In situ x-ray observation of shock compressed cristobalite and coesite
Seifertite (a high-pressure polymorph in SiO2) is stable above ~100GPa in the phase diagram. However, it can be observed in ~30GPa-shocked meteorites. This "seifertite puzzle" is still unresolved. Here, I will report the latest experimental results for SiO2 obtained using ultra-fast X-ray diffraction techniques with XFEL.