Advanced Light Source (ALS) – Page 10

Scientists confirm speculation on the chemistry of a high-performance battery

2018/02/282018/03/05

X-ray experiments at Berkeley Lab reveal what’s at work in an unconventional electrode.

Scientists have discovered a novel chemical state of the element manganese. This chemical state, first proposed about 90 years ago, enables a high-performance, low-cost sodium-ion battery that could quickly and efficiently store and distribute energy produced by solar panels and wind turbines across the electrical grid.

This direct proof of a previously unconfirmed charge state in a manganese-containing battery component could inspire new avenues of exploration for battery innovations.

X-ray experiments at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) were key in the discovery. The study results were published Feb. 28 in the journal Nature Communications.

Scientists at Berkeley Lab and New York University participated in the study, which was led by researchers at Natron Energy, formerly Alveo Energy, a Santa Clara, California-based battery technology company.

The battery that Natron Energy supplied for the study features an unconventional design for an anode, which is one of its two electrodes. Compared with the relatively mature designs of anodes used in lithium-ion batteries, anodes for sodium-ion batteries remain an active focus of R&D.

Photo: An array of solar panels and windmills.
Credit: PxHere

Unraveling the Complexities of Auto-Oxidation

2018/02/232018/03/07

A better understanding of auto-oxidation reaction mechanisms could lead to better engines, less air pollution, and improved climate models.

Oxygen plays a key role in chemical reactions that produce pollutants in the atmosphere and that fuel combustion engines. In these reactions, auto-oxidation (spontaneous oxidation in air or in the presence of oxygen) produces highly oxygenated molecules.

For example, volatile organic compounds (VOCs)—gas molecules emitted from vehicles, factories, and power plants (as well as living plants)—undergo a sequence of auto-oxidation reactions with the surrounding air, forming highly oxygenated molecules that contribute to air pollution, affecting health and climate. The same highly oxygenated molecules are also produced during the ignition of fuels in advanced combustion engines; controlling their formation and destruction processes can help to develop higher-efficiency engines.

However, because these highly oxygenated molecules are very reactive and decompose quickly, determining their identities has been difficult.

>Read more on the ALS website

Image: Illustration of the jet-stirred reactor used in this experiment. Jet nozzles in the reaction chamber (center) generate turbulence for mixing the incoming fuel molecules with oxidizer (lower right). After the fuels react, the products exit the apparatus (upper left) to be analyzed by advanced mass spectrometry.
Credit: Ahmed Najjar

Tuning magnetic frustration in a dipolar trident lattice

2018/02/212018/02/22

Frustrated interactions are key to a wide range of phenomena, from protein folding and magnetic memory to fundamental studies of emergent exotic states.

Geometrical frustration and “spin ice”

When bar magnets are brought together, opposite poles will attract and like poles will repel, and the magnets will arrange themselves accordingly, to minimize energy. However, if the magnets are constrained to a lattice structure where each one has just two possible orientations, some magnets could end up geometrically “frustrated,” with neither orientation being lower in energy than the other. The system becomes what’s known as a “spin ice,” analogous to water ice, which retains intrinsic randomness (residual entropy) even at absolute zero.

Systems incorporating geometrical frustration are fascinating because their hard-to-predict behavior is key to a wide range of phenomena, from protein folding and magnetic memory to the emergence of exotic states of matter. For example, the emergence of magnetic monopole–like excitations in spin ice raises the intriguing possibility of “magnetic-charge” circuitry based on currents of magnetic monopole excitations.

Image: (extract, entire image here) Magnetic scattering patterns calculated from XMCD data for various lattice parameters. While relatively sharp peaks indicative of long-range order are seen in (a) and (c), the diffuse patterns in (b) indicate highly disordered configurations.

The microstructure of a parrotfish tooth contributes to its toughness

2018/02/082018/02/15

During a 2012 visit to the Great Barrier Reef off the coast of Australia, ALS staff scientist Matthew Marcus became intrigued with parrotfish. “I was reminded that this is a fish that crunches up coral all day and is responsible for much of the white sand on beaches,” Marcus said. “But how can this fish eat coral and not lose its teeth?” So Marcus teamed up with Pupa Gilbert, a biophysicist at the University of Wisconsin–Madison, and an international team of researchers she assembled, to understand how parrotfish teeth work.

