Electrical Resistance of Copper at High Pressures and Temperatures: Equilibrium Model and Generation of Defects of the Crystal Structure under Shock Compression

Abstract

A simple phenomenological model of electrical resistance of metals at high pressures and temperatures is considered on the basis of the Bloch-Griineisen equation of electrical resistance and Mie-Gruneisen equation of state. Two free parameters of the model for copper are found through comparisons of model predictions with experimental data on isothermal compression and isobaric heating. The dependence of the specific electrical resistance of copper on the shock pressure in the range up to 20 GPa is determined on the basis of experiments including measurements of electrical conductivity of foil samples. Comparisons of the experimental shock wave results with the formulated model reveal the difference in the specific electrical resistance values. It is proposed to attribute the observed difference between the model and experimental results to the nonequilibrium nature of the physical state under shock compression, leading to generation of defects of the crystal structure of the metal. The electrical resistance component caused by the crystal structure defects is identified, and its dependence on the shock pressure is determined. The concentration of point defects in shock-compressed copper is estimated. The contribution of defects to electrical resistance of the shock-compressed metal is found to increase with increasing pressure. This effect should be taken into account in determining the equilibrium specific electrical conductivity and the derivatives of the physical variables (e.g., thermal conductivity).