X-ray diffraction measurements of laser-shocked forsterite above 200 GPa

Forsterite (Mg2SiO4) has been known to show several phase transitions at Earth’s mantle and can be one of important mantle minerals in super Earths’ mantles. The system MgO-SiO2 is the basic system in silicate mantle. The end member of MgO and SiO2 have been extensively studied, and the intermediate minerals of enstatite (MgSiO3) and forsterite at pressures of Earth’s mantle have been experimentally studied. However, there are limited theoretical and experimental studies at pressures relevant to super Earths’ mantles. For experiments, only dynamic pressure can reach such pressures. Recent technical developments of laser shock and laser-driven x-ray diffraction (XRD) measurements help us to explore phase changes of forsterite under shock-compressed at pressures over 200 GPa. We tried to carry out the XRD measurements of forsterite compressed by laser using laser-driven x-ray at SG IIIp laser facility. The obtained d-values were compared with forsterite III, B1 MgO, B2 MgO and possible other phases. We will present these d-value changes as a function of shock pressure and discuss dynamic phase transitions of forsterite under extreme conditions.