Category: Advanced Photon Source (APS)

An Exceptionally Long Experiment Reveals Unexpected Structural Evolution in a Metallic Glass

An Exceptionally Long Experiment Reveals Unexpected Structural Evolution in a Metallic Glass

Metallic glasses (MGs) are alloys that possess an amorphous (disordered) structure instead of a crystalline lattice. This jumbled atomic arrangement often yields materials with exceptional properties, for instance very high yield strength and toughness. These exceptional features have led to the incorporation of MGs into advanced biomedical implants, superior sports equipment, energy-saving electrical devices, and many other applications. 

Unfortunately, the disordered structure of MGs inevitably leads to their atoms migrating over time, which can seriously degrade their superior properties. For years scientists have investigated the complex structural rearrangements that occur within metallic glasses, but important details of this dynamic process remain obscure. In this study, researchers measured atomic-level movements in a metallic glass over the unprecedented time span of nearly 3½ days, using X-ray photon correlation spectroscopy (XPCS) performed at beamline 8-ID-E of the Advanced Photon Source (APS). The APS is a U.S. Department of Energy (DOE) Office of Science user facility at DOE’s Argonne National Laboratory. 

The extremely high-resolution XPCS measurements, recorded continuously over the entire experiment, provide new information about MG aging. For instance, the experiment revealed long stretches of robust structural changes punctuated by periods of minimal internal movements. This study demonstrates the feasibility of long-duration XPCS observations of metallic glasses, while also providing important new insights into their long-term internal dynamics.

Ordinary alloys such as bronze, brass and steel are mixtures of different metals (and often small amounts of non-metals) that readily form an orderly lattice when cast or forged. In contrast, the disorderly structure of metallic glasses is difficult to obtain since they only form under special conditions.

The first metallic glasses were created in the 1960s via extremely quick quenching, at cooling rates of thousands of degrees per millisecond. This extreme cooling protocol meant that only wires or thin ribbons could be formed. Eventually scientists developed thicker MGs (called bulk metallic glasses) that avoided rapid quenching in favor of, for example, employing numerous atomic elements that encompass a large range of sizes, a strategy which makes it difficult to form an orderly crystalline structure.

Immediately after a metallic glass solidifies, its atoms begin rearranging into a lower energy configuration. This energy-driven structural rearrangement has been studied by materials scientists for decades and has shown, for instance, that atoms migrate in groups, or clusters, in a process called cluster dynamics. However, a full characterization of the complex mechanisms driving the microscopic movements in MGs is still lacking, including whether those structural changes eventually settle upon a more-or-less uniform behavior.

The bulk metallic glass examined in this study was comprised of five distinct elements that formed a zirconium-titanium-copper-nickel-aluminum alloy. This alloy was annealed (heated) to a temperature of 668 Kelvin (about 743 degrees Fahrenheit), which is just below the glass transition temperature, where the metallic glass softens to a jelly-like consistency. The elevated temperature accelerated the MG’s structural changes.

Using a sensitive detector coupled with the intense X-ray beam provided by the APS, the XPCS technique yielded sub-angstrom resolution (dimensions less than one-tenth of a nanometer). Overall, the XPCS measurements, gathered every 2.5 seconds, spanned some 300,000 seconds, or 83 hours. In comparison, similar XPCS experiments with metallic glasses have lasted no more than 17 hours.

Read more on Argonne website

Image: A computer simulation depicts the formation and migration of atomic clusters over time within the metallic glass. Clusters of atoms appear as tiny colored segments. This and similar simulations helped clarify and extend the experimental X-ray results. The illustration’s background, transitioning from blue to yellow, depicts the emergence of longer decorrelation (reorganization) timescales. Superimposed on this background are four instantaneous snapshots of the changing metallic glass structure (only the low-energy structural features are visualized). From left to right, the density of atomic clusters is seen to increase with time, while the pace of structural changes decreases.

Grabbing a tRNA by the Tail

Grabbing a tRNA by the Tail

Transfer RNAs (tRNAs) are RNA molecules used by all forms of life, from bacteria to plants to humans, to transfer amino acids to growing protein molecules that have been coded by DNA and transcribed into messenger RNA (mRNA) for translation by ribosomes into proteins. This is one of the most basic, crucial processes of life.

However, tRNAs do more than just perform this essential function and are known to have regulatory roles in translation, transcription, stress response, and even immunity, via specific interactions with a wide array of cellular molecules. Disruption of these interactions has also been shown to be associated with some types of neurological disease and cancer, making it critical to understand how proteins in the cell recognize tRNAs.

Many different proteins have been shown to interact with tRNAs via known protein structural motifs. One of these is the oligonucleotide/oligosaccharide-binding (OB)-fold that has a highly conserved β-barrel structure found in organisms across all domains of life. However, the details of its interactions with tRNA are not completely understood. Recent research from a team at the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) has provided new, previously unrecognized, insights into how the OB-fold recognizes the 3’ tail of tRNA molecules and how these interactions impact the function of tRNAs.

The research team used X-ray diffraction data collected at the South East Regional Collaborative Access Team (SER-CAT) beamline 22-ID of the Advanced Photon Source, a U.S. Department of Energy (DOE) user facility at DOE’s Argonne National Laboratory.

The protein structure work in this project focused on a superfamily of proteins called the tRNA binding domain (TRBD) family. These proteins interact with tRNAs via an OB-fold domain that consists of five β strands that form a barrel structure with an α-helical cap. TRBD proteins are found in many different organisms and, while they don’t always have high levels of amino acid sequence conservation, they all contain the OB-fold.

