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Polymorphism, superheating, and amorphization of silica upon shock wave
 

Summary: Polymorphism, superheating, and
amorphization of silica upon shock wave
loading and release
Sheng-Nian Luo1
and Thomas J. Ahrens
Lindhurst Laboratory of Experimental Geophysics, Seismological Laboratory, California Institute of Technology, Pasadena,
California, USA
Paul D. Asimow
Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA
Received 21 November 2002; revised 12 May 2003; accepted 23 May 2003; published 10 September 2003.
[1] We present a detailed and quantitative examination of the thermodynamics and phase
change mechanisms (including amorphization) that occur upon shock wave loading and
unloading of silica. We apply Debye-Grušneisen theory to calculate both the Hugoniot of
quartz and isentropic release paths. Quartz converts to stishovite (or a stishovite-like
phase) between 15 and 46 GPa, and persistence of the solid phase above its liquidus (i.e.,
superheating) is confirmed between 77 and 110 GPa. Calculations compare favorably to
measurements of shock and post-shock temperatures. For silica, the method of measuring
post-shock temperature is insensitive to predicting whether phase transitions actually
occur during release. Measurements of release states in pressure-particle velocity space are
compared to computed frozen-phase release paths. This comparison suggests

  

Source: Asimow, Paul D. - Division of Geological and Planetary Sciences, California Institute of Technology,

 

Collections: Geosciences