A5002552964- Radioactive element chemistry and processing
- Iron oxide chemistry and applications
- Geological and Geochemical Analysis
- Geochemistry and Geologic Mapping
- High-pressure geophysics and materials
- Nuclear Materials and Properties
- Atmospheric and Environmental Gas Dynamics
- Radioactive contamination and transfer
- Geochemistry and Elemental Analysis
- Hydrocarbon exploration and reservoir analysis
- X-ray Diffraction in Crystallography
- Minerals Flotation and Separation Techniques
- Clay minerals and soil interactions
- Extraction and Separation Processes
- Glass properties and applications
- Nuclear materials and radiation effects
- Chemical Synthesis and Characterization
- X-ray Spectroscopy and Fluorescence Analysis
- Calcium Carbonate Crystallization and Inhibition
- Metal Extraction and Bioleaching
- Mine drainage and remediation techniques
- Mineralogy and Gemology Studies
- Radioactivity and Radon Measurements
- Nuclear Physics and Applications
- Pigment Synthesis and Properties
University of Chicago
2015-2025
Argonne National Laboratory
2011-2025
The University of Western Australia
2024
SLAC National Accelerator Laboratory
2012-2014
Stanford Synchrotron Radiation Lightsource
2010-2014
Stanford University
2011-2012
Johns Hopkins University
2006-2010
Indiana University Bloomington
2006
Direct air capture (DAC) may be feasible to remove carbon dioxide (CO2) from the atmosphere at gigaton scale, holding promise become a major contributor climate change mitigation. Mineral looping using magnesium oxide (MgO) is potentially an economical, efficient, and sustainable pathway gigaton-scale DAC. The hydroxylation carbonation of MgO determine efficiency process, but their rates mechanisms remain uncertain. In this work, single crystals were reacted in or CO2 varying humidities...
Redox transitions of uranium [from U(VI) to U(IV)] in low-temperature sediments govern the mobility environment and accumulation ore bodies, inform our understanding Earth’s geochemical history. The molecular-scale mechanistic pathways these determine U(IV) products formed, thus influencing isotope fractionation, reoxidation, transport sediments. Studies that improve have potential substantially advance process across a number earth sciences disciplines. Detailed information regarding redox...
The reduction of soluble hexavalent uranium to tetravalent can be catalyzed by bacteria and minerals. end-product this is often the mineral uraninite, which was long assumed only product U(VI) reduction. However, recent studies report formation other species including an adsorbed U(IV) species, operationally referred as monomeric U(IV). discovery important because likely more labile susceptible reoxidation than uraninite. Because there a need distinguish between these two we propose here wet...
In this report we describe detailed procedures for carrying out single crystal X-ray diffraction experiments with a diamond anvil cell (DAC) at the GSECARS 13-BM-C beamline Advanced Photon Source. The DAC program is part of Partnership Extreme Xtallography (PX^2) project. BX-90 type DACs conical-type anvils and backing plates are recommended these experiments. sample chamber should be loaded noble gas to maintain hydrostatic pressure environment. aligned rotation center goniometer. MARCCD...
The interaction of water with metal oxide surfaces plays a crucial role in the catalytic and geochemical behavior oxides. In vast majority studies, interfacial structure is assumed to arise from relatively static lowest energy configuration atoms, even at room temperature. Using hematite (α-Fe2O3) as model oxide, we show through direct comparison situ synchrotron X-ray scattering density functional theory-based molecular dynamics simulations that (11̅02) termination dynamically stabilized by...
Abstract Nanoscale morphology has a direct impact on the performance of materials for electrochemical energy storage. Despite this importance, little is known about evolution primary particle nor its effect chemical pathways during synthesis. In study, operando characterization combined with atomic‐scale and continuum simulations to clarify relationship between cathode particles their lithiation calcination LiNi 0.8 Mn 0.1 Co O 2 (NMC‐811). This approach reveals key role surface oxygen...
Abstract One-dimensional (1D) olivine iron phosphate (FePO 4 ) is widely proposed for electrochemical lithium (Li) extraction from dilute water sources, however, significant variations in Li selectivity were observed particles with different physical attributes. Understanding how particle features influence and sodium (Na) co-intercalation crucial system design enhancing selectivity. Here, we investigate a series of FePO various revealed the importance harnessing kinetic chemo-mechanical...
Reductive bioremediation is currently being explored as a possible strategy for uranium-contaminated aquifers such the Old Rifle site (Colorado). The stability of U(IV) phases under oxidizing conditions key to performance this procedure. An in situ method was developed study oxidative dissolution biogenic uraninite (UO₂), desirable U(VI) bioreduction product, Rifle, CO, aquifer different variable oxygen conditions. Overall uranium loss rates were 50-100 times slower than laboratory rates....