This work started with a TRBD protein from the bacteria Aquifex aeolicus called Trbp111 that is known to bind to many tRNAs. Solution of a new 2.3 Å crystal structure of Trbp111 showed that the protein forms an unusually stable homodimer with the two β-barrels stabilized by a very strong dimer interface. This is consistent with what is known about Trbp111, as A. aeolicus thrives at high temperatures (~90°C) and is also resistant to many common laboratory protein denaturing procedures, suggesting that this type of stable interface may provide a model for artificial protein design and structure-based drug design efforts.

Read more on Argonne website

Image: The figure shows how the OB beta barrel uses its two protruding loops as “pincers” to capture the terminal CA dinucleotide of the tRNA in various representations (tRNAs are shown in green in each panel).

Composite coarsening changes material properties

Composite coarsening changes material properties

Eutectic materials, naturally occurring composites of two or more crystals, are used in engine blocks, solder and 3D printing. Often, such applications involve heating the materials, which leads to changes in their microstructure that can affect their mechanical properties, such as strength. Using the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science user facility at DOE’s Argonne National Laboratory, a team of researchers has learned how the microstructure evolves upon heating, which may allow them to change the synthesis of eutectics to improve those mechanical properties.

They studied a model silver-aluminum-copper alloy composed of three phases, one silver-rich, one aluminum-rich and one copper-rich. They heated the material to 773K and annealed it for four hours at that temperature. The material started out as three crystals that were interwoven in a structure resembling a ladder. When heated, the material tries to find its lowest energy state by lengthening the interfaces between the crystals. The microstructure coarsens, with some of the crystals becoming larger at the expense of others.

Much of the theory about eutectics is based on microstructures that have a small volume of one phase embedded in another. That theory predicts that the material would be self-similar, appearing identical at different size scales. In the model system, with three phases making up equal fractions of the volume, researchers were surprised to find no self-similarity. Instead, the microstructure evolved in part by coalescence. Rods of the silver-rich phase, for instance, would grow and become thicker until they touched each other, then they would merge into one rod. That evolution was irreversible. Such a change in the microstructure alters the mechanical properties of the material.

Additionally, the three phases did not coarsen independently of each other, but rather affected how the others evolved. When neighboring silver-aluminum rods coalesce, they pushed out the copper-rich channels that had existed between them. That is one reason for the lack of self-similarity in the evolving material. 

Read more on Argonne website

Image: A eutectic material (left) contains three phases—silver-aluminum (red), aluminum-copper (blue) and aluminum (green). At an elevated temperature, the Ag2Al rods coarsen over time from zero hours (center) to 4 hours (right), where they have coalesced.

Credit: the University of Michigan

Gut enzymes may explain differential disease and FDA-approved drug outcomes

Gut enzymes may explain differential disease and FDA-approved drug outcomes

Our bodies need neurotransmitters and hormones to stay healthy, but too much or too little can cause conditions such as breast cancer or Parkinson’s disease. Normally, excess neurotransmitters and hormones in the body are removed through excretion via the gut. A team of scientists has discovered a new class of enzymes from bacteria in our guts that can alter levels of serotonin, the “feel good” neurotransmitter, and estradiol, a sex hormone, among other compounds. The scientists also found that certain FDA-approved drugs can inhibit these bacterial enzymes. In this way, a cancer drug may inadvertently cause depression in some people by interfering with excretion and thereby initiating a change in their serotonin levels.

These surprising findings could explain why some people respond well to certain drugs and other people don’t, leading the way to more personalized drug dosing based on genomic analysis of the patient and the microbes in their gut. The researchers used the Advanced Photon Source (APS), a U.S. Department of Energy (DOE) Office of Science user facility at DOE’s Argonne National Laboratory.

Our bodies maintain equilibrium in part by ensuring that detrimental substances, such as environmental toxins or excess molecules created naturally when we eat too much turkey at Thanksgiving, are flushed away. To do this, the liver attaches a sugar to the unwanted molecule that serves as a “tag” for trafficking it to the gut for excretion.

For the past 10-15 years, many scientists have focused their investigations on one detrimental substance in particular—drugs that cause adverse reactions in the GI tract—to discover what makes them toxic. They found that certain microbes living in the gut feed off the sugar attached to the detrimental substance by using an enzyme that removes the sugar for microbial growth. Rather than being excreted, the detrimental substance, freed of its sugar – or “reactivated,” in scientific language – remained in the body, causing off-target effects, from irritable bowel syndrome to Crohn’s disease.

Little was known, however, about how gut microbes were behaving toward naturally-occurring molecules like hormones or neurotransmitters. To fill that gap, the research team turned their attention to dopamine and serotonin, as well as estradiol and thyroid hormones, to see if the gut microbes were processing them the way they processed toxic drugs.

A primary question was: Why do the bacteria have these enzymes in the first place? 

Through structural biology, in vitro biochemistry, multi-omics, and in vivo studies, the team showed that specific enzymes in the gut acted on these naturally occurring molecules in the same way they processed man-made molecules like drugs. This suggested to the scientists that sugar-linked natural chemicals like hormones and neurotransmitters play an important role in the microbial evolution of an enzyme that allows gut bacteria to take advantage of this resident food supply.

The enzyme in question is called GUS, or beta-glucuronidase. Previous research had shown that certain types of FDA-approved drugs, including those that fight cancer and depression, inhibit a specific subset of gut microbial GUS enzymes. Different people have different types of microbes in their guts and, therefore, different GUS enzymes. The scientists wondered whether this could explain why different people react differently to these drugs: Might the difference lie in which enzymes were being inhibited and which enzymes were left to interfere with the body’s natural chemical balance, or homeostasis?  