Because conventional microscopes can overlook the unique orientation of crystals in tooth enamel, the team used the technique called polarization-dependent imaging contrast (PIC) mapping that Gilbert invented, which uses the photoemission electron microscopy (PEEM) Beamline 11.0.1 at the ALS. The PIC maps allowed them to visualize the orientation of individual crystals of fluorapatite, the main mineral component of parrotfish teeth.

Separate experiments used tomography (Beamline 8.3.2) and microdiffraction (Beamline 12.3.2) to further analyze the crystal orientations and strains in the teeth.

>Read more on the ALS website

Image: (extract) PIC maps acquired at the tips of four different parrotfish teeth show that they consist of 100-nm-wide, microns-long crystals, bundled into “fibers” interwoven like warp and weft fibers in fabric. These fibers gradually decrease in average diameter from 5 μm at the back of a tooth to 2 μm at the tip. Intriguingly, this decrease in size is spatially correlated with an increase in hardness and stiffness. The orientation angle of the crystals is color-coded (chart at bottom).

Modified antibody clarifies tumor-killing mechanisms

2018/01/262018/02/02

The structure of an antibody was modified to selectively activate a specific pathway of the immune system, demonstrating its value in killing tumor cells.

Immunotherapy—the use of the immune system to fight disease—has made tremendous progress in the fight against cancer. Antibodies such as immunoglobulin G (IgG) can identify and attack foreign or abnormal substances, including tumor cells. But to control and amplify this response, scientists need to know more about how elements of the immune system recognize tumor cells and trigger their destruction. There are two main pathways for this: antibody-dependent mechanisms and complement-dependent mechanisms.

The antibody pathway involves coating the surfaces of tumor cells with antibodies that recruit “natural killer” (NK) cells and macrophages (a type of white blood cell) to destroy the tumor cells. The complement pathway (so named because it complements the antibody pathway) also engages NK cells and macrophages and includes a third mechanism—a cascade of events culminating in tumor-cell destruction via a membrane attack complex (MAC).

>Read more on the ALS webpage

Image: extract of a schematic illustration (see on the ALS webpage)

X-ray experiments suggest high tunability of 2-D material

2018/01/262018/01/31

Scientists at Berkeley Lab use a new platform, called MAESTRO, to see microscale details in monolayer material’s electronic structure

To see what is driving the exotic behavior in some atomically thin – or 2-D – materials, and find out what happens when they are stacked like Lego bricks in different combinations with other ultrathin materials, scientists want to observe their properties at the smallest possible scales.

Enter MAESTRO, a next-generation platform for X-ray experiments at the Advanced Light Source (ALS) at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), that is providing new microscale views of this weird 2-D world.

In a study published Jan. 22 in the journal Nature Physics, researchers zeroed in on signatures of exotic behavior of electrons in a 2-D material with microscale resolution.

The new insights gleaned from these experiments show that the properties of the 2-D semiconductor material they studied, called tungsten disulfide (WS₂), may be highly tunable, with possible applications for electronics and other forms of information storage, processing, and transfer.

Those applications could include next-gen devices spawned from emerging fields of research like spintronics, excitonics and valleytronics. In these fields, researchers seek to manipulate properties like momentum and energy levels in a material’s electrons and counterpart particles to more efficiently carry and store information – analogous to the flipping of ones and zeroes in conventional computer memory.

