Category: Advanced Light Source (ALS)

A new leap in understanding nickel oxide superconductors

A new leap in understanding nickel oxide superconductors

Researchers discover they contain a phase of quantum matter, known as charge density waves, that’s common in other unconventional superconductors. In other ways, though, they’re surprisingly unique.

BY GLENNDA CHUI

A new study shows that nickel oxide superconductors, which conduct electricity with no loss at higher temperatures than conventional superconductors do, contain a type of quantum matter called charge density waves, or CDWs, that can accompany superconductivity.

The presence of CDWs shows that these recently discovered materials, also known as nickelates, are capable of forming correlated states – “electron soups” that can host a variety of quantum phases, including superconductivity, researchers from the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University reported in Nature Physics today.

“Unlike in any other superconductor we know about, CDWs appear even before we dope the material by replacing some atoms with others to change the number of electrons that are free to move around,” said Wei-Sheng Lee, a SLAC lead scientist and  investigator with the Stanford Institute for Materials and Energy Science (SIMES) who led the study.

“This makes the nickelates a very interesting new system – a new playground for studying unconventional superconductors.”

Nickelates and cuprates

In the 35 years since the first unconventional “high-temperature” superconductors were discovered, researchers have been racing to find one that could carry electricity with no loss at close to room temperature. This would be a revolutionary development, allowing things like perfectly efficient power lines, maglev trains and a host of other futuristic, energy-saving technologies.

But while a vigorous global research effort has pinned down many aspects of their nature and behavior, people still don’t know exactly how these materials become superconducting.

So the discovery of nickelate’s superconducting powers by SIMES investigators three years ago was exciting because it gave scientists a fresh perspective on the problem. 

Since then, SIMES researchers have explored the nickelates’ electronic structure – basically the way their electrons behave – and magnetic behavior. These studies turned up important similarities and subtle differences between nickelates and the copper oxides or cuprates – the first high-temperature superconductors ever discovered and still the world record holders for high-temperature operation at everyday pressures.

Since nickel and copper sit right next to each other on the periodic table of the elements, scientists were not surprised to see a kinship there, and in fact had suspected that nickelates might make good superconductors. But it turned out to be extraordinarily difficult to construct materials with just the right characteristics.

“This is still very new,” Lee said. “People are still struggling to synthesize thin films of these materials and understand how different conditions can affect the underlying microscopic mechanisms related to superconductivity.”

Read more on the SLAC website

Image: An illustration shows a type of quantum matter called charge density waves, or CDWs, superimposed on the atomic structure of a nickel oxide superconductor. (Bottom) The nickel oxide material, with nickel atoms in orange and oxygen atoms in red. (Top left) CDWs appear as a pattern of frozen electron ripples, with a higher density of electrons in the peaks of the ripples and a lower density of electrons in the troughs. (Top right) This area depicts another quantum state, superconductivity, which can also emerge in the nickel oxide. The presence of CDWs shows that nickel oxides are capable of forming correlated states – “electron soups” that can host a variety of quantum phases, including superconductivity.

Credit: Greg Stewart/SLAC National Accelerator Laboratory

Copper doping improves sodium-ion battery performance

Copper doping improves sodium-ion battery performance

Although lithium-ion batteries currently drive the electronic world, sodium-ion batteries are gaining ground. A big plus is that sodium is more earth-abundant than lithium, which lowers costs and eases environmental and supply-chain concerns. As a result, enormous research efforts are underway to improve the energy density and cycling longevity of sodium-ion batteries.

One promising strategy to enhance energy density is to exploit additional sources of a key chemical reaction—oxidation reduction (redox)—in the battery’s cathode. In cathodes made of layered transition-metal oxides (the sodium ions move in and out from between the layers), it turns out that the oxygen component in the layers unexpectedly contributes to redox activity. Unfortunately, oxygen redox is frequently accompanied by irreversible oxygen behavior, resulting in both voltage and capacity decays.

To enhance oxygen redox reversibility, researchers doped a sodium-ion cathode material (Na0.6Mg0.3Mn0.7O2, or NMMO) with copper ions (Na0.6Mg0.15Mn0.7Cu0.15O2, or NMMCO). To understand how this affects the oxygen redox activity, they used a technique developed at Beamline 8.0.1 of the Advanced Light Source (ALS), called mapping of resonant inelastic x-ray scattering (mRIXS), to measure the effect of the copper doping at different states of charge.