The key answers lay in detailed studies using structural biology, a field that investigates how complex biological macromolecules do their job. Drugs usually have one target, but in the expansive gut microbiome, hundreds of different proteins can all do the same job. The scientists set out to understand on an atomic level why some GUS are more active than others.

Using the National Institute of General Medical Sciences and National Cancer Institute Structural Biology Facility (GM/CA) beamlines at 23-ID-B and 23-ID-D at the APS, the team collected data that enabled them to solve the crystal structures of various species of gut microbes in complex with various anticancer and antidepressant drugs. What they found not only surprised them but also doubled the pool of enzymes that matter – they’d discovered that a whole other class of enzymes, called C-Terminal Domain GUS (CTD), are critically efficient at processing the sugar-attached molecules and are very potently inhibited by certain drugs.

Read more on Argonne website

Image: Simpson et al. pinpoint the gut microbial enzymes (green) that reactivate neurotransmitters and hormones (yellow, orange, and purple) essential to homeostasis and to diseases ranging from cancer to anxiety. They also show that a range of FDA-approved drugs (blue) inhibit these enzymes and impact local and systemic hormone and neurotransmitters levels. The study highlights the indispensable role of gut microbes in endobiotic homeostasis and indicates that therapeutic disruption of this role promotes interindividual variabilities in drug response.

 Leap toward more energy-efficient supercomputing

 Leap toward more energy-efficient supercomputing

Researchers have revealed an adaptive response with a ferroelectric device, which responds to light pulses in a way that resembles the plasticity of neural networks. This behavior could find application in energy-efficient microelectronics.

“Today’s supercomputers and data centers demand many megawatts of power,” said Haidan Wen, a physicist at the U.S. Department of Energy (DOE) Argonne National Laboratory. ​“One challenge is to find materials for more energy-efficient microelectronics. A promising candidate is a ferroelectric material that can be used for artificial neural networks as a component in energy-efficient microelectronics.”

Ferroelectric materials can be found in different kinds of information processing devices, such as computer memory, transistors, sensors and actuators. Argonne researchers report surprising adaptive behavior in a ferroelectric material that can evolve step-by-step to a desired end, depending on the amount of photons from light pulses striking the material. Working alongside Argonne researchers were scientists from Rice University, Pennsylvania State University and DOE’s Lawrence Berkeley National Laboratory.

This team’s material is laden with networked islands or domains that are as distinct as oil in water. These domains are nanometers in size — billionths of a meter — and can rearrange themselves in response to light pulses. This adaptive behavior could be used in the energy-efficient movement of information in microelectronics.

The team’s ferroelectric sample is structured as a sandwich of alternating layers of lead and strontium titanate. Prepared by the Rice University collaborators, this seven-layer sandwich is 1,000 times thinner than a piece of paper. Previously, the team had shined a single, intense light pulse on a sample and created uniform, nanoscale ordered structures.

“Today’s supercomputers and data centers demand many megawatts of power. One challenge is to find materials for more energy-efficient microelectronics. A promising candidate is ferroelectric material that can be used for artificial neural  networks as a component in energy-efficient microelectronics.” — Haidan Wen, Argonne physicist

“This time, we hit the sample with many weak light pulses, each of which lasts a quadrillionth of a second,” Wen said. ​“As a result, a family of domain structures, rather than a single structure, was created and imaged, depending on the optical dosage.”

To visualize the nanoscale responses, the team called upon the Nanoprobe (beamline 26-ID) operated by the Center for Nanoscale Materials and the Advanced Photon Source (APS). Both are DOE Office of Science user facilities at Argonne. With the Nanoprobe, an X-ray beam tens of nanometers in diameter scanned the sample as it was exposed to a barrage of ultrafast light pulses. 

The resulting images revealed networked nanodomains being created, erased and reconfigured due to the light pulses. The regions and boundaries of these domains evolved and rearranged at lengths of 10 nanometers — about 10,000 times smaller than a human hair — to 10 micrometers, roughly the size of a cloud droplet. The final product depended on the number of light pulses used to stimulate the sample.

“By coupling an ultrafast laser to the Nanoprobe beamline, we can initiate and control changes to the networked nanodomains by means of light pulses without requiring much energy,” said Martin Holt, an X-ray and electron microscopy scientist and group leader.

Read more on APS website

Image: Artistic rendering representing light pulses yielding adaptive transformations in nanodomain structures applicable to neuromorphic computing.

Credit: Argonne National Laboratory/Haidan Wen.

A greener possibility using lanthanide separation in two dimensions

A greener possibility using lanthanide separation in two dimensions

The lanthanides and other rare earth elements (REEs) aren’t really “rare” in the strict sense, but they are quite difficult to separate and purify from the other materials with which they’re usually found. Because of the great value and utility of these metals for many purposes, including electronics, computing, and various industrial processes that rely on their unique electronic and chemical properties, that difficulty is a major problem. 

Most current processes for REE separation and purification involve organic and acidic materials, making them both energy-intensive and environmentally unfriendly. Finding better separation techniques is therefore a pressing challenge. Researchers from the University of Chicago, Northwestern University, and Argonne National Laboratory took inspiration from nature to examine a new possibility for lanthanide separation. Their work was published in Science Advances. 

