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Despite the ubiquity of ferrihydrite in natural sediments and its importance as an industrial sorbent, the nanocrystallinity of this iron oxyhydroxide has hampered accurate structure determination by traditional methods that rely on long-range order. We uncovered the atomic arrangement by real-space modeling of the pair distribution function (PDF) derived(More)
We report development of micro-focusing optics for high-energy x-rays by combining a sagittally bent Laue crystal monchromator with Kirkpatrick-Baez (K-B) X-ray focusing mirrors. The optical system is able to provide a clean, high-flux X-ray beam suitable for pair distribution function (PDF) measurements at high pressure using a diamond anvil cell (DAC). A(More)
Keywords: X-discontinuity Water MgSiO3 Enstatite Clinoenstatite a b s t r a c t The mantle X-discontinuity, usually assigned to positive seismic velocity reflectors in the 260–330 km depth range, has proved difficult to explain in terms of a single mineralogical phase transformation in part because of its depth variability. The coesite to stishovite(More)
  • Lars Ehm, Sytle M Antao, Jiuhua Chen, Darren R Locke, F Marc Michel, C David +7 others
  • 2007
The method of high-energy total elastic X-ray scattering to determine the atomic structure of nanocrystalline, highly disordered and amorphous materials is presented. The current state of the technique, its potential, and limitations are discussed with two successful studies on the pressure induced phase transition in mackinawite (FeS) and the high-pressure(More)
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