Crystalchemistry and oxidation state of iron in oxides and silicates at conditions of Earth and super-Earth interiors

Iron is the only geo- and cosmo-chemically abundant element with variable oxidation state that could affect interiors of Earth and super-Earth planets. Recent work of our group and collegues reveal complex crystal chemistry of Fe-O system at pressures up to ~100 GPa. Even at this pressure range information about oxidation state of iron in different geochemically relevant compounds is inconsistent due to severe experimental problems. Aim of this project is to perform parallel single crystal X-ray diffraction and synchrotron Mossbauer study of three model compounds (ferropericalse (Mg0.8Fe0.2)O, ringwoodite (Mg0.5Fe0.5)2SiO4, and bridgmanite (Mg0.8Fe0.2)(Si0.95Al0.05)O3) at 150, 250, and 300 GPa heated up to ~4000 K. As outcome of this project we will establish if this materials are chemically stable, or what are products of their decomposition, what is oxidation and electronic state of iron in corresponding compounds and if it affected by relevant pressures and temperatures.