Noting that ion channels in cell membranes are capable of separating ions across cell membranes with great efficiency, speed and selectivity, the investigators chose to model this process with chemically functionalized inorganic membranes to see if REE purification could be accomplished in a similar way.  They constructed two-dimensional angstrom-scale artificial ion channels using MoS2 nanosheets that were covalently functionalized with acetic acid to generate MoS2-COOH membranes for lanthanide ion separation. 

The ion transport process was studied using a variety of tools, including electron microscopy, infrared spectroscopy, molecular dynamics simulations and X-ray absorption spectroscopy and X-ray diffraction studies. Data were collected at the DuPont-Northwestern-Dow Collaborative Access Team 5-BM-D beamline at the Advanced Photon Source, a U.S. Department of Energy (DOE) user facility at DOE’s Argonne National Laboratory.

Read more on Argonne website

Isolating active sites for more efficient catalysts

Isolating active sites for more efficient catalysts

Scientists are always searching for new catalysts to enable fast, energy-efficient chemical reactions to transform wastes into useful chemical fuels, such as converting carbon dioxide to methane. Single-site catalysts are a promising new class of catalyst, with well-defined, well-designed structures where each reaction site is isolated. The challenge with such materials is that the active catalytic sites, which can be as small as a single atom, tend to aggregate, degrading their efficiency and selectivity. 

Now researchers using the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science user facility at DOE’s Argonne National Laboratory, have demonstrated a design for such single-site catalysts that resist aggregating and retain their high efficiency.

The design starts with polyoxometalate clusters (POMs). These are discrete polyatomic anions in which three or more metals, including molybdenum, share oxygen atoms. Catalytic atoms, often noble metals such as platinum or rhodium, can be embedded with the POM. The POM essentially belts the single-site catalyst atom in place, so it has difficulty interacting with other catalytic sites.

But for the catalyst to be efficient, reacting molecules need to be able reach the active site, so the next step is to disperse them through a support with high surface area. In this case, the researchers used a zirconium-based metal-organic framework (MOF), a porous architecture that contains a high surface area within a small volume. This dual-confinement strategy allows the researchers to achieve a relatively high density of active sites, up to 3.2 weight percent, without the sites sintering together during use.

One previous strategy to prevent aggregation of the catalytic atoms had been to spread them far apart on a support material. That made it difficult to assess the structure of the catalysts. The high catalyst loading that is stable using the POM-MOF approach provides sufficient signal to see the catalyst sites using X-rays. The team used pair distribution function analysis (PDF) a technique that is a specialty of beamline 11-ID-B at the APS. PDF provides the structure and relative geometry of the atoms that make up the active catalyst site. Researchers heated samples of their material to 200 °C and used scattering measurements to determine the structure of the POMs when they entered an active state.

The team also performed X-ray absorption spectroscopy (XAS) at beamline 5-BM-D, the Dupont-Northwestern-Dow Collaborative Access Team (DND-CAT) beamline. This technique provides element-specific information, allowing them to isolate the platinum and the rhodium environments. Combining the PDF and XAS measurements allowed the researchers to figure out the local geometry of the catalyst’s active site during the catalytic reaction. They found, for instance, that the distance between the rhodium or platinum and the molybdenum in the active catalyst was shorter than the metal-to-metal bond lengths in bulk metals. 

Researchers were able to compare their experimental data with computer simulations and say which of almost 100 computer-generated models most closely matched their results. Now that they’ve identified the structure of their single-site catalysts and refined the models, they can undertake further computational studies to explore what other formulations might be most promising, before trying to synthesize them. 

Armed with this new understanding of POMs, scientists can now explore whether there are different versions that might achieve high efficiency while using cheaper or more abundant metals than platinum, making chemical reactions more energy and cost efficient. – Neil Savage

See: Z. Chen1, S.M.G. Rabbani2, Q. Liu3,4, W. Bi3,4, J. Duan3, Z. Lu3, N.M. Schweitzer3, R.B. Getman2, J.T. Hupp2, K.W. Chapman1, “Atomically precise single-site catalysts via exsolution in a polyoxometalate-metal-organic framework architecture,” Journal of the American Chemical Society 2024, 146, 12, 7950-7955 (March 2024)

Author affiliations: 1Stony Brook University; 2Clemson University; 3Northwestern University; 4University of Science and Technology of China

This work was initially supported as part of the Inorganometallic Catalyst Design Center, an Energy Frontier Research Center (EFRC) funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences (DE-SC0012702), and subsequently as part of the Catalyst Design for Decarbonization Center EFRC (DE-SC0023383). Q.L. and W.B. acknowledge the financial support as visiting scholars from the National Natural Science Foundation of China (No. 11705205, No. 22175051). This research used the beamline 5-BM-D for X-ray adsorption spectroscopy and 11-ID-B for total scattering measurements at the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under contract no. DE-AC02-06CH11357. This research used ambient pressure XPS of the Center for Functional Nanomaterials (CFN), which is a U.S. Department of Energy Office of Science User Facility, at Brookhaven National Laboratory under Contract No. DE-SC0012704. This work made use of the Reactor Engineering and Catalyst Testing (REACT) core facility of the Center for Catalysis and Surface Science at Northwestern University. The authors acknowledge Leighanne C. Gallington and Qing Ma for the help with remote measurements at the beamline. We thank Ashley R. Head for help with setting up the APXPS measurement. Q.L. thanks Yang Song and Wangsheng Chu for the analysis of XAS.