>Read more on the ALS website

Picture: Extract of a rendering showing a “ball-and-stick” representation of the atomic structure of a 2-D single crystalline layer of tungsten disulfide (blue and yellow) on top of layers of 2-D boron nitride (silver and gold). On top of these is a representation of the structure of electronic energy levels, or valence bands, within the tungsten disulfide, and the increased splitting between the two valence bands observed using an x-ray technique at the MAESTRO beamline. The experiments suggest the effect could be due to “trions,” made up of two holes and an electron in the bands, depicted as clear and dark spheres. The background is raw data of the electronic structure of the tungsten disulfide, as measured in the experiment.
Credit: Chris Jozwiak/Berkeley Lab

Fuel from the sun: insight into electrode performance

2018/01/232018/02/02

Soft x-ray studies of hematite electrodes—potentially key components in producing fuel from sunlight—revealed the material’s electronic band positions under realistic operating conditions.

In photosynthesis, plants use sunlight to split water into oxygen and hydrogen. The oxygen is released into the atmosphere, and the hydrogen is used to produce molecules—such as carbohydrates and sugars—that store energy in chemical bonds. Such compounds constitute the original feedstocks for subsequent forms of fuel consumed by society.

Photoelectrochemical (PEC) water splitting is a form of “artificial” photosynthesis that uses semiconductor material, rather than organic plant material, to facilitate water splitting. Electrodes made of semiconductor material are immersed in an electrolyte, with sunlight driving the water-splitting process. The performance of such PEC devices is largely determined at the interface between the photoanode (the electrode at which light gets absorbed) and the electrolyte.

>Read more on the ALS webpage

Photo: Roy Kaltschmidt

Berkeley Lab delivers injector that will drive X-Ray laser upgrade

2018/01/22

Unique device will create bunches of electrons to stimulate million-per-second X-ray pulses

Every powerful X-ray pulse produced for experiments at a next-generation laser project, now under construction, will start with a “spark” – a burst of electrons emitted when a pulse of ultraviolet light strikes a 1-millimeter-wide spot on a specially coated surface.

A team at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) designed and built a unique version of a device, called an injector gun, that can produce a steady stream of these electron bunches that will ultimately be used to produce brilliant X-ray laser pulses at a rapid-fire rate of up to 1 million per second.

The injector arrived Jan. 22 at SLAC National Accelerator Laboratory (SLAC) in Menlo Park, California, the site of the Linac Coherent Light Source II (LCLS-II), an X-ray free-electron laser project.

Getting up to speed

The injector will be one of the first operating pieces of the new X-ray laser. Initial testing of the injector will begin shortly after its installation.

The injector will feed electron bunches into a superconducting particle accelerator that must be supercooled to extremely low temperatures to conduct electricity with nearly zero loss. The accelerated electron bunches will then be used to produce X-ray laser pulses.

Image: Joe Wallig, left, a mechanical engineering associate, and Brian Reynolds, a mechanical technician, work on the final assembly of the LCLS-II injector gun in a specially designed clean room at Berkeley Lab in August.
Credit: Marilyn Chung/Berkeley Lab

Scientists discover material ideal for smart photovoltaic windows

2018/01/222018/01/24

Berkeley Lab researchers make thermochromic windows with perovskite solar cell

Smart windows that are transparent when it’s dark or cool but automatically darken when the sun is too bright are increasingly popular energy-saving devices. But imagine that when the window is darkened, it simultaneously produces electricity. Such a material – a photovoltaic glass that is also reversibly thermochromic – is a green technology researchers have long worked toward, and now, scientists at Lawrence Berkeley National Laboratory (Berkeley Lab) have demonstrated a way to make it work.

Researchers at Berkeley Lab, a Department of Energy (DOE) national lab, discovered that a form of perovskite, one of the hottest materials in solar research currently due to its high conversion efficiency, works surprisingly well as a stable and photoactive semiconductor material that can be reversibly switched between a transparent state and a non-transparent state, without degrading its electronic properties.

Image Credit: iStock

A path to a game-changing battery electrode

2018/01/162018/01/24

If you add more lithium to the positive electrode of a lithium-ion battery, it can store much more charge in the same amount of space, theoretically powering an electric car 30 to 50 percent farther between charges. But these lithium-rich cathodes quickly lose voltage, and years of research have not been able to pin down why—until now.