The three-dimensional structure of the barite (001)–water interface was studied using in situ specular and nonspecular X-ray reflectivity (XR). Displacements barium sulfate ions surface a crystal interfacial water were defined analyses. largest relaxations (0.13 Å lateral 0.08 vertical) observed for topmost unit cell layer, which diminished rapidly with depth. best fit identified four distinct adsorbed species, comparison molecular dynamics (MD) simulations reveals that they are associated...
Calcite is the most stable polymorph of calcium carbonate (CaCO3) under ambient conditions and ubiquitous in natural systems. It plays a major role controlling pH environmental settings. Electrostatic phenomena at calcite–water interface surface reactivity calcite general have important implications. They may strongly impact nutrient contaminant mobility soils other subsurface environments, they control oil recovery from limestone reservoirs, safety nuclear waste disposal sites. Besides...
Amorphous calcium carbonate (ACC) occurs as a precursor to geological and biogenic (CaCO3), yet its transformation pathways reaction mechanisms remain inconsistent controversial. In this study, we investigated the of ACC calcite under both solution dry conditions, in presence absence impurity ions, utilizing operando time-resolved synchrotron X-ray diffraction (TRXRD) reactive transport modeling. Results demonstrate that TRXRD techniques allow us differentiate dissolution-reprecipitation...
Despite extensive research on MgO's reactivity in the presence of CO2 under various conditions, little is known about whether impurities incorporated into solid, such as iron, enhance or impede hydroxylation and carbonation reactions. The purity MgO required for successful implementation looping a direct air capture technology affects deployment costs. With this motivation, we tested how iron impacts (100) passivation layer formation ambient conditions by using atomic force microscopy,...
New sources of rare earth elements (REEs) are needed to support a green energy transition. REEs adsorbed aluminum-rich clays in weathering deposits represent important resources, but the mechanisms responsible for their retention and ease extraction unresolved. Disordered coordination co-occurrence multiple species pose challenges investigating REE adsorption processes via established spectroscopic methods. In this study, we applied element-specific surface crystallography methods obtain new...
Abstract Upcycling of recycled LiNi 0.6 Mn 0.2 Co O 2 (NMC622) cathodes offers an economical route to produce cathode materials with increased energy density (i.e., 0.8 0.1 , NMC811) that meet the performance needs present‐day electric vehicles. In this work, solid‐state upcycling NMC622 via calcination Ni(OH) and LiOH was monitored using in situ synchrotron powder X‐ray diffraction measurements. Sequential Rietveld refinements indicate proceeds by initially converting a rocksalt NiO phase...
The U 4f line is commonly used to determine uranium oxidation states with X-ray photoelectron spectroscopy (XPS). In contrast, the XPS of shallow core-levels are rarely recorded. Nonetheless, theory has shown that 5d (and 5p) multiplet structure very sensitive state. this contribution we extracted U(iv) and U(v) peak shapes from near stoichiometric oxidized UO2 single crystal samples, respectively, where state was constrained by fitting line. empirically spectra were similar theoretically...
Two samples of uranium-contaminated soil from the Department Energy's Oak Ridge Reservation in Ridge, Tennessee were investigated using electron microprobe analysis and transmission microscopy. The objectives this research to identify characterize particles rock chips with high uranium concentrations, investigate extent penetration into parent material, solid-phase hosts for samples. Three distinct have been identified: (1) iron oxyhydroxides, including goethite ferrihydrite; (2) mixed Mn−Fe...
The formation of Pu(IV)-oxo-nanoparticles from Pu(III) solutions by a surface-enhanced redox/polymerization reaction at the muscovite (001) basal plane is reported, with continuous increase in plutonium coverage observed situ over several hours. sorbed Pu extends >70 Å surface maximum concentration 10.5 and total >9 atoms per unit cell area (0.77 μg Pu/cm(2)) (determined independently resonant anomalous X-ray reflectivity ex-situ alpha-spectrometry). presence discrete nanoparticles confirmed...
Using x-ray scattering, spectroscopy, and density-functional theory, we determine the structure of oxidation front when a ${\mathrm{UO}}_{2}$ (111) surface is exposed to oxygen at ambient conditions. In contrast classical diffusion previously reported bulk ${\mathrm{UO}}_{2+x}$ structures, find interstitials order into nanoscale superlattice with three-layer periodicity uranium in three states: IV, V, VI. This oscillatory profile driven by nature electron transfer process, has implications...
Ionically bonded minerals are ubiquitous and play a determinative role in controlling the mobility of toxic metals natural environments. However, little is known about mechanism ion uptake by these mineral surfaces. Here, sorption strontium ions (Sr2+) to barite (001)–water interface was studied using combination synchrotron X-ray scattering three types computational simulations (density functional theory, classical molecular dynamics (CMD), CMD-metadynamics). In situ resonant anomalous...