“The mRIXS technique is one of the most powerful characterization tools available for detecting oxygen redox activities in battery electrodes,” said Liang Zhang, a professor at Soochow University and co-corresponding author of the published work. “With mRIXS, it’s also possible to quantify the reversibility of the oxygen redox reaction, which could greatly help us understand the oxygen evolution process during electrochemical cycling.”

Read more on the ALS website

Image: The partial substitution of Mg ions in the cathode with Cu ions, which possess similar ionic radii but distinct electronic states, led to strong Cu–O bonds (i.e., modulated transition metal (TM)–O covalency), which helped stabilize the lattice during repeated cycles. Light blue = Cu, dark green = Na, red = O, dark yellow = Mn, blue = Mg

Safely studying dangerous infections just got a lot easier

Safely studying dangerous infections just got a lot easier

An extremely fast new 3D imaging method can show how cells respond to infection and to possible treatments

To combat a pandemic, science needs to move quickly. With safe and effective vaccines now widely available and a handful of promising COVID-19 treatments coming soon, there’s no doubt that many aspects of biological research have been successfully accelerated in the past two years.

Now, researchers from Lawrence Berkeley National Laboratory (Berkeley Lab) and Heidelberg University in Germany have cranked up the speed of imaging infected cells using soft X-ray tomography, a microscopic imaging technique that can generate incredibly detailed, three-dimensional scans.

Their approach takes mere minutes to gather data that would require weeks of prep and analysis with other methods, giving scientists an easy way to quickly examine how our cells’ internal machinery responds to SARS-CoV-2, or other pathogens, as well as how the cells respond to drugs designed to treat the infection.

“Prior to our imaging technique, if one wanted to know what was going on inside a cell, and to learn what changes had occurred upon an infection, they’d have to go through the process of fixing, slicing, and staining the cells in order to analyze them by electron microscopy. With all the steps involved, it would take weeks to get the answer. We can do it in a day,” said project co-lead Carolyn Larabell, a Berkeley Lab faculty scientist in the Biosciences Area. “So, it really speeds up the process of examining cells, the consequences to infection, and the consequences of treating a patient with a drug that may or may not cure or prevent the disease.”

Taking cellular freeze frames

Larabell is a professor of anatomy at UC San Francisco and director of the National Center for X-Ray Tomography, a facility based at Berkeley Lab’s Advanced Light Source (ALS). The facility’s staff developed soft X-ray tomography (SXT) in the early 2000s to fill in the gaps left by other cellular imaging techniques. They currently offer the SXT to investigators worldwide and continue to refine the approach. As part of a study published in Cell Reports Methods late last year, she and three colleagues performed SXT on human lung cell samples prepared by their colleagues at Heidelberg University and the German Center for Infection Research.

Read more on the Berkeley Lab website

Image: Digital images of cells infected with SARS-CoV-2, created from soft X-ray tomography taken of chemically fixed cells at the Advanced Light Source

Credit: Loconte et al./Berkeley Lab

Metal-Organic Frameworks can capture toxic air pollutants

Metal-Organic Frameworks can capture toxic air pollutants

The air that we breathe

According to the World Health Organisation1 (WHO), 92% of people worldwide live in places with poor air quality, and outdoor air pollution causes 4.2 million deaths a year, with another 3.8 million caused by indoor air pollution.

Figures published by Public Health England2 showed that the health and social care costs of air pollution in England alone were £42.88 million in 2017 and could reach £5.3 billion by 2035.

There are many different types of air pollution, which arise from a wide range of sources. In the UK, five types are of particular concern: 

  1. The mixture of liquid droplets and solid particles found in the air is called particulate matter (PM). Some PM comes from natural sources (e.g., pollen, sea spray and desert dust), but it also includes dust from car exhausts, brakes and tyres and smoke. PM is classified according to size, with PM2.5 (particles less than 2.5 micrometres across) able to reach and damage the lungs and other organs.
  2. Volatile organic compounds (VOCs) are a range of organic molecules that display similar behaviour in the atmosphere. These include vapours from household products such as air fresheners, cleaning products and perfumes, as well as petrol and solvents.
  3. Ammonia (NH3) gas is mainly released from agricultural sources such as slurry, other rotting farm waste and fertilisers.
  4. Nitrogen oxide (NOx) gases, including nitrogen dioxide (NO2), are mainly created by burning fossil fuels. 
  5. Sulphur dioxide (SO2) is an acidic gas that can irritate airways, particularly in people with asthma.