Read more at Argonne website

Image: A POM consisting of ring of molybdenum (purple)-oxygen (red) octahedra that surrounds a catalytically active rhodium (green) site, all supported on Zr-MOF. When the pristine catalyst (top) is activated under hydrogen at high temperature, its structure changes (bottom) and the Rh protrudes from the Mo-oxo ring.

Producing one-dimensional electronic behavior in bulk crystals

Producing one-dimensional electronic behavior in bulk crystals

Ever had your phone heat up in your hand? Scientists are exploring materials whose electronic properties could reduce the amount of resistive heating created by the transistors in computer chips. These new materials incorporate a one-dimensional electronic structure—meaning that the electrons which create current are confined to a single dimension—inside a three-dimensional crystal with insulating properties. 

It isn’t straightforward, however, to synthesize a material with true one-dimensional conductive components and no electronic interactions in the other dimensions. Recent research results by a team whose members collaborate from universities in Spain, Germany and the United States propose and evaluate the chemical criteria required to synthesize such a material and demonstrate the ability of a bulk crystal (BiIr4Se8) fabricated according to such criteria to produce one-dimensional electronic structure.

The team reasoned that such a bulk crystal would need to have the following three characteristics. First, the material would need to include a one-dimensional conductive component and an insulating component which physically surrounds the conductive one. Second, the atoms of the conductive component would need to have charged particles available in their outermost electron shell so those particles could move and produce a current. Lastly, the insulating and conductive components must have no electronic interactions; this is most easily accomplished by choosing components which do not form covalent bonds. 

Previously published literature on this topic explored a crystal structure (called “hollandite”) that consists of octahedral tunnels formed by one compound (termed the scaffolding) surrounding a second compound whose shape is linear (called the chain). The team decided to use a variant of the hollandite structure that consists of scaffolding made from iridium hexaselenium (IrSe6) and chains of bismuth atoms; the bulk crystal structure is BiIr4Se8.

To characterize the physical and electronic structure of the BiIr4Se8 bulk crystal, the team performed multiple types of examination. They used previously published high-symmetry structures to perform electron counting, which assigns valence electrons to the atoms which make up the crystal’s unit cell; this exercise told them the bismuth atoms have an unpaired single electron in their outer orbital, which would require stabilization. Stabilization would most likely occur through bonding between bismuth atoms. The team applied density functional theory—which predicts a material’s electronic behavior based on quantum mechanics—to calculate that the crystal would contain a conductive component (a metallic band) and that component was concentrated around the bismuth chain. 

Read more on Argonne website

Advanced Photon Source achieves world-record electron beam emittance measurement

Advanced Photon Source achieves world-record electron beam emittance measurement

The new measurement confirms the world-leading status of the APS as it returns to operation following a shutdown for a comprehensive upgrade.

A new set of electron beam measurements puts the upgraded Advanced Photon Source (APS) at the top of the list of the world’s synchrotron X-ray research facilities.

The APS, a U.S. Department of Energy (DOE) Office of Science user facility at DOE’s Argonne National Laboratory, is one of the most productive X-ray light sources in the world. Since April 2023, the more than 5,000 scientists who make use of its ultrabright X-ray beams for research each year have waited patiently as the APS underwent a comprehensive upgrade. Central to that upgrade was  replacing the over 25-year-old electron storage ring that is used to generate those X-ray beams. A brand new one now sits at the heart of the facility.

The APS works by circulating electrons at nearly the speed of light around that storage ring. At special locations in the ring, arrays of alternating magnetic fields cause the electron beam to emit intense X-ray beams which are delivered to experiment stations around the facility. Scientists then use that light to see deep into materials. Those experiments lay the groundwork for potential breakthroughs in battery and solar cell technology and more efficient microelectronics, to name a few.

“It’s exciting not just for our team, who worked hard to imagine, design, engineer, build and commission the new storage ring, but also for the entire light source community and the scientists who will make use of the brighter beams for decades to come to positively impact science and society.” — Laurent Chapon, director of the APS

The brightness of that light is determined, in part, by the emittance of the electron beam. Emittance is a measurement of the size and angular spread of the electron beam, and a lower-emittance beam essentially means that the particles are packed into a smaller space. The more electrons you can pack in a smaller region, the brighter the X-ray beams you can generate with those electrons.

“The new APS electron storage ring was designed to deliver the lowest possible emittance for a facility of this size,” said Michael Borland, associate director of the Accelerator Systems Division at the APS and one of the visionaries behind the upgraded design. ​“It relies on several never-before-used ideas: reverse-bending magnets and a novel method of replenishing electrons in the ring.”

The design and implementation of the new ring has resulted in an emittance measurement that is comfortably the best (meaning lowest) in the world for synchrotron X-ray facilities. The previous record, held by the Extremely Brilliant Source (EBS) at the European Synchrotron Radiation Facility (ESRF), is 134 picometers radians (pm.rad).

The APS measurement, conducted at 50 milliamps of beam current, leads to an emittance of 45 pm.rad. For certain configurations of the APS, such as round beam mode, the emittance is as low as 28 pm.rad.

Read more on Argonne website

Image: The new APS electron storage ring at the heart of the upgraded facility. New measurements have shown the electron beam emittance of this ring to be a world record low.

Credit: Mark Lopez/Argonne National Laboratory.

Using Machine Learning to Find Better Electrochemical Catalysts

Using Machine Learning to Find Better Electrochemical Catalysts

Hydrogen may be the most common element in the universe, but that doesn’t mean it’s easy to get when we need it, such as for use as an energy source and storage method. “Green hydrogen,” as it’s known, is generated by splitting water into its component atoms through electrolysis, but that requires materials for an electrolyzer that can catalyze the reaction, some of which are rare and expensive. 

