Advanced Photon Source

This paper reviews the research activities on the mechanistic understanding and solutions to overcome the TM DMD process, from the earliest discoveries to the latest progress.

We report a successful observation of pressure-induced superconductivity in a topological compound Bi(2)Te(3) with T(c) of ∼3 K between 3 to 6 GPa. The combined high-pressure structure investigations with synchrotron radiation indicated that the superconductivity occurred at the ambient phase without crystal structure phase transition. The Hall effects measurements indicated the hole-type carrier in the pressure-induced superconducting Bi(2)Te(3) single crystal. Consequently, the first-principles calculations based on the structural data obtained by the Rietveld refinement of X-ray diffraction patterns at high pressure showed that the electronic structure under pressure remained topologically nontrivial. The results suggested that topological superconductivity can be realized in Bi(2)Te(3) due to the proximity effect between superconducting bulk states and Dirac-type surface states. We also discuss the possibility that the bulk state could be a topological superconductor.

Key insights into the behavior of materials can be gained by observing their structure as they undergo lattice distortion. Laser pulses on the femtosecond time scale can be used to induce disorder in a "pump-probe" experiment with the ensuing transients being probed stroboscopically with femtosecond pulses of visible light, x-rays, or electrons. Here we report three-dimensional imaging of the generation and subsequent evolution of coherent acoustic phonons on the picosecond time scale within a single gold nanocrystal by means of an x-ray free-electron laser, providing insights into the physics of this phenomenon. Our results allow comparison and confirmation of predictive models based on continuum elasticity theory and molecular dynamics simulations.

We report phonon densities of states (DOS) of iron measured by nuclear resonant inelastic x-ray scattering to 153 gigapascals and calculated from ab initio theory. Qualitatively, they are in agreement, but the theory predicts density at higher energies. From the DOS, we derive elastic and thermodynamic parameters of iron, including shear modulus, compressional and shear velocities, heat capacity, entropy, kinetic energy, zero-point energy, and Debye temperature. In comparison to the compressional and shear velocities from the preliminary reference Earth model (PREM) seismic model, our results suggest that Earth's inner core has a mean atomic number equal to or higher than pure iron, which is consistent with an iron-nickel alloy.

Cadmium selenide nanoparticles are found to diffuse approximately 200 times faster in a polymeric liquid than predicted by the Stokes-Einstein relation. This remarkable behavior is hypothesized to be due to the nanoparticles being smaller than the entanglement mesh to create a frictional drag that does not follow continuum expectations, in line with a theoretical calculation presented before. This is one of the first demonstrations of X-ray photo correlation spectroscopy applied to polymeric liquids, which we use to explain the simultaneous 60% viscosity reduction of the mixture through a proposed constraint release mechanism.

Percolation theory enables the design of high capacity cation-disordered oxides for rechargeable lithium battery cathodes.

High performance benzylpyrrolidinium anion-exchange membrane.

The electrochemical performance and mechanism of a MIL-101(Fe) metal–organic framework (MOF) as a lithium ion battery electrode is reported for the first time.

Energy storage and conversion systems, including batteries, supercapacitors, fuel cells, solar cells, and photoelectrochemical water splitting, have played vital roles in the reduction of fossil fuel usage, addressing environmental issues and the development of electric vehicles. The fabrication and surface/interface engineering of electrode materials with refined structures are indispensable for achieving optimal performances for the different energy-related devices. Atomic layer deposition (ALD) and molecular layer deposition (MLD) techniques, the gas-phase thin film deposition processes with self-limiting and saturated surface reactions, have emerged as powerful techniques for surface and interface engineering in energy-related devices due to their exceptional capability of precise thickness control, excellent uniformity and conformity, tunable composition and relatively low deposition temperature. In the past few decades, ALD and MLD have been intensively studied for energy storage and conversion applications with remarkable progress. In this review, we give a comprehensive summary of the development and achievements of ALD and MLD and their applications for energy storage and conversion, including batteries, supercapacitors, fuel cells, solar cells, and photoelectrochemical water splitting. Moreover, the fundamental understanding of the mechanisms involved in different devices will be deeply reviewed. Furthermore, the large-scale potential of ALD and MLD techniques is discussed and predicted. Finally, we will provide insightful perspectives on future directions for new material design by ALD and MLD and untapped opportunities in energy storage and conversion.

