The goal of this proposal is to study the fundamental chemical properties of deep mantle and core materials at the relevant pressures and temperatures in order to obtain experimental information on the chemical composition, formation, and evolution of the planet's interior. The project takes advantage of numerous new developments in high-pressure techniques, including synchrotron x-ray diffraction, x-ray spectroscopy, infrared, and optical techniques, as well as laser heating diamond-cell methods. Fundamental bonding properties of key materials will be investigated with these methods, focusing particularly on the behavior of transition-metal oxides at deep mantle and core pressures. This will be extended to high pressure-temperature studies of phase transitions, phase relations, and element partitioning of deep mantle silicates and oxides. The behavior of volatile components at very high pressure-temperature conditions will be examined. New techniques will be used to study phase relations, including melting of natural and model multicomponent materials. Finally, phase transformations, structures, and phase diagrams, of iron and iron alloys will be studied.