SO2 and NO2 are both reactive, corrosive gases. Removing them from the air is challenging but would have enormous benefits for human health. 

Can we clean up our act with MOFs?

Metal-Organic Frameworks (MOFs) are sponge-like materials that can adsorb and hold “guest” molecules. By fine-tuning their properties – pore size and geometry, framework topology and chemical functionality – they can be tailored for specific applications, including gas adsorption, separation, catalysis, substrate binding and delivery. MOFs containing open metal sites (OMSs), in particular, can provide highly selective adsorption of target gases. 

However, stable MOFs with OMSs are rare, as are MOF materials that can reversibly adsorb SO2 and NO2. While there are already over 100,000 known MOFs (and over half a million structures have so far been predicted), screening each one individually for its suitability for this application would be time-consuming and costly. A far better approach is to improve our understanding of the mechanism of active sites within capture materials so that we can design or discover new functional MOF materials. This in itself is a challenging task, as host-guest interactions are often dynamic processes, where multiple binding sites of similar energies affect the movement of guest molecules in the pores.

Using synchrotron techniques, an international team of researchers has described the synthesis, crystal structure and gas adsorption and separation properties of a unique {Ni12}- wheel-based MOF that exhibits high isothermal uptake of SO2 and NO2.

Using single crystal X-ray diffraction (SCXRD) at the Advanced Light Source in California and infrared (IR) single crystal micro-spectroscopy at Diamond’s B22 beamline, the team performed dynamic breakthrough experiments that confirmed the selective retention of SO2 and NO2 at low concentrations under dry conditions. Their results show, at a crystallographic resolution, a detailed molecular mechanism with reversible coordination of SO2 and NO2 at the six open Ni(II) sites on the {Ni12}-wheel and at oxygen atom and ligand sites. 

Read more on the Diamond website

Image: Artist’s impression of the unique {Ni12}- wheel-based MOF in action, exhibiting high isothermal uptake of SO2 and NO2.


Credit: Dr Sihai Yang

More to life than light

More to life than light

The #LightSourceSelfies video campaign highlights the dedication and enthusiasm that is felt by those working in this field. To maintain a sense of physical and mental wellbeing, it is also important to make time for non-work related things like family, hobbies and interests. This montage, with contributors from the ESRF, ALS, MAX IV and Diamond, gives a flavour of the wide range of activities that those in the light source community enjoy when they are not working.

Nights!

Nights!

Experimental time at light sources is very precious. When a synchrotron or X-ray Free Electron Laser (XFEL) is in operating mode the goal is to allocate as many experimental shifts to external scientists and in-house research as possible. This includes night shifts! So, how do light source users survive the night shifts? #LightSourceSelfies brings you top tips from scientists based at, or using, 5 light sources in our collaboration – the ESRF, Advanced Light Source (ALS), ANSTO’s Australian Synchrotron, CHESS and the PAL XFEL.

A recipe for successful science

A recipe for successful science

Synchrotrons and free electron lasers (FELs) look stunning. The experimental equipment is state-of-the-art, which makes being a light source user both exhilarating and nerve racking. A key ingredient for success is excellent support from the beamline staff on the experimental station you are using. As Kuda Jakata, a postdoc who supports users at the ESRF in Grenoble, France, says in this #LightSourceSelfie, “The light sources community, they are very helpful people and they actually want to push boundaries and so they work hard and they do a lot of really interesting science.”

#LightSourceSelfies Monday Montage!
Unexpected Transformations Reinforce Roman Concrete

Unexpected Transformations Reinforce Roman Concrete

Researchers used the Advanced Light Source (ALS) to study binding phases in Roman architectural concrete, revealing reactions and profound transformations that contribute to the material’s long-term cohesion and durability.

The findings add to our growing understanding of cementing processes in Roman concretes, informing resilient materials of the future.

Marie Jackson, a research associate professor at the University of Utah, has devoted much of her career to understanding the scientific mysteries underlying the exceptional durability of Roman concretes. The ALS has been essential to her and her colleagues’ studies, helping to reveal the chemical and microstructural evolution of the materials.

Concrete is made of rock aggregates and a binder. Modern concretes typically use Portland cement—made by burning a mixture of limestone and clay at high temperature—as binder. Roman concretes, in contrast, consist of coarse volcanic rock (or brick) aggregate bound with mortar made from hydrated lime and reactive tephra—the particles ejected from explosive volcanic eruptions.