Spatial distribution of lithium cations in the graphite electrode of a lithium-ion battery is quantified using <italic>operando</italic> energy dispersive X-ray diffraction.

The lithiation mechanism of the Li-Se cell in a carbonate-based electrolyte is discussed. It is found that Se is directly reduced to Li2Se in discharge without intermediate phases detected by in situ X-ray diffraction or X-ray absorption spectroscopy. The reason is that the redox products Se and Li2Se, as well as lithium polyselenides are insoluble in the electrolyte.

, despite the different metals and synthetic conditions. The proposed model and kinetic descriptor could serve as powerful tools for the design of colloidal nanoparticles with specific sizes.

Design rules for high capacity disordered rocksalt Li-ion cathodes applied to the Li–Mn–V–O–F system.

Dynamic and flexible metal–organic frameworks (MOFs) that respond to external stimuli, such as stress, light, heat, and the presence of guest molecules, hold promise for applications in chemical sensing, drug delivery, gas separations, and catalysis.

Synchrotron x-radiography and a fast x-ray detector were used to record the time evolution of the transient fuel sprays from a high-pressure injector. A succession of 5.1-microsecond radiographs captured the propagation of the spray-induced shock waves in a gaseous medium and revealed the complex nature of the spray hydrodynamics. The monochromatic x-radiographs also allow quantitative analysis of the shock waves that has been difficult if not impossible with optical imaging. Under injection conditions similar to those found in operating engines, the fuel jets can exceed supersonic speeds and result in gaseous shock waves.

An in-depth understanding of Na2Ti3O7 as a Na-ion battery anode is reported. The battery performance is enhanced by carbon coating, due to increased electronic conductivity and reduced solid electrolyte interphase formation. Ti(4+) reduction upon discharge is demonstrated using in situ XAS. The self-relaxation behaviour of the fully intercalated phase is revealed.

Transition of phosphate bidentate-binuclear surface complexation to precipitation with increasing P sorption loading was explored using differential pair distribution function (d-PDF) analysis.

This work introduces the first practical platinum group metal-free (PGM-free) electrocatalyst for the hydrogen oxidation reaction (HOR) in alkaline membrane fuel cells (AMFC), based on nickel-rich Ni₉₅Cu₅-alloy nanoparticles.

Capture of CO2 from flue gas is considered to be a feasible approach to mitigate the effects of anthropogenic emission of CO2. Herein we report that an isostructural family of metal organic materials (MOMs) of general formula [M(linker)2(pillar)], linker = pyrazine, pillar = hexaflourosilicate and M = Zn, Cu, Ni and Co exhibits highly selective removal of CO2 from dry and wet simulated flue gas. Two members of the family, M = Ni and Co, SIFSIX-3-Ni and SIFSIX-3-Co, respectively, are reported for the first time and compared with the previously reported Zn and Cu analogs.

During subsurface bioremediation of uranium-contaminated sites, indigenous metal and sulfate-reducing bacteria may utilize a variety of electron acceptors, including ferric iron and sulfate that could lead to the formation of various biogenic minerals in situ. Sulfides, as well as structural and adsorbed Fe(II) associated with biogenic Fe(II)-sulfide phases, can potentially catalyze abiotic U(VI) reduction via direct electron transfer processes. In the present work, the propensity of biogenic mackinawite (Fe 1+x S, x = 0 to 0.11) to reduce U(VI) abiotically was investigated. The biogenic mackinawite produced by Shewanella putrefaciens strain CN32 was characterized by employing a suite of analytical techniques including TEM, SEM, XAS, and Mössbauer analyses. Nanoscale and bulk analyses (microscopic and spectroscopic techniques, respectively) of biogenic mackinawite after exposure to U(VI) indicate the formation of nanoparticulate UO2. This study suggests the relevance of sulfide-bearing biogenic minerals in mediating abiotic U(VI) reduction, an alternative pathway in addition to direct enzymatic U(VI) reduction.