The principal focus of this ongoing research involves structural and crystal chemical characterization of earth materials believed to occur in the Earth's upper mantle and transition zone. Information on Fe/Mg ordering in mantle silicates and its effect on mantle mineral equations of state and on the extent of polyhedral distortion in silicates above 10 GPa will be obtained at high temperatures and pressures using diamond anvil pressure cells. This research has application in understanding earth processes as the dynamic history and present state of the Earth's deep interior result from properties of its constituent materials. The research will conducted at the Geophysical Laboratory (Carnegie Institute of Washington), which supports the only American facility engaged primarily in high-pressure, single-crystal, x-ray diffraction studies of minerals and their analogues. The crystallographic laboratory will also continue to serve the American materials research community.
