A. Herring, OSU, uses tomography at 13 BMD to quantify pore scale trapping and to analyze how mechanisms affect the efficiency of capillary trapping of CO2 in saline aquifers.

Tomography at 13 BMD

Work at GSECARS discovers water deep below Earth’s surface

A team utilizing GSECARS bealines has identified a weird form of crystallized water known as ice VII, suggesting that this material may circulate more freely at some depths within Earth than previously thought. Pockets of water may lay deep below Earth’s surface

Work at GSECARS discovers water deep below Earth’s surface

X-ray diffraction patterns from a diamond anvil cell (DAC).

X-ray diffraction is the most powerful technique for crystal structure determination. From left to right, patterns from a single crystal, polychrystalline, nano-cyrstalline and amorphous crystals.

X-ray diffraction patterns from a diamond anvil cell.

High pressure x-ray tomographic microscopy module

The HPXTM module helps researchers study the texture change of their sample under extreme pressure and temperature conditions by collecting in-situ HP/HT 3D x-ray tomographic images.

High Pressure X-ray Tomographic Microscopy Module sitting outside of the 250 ton press in 13 BMD.

GSECARS hosts experiments at 13 IDE for high school students in the Exemplary Student Research Program (ESRP) representing local area high schools. GSECARS Outreach

GSECARS Outreach

GSECARS is a national user facility
for frontier research in the earth sciences using synchrotron radiation at the
Advanced Photon Source, Argonne National Laboratory.

GSECARS provides earth scientists with access to the high-brilliance hard x-rays from this third-generation synchrotron light source. All principal synchrotron-based analytical techniques in demand by earth scientists are being brought to bear on earth science problems:

  • High-pressure/high-temperature crystallography and spectroscopy using the diamond anvil cell
  • High-pressure/high-temperature crystallography and imaging using the large-volume press
  • Powder, single crystal and interface diffraction
  • Inelastic x-ray scattering
  • X-ray absorption fine structure spectroscopy
  • X-ray fluorescence microprobe analysis
  • Microtomograph

Science Highlights
 

► Ultrasonic wave propagation, a new technique developed for determining the liquidus and eutectic temperatures of Fe-light element alloys.

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Multianvil cell assembly used for ultrasonic measurements at high pressures. BR: buffer rod; BP: backing plate.

Abstract : We have developed a new technique for determining the liquidus and eutectic (or solidus) temperatures of Fe‐light element alloys at high pressures in a multianvil apparatus, by studying ultrasonic wave propagation through the sample. While the onset of melting is manifested by the loss of both compressional (P‐) and shear (S‐) wave signals due to the scattering of sound waves by partial melts, the completion of melting is confirmed by the reappearance of the P wave signal when the scattering due to residual crystals disappears. By applying this technique to the Fe‐P binary system with three different phosphorus contents, we were able to constrain the Fe‐rich portion of the phase diagram up to 7 GPa and 1,733 K.

Our results show that the liquidus temperatures of the Fe‐P alloys exhibit different pressure dependencies according to their phosphorus contents. Consequently, depending on their phosphorus contents, molten metallic cores of planetary bodies would start crystallization either from the bottom, extending upward resulting in a growing inner core, or start from the top and extend downward resulting in a “snowing” scenario.

Chantel, J., Jing, Z., Xu, M., Yu, T., Wang, Y. (2018). Pressure dependence of the liquidus and solidus temperatures in the Fe-P binary system determined by in situ ultrasonics: Implications to the solidification of Fe-P liquids in planetary cores. Journal of Geophysical Research: Planets, 123, 1113–1124. https://doi.org/10.1029/2017JE005376


► Work done at 13 BMC has provided evidence for using Fe-(oxyhydr) oxides as potential treatment substrates to remediate Pb contaminated soils.

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The structure above has been oriented to highlight the geometric relationship between Pb complex and the associated anchored Fe octahedra.

Abstract

A structural study of the surface complexation of Pb(II) on the (1102) surface of hematite was undertaken using crystal truncation rod (CTR) X-ray diffraction measurements under in situ   conditions. The sorbed Pb was found to form inner sphere (IS) complexes at two types of edge-sharing sites on the half layer termination of the hematite (1102) surface. The best fit model contains Pb in distorted trigonal pyramids with an average Pb_O bond length of 2.27(4) Å and two characteristic Pb-Fe distances of 3.19(1) Å and 3.59(1) Å. In addition, a site coverage model was developed to simulate coverage as a function of sorbate-sorbate distance. The simulation results suggest a plausible Pb-Pb distance of 5.42 Å, which is slightly larger than the diameter of Pb’s first hydration shell. This relates the best fit surface coverage of 0.59(4) Pb per unit cell at monolayer saturation to steric constraints as well as electrostatic repulsion imposed by the hydrated Pb complex. Based on the structural results we propose a stoichiometry of the surface complexation reaction of Pb(II) on the hematite (102) surface and use bond valence analysis to assign the protonation schemes of surface oxygens. Surface reaction stoichiometry suggests that the proton release in the course of surface complexation occurs from the Pb-bound surface O atoms at pH 5.5.

C. Qiu, F. Majs, P.J. Eng, J.E. Stubbs, T.A. Douglas, M. Schmidt, T. Trainor, "In situ structural study of the surface complexation of lead(II) on the chemically mechanically polished hematite (1102) surface", J. Colloid and Interface Science,(2018)  Vol. 524, pp. 65-75, DOI : 10.1016/j.jcis.2018.04.005


► Inclusions of ice-VII found in diamonds from the mantle transition zone. 

National Science Foundation "News From the Field " Highlight
Argonne National Laboratory Science Highlight
UChicago News

 

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An international team of scientists have discovered the presence of a high pressure phase of water preserved as inclusions in diamonds which formed in the Earth's mantle at depths exceeding 410 km. Using a combination of high resolution synchrotron techniques including X-ray diffraction and fluorescence at the Advanced Photon Source (GSECARS sector 13) and infrared spectroscopy at the Advanced Light Source and at CalTech, the discovery of ice-VII in these diamonds provides potential evidence for the presence of aqueous fluids in the Earth's mantle. Ice-VII is a high pressure polymorph of water-ice and has been recently approved as a mineral by the International Mineralogical Association based on X-ray diffraction data collected at GSECARS. Earth scientists have long debated how much water may be preserved in the regions of the mantle from where these diamonds are believed to have formed, the transition zone and at lower mantle boundary. These inclusions are believed to be residues of aqueous fluids present in the mantle when the diamonds formed, at pressures as high as 24 GPa, with the ice-VII phase crystallizing within the diamond upon ascent. The included ice-VII preserves the high pressures at which the fluids were included and represent the highest pressure of a molecular solid directly observed in nature. This finding has important implications for our understanding of how water and heat-generating elements such as K, U, Th, which have increased solubility in aqueous fluids, may be recycled in the deep Earth, for example though subduction zone processes.

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Above (left to right) : Vitali Prakapenka, Tony Lanzirotti, Matt Newville, Eran Greenberg, Dongzhou Zhang.

O. Tschauner, S. Huang, E. Greenberg, V.B. Prakapenka, C. Ma, G.R. Rossman, A.H. Shen, D. Zhang, M. Newville, A. Lanzirotti, K. Tait, “Ice-VII inclusions in diamonds: Evidence for aqueous fluid in Earth’s deep mantle,” Science 359, 1136 (9 March 2018). DOI: 10.1126/science.aao3030