Finding alternative electrocatalysts is therefore an important goal in the quest for a carbon-neutral energy grid. But it’s a big job because so many chemical possibilities must be evaluated. Researchers from the University of Toronto and Carnegie Mellon University turned to the artificial intelligence technique of machine learning to efficiently screen thousands of possible catalysts and identify some likely choices.  Their work appeared in the Journal of the American Chemical Society.

While most commercial electrolysis uses alkaline water electrolyzers, a promising alternative is the proton exchange membrane (PEM) electrolyzer, which uses a solid polymer electrolyte membrane to separate out hydrogen gas at higher pressures and current density than is possible with alkaline electrolyzers.  At present, however, the only oxygen evolution reaction (OER) catalyst that can endure the extreme acidic environment at the anode in the PEM electrolyzer is iridium oxide (IrO2), which is expensive because of its great demand for many other uses. In the current work, the researchers explored the prospects for an OER catalyst based on ruthenium in the form of RuO2, which would be a far less expensive and more abundant alternative.
    
A disadvantage of ruthenium when used in the OER process is its tendency to become overoxidized, with the formation of soluble Ru atoms that can limit its catalytic lifetime and stability. To overcome this problem, the experimenters sought metallic oxides that could alloy with RuO2 and create a more robust and stable OER catalyst. They used a neural net computational pipeline approach applied to density function theory calculations to efficiently screen a large set of mixed metallic oxides to isolate likely candidates.

After training a neural network algorithm model on 36,465 metal oxide structures, the investigators substituted 46 elements in the oxide structure while keeping the rutile oxide structure intact. This led to a set of 2070 hypothetical candidates, which were then evaluated for their Pourbaix electrochemical stability. The investigators note that Pourbaix stability provides an excellent benchmark for gauging the electrochemical stability of catalysts prior to reaction.
    
Further calculations narrowed down the candidate set to the Ru-Cr-Ti-Ox group, particularly Ti and Cr, so the research team focused on these for experimental validation. They synthesized materials for testing various dopant amounts in the OER catalyst compounds, including in-situ X-ray absorption spectroscopy (XANES) at the 9-BM and 20-BM beamlines of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science user facility at DOE’s Argonne National Laboratory.

Read more on APS website

Image: The AI-accelerated workflow for catalyst design in this work, starting from design and synthesis, through characterization, and ending with testing the catalyst in a real electrolyzer for hydrogen production.

Ushering in a brilliant future at the APS

Ushering in a brilliant future at the APS

Elected officials, Department of Energy leaders and other luminaries joined Argonne today to dedicate the upgraded APS

On a bright day in July, a crowd of hundreds gathered at the site of the Advanced Photon Source (APS) in Lemont, Illinois to welcome even brighter days ahead.

The APS, a U.S. Department of Energy (DOE) Office of Science user facility at DOE’s Argonne National Laboratory, has emerged from a year-long shutdown ready for its second act. A comprehensive upgrade to the facility is underway, and its centerpiece was the removal of the original electron storage ring — installed in the early 1990s — and the installation of a brand new one. Powered by this new assemblage of magnets, vacuum chambers and wires, the upgraded APS will generate X-ray beams that are up to 500 times brighter than the already formidable beams of the original APS.

This puts the APS at the top of the list of the world’s synchrotron X-ray light sources. The upgraded facility has been operating for months, and scientific beamlines — the experiment stations where data is taken and discoveries made — have been gradually coming back online. When at its full brightness, the upgraded APS will be untouchable in the realm of X-ray science, enabling new insights and laying the groundwork for innovations in every field imaginable.

“The Advanced Photon Source has been a preeminent destination for the world’s scientists for decades, and with its expanded capabilities, it will continue to set the bar for X-ray research for decades to come.” — Geri Richmond, DOE undersecretary for science and innovation

“The upgraded Advanced Photon Source represents a significant investment by the Department of Energy in the future of American science and innovation,” said Harriet Kung, DOE’s Acting Director for the Office of Science. ​“DOE’s mission is to enable research that will help us tackle the energy challenges of the future, and the advancements that will come from the renewed APS will chart that path forward.”

Today’s ceremony dedicating the upgraded APS featured remarks from DOE Undersecretary for Science and Innovation Geri Richmond, along with a bevy of elected officials, CEOs and laboratory leaders. Richmond praised the APS’s contributions to American leadership in science and technology.

“The Advanced Photon Source has been a preeminent destination for the world’s scientists for decades, and with its expanded capabilities, it will continue to set the bar for X-ray research for decades to come,” Richmond said.

In a typical year, more than 5,500 scientists from across the country and around the world use the APS to probe the secrets of materials and natural phenomena. APS research tells us more about the materials that make up the world we live in and lays the groundwork for more durable microelectronic devices, longer-lasting and faster-charging batteries and more portable and efficient solar panels to combat the energy challenges of the future.

The upgrade to the APS has been more than a decade in the planning and includes not just the new storage ring but several new experiment stations — called beamlines — to take advantage of the enhanced X-ray beams. The updated facility is powered by a world’s-first injection technique called swap-out (see infographic), and the new and enhanced beamlines offer scientists new techniques to examine their samples in unprecedented detail.

Read more on the APS website

New artificial intelligence method to create material ​‘fingerprints’

New artificial intelligence method to create material ​‘fingerprints’

Like people, materials evolve over time. They also behave differently when they are stressed and relaxed. Scientists looking to measure the dynamics of how materials change have developed a new technique that leverages X-ray photon correlation spectroscopy (XPCS), artificial intelligence (AI) and machine learning.

