Argonne National Laboratory

Science Highlights

Date Postedsort ascending
Water can serve a previously undiscovered role to help micelles spontaneously form long fibers. Molecular dynamics simulations highlight the transition of a peptide amphiphile (from C16-AHL3K3-CO2H molecules) assembly from micelles to fibers within microseconds. Water becomes more ordered with fiber formation. (Image courtesy of Robert Horn/Argonne National Laboratory.)
Drop-by-Drop: water helps assembly of biofibers that could capture sunlight

Simulations reveal water’s role in driving the self-assembly of peptide amphiphiles from monomers to micelles to fibers. Dual computational and experimental results provide a basis for designing new peptide materials capable of exhibiting light harvesting properties. Such artificial systems have potential in photochemical reactions and solar fuels.

October 4, 2016
A magnetic charge ice with nanoscale magnets arranged in a two-dimensional lattice. Each nanomagnet produces a pair of magnetic charges, one positive (red ball on the north pole) and one negative (blue ball on the south pole). The magnetic flux lines (white) point from positive charges to negative charges. (Image credit: Yonglei Wang and Zhili Xiao)
Rewritable Artificial Magnetic Charge Ice

An artificial magnetic charge structure with tunable long-range ordering to achieve the elusive ground state of a magnetic spin-ice structure was achieved. Manipulation of local magnetic charge states for write-read-erase multi-functionality at room temperature was demonstrated.

June 17, 2016
A patchwork map of lattices in a butterfly wing with slightly different orientations (colors added to illustrate the domains). This structure, and the irregularities along the edges where they meet, help create the “sparkle” of the wings. Image courtesy Ian McNulty/Science.
Butterfly Effects: X-rays reveal the photonic crystals in butterfly wings that create color

CNM scientists in collaboration with others used X-rays at the APS to discover what creates one butterfly effect: how the microscopic structures on the insect’s wings reflect light to appear as brilliant colors to the eye. The results may help researchers mimic the effect for reflective coatings, fiber optics or other applications.

June 17, 2016
Researchers from Argonne National Laboratory developed a first-principles-based, variable-charge force field that has shown to accurately predict bulk and nanoscale structural and thermodynamic properties of IrO2. Catalytic properties pertaining to the oxygen reduction reaction, which drives water-splitting for the production of hydrogen fuel, were found to depend on the coordination and charge transfer at the IrO2 nanocluster surface. (Image courtesy of Maria Chan, Argonne National Laboratory)
More accurate predictions for harvesting hydrogen with iridium oxide nanoparticles

Researchers from Argonne National Laboratory developed a first-principles-based, variable-charge force field that has shown to accurately predict bulk and nanoscale structural and thermodynamic properties of IrO2.

May 3, 2016
Molecular model, overlaying rectification ratio map, and current-voltage statistics “I(V)” of a pentacene/C60 heterojunction (top) and a C60 monolayer (bottom) on Cu(111).
Large rectification in molecular heterojunctions

C60 and pentacene self-assemble on a copper surface into stacked molecular heterojunctions which reveal robust diode-like behavior with rectification ratios (RR) >1000. Most organic systems have RRs <100. The new bilayer system has a novel mechanism, the RR >1000 is a lower bound, and the design is not yet optimized. Using this design, large rectification at metallic electrodes may be engineered by adding a ~2 nm-thick molecular layer for potential use in organic optoelectronics and photovoltaics.

April 19, 2016
On the left, a schematic shows the experimental setup for measuring spin dynamics in a sample of YIG. On the right, a Brillouin light scattering map of a micro-sized bar of YIG excited via an electrical current through a platinum overlayer reveals a strong spin-wave localization in the center of the sample known as a “bullet.” The color red indicates a high-spin wave intensity and the color blue indicates an absence of spin waves. (Image provided by M. Benjamin Jungfleisch)
Could the future of low-power computing be magnetism?

Researchers at the U.S. Department of Energy's (DOE's) Argonne National Laboratory have made two recent advances in the field of spin-wave logic, or the potential use of magnetic spins to transmit and manipulate data.

February 15, 2016
AC-TEM image of an individual Pt catalyst nanoparticle. The distances labeled 1 and 2 blue are 2.4 Å and 2.8 Å resp. Overlaid on the image are two layers of cubic Pt (magenta and green dots). The cubic 3-dimensional structure of Pt as a model is shown at the upper right, displaying the location of the Pt atoms in the two layers (corresponding magenta and green colors).
Advantages of Microscopy Method for Imaging Nanocatalysts

In work with UOP-Honeywell, a comparison of advanced microscopy methods for imaging platinum (Pt) catalyst nanoparticles suggests the aberration-corrected transmission electron microscopy (AC-TEM) mode may be advantageous because of the less pronounced beam-induced structural changes that occur when imaging with a fine scanning TEM (STEM) probe.

February 11, 2016
Measured and calculated electrical conductivities of conducting (right) and semiconducting (left) phases of VO2  (large gray circles represent vanadium, small red circles represent oxygen). The plot shows electrical conductivity increases with temperature because the phase changes the structure slightly.
Dialing in the Properties of Dual Metallic-Insulating Materials

By calibrating how strongly electrons interact using experimental measurements from vanadium oxide VO2 films, CNM users from Toyota showed the metallic and semiconducting behavior can be modeled computationally with density functional theory (DFT).

February 11, 2016
Density functional calculations of, left, lattice match between LiO2 and Ir3Li responsible for the LiO2 discharge product on Ir–rGO cathodes. The gray rod-like structures represent the crystalline LiO2 morphology actually observed. (courtesy of Nature Publishing Group)
A Lithium-Air Battery Based on Lithium Superoxide

A novel templating growth mechanism involving iridium nanoparticles on a cathode surface may be responsible for the growth of crystalline LiO2. Results demonstrate the LiO2 formed in the Li–O2 battery is stable enough for the battery to be repeatedly charged and discharged with a very low charge potential (about 3.2 volts).

January 20, 2016
Atomic-resolution topographic rendering of a borophene surface, taken in a scanning tunneling microscope. The borophene sheet forms large buckled wrinkles, as seen in the center, in response to the underlying silver crystal.
Atomically Thin Metallic Boron

For the first time a two-dimensional sheet of boron known as borophene was created. Borophene is an unusual because it shows metallic properties at the nanoscale even though three-dimensional, or bulk, boron is nonmetallic and semiconducting. Because borophene is both metallic and atomically thin, it holds promise for possible applications ranging from electronics to photovoltaics.

December 22, 2015