In this study, Jackson, along with collaborators Admir Masic and Linda Seymour of the Massachusetts Institute of Technology and Nobumichi Tamura of the ALS, examined mortar samples from the Tomb of Caecilia Metella in Rome. The team hoped that the 2,050-year-old monument would provide insights into how Roman builders’ selections of reactive volcanic rock influenced the material characteristics of the very robust concrete.

Read more on the ALS website

Image: The Tomb of Caecilia Metella on the Via Appia Antica in Rome. The edifice is one of the most refined concrete and dimension stone structures of the latest Roman Republican era.

Credit: Emmanuel Brunner

Preparing yourself for setbacks

Preparing yourself for setbacks

Experimental time at light sources is precious. It can also be unpredictable as Ro-Ya Liu, a Beamline Scientist at NSRRC in Taiwan, discovered during her first synchrotron experiment at the Photon Factory in Japan. As setbacks go it was a pretty dramatic one, as you’ll discover in this #LightSourceSelfie. Quinn Carvalho, a PhD student at Oregon State University and a user at the Advanced Light Source (ALS) in California, advises light sources users to, “Go into anything with a healthy mentality of optimism, but a realistic sense of what will go wrong. Things will go wrong and you will have to overcome those, so being able to face failure and embrace it and learn from it is much more valuable than fearing it, I think.”

A scientist’s life: At the edge of what is known

A scientist’s life: At the edge of what is known

Quinn Carvalho is a PhD student at Oregon State University and a user at the Advanced Light Source (ALS) at Lawrence Berkeley National Lab in California. Quinn and his colleagues are using spectroscopic techniques to develop design strategies for electrocatalysts that will provide the resources we need for a carbon-free world. In his #LightSourceSelfie, Quinn shares what excites him about his research and his experiences on the support provided by beamline staff at the ALS. Reflecting on what drives him as a research scientist, Quinn explains, “That moment when you realise that you’re the first person to observe, measure and describe a physical phenomenon is one of the greatest sensations I’ve experienced as a professional and something that motivates me still to this day.”

Beginning your light source journey

Beginning your light source journey

Scientists who use synchrotrons such as the Advanced Light Source in California and CHESS at Cornell University, along with staff scientists at Free Electron Lasers in South Korea (the PAL-XFEL) and California (LCLS at SLAC), reflect on how they felt the first time they used a light source facility to conduct research experiments.  The expertise available from the staff scientists who work on the beamlines is also highlighted in this #LightSourceSelfie video.

Secrets of skyrmions revealed

Secrets of skyrmions revealed

Why skyrmions could have a lot in common with glass and high-temperature superconductors

Spawned by the spins of electrons in magnetic materials, these tiny whirlpools behave like independent particles and could be the future of computing. Experiments with SLAC’s X-ray laser are revealing their secrets.

Scientists have known for a long time that magnetism is created by the spins of electrons lining up in certain ways. But about a decade ago, they discovered another astonishing layer of complexity in magnetic materials: Under the right conditions, these spins can form little vortexes or whirlpools that act like particles and move around independently of the atoms that spawned them.

The tiny whirlpools are called skyrmions, named after Tony Skyrme, the British physicist who predicted their existence in 1962. Their small size and sturdy nature – like knots that are hard to undo – have given rise to a rapidly expanding field devoted to understanding them better and exploiting their strange qualities.

“These objects represent some of the most sophisticated forms of magnetic order that we know about,” said Josh Turner, a staff scientist at the Department of Energy’s SLAC National Accelerator Laboratory and principal investigator with the Stanford Institute for Materials and Energy Sciences (SIMES) at SLAC.

Read more on the SLAC website

Images: Top: Images based on simulations show how three phases of matter, including skyrmions – tiny whirlpools created by the spins of electrons – can form in certain magnetic materials. They are stripes of electron spin (left); hexagonal lattices (right); and an in-between phase (center) that’s a mixture of the two. In this middle, glass-like state, skyrmions move very slowly, like cars in a traffic jam – one of several discoveries made in recent studies by scientists at SLAC, Stanford, Berkeley Lab and UC San Diego. Bottom: Patterns formed in a detector during experiments that explored fundamentals of skyrmion behavior at SLAC’s Linac Coherent Light Source X-ray free-electron laser.

