Shock experiments on quartz targets pre-cooled to 77 K

The influence of temperature on the development of shock deformation effects in quartz single-crystal targets has been investigated in this parameter study. Quartz targets were pre-cooled to 77 K and shocked parallel to their image orientation in shock reverberation experiments of microsecond shock duration. Shock deformation effects in quartz were characterized by optical and spectroscopic methods. The degree of shock metamorphism in pre-cooled quartz targets has then been compared with literature data from μs-shock reverberation experiments on quartz targets shocked parallel to the same crystallographic orientation but at initial temperatures of 293–903 K. The degree of shock metamorphic overprint in quartz was found to be rather insensitive to temperature variation in the low-temperature region (<548 K), but sensitive to temperature variation in the high-temperature region up to 903 K. This temperature dependence allows to distinguish between different mechanisms that had been proposed to explain the formation of shock deformation effects in quartz. The identified temperature dependence points toward a simple mechanism in which the crystal lattice collapses due to overpressure at low to moderate temperatures. Very high temperatures result in weakening of the silicon-oxygen bonds that support the crystal lattice, leading to a decrease of the onset pressure for structural collapse.