzing we find that Keeler's conductivity data were overestimated due to the shunting effect.(3) By analyzing the reverberation of shock wave between the front- and rear- interfaces of sample and the sapphire disks, and after taking into account of the influence of the demagnetization on the signal profile resulting from the a - s phase transition of iron, the electrical conductivity of iron was finally deduced. This provides useful techniques for the similar measurements in the future.(4) The high-pressure conductivity relation of e -iron. Our measured data strongly supports that the Bloch- Griineisen formula describing the electrical conductivity of metals under high-pressure and high-temperature holds true up to 200GPa for iron even in the solid-liquid mixed phase region (the equilibrium temperature reaches 5220K). To exam the validity of the Bloch- Griineisen formula at megabar pressures, we...
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