Electrical resistivity of silver foils under uniaxial shock−wave compression

Abstract

The electrical resistivity of silver foils 15−25 μm thick was measured during shock−wave compression between sapphire anvils in the pressure range 25−120 kbar. Comparison of isothermal resistivity vs compression from shock measurement to a simple semiempirical calculation of resistivity under hydrostatic compression shows shock data to be consistently higher than hydrostatic results. Shock results depend on purity and thermal history of the silver foils. Deviation between shock and hydrostatic results is attributed to resistivity of vacant lattice sites generated by high−strain−rate plastic deformation in uniaxial shock compression. Estimated vacancy concentrations at 100 kbar are (1−2) ×10⁻³ per lattice site and concentrations vary approximately as the three−halves power of total strain. The high vacancy concentrations may be evidence for dislocation speeds near shear−wave speed. Annealing and microscopy studies of foils recovered after shocking give additional support to the above conclusions.