Resonant soft x-ray scattering (RSoXS) at the carbon K-edge was used to probe periodic structures of phases with orientational molecular order but homogeneous electron density distribution. This approach can be applied to structures with periodicities below the optical wavelength, to which neither optical nor classical x-ray diffraction techniques are sensitive. Read more »
Journal Covers
Elucidating the mechanism of MgB2 initial hydrogenation via a combined experimental–theoretical study
Magnesium borohydride Mg(BH4)2 is a promising solid-state hydrogen-storage material, releasing 14.9 wt% hydrogen upon conversion to MgB2. Although several dehydrogenation pathways have been proposed, the hydrogenation process is less well understood. This study elucidates the key atomistic mechanisms associated with the initial stages of hydrogen uptake within MgB2. Read more »
Amorphous calcium carbonate particles form coral skeletons
Skeletons of Stylophora pistillata corals form by the attachment of amorphous calcium carbonate precursor particles, formed within the coral tissue, to the coral skeleton surface. This mechanism is faster than the precipitation of ions from solution and may render the corals less susceptible to ocean acidification than previously assumed. Read more »
In Situ Electrical Resistance and X-Ray Tomography Study of Copper–Tin Polymer Composites during Thermal Annealing
In situ electrical conductivity and x-ray tomography experiments were conducted on a conductive polymer composite containing polyvinylidene fluoride (PVDF) copolymer, copper (Cu), and tin (Sn) during thermal annealing. This study provides detailed insight into the morphological origins of the beneficial effect of thermal annealing on the electrical properties of conductive composites containing low melting metal fillers. Read more »
Electronic Phase Separation and Dramatic Inverse Band Renormalization in the Mixed-Valence Cuprate LiCu2O2
Angle-resolved photoemission spectroscopy was used to measure the electronic structure of LiCu2O2, a mixed-valence cuprate where planes of Cu(I) (3d10) ions are sandwiched between layers containing one-dimensional edge-sharing Cu(II) (3d9) chains. Read more »
Near-Edge X-Ray Refraction Fine Structure Microscopy
Soft x-ray ptychography was used to measure the absorption and refraction of x-rays through pristine reference materials as a basis for decomposing spatially resolved spectra from a heterogeneous sample, thereby quantifying the composition at high resolution. The novel method provided a nearly five-fold improvement in spatial resolution on resonance. Read more »
Ambient Pressure XPS and IRRAS Investigation of Ethanol Steam Reforming on Nickel–Ceria Catalysts
Ambient-pressure x-ray photoelectron spectroscopy (AP-XPS) and infrared reflection absorption spectroscopy (AP-IRRAS) have been used to elucidate the active sites and mechanistic steps associated with the ethanol steam reforming reaction (ESR) over Ni–CeO2(111) model catalysts. Read more »
High spatial resolution mapping of chemically-active self-assembled N-heterocyclic carbenes on Pt nanoparticles
Many functional materials (e.g. catalysts) critically depend on the spatial distribution of surface active sites. However, most spectroscopic measurements are ensemble-based, where reactivity is averaged over millions of nanoparticles. Here, carbene attached to nanoparticle surfaces serves a model system for studying catalytic reactions on single nanoparticles. Read more »
Nanocrystals in compression: unexpected structural phase transition and amorphization due to surface impurities
We report an unprecedented surface doping-driven anomaly in the compression behaviors of nanocrystals. The results suggest that the physical properties of the interior of nanocrystals can be controlled by the surface, providing an unconventional and new degree of freedom in search for nanocrystals with novel tunable properties that can trigger applications in multiple areas of industry and provoke more related basic science research. Read more »
Quantitative Microstructural Imaging by Scanning Laue X-ray Micro- and Nanodiffraction
Synchrotron Laue x-ray microdiffraction turns 20 this year. The June 2016 issue of MRS Bulletin is dedicated to synchrotron radiation research in materials science and features a review article on the current capabilities, latest technical developments, and emerging applications of Laue x-ray micro- and nanodiffraction co-authored by ALS beamline scientist Nobumichi Tamura. The cover image shows a Laue x-ray microdiffraction pattern from a sea urchin tooth taken on Beamline 12.3.2. Read more »