This technique creates ​“fingerprints” of different materials that can be read and analyzed by a neural network to yield new information that scientists previously could not access. A neural network is a computer model that makes decisions in a manner similar to the human brain.

In a new study by researchers in the Advanced Photon Source (APS) and Center for Nanoscale Materials (CNM) at the U.S. Department of Energy’s (DOE) Argonne National Laboratory, scientists have paired XPCS with an unsupervised machine learning algorithm, a form of neural network that requires no expert training. The algorithm teaches itself to recognize patterns hidden within arrangements of X-rays scattered by a colloid — a group of particles suspended in solution. The APS and CNM are DOE Office of Science user facilities.

“The goal of the AI is just to treat the scattering patterns as regular images or pictures and digest them to figure out what are the repeating patterns. The AI is a pattern recognition expert.” — James (Jay) Horwath, Argonne National Laboratory

“The way we understand how materials move and change over time is by collecting X-ray scattering data,” said Argonne postdoctoral researcher James (Jay) Horwath, the first author of the study.

These patterns are too complicated for scientists to detect without the aid of AI. ​“As we’re shining the X-ray beam, the patterns are so diverse and so complicated that it becomes difficult even for experts to understand what any of them mean,” Horwath said.

For researchers to better understand what they are studying, they have to condense all the data into fingerprints that carry only the most essential information about the sample. ​“You can think of it like having the material’s genome, it has all the information necessary to reconstruct the entire picture,” Horwath said.

The project is called Artificial Intelligence for Non-Equilibrium Relaxation Dynamics, or AI-NERD. The fingerprints are created by using a technique called an autoencoder. An autoencoder is a type of neural network that transforms the original image data into the fingerprint — called a latent representation by scientists — and that also includes a decoder algorithm used to go from the latent representation back to the full image.

The goal of the researchers was to try to create a map of the material’s fingerprints, clustering together fingerprints with similar characteristics into neighborhoods. By looking holistically at the features of the various fingerprint neighborhoods on the map, the researchers were able to better understand how the materials were structured and how they evolved over time as they were stressed and relaxed.

AI, simply put, has good general pattern recognition capabilities, making it able to efficiently categorize the different X-ray images and sort them into the map. ​“The goal of the AI is just to treat the scattering patterns as regular images or pictures and digest them to figure out what are the repeating patterns,” Horwath said. ​“The AI is a pattern recognition expert.”

Using AI to understand scattering data will be especially important as the upgraded APS comes online. The improved facility will generate 500 times brighter X-ray beams than the original APS. ​“The data we get from the upgraded APS will need the power of AI to sort through it,” Horwath said.

Read more on Argonne website

Image: The AI-NERD model learns to produce a unique fingerprint for each sample of XPCS data. Mapping fingerprints from a large experimental dataset enables the identification of trends and repeating patterns which aids our understanding of how materials evolve.

Credit: Argonne National Laboratory.

Shine on: Upgraded APS sees first X-ray light for science

Shine on: Upgraded APS sees first X-ray light for science

A new era of scientific discovery is ready to begin at the Advanced Photon Source as the first scientific beamline receives photons

After a year of installation and commissioning, the new electron storage ring at the heart of the Advanced Photon Source — powered by a world’s first injection technique — is ready for business.

A new era of science at the Advanced Photon Source (APS) is ready to begin. On June 17, 2024, the facility at the U.S. Department of Energy’s (DOE) Argonne National Laboratory delivered its first X-ray light beams to a scientific beamline as part of a comprehensive and complex upgrade.

The APS, a DOE Office of Science user facility, has been a leading destination for X-ray science for nearly 30 years. Scientists from around the world use its ultrabright X-ray beams to learn more about our universe and lay the groundwork for longer-lasting batteries, more efficient solar cells and tougher materials for roads and bridges, to name a few. For the past year, operations have been paused at the facility while the original storage ring, which generates the X-ray beams, was removed and a brand-new ring installed.

Read more on the APS website

Image: Mohan Ramanathan, associate project manager of the APS Upgrade, opens the shutter at the 27-ID beamline, letting in light for the first time since the facility paused operations in April 2023

Credit: Jason Creps/Argonne National Laboratory

Clays transport more water into the Earth’s interior than we thought

Clays transport more water into the Earth’s interior than we thought

Nobody knows how much water is contained in the Earth’s interior. It’s 6400 kilometres from the surface to the centre, but the deepest point we can get to is mere 12 kilometres, so most estimations are based on assumptions and extrapolations about the composition of our planet’s mantle and core. A study by a research team led by Yongjae Lee from Yonsei University (South Korea), conducted at PETRA III as well as at Pohang (South Korea) and the Advanced Photons Source at Argonne National Laboratory (USA), now shows that minerals might carry more water into the Earth’s deep mantle than previously assumed.

Water affects many properties of Earth’s interior: heat, deformation, volcanic and seismic activity and more. These in turn have a direct influence on life on Earth. Knowing more precisely how water distribution across the Earth began and how it has changed over the Earth’s 4.6 billion-year history might give us clues as to how it will evolve in the future.

Experiments performed at DESY’s synchrotron facility PETRA III, PLS-II at Pohang, South Korea and the Advanced Photons Source at Argonne National Laboratory, USA demonstrated that sediment minerals from Earth’s continents called clays can significantly influence the water household of the Earth’s interior. This study was conducted as part of an effort to understand how the subduction process that sends tectonic plates down to the mantle affects the global transport and distribution of water through changes in the water content contained in minerals composing the subducting plate.