Image: Electric car makers are intensely interested in lithium-rich battery cathodes made of layers of lithium sandwiched between layers of transition-metal oxides. Such cathodes could significantly increase driving range.
Credit: Stanford University/3Dgraphic

X-Rays Reveal ‘Handedness’ in Swirling Electric Vortices

2018/01/152018/01/17

Scientists at Berkeley Lab study exotic material’s properties, which could make possible a new form of data storage

Scientists used spiraling X-rays at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) to observe, for the first time, a property that gives handedness to swirling electric patterns – dubbed polar vortices – in a synthetically layered material.

Ingredients for Life Revealed in Meteorites That Fell to Earth

2018/01/102018/01/17

Study, based in part at Berkeley Lab, also suggests dwarf planet in asteroid belt may be a source of rich organic matter

Two wayward space rocks, which separately crashed to Earth in 1998 after circulating in our solar system’s asteroid belt for billions of years, share something else in common: the ingredients for life. They are the first meteorites found to contain both liquid water and a mix of complex organic compounds such as hydrocarbons and amino acids.

Studying Gas Mask Filters So People Can Breathe Easier

2017/12/072018/01/17

Scientists have put the x-ray spotlight on composite materials in respirators used by the military, police, and first responders. The results provide reassuring news about the effectiveness of current filters and provide fundamental information that could lead to more advanced gas masks as well as protective gear for civilian applications.

Ferromagnetism Emerges to Alleviate Polar Mismatch

2017/12/042018/01/17

Alchemists dreamed of turning boring, base metals into exotic, noble metals. Although such dreams were never realized, scientists today can induce unexpected properties at the interface between two materials—including properties not present in either parent material. For example, researchers have discovered that if they combine SrTiO3 (a dielectric and paramagnetic material) together with LaMnO3 (an insulating and antiferromagnetic material) in just the right way, they can induce an insulating ferromagnetic state at the interface.

Watching a Quantum Material Lose Its Stripes

2017/11/292017/12/07

Berkeley Lab study uses terahertz laser pulses to reveal ultrafast coupling of atomic-scale patterns

Stripes can be found everywhere, from zebras roaming in the wild to the latest fashion statement. In the world of microscopic physics, periodic stripe patterns can be formed by electrons within so-called quantum materials.

Scientists at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) have now disentangled the intriguing dynamics of how such atomic-scale stripes melt and form, providing fundamental insights that could be useful in the development of novel energy materials.

>Read more on the ALS website

Image: Illustration of an ultrashort laser light striking a lanthanum strontium nickel oxide crystal, triggering the melting of atomic-scale stripes. The charges (yellow) quickly become mobile while the crystal distortions react only with delay, exposing the underlying interactions.
Credit: Robert Kaindl/Berkeley Lab

New Catalyst Gives Artificial Photosynthesis a Big Boost

2017/11/292017/12/07

Inspired by plants: Inorganic catalyst converts electrical energy to chemical energy at 64% efficiency

Researchers have created a new catalyst that brings them one step closer to artificial photosynthesis — a system that would use renewable energy to convert carbon dioxide (CO₂) into stored chemical energy.

As in plants, their system consists of two linked chemical reactions: one that splits water (H₂O) into protons and oxygen gas, and another that converts CO₂ into carbon monoxide (CO). The CO can then be converted into hydrocarbon fuels through an established industrial process. The system would allow both the capture of carbon emissions and the storage of energy from solar or wind power.

Yufeng Liang and David Prendergast – scientists at the Molecular Foundry, a nanoscale research facility at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) – performed theoretical modeling work used to interpret X-ray spectroscopy measurements made in the study, published Nov. 20 in Nature Chemistry. This work was done in support of a project originally proposed by the University of Toronto team to the Molecular Foundry, a DOE Office of Science User Facility.

>Read more on the ALS website

Image: Phil De Luna of University of Toronto is one of the lead authors of a new study that reports a low-cost, highly efficient catalyst for chemical conversion of water into oxygen. The catalyst is part of an artificial photosynthesis system in development at the University of Toronto.
Credit: Tyler Irving/University of Toronto