Credit: Esposito et al., Applied Physics Letters, 2020

A new approach creates an exceptional single-atom catalyst for water splitting

A new approach creates an exceptional single-atom catalyst for water splitting

Anchoring individual iridium atoms on the surface of a catalytic particle boosted its performance in carrying out a reaction that’s been a bottleneck for sustainable energy production.

A new way of anchoring individual iridium atoms to the surface of a catalyst increased its efficiency in splitting water molecules to record levels, scientists from the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University reported today.

It was the first time this approach had been applied to the oxygen evolution reaction, or OER ­–part of a process called electrolysis that uses electricity to split water into hydrogen and oxygen. If powered by renewable energy sources, electrolysis could produce fuels and chemical feedstocks more sustainably and reduce the use of fossil fuels. But the sluggish pace of OER has been a bottleneck to improving its efficiency so it can compete in the open market.

The results of this study could ease the bottleneck and open new avenues to observing and understanding how these single-atom catalytic centers operate under realistic working conditions, the research team said.

They published their results today in the Proceedings of the National Academy of Sciences.

Read more on the SLAC website

Image: An illustration depicts a new system developed at SLAC and Stanford that anchors individual iridium atoms to the surface of a catalyst, increasing its efficiency at splitting water to record levels. The eight-sided support structures, shaded in blue, each contain a single iridium atom (large blue spheres). The iridium atoms grab passing water molecules (floating above and to the left of them), and encourage them to react with each other, releasing oxygen molecules (above and to the right). This reaction, known as the oxygen evolution reaction or OER, plays a key role in producing sustainable fuels and chemicals.

Credit: Greg Stewart/SLAC National Accelerator Laboratory

A powerful infrared technique broadens its horizons

A powerful infrared technique broadens its horizons

Infrared light has the right energy range to probe many interesting material properties, including the vibrational modes of molecules and the way electrons interact with external photons. As devices get smaller and faster, the ability to study the way light and matter interact at the nanoscale will become crucial for the development of quantum and microelectronic technologies.

A powerful infrared method for probing such phenomena is called scattering-type scanning near-field optical microscopy (s-SNOM), which uses the tip of an atomic force microscope (AFM) to focus infrared light down to about 10 nm, below the wavelength of the light itself (i.e., below the diffraction limit). However, because of the elongated geometry of the AFM tip, oriented perpendicular to the sample, s-SNOM is less sensitive to features of interest that lie parallel to the sample surface.

“Probing in-plane responses at the subwavelength scale has been a long-time hurdle for the technique,” said Ziheng Yao, a former ALS doctoral fellow and co-first author of a Nature Communications paper that reports on a way around this hurdle. “With our results, we can get not only the the top view of the object, but also the side views.”

At ALS Beamline 2.4, the researchers used s-SNOM to study samples of sapphire and LiNbO3, two well-characterized, prototypical materials suitable for a proof-of-concept demonstration. Both have a property (the dielectric function) that varies along different in-plane crystal axes.

Read more on the ALS website

Image: Schematic of the s-SNOM nanospectroscopy setup and the crystal orientation of the sample (a, b, and c axes). Red arrow indicates the in-plane component of the incident light, kin-plane. Rotating the sample changes θ, the angle between kin-plane and the c-axis. Inset: Image of the gold disk on sapphire (m-cut Al2O3). Sdark and Sbright are the two locations were spectra were collected. Scale bar = 1 µm.

Credit: Xinzhong Chen and Ziheng Yao/Stony Brook University

When vibrations increase on cooling: Anti-freezing observed

When vibrations increase on cooling: Anti-freezing observed

An international team has observed an amazing phenomenon in a nickel oxide material during cooling: Instead of freezing, certain fluctuations actually increase as the temperature drops. Nickel oxide is a model system that is structurally similar to high-temperature superconductors. The experiment, which was carried out at the Advanced Light Source (ALS) in California, shows once again that the behaviour of this class of materials still holds surprises.

In virtually all matter, lower temperatures mean less movement of its microscopic components. The less heat energy is available, the less often atoms change their location or magnetic moments their direction: they freeze. An international team led by scientists from HZB and DESY has now observed for the first time the opposite behaviour in a nickel oxide material closely related to high-temperature superconductors. Fluctuations in this nickelate do not freeze on cooling, but become faster.

Read more on the HZB website

Image: The development of this speckle pattern over time reveals microsocopic fluctuations in the material.

Credit: © 10.1103/PhysRevLett.127.057001