The team of scientists led by Yongjae Lee from Yonsei University (South Korea) used a heated diamond anvil cell, an experimental device that can expose material to extremely high pressures and temperatures, for experiments to simulate the path clay minerals would take in a cold subduction zone, where one tectonic plate disappears into the mantle underneath another tectonic plate. They then studied the breakdown of those clays in detail. The study published in Nature Communications concludes that clays in subducting sediments are responsible for delivering up to 22% of the total water transported into the lower mantle, which is a significant amount and helps constrain the question of how much water could be in the Earth’s deep interior in total.

When continental rocks weather and break down they eventually transform into clay minerals. “Clays are layered sheet silicates that are easily transported to the ocean via rivers and make up the top most part of the oceanic plate. When these sediments are transported via tectonic movement to the edges of the continents and dive down into the Earth’s interior via the subduction process, they are exposed to elevated pressures and temperatures,” explains Yoonah Bang, lead author and former student at Yonsei University. One of the major minerals contributing to the clays in the sediments is the alumina-carrying silicate mineral called pyrophyllite (Al2Si4O10(OH)2), “Using a pressure cell consisting of resistively heated diamond anvils, we are able to simulate pressures of up to some 230,000 atmospheres and temperatures of 900 degrees Celsius to mimic the subduction path pyrophyllite will take when it dives down to the lower mantle” says Bang.

In cold subduction zones like those located in the west Pacific, pyrophyllite transforms to the minerals gibbsite (Al(OH)3) and diaspore (AlO(OH)) at a depth of some 135 kilometres. During this process, the minerals take up water from the surrounding hydrated slab and carry it down to a depth of 185 kilometres. From here sequential transformations take place to other water-bearing minerals that eventually drag the same amount of water initially contained in pyrophyllite to a depth of 700 kilometres in the lower mantle. “This shows how important it is to clearly understand the role of clay minerals during the subduction process,” explains Y. Lee, who led this work. “Our research implies that clay minerals such as pyrophyllite would have transported about 2~3% of global ocean water down to the lower mantle over 2.5 billion years.”

“The findings contribute to the overall understanding of the hydration of the Earth through its history”, says Hanns-Peter Liermann, leader of the ‘Extreme Conditions Beamline’ P02.2 at PETRA III, where part of the research was performed.

Read more on DESY website

Image: An illustration depicting that water contained in clay minerals is transported to the lower mantle through breakdown reactions along the subducting plate

Credit: Authors/Original Publication

World’s first successful multi-bunch swap-out injection at the APS

World’s first successful multi-bunch swap-out injection at the APS

The upgraded Advanced Photon Source (APS), a U.S. Department of Energy Office of Science user facility located at Argonne National Laboratory, is now the world’s first synchrotron light source to use a multi-bunch swap-out method of replenishing the electron beam in its storage ring.

On April 29, 2024, Argonne’s Accelerator Systems Division (ASD) team successfully demonstrated multi-bunch swap-out injection of a stored beam of electrons. Regular injections into the ring are required because electron beams have a limited lifetime. Electrons scatter as they circulate, and eventually the beam is depleted and must be replenished. In the late 1990s, the APS pioneered top-up injection, which provides nearly constant stored beam current to X-ray experiments by “topping up” electron bunches that have lost electrons. This has become a standard operation mode for light sources worldwide.

Read more on APS website

Image: The near constant storage ring current is the result of electron bunches being injected through the booster to storage ring transfer line (BTS) while a corresponding electron bunch in the storage ring is kicked out into the swap-out dump.

Keane wins 2024 Gopal K. Shenoy Excellence in Beamline Science Award

Keane wins 2024 Gopal K. Shenoy Excellence in Beamline Science Award

Physicist Denis T. Keane is the 2024 recipient of the Gopal K. Shenoy Excellence in Beamline Science Award. He is a beamline scientist and director of the Dupont-Northwestern-Dow Collaborative Access Team (DND-CAT) at the U.S. Department of Energy’s (DOE) Advanced Photon Source (APS) at DOE’s Argonne National Laboratory. He is also a research professor in the Materials Science and Engineering Department at Northwestern University.

The annual award recognizes active beamline scientists at the APS, a DOE Office of Science user facility, for significant contributions to research or instrumentation and support of the beamline user community. The APS Users Office, which grants the award, renamed it in 2017 in honor of the late Gopal K. Shenoy. Shenoy was an accomplished materials scientist closely involved in the inception of the APS as well as an enthusiastic supporter of scientists who conducted research there.

“It is a special honor to receive the Gopal K. Shenoy award,” said Keane. ​“Thirty years ago, Gopal welcomed us to the APS as we began building the DND beamlines, and his leadership was vital in enabling us and the APS to succeed. I am grateful to my scientific collaborators and the DND staff for our partnership, and to DuPont, Northwestern, Dow and the APS for their support.”

Keane has served as director of DND-CAT since 2005. Located in sector five of the APS, the state-of-the-art X-ray facility is unique in that it combines industrial scale testing and product development with academic vigor, meaning Keane has the challenging task of balancing the needs and expectations of both industry and academic partners. He is also taking on the job of upgrading the DND-CAT facility concurrently with the APS Upgrade.

Read more on APS website

Image: Physicist Denis T. Keane is the 2024 recipient of the Gopal K. Shenoy Excellence in Beamline Science Award.

Credit: Denis T. Keane